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Question 1
Correct
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A 29-year-old man comes to your clinic with a complaint of ear pain that has been bothering him for the past 2 days. He reports no hearing loss or discharge and feels generally healthy. During the physical examination, you observe that he has no fever. When you palpate the tragus of the affected ear, he experiences pain. Upon otoscopy, you notice that the external auditory canal is red. The tympanic membrane is not bulging, and there is no visible fluid level. Which bone can you see pressing against the tympanic membrane?
Your Answer: Malleus
Explanation:The ossicle that is in contact with the tympanic membrane is called the malleus. The middle ear contains three bones known as ossicles, which are arranged from lateral to medial. The malleus is the most lateral ossicle and its handle and lateral process attach to the tympanic membrane, making it visible during otoscopy. The head of the malleus articulates with the incus. The incus is located between the other two ossicles and articulates with both. The body of the incus articulates with the malleus, while the long limb of the bone articulates with the stapes. The Latin word for ‘hammer’ is used to describe the malleus, while the Latin word for ‘anvil’ is used to describe the incus.
Anatomy of the Ear
The ear is divided into three distinct regions: the external ear, middle ear, and internal ear. The external ear consists of the auricle and external auditory meatus, which are innervated by the greater auricular nerve and auriculotemporal branch of the trigeminal nerve. The middle ear is the space between the tympanic membrane and cochlea, and is connected to the nasopharynx by the eustachian tube. The tympanic membrane is composed of three layers and is approximately 1 cm in diameter. The middle ear is innervated by the glossopharyngeal nerve. The ossicles, consisting of the malleus, incus, and stapes, transmit sound vibrations from the tympanic membrane to the inner ear. The internal ear contains the cochlea, which houses the organ of corti, the sense organ of hearing. The vestibule accommodates the utricule and saccule, which contain endolymph and are surrounded by perilymph. The semicircular canals, which share a common opening into the vestibule, lie at various angles to the petrous temporal bone.
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This question is part of the following fields:
- Respiratory System
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Question 2
Correct
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A 35-year-old man comes to the clinic complaining of worsening retrosternal chest pain that radiates to the neck and shoulders and is pleuritic in nature. During examination, a pericardial friction rub is heard at the end of expiration. The diagnosis is pericarditis. What nerve supplies this area?
Your Answer: Phrenic nerve
Explanation:The correct answer is the phrenic nerve, which provides sensory innervation to the pericardium, the central part of the diaphragm, and the mediastinal part of the parietal pleura. It also supplies motor function to the diaphragm. The long thoracic nerve, medial pectoral nerve, thoracodorsal nerve, and vagus nerve are all incorrect answers.
The Phrenic Nerve: Origin, Path, and Supplies
The phrenic nerve is a crucial nerve that originates from the cervical spinal nerves C3, C4, and C5. It supplies the diaphragm and provides sensation to the central diaphragm and pericardium. The nerve passes with the internal jugular vein across scalenus anterior and deep to the prevertebral fascia of the deep cervical fascia.
The right phrenic nerve runs anterior to the first part of the subclavian artery in the superior mediastinum and laterally to the superior vena cava. In the middle mediastinum, it is located to the right of the pericardium and passes over the right atrium to exit the diaphragm at T8. On the other hand, the left phrenic nerve passes lateral to the left subclavian artery, aortic arch, and left ventricle. It passes anterior to the root of the lung and pierces the diaphragm alone.
Understanding the origin, path, and supplies of the phrenic nerve is essential in diagnosing and treating conditions that affect the diaphragm and pericardium.
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This question is part of the following fields:
- Respiratory System
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Question 3
Incorrect
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Mrs. Johnson is an 82-year-old woman who visited her General practitioner complaining of gradual worsening shortness of breath over the past two months. During the medical history, it was discovered that she has had Chronic Obstructive Pulmonary Disease (COPD) for 20 years.
Upon examination, there are no breath sounds at both lung bases and a stony dull note to percussion over the same areas. Based on this clinical scenario, what is the probable cause of her recent exacerbation of shortness of breath?Your Answer: Infective exacerbation of COPD
Correct Answer: Pleural transudate effusion secondary to cor pulmonale
Explanation:The most likely cause of a pleural transudate is heart failure. This is due to the congestion of blood into the systemic venous circulation, which can result from long-standing COPD and increase in pulmonary vascular resistance leading to right-sided heart failure or cor pulmonale. Other options such as infective exacerbation of COPD or pulmonary edema secondary to heart failure are less likely to explain the clinical signs. Pleural exudate effusion secondary to cor pulmonale is also not the most appropriate answer as it would cause a transudate pleural effusion, not an exudate.
Understanding the Causes and Features of Pleural Effusion
Pleural effusion is a medical condition characterized by the accumulation of fluid in the pleural space, which is the area between the lungs and the chest wall. The causes of pleural effusion can be classified into two types: transudate and exudate. Transudate is characterized by a protein concentration of less than 30g/L and is commonly caused by heart failure, hypoalbuminemia, liver disease, and other conditions. On the other hand, exudate is characterized by a protein concentration of more than 30g/L and is commonly caused by infections, pneumonia, tuberculosis, and other conditions.
The symptoms of pleural effusion may include dyspnea, non-productive cough, and chest pain. Upon examination, patients may exhibit dullness to percussion, reduced breath sounds, and reduced chest expansion. It is important to identify the underlying cause of pleural effusion to determine the appropriate treatment plan. Early diagnosis and treatment can help prevent complications and improve the patient’s overall health.
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This question is part of the following fields:
- Respiratory System
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Question 4
Incorrect
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A 75-year-old man visits his doctor complaining of a productive cough that has lasted for 5 days. He has also been feeling generally unwell and has had a fever for the past 2 days. The doctor suspects a bacterial respiratory tract infection and orders a blood panel, sputum microscopy, and culture. What is the most likely abnormality to be found in the blood results?
Your Answer: Eosinophils
Correct Answer: Neutrophils
Explanation:Neutrophils are typically elevated during an acute bacterial infection, while eosinophils are commonly elevated in response to parasitic infections and allergies. Lymphocytes tend to increase during acute viral infections and chronic inflammation. IgE levels are raised in cases of allergic asthma, malaria, and type 1 hypersensitivity reactions. Anti-CCP antibody is a diagnostic tool for Rheumatoid arthritis.
Pneumonia is a common condition that affects the alveoli of the lungs, usually caused by a bacterial infection. Other causes include viral and fungal infections. Streptococcus pneumoniae is the most common organism responsible for pneumonia, accounting for 80% of cases. Haemophilus influenzae is common in patients with COPD, while Staphylococcus aureus often occurs in patients following influenzae infection. Mycoplasma pneumoniae and Legionella pneumophilia are atypical pneumonias that present with dry cough and other atypical symptoms. Pneumocystis jiroveci is typically seen in patients with HIV. Idiopathic interstitial pneumonia is a group of non-infective causes of pneumonia.
Patients who develop pneumonia outside of the hospital have community-acquired pneumonia (CAP), while those who develop it within hospitals are said to have hospital-acquired pneumonia. Symptoms of pneumonia include cough, sputum, dyspnoea, chest pain, and fever. Signs of systemic inflammatory response, tachycardia, reduced oxygen saturations, and reduced breath sounds may also be present. Chest x-ray is used to diagnose pneumonia, with consolidation being the classical finding. Blood tests, such as full blood count, urea and electrolytes, and CRP, are also used to check for infection.
Patients with pneumonia require antibiotics to treat the underlying infection and supportive care, such as oxygen therapy and intravenous fluids. Risk stratification is done using a scoring system called CURB-65, which stands for confusion, respiration rate, blood pressure, age, and is used to determine the management of patients with community-acquired pneumonia. Home-based care is recommended for patients with a CRB65 score of 0, while hospital assessment is recommended for all other patients, particularly those with a CRB65 score of 2 or more. The CURB-65 score also correlates with an increased risk of mortality at 30 days.
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This question is part of the following fields:
- Respiratory System
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Question 5
Correct
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How many fissures can be found in the right lung?
At what age do these fissures typically develop?Your Answer: Two
Explanation:The oblique and horizontal fissures are present in the right lung. The lower lobe is separated from the middle and upper lobes by the upper oblique fissure. The superior and middle lobes are separated by the short horizontal fissure.
Anatomy of the Lungs
The lungs are a pair of organs located in the chest cavity that play a vital role in respiration. The right lung is composed of three lobes, while the left lung has two lobes. The apex of both lungs is approximately 4 cm superior to the sternocostal joint of the first rib. The base of the lungs is in contact with the diaphragm, while the costal surface corresponds to the cavity of the chest. The mediastinal surface contacts the mediastinal pleura and has the cardiac impression. The hilum is a triangular depression above and behind the concavity, where the structures that form the root of the lung enter and leave the viscus. The right main bronchus is shorter, wider, and more vertical than the left main bronchus. The inferior borders of both lungs are at the 6th rib in the mid clavicular line, 8th rib in the mid axillary line, and 10th rib posteriorly. The pleura runs two ribs lower than the corresponding lung level. The bronchopulmonary segments of the lungs are divided into ten segments, each with a specific function.
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This question is part of the following fields:
- Respiratory System
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Question 6
Correct
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A 35-year-old man arrives at the emergency department following an assault with a baseball bat. He has significant swelling around his eye, which has caused him to lose vision in that eye. A CT scan reveals a fracture in the floor of the orbit. This type of fracture creates an unusual connection between the orbit and which of the following facial regions?
Your Answer: Maxillary sinus
Explanation:The correct answer is the maxillary sinus, which is the largest of the paranasal air sinuses found in the maxillary bone below the orbit. Fractures of the orbit’s floor can lead to herniation of the orbital contents into the maxillary sinus. The ethmoidal air cells are smaller air cells in the ethmoid bone, separated from the orbit by a thin plate of bone called the lamina papyracea. Fractures of the medial wall of the orbit can lead to communication between the ethmoidal air cells and the orbit. The frontal sinuses are located in the frontal bones above the orbits and fractures of the roof of the orbit can lead to communication between the frontal sinus and orbit. The sphenoid sinuses are found in the sphenoid bone and are located in the posterior portion of the roof of the nasal cavity. The nasal cavity is located more medial and inferior than the orbits and is not adjacent to the orbit.
Paranasal Air Sinuses and Carotid Sinus
The paranasal air sinuses are air-filled spaces found in the bones of the skull. They are named after the bone in which they are located and all communicate with the nasal cavity. The four paired paranasal air sinuses are the frontal sinuses, maxillary sinuses, ethmoid air cells, and sphenoid sinuses. The frontal sinuses are located above each eye on the forehead, while the maxillary sinuses are the largest and found in the maxillary bone below the orbit. The ethmoidal air cells are a collection of smaller air cells located lateral to the anterior superior nasal cavity, while the sphenoid sinuses are found in the posterior portion of the roof of the nasal cavity.
On the other hand, the carotid sinus is not a paranasal air sinus. It is a dilatation of the internal carotid artery, located just beyond the bifurcation of the common carotid artery. It contains baroreceptors that enable it to detect changes in arterial pressure.
Overall, understanding the location and function of these sinuses and the carotid sinus is important in various medical procedures and conditions.
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This question is part of the following fields:
- Respiratory System
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Question 7
Correct
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A 36-year-old male patient complains of fever, malaise, weight loss, dyspnoea, and shoulder & hip joint pain. He has raised erythematous lesions on both legs. His blood tests reveal elevated calcium levels and serum ACE levels. A chest x-ray shows bilateral hilar lymphadenopathy.
What is the probable diagnosis?Your Answer: Sarcoidosis
Explanation:If a patient presents with raised serum ACE levels, sarcoidosis should be considered as a possible diagnosis. The combination of erythema nodosum and bilateral hilar lymphadenopathy on a chest x-ray is pathognomonic of sarcoidosis. Lung cancer is unlikely in a young patient without a significant smoking history, and tuberculosis would require recent foreign travel to a TB endemic country. Multiple myeloma would not cause the same symptoms as sarcoidosis. Exposure to organic material would not be a likely cause of raised serum ACE levels.
Understanding Sarcoidosis: A Multisystem Disorder
Sarcoidosis is a condition that affects multiple systems in the body and is characterized by the presence of non-caseating granulomas. The exact cause of this disorder is unknown, but it is more commonly seen in young adults and individuals of African descent.
The symptoms of sarcoidosis can vary depending on the severity of the condition. Acute symptoms may include erythema nodosum, bilateral hilar lymphadenopathy, swinging fever, and polyarthralgia. On the other hand, insidious symptoms may include dyspnea, non-productive cough, malaise, and weight loss. Additionally, some individuals may develop skin symptoms such as lupus pernio, while others may experience hypercalcemia due to increased conversion of vitamin D to its active form.
Sarcoidosis is also associated with several syndromes, including Lofgren’s syndrome, Mikulicz syndrome, and Heerfordt’s syndrome. Lofgren’s syndrome is an acute form of the disease that typically presents with bilateral hilar lymphadenopathy, erythema nodosum, fever, and polyarthralgia. Mikulicz syndrome is characterized by enlargement of the parotid and lacrimal glands due to sarcoidosis, tuberculosis, or lymphoma. Finally, Heerfordt’s syndrome, also known as uveoparotid fever, presents with parotid enlargement, fever, and uveitis secondary to sarcoidosis.
In conclusion, sarcoidosis is a complex disorder that can affect multiple systems in the body. While the exact cause is unknown, early diagnosis and treatment can help manage symptoms and improve outcomes.
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This question is part of the following fields:
- Respiratory System
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Question 8
Incorrect
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A 23-year-old woman comes to your clinic with a complaint of ear pain and difficulty hearing on one side. During the examination, you observe that she has a fever and a bulging tympanic membrane. What nerve transmits pain from the middle ear?
Your Answer: Facial nerve
Correct Answer: Glossopharyngeal nerve
Explanation:The correct answer is the glossopharyngeal nerve, which is responsible for carrying sensation from the middle ear.
The ninth cranial nerve, or glossopharyngeal nerve, carries taste and sensation from the posterior one-third of the tongue, as well as sensation from various areas such as the pharyngeal wall, tonsils, pharyngotympanic tube, middle ear, tympanic membrane, external auditory canal, and auricle. It also provides motor fibers to the stylopharyngeus and parasympathetic fibers to the parotid gland. Additionally, it carries information from the baroreceptors and chemoreceptors of the carotid sinus.
On the other hand, the seventh cranial nerve, or facial nerve, innervates the muscles of facial expression, stylohyoid, stapedius, and the posterior belly of digastric. It carries sensation from part of the external acoustic meatus, auricle, and behind the auricle, and taste from the anterior two-thirds of the tongue. It also provides parasympathetic fibers to the submandibular, sublingual, nasal, and lacrimal glands.
The eighth cranial nerve, or vestibulocochlear nerve, has a vestibular component that carries balance information from the labyrinths of the inner ear and a cochlear component that carries hearing information from the cochlea of the inner ear.
The twelfth cranial nerve, or hypoglossal nerve, supplies motor innervation to all of the intrinsic muscles of the tongue and all of the extrinsic muscles of the tongue except for palatoglossus.
Lastly, the maxillary nerve is the second division of the trigeminal nerve, the fifth cranial nerve, which carries sensation from the upper teeth and gingivae, the nasal cavity, and skin across the lower eyelids and cheeks.
Based on the patient’s symptoms of ear pain, the most likely diagnosis is otitis media, as indicated by her fever and the presence of a bulging tympanic membrane on otoscopy.
Anatomy of the Ear
The ear is divided into three distinct regions: the external ear, middle ear, and internal ear. The external ear consists of the auricle and external auditory meatus, which are innervated by the greater auricular nerve and auriculotemporal branch of the trigeminal nerve. The middle ear is the space between the tympanic membrane and cochlea, and is connected to the nasopharynx by the eustachian tube. The tympanic membrane is composed of three layers and is approximately 1 cm in diameter. The middle ear is innervated by the glossopharyngeal nerve. The ossicles, consisting of the malleus, incus, and stapes, transmit sound vibrations from the tympanic membrane to the inner ear. The internal ear contains the cochlea, which houses the organ of corti, the sense organ of hearing. The vestibule accommodates the utricule and saccule, which contain endolymph and are surrounded by perilymph. The semicircular canals, which share a common opening into the vestibule, lie at various angles to the petrous temporal bone.
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This question is part of the following fields:
- Respiratory System
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Question 9
Incorrect
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A 10-year-old boy comes to your clinic with a complaint of ear pain that started last night and kept him awake. He missed school today because of the pain and reports muffled sounds on the affected side. During otoscopy, you observe a bulging tympanic membrane with visible fluid behind it, indicating a middle ear infection. Can you identify which nerves pass through the middle ear?
Your Answer: Glossopharyngeal nerve
Correct Answer: Chorda tympani
Explanation:The chorda tympani is the correct answer. It is a branch of the seventh cranial nerve, the facial nerve, and carries parasympathetic and taste fibers. It passes through the middle ear before exiting and joining with the lingual nerve to reach the tongue and salivary glands.
The vestibulocochlear nerve is the eighth cranial nerve and carries balance and hearing information.
The maxillary nerve is the second division of the fifth cranial nerve and carries sensation from the upper teeth, nasal cavity, and skin.
The mandibular nerve is the third division of the fifth cranial nerve and carries sensation from the lower teeth, tongue, mandible, and skin. It also carries motor fibers to certain muscles.
The glossopharyngeal nerve is the ninth cranial nerve and carries taste and sensation from the posterior one-third of the tongue, as well as sensation from various areas. It also carries motor and parasympathetic fibers.
The patient in the question has ear pain, likely due to otitis media, as evidenced by a bulging tympanic membrane and fluid level on otoscopy.
Anatomy of the Ear
The ear is divided into three distinct regions: the external ear, middle ear, and internal ear. The external ear consists of the auricle and external auditory meatus, which are innervated by the greater auricular nerve and auriculotemporal branch of the trigeminal nerve. The middle ear is the space between the tympanic membrane and cochlea, and is connected to the nasopharynx by the eustachian tube. The tympanic membrane is composed of three layers and is approximately 1 cm in diameter. The middle ear is innervated by the glossopharyngeal nerve. The ossicles, consisting of the malleus, incus, and stapes, transmit sound vibrations from the tympanic membrane to the inner ear. The internal ear contains the cochlea, which houses the organ of corti, the sense organ of hearing. The vestibule accommodates the utricule and saccule, which contain endolymph and are surrounded by perilymph. The semicircular canals, which share a common opening into the vestibule, lie at various angles to the petrous temporal bone.
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This question is part of the following fields:
- Respiratory System
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Question 10
Correct
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A 67-year-old man with a suspected ruptured abdominal aortic aneurysm is brought to the emergency department. Upon arrival, the patient appears pale, cold, and clammy. His vital signs are as follows: temperature 35.3 degrees Celsius, respiratory rate 40, heart rate 116bpm, and blood pressure 90/65mmHg.
When there is a decrease in the concentration of oxygen in the blood, the inspiratory center is stimulated, and any voluntary cortical control of breathing pattern is overridden. Where are the peripheral chemoreceptors located that detect these changes?Your Answer: Aortic arch
Explanation:The peripheral chemoreceptors, found in the aortic and carotid bodies, are capable of detecting alterations in the levels of carbon dioxide in the arterial blood. These receptors are located in the aortic arch and at the bifurcation of the common carotid artery. However, they are not as sensitive as the central chemoreceptors in the medulla oblongata, which monitor the cerebrospinal fluid. It is important to note that there are no peripheral chemoreceptors present in veins.
The Control of Ventilation in the Human Body
The control of ventilation in the human body is a complex process that involves various components working together to regulate the respiratory rate and depth of respiration. The respiratory centres, chemoreceptors, lung receptors, and muscles all play a role in this process. The automatic, involuntary control of respiration occurs from the medulla, which is responsible for controlling the respiratory rate and depth of respiration.
The respiratory centres consist of the medullary respiratory centre, apneustic centre, and pneumotaxic centre. The medullary respiratory centre has two groups of neurons, the ventral group, which controls forced voluntary expiration, and the dorsal group, which controls inspiration. The apneustic centre, located in the lower pons, stimulates inspiration and activates and prolongs inhalation. The pneumotaxic centre, located in the upper pons, inhibits inspiration at a certain point and fine-tunes the respiratory rate.
Ventilatory variables, such as the levels of pCO2, are the most important factors in ventilation control, while levels of O2 are less important. Peripheral chemoreceptors, located in the bifurcation of carotid arteries and arch of the aorta, respond to changes in reduced pO2, increased H+, and increased pCO2 in arterial blood. Central chemoreceptors, located in the medulla, respond to increased H+ in brain interstitial fluid to increase ventilation. It is important to note that the central receptors are not influenced by O2 levels.
Lung receptors also play a role in the control of ventilation. Stretch receptors respond to lung stretching, causing a reduced respiratory rate, while irritant receptors respond to smoke, causing bronchospasm. J (juxtacapillary) receptors are also involved in the control of ventilation. Overall, the control of ventilation is a complex process that involves various components working together to regulate the respiratory rate and depth of respiration.
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This question is part of the following fields:
- Respiratory System
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Question 11
Correct
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A 43-year-old woman comes to the respiratory clinic for an outpatient appointment. She has been experiencing increased breathlessness, particularly at night. Her medical history includes long-standing COPD, heart failure, and previous breast cancer that was treated with a mastectomy and radiotherapy. She used to smoke 20 cigarettes a day for 22 years but has since quit.
During the examination, her respiratory rate is 23/min, oxygen saturation is 93%, blood pressure is 124/98mmHg, and temperature is 37.2ÂșC. A gas transfer test is performed, and her transfer factor is found to be low.
What is the most likely diagnosis?Your Answer: Pulmonary oedema
Explanation:TLCO, also known as transfer factor, is a measurement of how quickly gas can move from a person’s lungs into their bloodstream. To test TLCO, a patient inhales a mixture of carbon monoxide and a tracer gas, holds their breath for 10 seconds, and then exhales forcefully. The exhaled gas is analyzed to determine how much tracer gas was absorbed during the 10-second period.
A high TLCO value is associated with conditions such as asthma, pulmonary hemorrhage, left-to-right cardiac shunts, polycythemia, hyperkinetic states, male gender, and exercise. Conversely, most other conditions result in a low TLCO value, including pulmonary fibrosis, pneumonia, pulmonary emboli, pulmonary edema, emphysema, and anemia.
Understanding Transfer Factor in Lung Function Testing
The transfer factor is a measure of how quickly a gas diffuses from the alveoli into the bloodstream. This is typically tested using carbon monoxide, and the results can be given as either the total gas transfer (TLCO) or the transfer coefficient corrected for lung volume (KCO). A raised TLCO may be caused by conditions such as asthma, pulmonary haemorrhage, left-to-right cardiac shunts, polycythaemia, hyperkinetic states, male gender, or exercise. On the other hand, a lower TLCO may be indicative of pulmonary fibrosis, pneumonia, pulmonary emboli, pulmonary oedema, emphysema, anaemia, or low cardiac output.
KCO tends to increase with age, and certain conditions may cause an increased KCO with a normal or reduced TLCO. These conditions include pneumonectomy/lobectomy, scoliosis/kyphosis, neuromuscular weakness, and ankylosis of costovertebral joints (such as in ankylosing spondylitis). Understanding transfer factor is important in lung function testing, as it can provide valuable information about a patient’s respiratory health and help guide treatment decisions.
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This question is part of the following fields:
- Respiratory System
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Question 12
Incorrect
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A 55-year-old Caucasian man presents to the ENT clinic with complaints of gradual hearing loss over the past year. He reports having to turn up the volume on his television to the maximum to hear it comfortably. There are no associated symptoms such as tinnitus or dizziness, and the patient has no significant medical history.
Upon examination, a Weber and Rinne test reveal conductive hearing loss in the left ear. Otoscope examination shows no signs of middle ear effusion or tympanic membrane involvement in either ear. A pure tone audiometry confirms conductive hearing loss in the left ear, with a Carhart's notch present.
The physician diagnoses the patient with otosclerosis and discusses treatment options.
What is the underlying pathology of otosclerosis?Your Answer: Accumulation of desquamated, stratified squamous epithelium within the middle ear, causing erosion of the ossicles
Correct Answer: Replacement of normal bone by vascular spongy bone
Explanation:Otosclerosis is a condition where normal bone is replaced by spongy bone with a high vascularity. This leads to progressive conductive hearing loss, without any other neurological impairments. The replacement of the normal endochondral layer of the bony labyrinth by spongy bone affects the ability of the stapes to act as a piston, resulting in the conduction of sound from the middle ear to the inner ear being affected. Caucasians are most commonly affected by this condition.
Benign paroxysmal positional vertigo (BPPV) is caused by the dislodgement of otoliths into the semicircular canals. This condition results in vertiginous dizziness upon positional changes, but does not affect auditory function.
Meniere’s disease is caused by endolymphatic hydrops, which is the accumulation of fluid in the inner ear. The pathophysiology of this condition is not well understood, but it leads to vertigo, tinnitus, hearing loss, and aural fullness.
Cholesteatoma is caused by the accumulation of desquamated, stratified squamous epithelium. This leads to the formation of a mass that can gradually enlarge and erode the ossicle chain, resulting in conductive hearing loss.
Presbycusis is a type of sensorineural hearing loss that occurs as a result of aging. The degeneration of the organ of Corti is one of the underlying pathological mechanisms that causes this condition. This leads to the destruction of outer hair cells and a decrease in hearing sensitivity.
Understanding Otosclerosis: A Progressive Conductive Deafness
Otosclerosis is a medical condition that occurs when normal bone is replaced by vascular spongy bone. This condition leads to a progressive conductive deafness due to the fixation of the stapes at the oval window. It is an autosomal dominant condition that typically affects young adults, with onset usually occurring between the ages of 20-40 years.
The main features of otosclerosis include conductive deafness, tinnitus, a normal tympanic membrane, and a positive family history. In some cases, patients may also experience a flamingo tinge, which is caused by hyperemia and affects around 10% of patients.
Management of otosclerosis typically involves the use of a hearing aid or stapedectomy. A hearing aid can help to improve hearing, while a stapedectomy involves the surgical removal of the stapes bone and replacement with a prosthesis.
Overall, understanding otosclerosis is important for individuals who may be at risk of developing this condition. Early diagnosis and management can help to improve hearing and prevent further complications.
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This question is part of the following fields:
- Respiratory System
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Question 13
Correct
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A 70-year-old man is admitted to the respiratory ward with an exacerbation of COPD. He has been experiencing increased breathlessness and a productive cough for the past week. He is currently on day three of his rescue medication regimen consisting of amoxicillin and prednisolone. According to his previous discharge summary, this patient has a history of carbon dioxide retention. He is currently receiving controlled oxygen therapy via a 28% venturi mask. What is the target oxygen saturation level for this patient?
Your Answer: 88%-92%
Explanation:As a junior doctor, you will often encounter patients who retain carbon dioxide and depend on their hypoxic drive to breathe. When using Venturi masks to deliver controlled oxygen, it is important to set a target that balances the patient’s need for oxygen with their reliance on hypoxia to stimulate breathing. Answer 4 is the correct choice in this scenario. Providing too much oxygen, as in answers 2 and 3, can cause the patient to lose their hypoxic drive and become drowsy or confused. Answer 5 does not provide enough oxygen to properly perfuse the tissues. Failing to set a target for these patients is not good clinical practice.
Guidelines for Oxygen Therapy in Emergency Situations
In 2017, the British Thoracic Society updated its guidelines for emergency oxygen therapy. The guidelines state that in critically ill patients, such as those experiencing anaphylaxis or shock, oxygen should be administered through a reservoir mask at a rate of 15 liters per minute. However, certain conditions, such as stable myocardial infarction, are excluded from this recommendation.
The guidelines also provide specific oxygen saturation targets for different patient populations. Acutely ill patients should have a saturation level between 94-98%, while patients at risk of hypercapnia, such as those with COPD, should have a saturation level between 88-92%. Oxygen levels should be reduced in stable patients with satisfactory oxygen saturation.
For COPD patients, a 28% Venturi mask at 4 liters per minute should be used prior to the availability of blood gases. The target oxygen saturation level for these patients should be 88-92% if they have risk factors for hypercapnia but no prior history of respiratory acidosis. If the patient’s pCO2 is normal, the target range should be adjusted to 94-98%.
The guidelines also state that oxygen therapy should not be used routinely in certain situations where there is no evidence of hypoxia, such as in cases of myocardial infarction, acute coronary syndromes, stroke, obstetric emergencies, and anxiety-related hyperventilation.
Overall, these guidelines provide important recommendations for the appropriate use of oxygen therapy in emergency situations, taking into account the specific needs of different patient populations.
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This question is part of the following fields:
- Respiratory System
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Question 14
Incorrect
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A 14-year-old girl presents to her GP with complaints of earache and hearing difficulty in her left ear. Upon examination, her GP observes a bulging tympanic membrane and diagnoses her with acute otitis media. The GP prescribes a course of oral antibiotics.
However, after a few days, the girl's fever persists and her pain worsens, prompting her to visit the emergency department. Upon examination, the girl has a tender and erythematous retro-auricular swelling with a temperature of 38.9ÂșC. She has no ear discharge, and the rest of her examination is unremarkable.
What complication has developed in this case?Your Answer: Brain abscess
Correct Answer: Mastoiditis
Explanation:Mastoiditis is a potential complication of acute otitis media, which can cause pain and swelling behind the ear over the mastoid bone. However, there is no evidence of tympanic membrane perforation, neurological symptoms or signs of meningitis or brain abscess, or facial nerve injury in this case.
Acute otitis media is a common condition in young children, often caused by bacterial infections following viral upper respiratory tract infections. Symptoms include ear pain, fever, and hearing loss, and diagnosis is based on criteria such as the presence of a middle ear effusion and inflammation of the tympanic membrane. Antibiotics may be prescribed in certain cases, and complications can include perforation of the tympanic membrane, hearing loss, and more serious conditions such as meningitis and brain abscess.
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This question is part of the following fields:
- Respiratory System
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Question 15
Correct
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A 50-year-old man with laryngeal cancer is undergoing a challenging laryngectomy. During the procedure, the surgeons cut the thyrocervical trunk. What vessel does this structure typically originate from?
Your Answer: Subclavian artery
Explanation:The subclavian artery gives rise to the thyrocervical trunk, which emerges from the first part of the artery located between the inner border of scalenus anterior and the subclavian artery. The thyrocervical trunk branches off from the subclavian artery after the vertebral artery.
Thoracic Outlet: Where the Subclavian Artery and Vein and Brachial Plexus Exit the Thorax
The thoracic outlet is the area where the subclavian artery and vein and the brachial plexus exit the thorax and enter the arm. This passage occurs over the first rib and under the clavicle. The subclavian vein is the most anterior structure and is located immediately in front of scalenus anterior and its attachment to the first rib. Scalenus anterior has two parts, and the subclavian artery leaves the thorax by passing over the first rib and between these two portions of the muscle. At the level of the first rib, the lower cervical nerve roots combine to form the three trunks of the brachial plexus. The lowest trunk is formed by the union of C8 and T1, and this trunk lies directly posterior to the artery and is in contact with the superior surface of the first rib.
Thoracic outlet obstruction can cause neurovascular compromise.
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This question is part of the following fields:
- Respiratory System
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Question 16
Correct
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A 24-year-old male patient arrives at the Emergency Department complaining of abdominal pain, nausea, vomiting, and a decreased level of consciousness. Upon examination, the patient exhibits Kussmaul respiration and an acetone-like breath odor.
What type of metabolic disturbance is most consistent with the symptoms and presentation of this patient?Your Answer: Metabolic acidosis, oxygen dissociation curve shifts to the right
Explanation:The correct answer is that metabolic acidosis shifts the oxygen dissociation curve to the right. This is seen in the condition described in the question, diabetic ketoacidosis, which is associated with metabolic acidosis. Acidosis causes more oxygen to be unloaded from haemoglobin, leading to a rightward shift in the curve. The other answer options are incorrect, as they either describe a different type of acidosis or an incorrect direction of the curve shift.
Understanding the Oxygen Dissociation Curve
The oxygen dissociation curve is a graphical representation of the relationship between the percentage of saturated haemoglobin and the partial pressure of oxygen in the blood. It is not influenced by the concentration of haemoglobin. The curve can shift to the left or right, indicating changes in oxygen delivery to tissues. When the curve shifts to the left, there is increased saturation of haemoglobin with oxygen, resulting in decreased oxygen delivery to tissues. Conversely, when the curve shifts to the right, there is reduced saturation of haemoglobin with oxygen, leading to enhanced oxygen delivery to tissues.
The L rule is a helpful mnemonic to remember the factors that cause a shift to the left, resulting in lower oxygen delivery. These factors include low levels of hydrogen ions (alkali), low partial pressure of carbon dioxide, low levels of 2,3-diphosphoglycerate, and low temperature. On the other hand, the mnemonic ‘CADET, face Right!’ can be used to remember the factors that cause a shift to the right, leading to raised oxygen delivery. These factors include carbon dioxide, acid, 2,3-diphosphoglycerate, exercise, and temperature.
Understanding the oxygen dissociation curve is crucial in assessing the oxygen-carrying capacity of the blood and the delivery of oxygen to tissues. By knowing the factors that can shift the curve to the left or right, healthcare professionals can make informed decisions in managing patients with respiratory and cardiovascular diseases.
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This question is part of the following fields:
- Respiratory System
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Question 17
Incorrect
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A 30-year-old female complains of weakness, weight gain, and cold intolerance. You suspect hypothyroidism. What vocal change would you anticipate to have occurred, increasing the probability of this potential diagnosis?
Your Answer: Tremor in voice
Correct Answer: Hoarse voice
Explanation:Hoarseness is a symptom that can be caused by hypothyroidism.
When a patient presents with hoarseness, it can be difficult to determine the underlying cause. However, if the hoarseness is accompanied by other symptoms commonly associated with hypothyroidism, it can help narrow down the diagnosis.
The reason for the voice change in hypothyroidism is due to the thickening of the vocal cords caused by the accumulation of mucopolysaccharide. This substance, also known as glycosaminoglycans, is found throughout the body in mucus and joint fluid. When it builds up in the vocal cords, it can lower the pitch of the voice. The thyroid hormone plays a role in preventing this buildup.
Hoarseness can be caused by various factors such as overusing the voice, smoking, viral infections, hypothyroidism, gastro-oesophageal reflux, laryngeal cancer, and lung cancer. It is important to investigate the underlying cause of hoarseness, and a chest x-ray may be necessary to rule out any apical lung lesions.
If laryngeal cancer is suspected, it is recommended to refer the patient to an ENT specialist through a suspected cancer pathway. This referral should be considered for individuals who are 45 years old and above and have persistent unexplained hoarseness or an unexplained lump in the neck. Early detection and treatment of laryngeal cancer can significantly improve the patient’s prognosis.
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This question is part of the following fields:
- Respiratory System
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Question 18
Incorrect
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A 23-year-old woman comes to your clinic complaining of difficulty hearing her partner at home. She has been experiencing a high-pitched ringing in her left ear for the past 6 months. She attributes this to attending loud concerts frequently and has not sought medical attention until now. She reports that she can hear better when she is outside but struggles in quiet environments. Upon examination, there are no abnormalities seen during otoscopy. One of the possible diagnoses for this patient is otosclerosis, a condition that primarily affects the stapes bone. Which structure does the stapes bone come into contact with in the cochlea?
Your Answer: Tectorial membrane
Correct Answer: Oval window
Explanation:The oval window is where the stapes connects with the cochlea, and it is the most inner of the ossicles. The stapes has a stirrup-like shape, with a head that articulates with the incus and two limbs that connect it to the base. The base of the stapes is in contact with the oval window, which is one of the only two openings between the middle and inner ear. The organ of Corti, which is responsible for hearing, is located on the basilar membrane within the cochlear duct. The round window is the other opening between the middle and inner ear, and it allows the fluid within the cochlea to move, transmitting sound to the hair cells. The helicotrema is the point where the scala tympani and scala vestibuli meet at the apex of the cochlear labyrinth. The tectorial membrane is a membrane that extends along the entire length of the cochlea. A female in her third decade of life with unilateral conductive hearing loss and a family history of hearing loss is likely to have otosclerosis, a condition that affects the stapes and can cause severe or total hearing loss due to abnormal bone growth and fusion with the cochlea.
Anatomy of the Ear
The ear is divided into three distinct regions: the external ear, middle ear, and internal ear. The external ear consists of the auricle and external auditory meatus, which are innervated by the greater auricular nerve and auriculotemporal branch of the trigeminal nerve. The middle ear is the space between the tympanic membrane and cochlea, and is connected to the nasopharynx by the eustachian tube. The tympanic membrane is composed of three layers and is approximately 1 cm in diameter. The middle ear is innervated by the glossopharyngeal nerve. The ossicles, consisting of the malleus, incus, and stapes, transmit sound vibrations from the tympanic membrane to the inner ear. The internal ear contains the cochlea, which houses the organ of corti, the sense organ of hearing. The vestibule accommodates the utricule and saccule, which contain endolymph and are surrounded by perilymph. The semicircular canals, which share a common opening into the vestibule, lie at various angles to the petrous temporal bone.
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This question is part of the following fields:
- Respiratory System
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Question 19
Incorrect
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A 65-year-old man presents with a persistent dry cough and unintentional weight loss of 5kg over the past 3 months. He denies experiencing chest pain, dyspnoea, fever or haemoptysis. The patient has a history of smoking 10 cigarettes a day for the last 50 years and has been diagnosed with COPD. A nodule is detected on chest x-ray, and biopsy results indicate a tumour originating from the bronchial glands.
What is the most probable diagnosis?Your Answer: Squamous cell carcinoma of the lung
Correct Answer: Adenocarcinoma of the lung
Explanation:Adenocarcinoma has become the most prevalent form of lung cancer, originating from the bronchial glands as a type of non-small-cell lung cancer.
While a bronchogenic cyst may cause chest pain and dysphagia, it is typically diagnosed during childhood and does not stem from the bronchial glands.
Sarcoidosis may result in a persistent cough and weight loss, but it typically affects multiple systems and does not involve nodules originating from the bronchial glands.
Small cell carcinoma of the lung is a significant consideration, but given the description of a tumor originating from the bronchial glands, adenocarcinoma is the more probable diagnosis.
Lung cancer can be classified into two main types: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). SCLC is less common, accounting for only 15% of cases, but has a worse prognosis. NSCLC, on the other hand, is more prevalent and can be further broken down into different subtypes. Adenocarcinoma is now the most common type of lung cancer, likely due to the increased use of low-tar cigarettes. It is often seen in non-smokers and accounts for 62% of cases in ‘never’ smokers. Squamous cell carcinoma is another subtype, and cavitating lesions are more common in this type of lung cancer. Large cell carcinoma, alveolar cell carcinoma, bronchial adenoma, and carcinoid are other subtypes of NSCLC. Differentiating between these subtypes is crucial as different drugs are available to treat each subtype.
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This question is part of the following fields:
- Respiratory System
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Question 20
Correct
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Which one of the following does not decrease the functional residual capacity?
Your Answer: Upright position
Explanation:When a patient is in an upright position, the functional residual capacity (FRC) can increase due to less pressure from the diaphragm and abdominal organs on the lung bases. This increase in FRC can also be caused by emphysema and asthma. On the other hand, factors such as abdominal swelling, pulmonary edema, reduced muscle tone of the diaphragm, and aging can lead to a decrease in FRC. Additionally, laparoscopic surgery, obesity, and muscle relaxants can also contribute to a reduction in FRC.
Understanding Lung Volumes in Respiratory Physiology
In respiratory physiology, lung volumes can be measured to determine the amount of air that moves in and out of the lungs during breathing. The diagram above shows the different lung volumes that can be measured.
Tidal volume (TV) refers to the amount of air that is inspired or expired with each breath at rest. In males, the TV is 500ml while in females, it is 350ml.
Inspiratory reserve volume (IRV) is the maximum volume of air that can be inspired at the end of a normal tidal inspiration. The inspiratory capacity is the sum of TV and IRV. On the other hand, expiratory reserve volume (ERV) is the maximum volume of air that can be expired at the end of a normal tidal expiration.
Residual volume (RV) is the volume of air that remains in the lungs after maximal expiration. It increases with age and can be calculated by subtracting ERV from FRC. Speaking of FRC, it is the volume in the lungs at the end-expiratory position and is equal to the sum of ERV and RV.
Vital capacity (VC) is the maximum volume of air that can be expired after a maximal inspiration. It decreases with age and can be calculated by adding inspiratory capacity and ERV. Lastly, total lung capacity (TLC) is the sum of vital capacity and residual volume.
Physiological dead space (VD) is calculated by multiplying tidal volume by the difference between arterial carbon dioxide pressure (PaCO2) and end-tidal carbon dioxide pressure (PeCO2) and then dividing the result by PaCO2.
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This question is part of the following fields:
- Respiratory System
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Question 21
Correct
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Sophie, a 4-year-old patient with Down's syndrome, is brought to the general practitioner by her father. He is worried as Sophie has been crying more than usual and has started holding her right ear. She is diagnosed with acute bacterial otitis media.
What is the most probable bacteria responsible for this infection?Your Answer: Haemophilus influenzae
Explanation:Haemophilus influenzae is a frequent culprit behind bacterial otitis media, a common ear infection.
The majority of cases of acute bacterial otitis media are caused by Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella.
Genital gonorrhoeae is caused by N. gonorrhoeae, a sexually transmitted infection that presents with discharge and painful urination.
Meningococcal sepsis, a life-threatening condition, is caused by N. meningitides.
Staph. aureus is responsible for superficial skin infections like impetigo.
Syphilis, which typically manifests as a painless genital sore called a chancre, is caused by T. pallidum.
Acute otitis media is a common condition in young children, often caused by bacterial infections following viral upper respiratory tract infections. Symptoms include ear pain, fever, and hearing loss, and diagnosis is based on criteria such as the presence of a middle ear effusion and inflammation of the tympanic membrane. Antibiotics may be prescribed in certain cases, and complications can include perforation of the tympanic membrane, hearing loss, and more serious conditions such as meningitis and brain abscess.
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This question is part of the following fields:
- Respiratory System
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Question 22
Correct
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A 36-year-old man presents to his GP with symptoms of vertigo. He reports that he has been experiencing constant dizziness for the past 2 days, which has prevented him from going to work. He also reports hearing difficulties and tinnitus in his right ear, as well as nausea and difficulty with balance. He notes that these symptoms are not related to changes in position. He has no significant medical history, except for a recent bout of flu that resolved on its own.
During the examination, the man is observed to sway to the right while attempting to walk in a straight line. He also has a positive head thrust test to the right side. A complete neurological examination is performed, and aside from mild sensorineural hearing loss in the right ear, his neurological function is normal.
Which structures are most likely involved in this man's condition?Your Answer: Vestibular nerve and labyrinth
Explanation:The patient is displaying symptoms of labyrinthitis, which affects both the vestibular nerve and labyrinth, resulting in vertigo and hearing impairment. In contrast, pure vestibular neuritis only causes vestibular symptoms without affecting hearing. Benign paroxysmal positional vertigo (BPPV) involves otolith displacement and is triggered by head position changes, which is not the case for this patient’s constant vertigo. Facial nerve palsy primarily causes facial drooping and does not affect hearing or vestibular function, making it an unlikely diagnosis for this patient.
Understanding Viral Labyrinthitis
Labyrinthitis is a condition that affects the membranous labyrinth, which includes the vestibular and cochlear end organs. It can be caused by a viral or bacterial infection, or it may be associated with systemic diseases. Viral labyrinthitis is the most common form of the condition.
It’s important to distinguish labyrinthitis from vestibular neuritis, which only affects the vestibular nerve and doesn’t cause hearing impairment. Labyrinthitis, on the other hand, affects both the vestibular nerve and the labyrinth, resulting in both vertigo and hearing loss.
The condition typically affects people between the ages of 40 and 70 and is characterized by an acute onset of symptoms, including vertigo, nausea and vomiting, hearing loss, and tinnitus. Patients may also experience gait disturbance and fall towards the affected side.
Diagnosis is based on a patient’s history and examination, which may reveal spontaneous unidirectional horizontal nystagmus towards the unaffected side, sensorineural hearing loss, and an abnormal head impulse test.
While episodes of labyrinthitis are usually self-limiting, medications like prochlorperazine or antihistamines may help reduce the sensation of dizziness. Understanding the symptoms and management of viral labyrinthitis can help patients seek appropriate treatment and manage their condition effectively.
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This question is part of the following fields:
- Respiratory System
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Question 23
Correct
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A 35-year-old patient has been experiencing breathing difficulties for the past year. He finds it challenging to climb small hills, has developed a persistent cough, and has had two chest infections that were treated effectively by his doctor. He has never smoked, and his mother had comparable symptoms when she was his age. Based on his spirometry results, which indicate an FEV1/FVC ratio of 60%, his doctor suspects that his symptoms are caused by a genetic disorder. What is the molecular mechanism that underlies his probable condition?
Your Answer: Failure to break down neutrophil elastase
Explanation:The patient’s medical history suggests that they may be suffering from alpha-1 antitrypsin deficiency.
When there is a shortage of alpha-1 antitrypsin, neutrophil elastase is not inhibited and can break down proteins in the lung interstitium. Although neutrophil elastase is a crucial part of the innate immune system, its unregulated activity can lead to excessive breakdown of extracellular proteins like elastin, collagen, fibronectin, and fibrin. This results in reduced pulmonary elasticity, which can cause emphysema and COPD.
Alpha-1 antitrypsin (A1AT) deficiency is a genetic condition that occurs when the liver does not produce enough of a protein called protease inhibitor (Pi). This protein is responsible for protecting cells from enzymes like neutrophil elastase. A1AT deficiency is inherited in an autosomal recessive or co-dominant manner and is located on chromosome 14. The alleles are classified by their electrophoretic mobility, with M being normal, S being slow, and Z being very slow. The normal genotype is PiMM, while heterozygous individuals have PiMZ. Homozygous PiSS individuals have 50% normal A1AT levels, while homozygous PiZZ individuals have only 10% normal A1AT levels.
A1AT deficiency is most commonly associated with panacinar emphysema, which is a type of chronic obstructive pulmonary disease (COPD). This is especially true for patients with the PiZZ genotype. Emphysema is more likely to occur in non-smokers with A1AT deficiency, but they may still pass on the gene to their children. In addition to lung problems, A1AT deficiency can also cause liver issues such as cirrhosis and hepatocellular carcinoma in adults, and cholestasis in children.
Diagnosis of A1AT deficiency involves measuring A1AT concentrations and performing spirometry to assess lung function. Management of the condition includes avoiding smoking and receiving supportive care such as bronchodilators and physiotherapy. Intravenous alpha1-antitrypsin protein concentrates may also be used. In severe cases, lung volume reduction surgery or lung transplantation may be necessary.
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This question is part of the following fields:
- Respiratory System
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Question 24
Correct
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A 9-year-old boy is rushed to the emergency department following a fish bone choking incident during dinner. The patient is not experiencing any airway obstruction and has been given sufficient pain relief.
After being referred for laryngoscopy, a fish bone is discovered in the piriform recess. What is the potential structure that could be harmed due to the location of the fish bone?Your Answer: Internal laryngeal nerve
Explanation:Foreign objects lodged in the piriform recess can cause damage to the internal laryngeal nerve, which is in close proximity to this area. The internal laryngeal nerve is responsible for providing sensation to the laryngeal mucosa. The ansa cervicalis, external laryngeal nerve, glossopharyngeal nerve, and superior laryngeal nerve are not at high risk of injury from foreign bodies in the piriform recess.
Anatomy of the Larynx
The larynx is located in the front of the neck, between the third and sixth cervical vertebrae. It is made up of several cartilaginous segments, including the paired arytenoid, corniculate, and cuneiform cartilages, as well as the single thyroid, cricoid, and epiglottic cartilages. The cricoid cartilage forms a complete ring. The laryngeal cavity extends from the laryngeal inlet to the inferior border of the cricoid cartilage and is divided into three parts: the laryngeal vestibule, the laryngeal ventricle, and the infraglottic cavity.
The vocal folds, also known as the true vocal cords, control sound production. They consist of the vocal ligament and the vocalis muscle, which is the most medial part of the thyroarytenoid muscle. The glottis is composed of the vocal folds, processes, and rima glottidis, which is the narrowest potential site within the larynx.
The larynx is also home to several muscles, including the posterior cricoarytenoid, lateral cricoarytenoid, thyroarytenoid, transverse and oblique arytenoids, vocalis, and cricothyroid muscles. These muscles are responsible for various actions, such as abducting or adducting the vocal folds and relaxing or tensing the vocal ligament.
The larynx receives its arterial supply from the laryngeal arteries, which are branches of the superior and inferior thyroid arteries. Venous drainage is via the superior and inferior laryngeal veins. Lymphatic drainage varies depending on the location within the larynx, with the vocal cords having no lymphatic drainage and the supraglottic and subglottic parts draining into different lymph nodes.
Overall, understanding the anatomy of the larynx is important for proper diagnosis and treatment of various conditions affecting this structure.
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This question is part of the following fields:
- Respiratory System
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Question 25
Incorrect
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A 16-year-old male presents to the emergency department with a 48-hour history of tachypnea and tachycardia. His blood glucose level is 18mmol/l. While breathing 40% oxygen, an arterial blood sample is taken. The results show a PaO2 of 22kPa, pH of 7.35, PaCO2 of 3.5kPa, and HCO3- of 18.6 mmol/l. How should these blood gas results be interpreted?
Your Answer: Metabolic acidosis with partial respiratory compensation
Correct Answer: Metabolic acidosis with full respiratory compensation
Explanation:The patient’s blood gas analysis shows a lower oxygen pressure by about 10kPa than the percentage of oxygen. The PaCo2 level is 3.5, indicating respiratory alkalosis or compensation for metabolic acidosis. The HCO3- level is 18.6, which suggests metabolic acidosis or metabolic compensation for respiratory alkalosis. These results indicate that the patient has metabolic acidosis with complete respiratory compensation. Additionally, the patient’s high blood glucose level suggests that the metabolic acidosis is due to diabetic ketoacidosis.
Arterial Blood Gas Interpretation: A 5-Step Approach
Arterial blood gas interpretation is a crucial aspect of patient care, particularly in critical care settings. The Resuscitation Council (UK) recommends a 5-step approach to interpreting arterial blood gas results. The first step is to assess the patient’s overall condition. The second step is to determine if the patient is hypoxaemic, with a PaO2 on air of less than 10 kPa. The third step is to assess if the patient is acidaemic (pH <7.35) or alkalaemic (pH >7.45).
The fourth step is to evaluate the respiratory component of the arterial blood gas results. A PaCO2 level greater than 6.0 kPa suggests respiratory acidosis, while a PaCO2 level less than 4.7 kPa suggests respiratory alkalosis. The fifth step is to assess the metabolic component of the arterial blood gas results. A bicarbonate level less than 22 mmol/l or a base excess less than -2mmol/l suggests metabolic acidosis, while a bicarbonate level greater than 26 mmol/l or a base excess greater than +2mmol/l suggests metabolic alkalosis.
To remember the relationship between pH, PaCO2, and bicarbonate, the acronym ROME can be used. Respiratory acidosis or alkalosis is opposite to the pH level, while metabolic acidosis or alkalosis is equal to the pH level. This 5-step approach and the ROME acronym can aid healthcare professionals in interpreting arterial blood gas results accurately and efficiently.
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This question is part of the following fields:
- Respiratory System
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Question 26
Incorrect
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Which one of the following statements relating to the root of the spine is false?
Your Answer: The lung projects into the neck beyond the first rib and is constrained by Sibson's fascia
Correct Answer: The subclavian artery arches over the first rib anterior to scalenus anterior
Explanation:The suprapleural membrane, also known as Sibson’s fascia, is located above the pleural cavity. The scalenus anterior muscle is positioned in front of the subclavian vein, while the subclavian artery is situated behind it.
Thoracic Outlet: Where the Subclavian Artery and Vein and Brachial Plexus Exit the Thorax
The thoracic outlet is the area where the subclavian artery and vein and the brachial plexus exit the thorax and enter the arm. This passage occurs over the first rib and under the clavicle. The subclavian vein is the most anterior structure and is located immediately in front of scalenus anterior and its attachment to the first rib. Scalenus anterior has two parts, and the subclavian artery leaves the thorax by passing over the first rib and between these two portions of the muscle. At the level of the first rib, the lower cervical nerve roots combine to form the three trunks of the brachial plexus. The lowest trunk is formed by the union of C8 and T1, and this trunk lies directly posterior to the artery and is in contact with the superior surface of the first rib.
Thoracic outlet obstruction can cause neurovascular compromise.
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This question is part of the following fields:
- Respiratory System
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Question 27
Correct
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An 75-year-old woman presents to her GP with a 4-month history of dysphagia, weight loss, and a change in her voice tone. After a nasendoscopy, laryngeal carcinoma is confirmed. The surgical team plans her operation based on a head and neck CT scan. Which vertebrae are likely located posterior to the carcinoma?
Your Answer: C3-C6
Explanation:The larynx is situated in the front of the neck, specifically at the level of the C3-C6 vertebrae. It is positioned below the pharynx and contains the vocal cords that produce sound. The C1-C3 vertebrae are located much higher than the larynx, while the C2-C4 vertebrae cover the area from the oropharynx to the first part of the larynx. The C6-T1 vertebrae are situated behind the larynx and the upper portions of the trachea and esophagus.
Anatomy of the Larynx
The larynx is located in the front of the neck, between the third and sixth cervical vertebrae. It is made up of several cartilaginous segments, including the paired arytenoid, corniculate, and cuneiform cartilages, as well as the single thyroid, cricoid, and epiglottic cartilages. The cricoid cartilage forms a complete ring. The laryngeal cavity extends from the laryngeal inlet to the inferior border of the cricoid cartilage and is divided into three parts: the laryngeal vestibule, the laryngeal ventricle, and the infraglottic cavity.
The vocal folds, also known as the true vocal cords, control sound production. They consist of the vocal ligament and the vocalis muscle, which is the most medial part of the thyroarytenoid muscle. The glottis is composed of the vocal folds, processes, and rima glottidis, which is the narrowest potential site within the larynx.
The larynx is also home to several muscles, including the posterior cricoarytenoid, lateral cricoarytenoid, thyroarytenoid, transverse and oblique arytenoids, vocalis, and cricothyroid muscles. These muscles are responsible for various actions, such as abducting or adducting the vocal folds and relaxing or tensing the vocal ligament.
The larynx receives its arterial supply from the laryngeal arteries, which are branches of the superior and inferior thyroid arteries. Venous drainage is via the superior and inferior laryngeal veins. Lymphatic drainage varies depending on the location within the larynx, with the vocal cords having no lymphatic drainage and the supraglottic and subglottic parts draining into different lymph nodes.
Overall, understanding the anatomy of the larynx is important for proper diagnosis and treatment of various conditions affecting this structure.
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This question is part of the following fields:
- Respiratory System
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Question 28
Incorrect
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A patient with a body mass index (BMI) of 40kg/mÂČ presents to the GP describing apnoeic episodes during sleep. He is referred to the hospital's respiratory team where he receives an initial spirometry test which is shown below.
Forced expiratory volume in 1 sec (FEV1) 2.00 48% of predicted
Vital capacity (VC) 2.35 43% of predicted
Total lung capacity (TLC) 4.09 51% of predicted
Residual volume (RV) 1.74 75% of predicted
Total lung coefficient (TLCO) 5.37 47% of predicted
Transfer coefficient (KCO) 1.83 120% of predicted
What type of lung disease pattern is shown in a patient with a body mass index (BMI) of 30kg/mÂČ who presents to the GP with similar symptoms?Your Answer: Obstructive
Correct Answer: Extrapulmonary
Explanation:Understanding Pulmonary Function Tests
Pulmonary function tests are a useful tool in determining whether a respiratory disease is obstructive or restrictive. These tests measure various aspects of lung function, such as forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). By analyzing the results of these tests, doctors can diagnose and monitor conditions such as asthma, COPD, pulmonary fibrosis, and neuromuscular disorders.
In obstructive lung diseases, such as asthma and COPD, the FEV1 is significantly reduced, while the FVC may be reduced or normal. The FEV1% (FEV1/FVC) is also reduced. On the other hand, in restrictive lung diseases, such as pulmonary fibrosis and asbestosis, the FEV1 is reduced, but the FVC is significantly reduced. The FEV1% (FEV1/FVC) may be normal or increased.
It is important to note that there are many conditions that can affect lung function, and pulmonary function tests are just one tool in diagnosing and managing respiratory diseases. However, understanding the results of these tests can provide valuable information for both patients and healthcare providers.
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This question is part of the following fields:
- Respiratory System
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Question 29
Incorrect
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A 78-year-old man comes to your clinic with a complaint of hoarseness in his voice for the past 2 months. He is unsure if he had a viral infection prior to this and has attempted using over-the-counter remedies with no improvement. How would you approach managing this patient?
Your Answer: Routine referral to ENT
Correct Answer: Red flag referral to ENT
Explanation:An urgent referral to an ENT specialist is necessary when a person over the age of 45 experiences persistent hoarseness without any apparent cause. In this case, the patient has been suffering from a hoarse voice for 8 weeks, which warrants an urgent referral. A routine referral would not be sufficient as it may not be quick enough to address the issue. Although it could be a viral or bacterial infection, the duration of the hoarseness suggests that there may be an underlying serious condition. Merely informing the patient that their voice may not return is not helpful and may overlook the possibility of a more severe problem.
Hoarseness can be caused by various factors such as overusing the voice, smoking, viral infections, hypothyroidism, gastro-oesophageal reflux, laryngeal cancer, and lung cancer. It is important to investigate the underlying cause of hoarseness, and a chest x-ray may be necessary to rule out any apical lung lesions.
If laryngeal cancer is suspected, it is recommended to refer the patient to an ENT specialist through a suspected cancer pathway. This referral should be considered for individuals who are 45 years old and above and have persistent unexplained hoarseness or an unexplained lump in the neck. Early detection and treatment of laryngeal cancer can significantly improve the patient’s prognosis.
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This question is part of the following fields:
- Respiratory System
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Question 30
Correct
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A 15-year-old girl presents with difficulty breathing and is unable to speak in full sentences due to panic. She has a history of asthma. Upon examination, her respiratory rate is 28 breaths/minute, heart rate is 105 beats/minute, and her chest is silent. What is the most concerning feature in this girl's history?
Your Answer: Silent chest
Explanation:Identify the life-threatening features of an asthma attack.
Assessing the severity of asthma attacks in children is crucial for effective management. The 2016 BTS/SIGN guidelines provide criteria for assessing the severity of asthma in general practice. These criteria include measuring SpO2 levels, PEF (peak expiratory flow) rates, heart rate, respiratory rate, use of accessory neck muscles, and other symptoms such as breathlessness, agitation, altered consciousness, and cyanosis.
A severe asthma attack is characterized by a SpO2 level below 92%, PEF rates between 33-50% of the best or predicted, being too breathless to talk or feed, and a high heart and respiratory rate. On the other hand, a life-threatening asthma attack is indicated by a SpO2 level below 92%, PEF rates below 33% of the best or predicted, a silent chest, poor respiratory effort, use of accessory neck muscles, agitation, altered consciousness, and cyanosis.
It is important for healthcare professionals to be familiar with these criteria to ensure prompt and appropriate management of asthma attacks in children. Early recognition of the severity of an asthma attack can help prevent complications and reduce the risk of hospitalization or death.
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This question is part of the following fields:
- Respiratory System
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Question 31
Incorrect
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A 63-year-old man arrives at the ER with a recent onset of left-sided facial paralysis. He reports experiencing a painful rash around his ear on the affected side for the past five days. Your suspicion is Ramsay Hunt syndrome. What virus is responsible for this condition?
Your Answer: Epstein Barr virus
Correct Answer: Varicella zoster virus
Explanation:The geniculate ganglion of the facial nerve (CN VII) reactivates the varicella-zoster virus, causing Ramsay Hunt syndrome.
Infectious mononucleosis (glandular fever) is primarily linked to the Epstein-Barr virus.
Viral warts are commonly caused by human papillomavirus (HPV), with certain types being associated with gynaecological malignancy. Vaccines are now available to protect against the carcinogenic strains of HPV.
Oral or genital herpes infections are caused by the herpes simplex virus.
Understanding Ramsay Hunt Syndrome
Ramsay Hunt syndrome, also known as herpes zoster oticus, is a condition that occurs when the varicella zoster virus reactivates in the geniculate ganglion of the seventh cranial nerve. The first symptom of this syndrome is often auricular pain, followed by facial nerve palsy and a vesicular rash around the ear. Other symptoms may include vertigo and tinnitus.
To manage Ramsay Hunt syndrome, doctors typically prescribe oral acyclovir and corticosteroids. These medications can help reduce the severity of symptoms and prevent complications.
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This question is part of the following fields:
- Respiratory System
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Question 32
Correct
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A 75-year-old man visits his doctor complaining of weight loss and feeling full quickly. During the abdominal examination, the doctor notices a swollen lymph node in the left supraclavicular region. The doctor suspects that this could be a sign of gastric cancer with the spread of tumor emboli through the thoracic duct as it ascends from the abdomen into the mediastinum. Can you name the two other structures that pass through the diaphragm along with the thoracic duct?
Your Answer: Aorta and azygous vein
Explanation:The point at which the aorta, thoracic duct, and azygous vein cross the diaphragm is at T12, specifically at the aortic opening. This is also where the oesophageal branches of the left gastric veins, the vagal trunk, and the oesophagus pass through the diaphragm, at the oesophageal opening located at T10. The left phrenic nerve and sympathetic trunk have their own separate openings in the diaphragm. A lymph node in the left supraclavicular fossa, known as Virchow’s node, is a characteristic sign of early gastric carcinoma.
Structures Perforating the Diaphragm
The diaphragm is a dome-shaped muscle that separates the thoracic and abdominal cavities. It plays a crucial role in breathing by contracting and relaxing to create negative pressure in the lungs. However, there are certain structures that perforate the diaphragm, allowing them to pass through from the thoracic to the abdominal cavity. These structures include the inferior vena cava at the level of T8, the esophagus and vagal trunk at T10, and the aorta, thoracic duct, and azygous vein at T12.
To remember these structures and their corresponding levels, a helpful mnemonic is I 8(ate) 10 EGGS AT 12. This means that the inferior vena cava is at T8, the esophagus and vagal trunk are at T10, and the aorta, thoracic duct, and azygous vein are at T12. Knowing these structures and their locations is important for medical professionals, as they may need to access or treat them during surgical procedures or diagnose issues related to them.
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This question is part of the following fields:
- Respiratory System
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Question 33
Incorrect
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Which of the following physiological changes does not take place after a tracheostomy?
Your Answer: Anatomical dead space is reduced by 50%.
Correct Answer: Work of breathing is increased.
Explanation:HFNC is a popular option for weaning ventilated patients as it reduces work of breathing and humidified air helps to reduce mucous viscosity.
Anatomy of the Trachea
The trachea, also known as the windpipe, is a tube-like structure that extends from the C6 vertebrae to the upper border of the T5 vertebrae where it bifurcates into the left and right bronchi. It is supplied by the inferior thyroid arteries and the thyroid venous plexus, and innervated by branches of the vagus, sympathetic, and recurrent nerves.
In the neck, the trachea is anterior to the isthmus of the thyroid gland, inferior thyroid veins, and anastomosing branches between the anterior jugular veins. It is also surrounded by the sternothyroid, sternohyoid, and cervical fascia. Posteriorly, it is related to the esophagus, while laterally, it is in close proximity to the common carotid arteries, right and left lobes of the thyroid gland, inferior thyroid arteries, and recurrent laryngeal nerves.
In the thorax, the trachea is anterior to the manubrium, the remains of the thymus, the aortic arch, left common carotid arteries, and the deep cardiac plexus. Laterally, it is related to the pleura and right vagus on the right side, and the left recurrent nerve, aortic arch, and left common carotid and subclavian arteries on the left side.
Overall, understanding the anatomy of the trachea is important for various medical procedures and interventions, such as intubation and tracheostomy.
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This question is part of the following fields:
- Respiratory System
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Question 34
Incorrect
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A 55-year-old woman comes to the clinic complaining of a persistent cough and increased production of sputum over the past year. She also reports feeling fatigued and experiencing shortness of breath. The patient mentions having had four chest infections in the last 12 months, all of which were treated with antibiotics. She has no medical or family history and has never smoked.
The healthcare provider suspects that bronchiectasis may be the underlying cause of her symptoms and orders appropriate tests, including a sputum sample.
What is the most likely organism to be identified?Your Answer: Haemophilus influenzae
Correct Answer:
Explanation:Bronchiectasis patients may have various bacteria present in their respiratory system, with Haemophilus influenzae and Pseudomonas aeruginosa being the most common. Staphylococcus aureus has also been found but not as frequently. Respiratory syncytial virus has not been detected in acute exacerbations of bronchiectasis. It is crucial to identify the specific bacteria causing exacerbations as antibiotic sensitivity patterns differ, and sputum culture results can impact the effectiveness of treatment. These findings are outlined in the British Thoracic Society’s guideline for non-CF bronchiectasis and a study by Metaxas et al. on the role of atypical bacteria and respiratory syncytial virus in bronchiectasis exacerbations.
Bronchiectasis is a condition where the airways become permanently dilated due to chronic inflammation or infection. Before treatment, it is important to identify any underlying causes that can be addressed, such as immune deficiencies. Management of bronchiectasis includes physical training, such as inspiratory muscle training, which has been shown to be effective for patients without cystic fibrosis. Postural drainage, antibiotics for exacerbations, and long-term rotating antibiotics for severe cases are also recommended. Bronchodilators may be used in selected cases, and immunizations are important to prevent infections. Surgery may be considered for localized disease. The most common organisms isolated from patients with bronchiectasis include Haemophilus influenzae, Pseudomonas aeruginosa, Klebsiella spp., and Streptococcus pneumoniae.
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This question is part of the following fields:
- Respiratory System
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Question 35
Incorrect
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A 50-year-old man visits the GP clinic for a routine hearing examination. He reports no issues with his hearing and has no significant medical history or medication use. After conducting Rinne and Weber tests on the patient, you determine that his hearing is within normal limits.
What are the test findings for this patient?Your Answer: Rinne: bone conduction > air conduction bilaterally; Weber: equal in both ears
Correct Answer: Rinne: air conduction > bone conduction bilaterally; Weber: equal in both ears
Explanation:The patient’s hearing exam results indicate normal hearing. The Rinne test showed more air conduction than bone conduction in both ears, which is typical for normal hearing. The Weber test also showed equal results in both ears, indicating no significant difference in hearing between the ears.
Rinne’s and Weber’s Test for Differentiating Conductive and Sensorineural Deafness
Rinne’s and Weber’s tests are used to differentiate between conductive and sensorineural deafness. Rinne’s test involves placing a tuning fork over the mastoid process until the sound is no longer heard, then repositioning it just over the external acoustic meatus. A positive test indicates that air conduction (AC) is better than bone conduction (BC), while a negative test indicates that BC is better than AC, suggesting conductive deafness.
Weber’s test involves placing a tuning fork in the middle of the forehead equidistant from the patient’s ears and asking the patient which side is loudest. In unilateral sensorineural deafness, sound is localized to the unaffected side, while in unilateral conductive deafness, sound is localized to the affected side.
The table below summarizes the interpretation of Rinne and Weber tests. A normal result indicates that AC is greater than BC bilaterally and the sound is midline. Conductive hearing loss is indicated by BC being greater than AC in the affected ear and AC being greater than BC in the unaffected ear, with the sound lateralizing to the affected ear. Sensorineural hearing loss is indicated by AC being greater than BC bilaterally, with the sound lateralizing to the unaffected ear.
Overall, Rinne’s and Weber’s tests are useful tools for differentiating between conductive and sensorineural deafness, allowing for appropriate management and treatment.
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This question is part of the following fields:
- Respiratory System
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Question 36
Incorrect
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A 26-year-old male is brought to the emergency department by his mother. He is agitated, restless, and anxious.
Upon examination, dilated pupils are observed, and an ECG reveals sinus tachycardia.
The patient has a medical history of chronic asthma and is currently taking modified-release theophylline tablets.
According to his mother, he returned from a trip to Pakistan last night and has been taking antibiotics for bacterial gastroenteritis for the past four days. He has three days left on his antibiotic course.
What could be the cause of his current presentation?Your Answer: Terbinafine
Correct Answer: Ciprofloxacin
Explanation:Terbinafine is frequently prescribed for the treatment of fungal nail infections as an antifungal medication.
Theophylline and its Poisoning
Theophylline is a naturally occurring methylxanthine that is commonly used as a bronchodilator in the management of asthma and COPD. Its exact mechanism of action is still unknown, but it is believed to be a non-specific inhibitor of phosphodiesterase, resulting in an increase in cAMP. Other proposed mechanisms include antagonism of adenosine and prostaglandin inhibition.
However, theophylline poisoning can occur and is characterized by symptoms such as acidosis, hypokalemia, vomiting, tachycardia, arrhythmias, and seizures. In such cases, gastric lavage may be considered if the ingestion occurred less than an hour prior. Activated charcoal is also recommended, while whole-bowel irrigation can be performed if theophylline is in sustained-release form. Charcoal hemoperfusion is preferable to hemodialysis in managing theophylline poisoning.
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This question is part of the following fields:
- Respiratory System
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Question 37
Incorrect
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A 27-year-old woman, who has had eczema and asthma since childhood, comes for her yearly asthma check-up. She has been using her salbutamol inhaler more frequently over the last 3 months and is concerned that it may be due to getting a new kitten. In allergic asthma, which cell is present in excessive amounts?
Your Answer: Mast cells
Correct Answer: Eosinophils
Explanation:The patient’s medical background indicates that she may have atopic asthma. It is probable that her symptoms have worsened and she has had to use more salbutamol reliever due to an allergy to her new kitten’s animal dander.
Individuals with allergic asthma have been found to have increased levels of eosinophils in their airways. The severity of asthma is linked to the number of eosinophils present, as they contribute to long-term airway inflammation by causing damage, blockages, and hyperresponsiveness.
The immediate symptoms of asthma after exposure are caused by mast cell degranulation.
Asthma is a common respiratory disorder that affects both children and adults. It is characterized by chronic inflammation of the airways, resulting in reversible bronchospasm and airway obstruction. While asthma can develop at any age, it typically presents in childhood and may improve or resolve with age. However, it can also persist into adulthood and cause significant morbidity, with around 1,000 deaths per year in the UK.
Several risk factors can increase the likelihood of developing asthma, including a personal or family history of atopy, antenatal factors such as maternal smoking or viral infections, low birth weight, not being breastfed, exposure to allergens and air pollution, and the hygiene hypothesis. Patients with asthma may also suffer from other atopic conditions such as eczema and hay fever, and some may be sensitive to aspirin. Occupational asthma is also a concern for those exposed to allergens in the workplace.
Symptoms of asthma include coughing, dyspnea, wheezing, and chest tightness, with coughing often worse at night. Signs may include expiratory wheezing on auscultation and reduced peak expiratory flow rate. Diagnosis is typically made through spirometry, which measures the volume and speed of air during exhalation and inhalation.
Management of asthma typically involves the use of inhalers to deliver drug therapy directly to the airways. Short-acting beta-agonists such as salbutamol are the first-line treatment for relieving symptoms, while inhaled corticosteroids like beclometasone dipropionate and fluticasone propionate are used for daily maintenance therapy. Long-acting beta-agonists like salmeterol and leukotriene receptor antagonists like montelukast may also be used in combination with other medications. Maintenance and reliever therapy (MART) is a newer approach that combines ICS and a fast-acting LABA in a single inhaler for both daily maintenance and symptom relief. Recent guidelines recommend offering a leukotriene receptor antagonist instead of a LABA for patients on SABA + ICS whose asthma is not well controlled, and considering MART for those with poorly controlled asthma.
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This question is part of the following fields:
- Respiratory System
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Question 38
Incorrect
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A 75-year-old man is having a left pneumonectomy for bronchial carcinoma. When the surgeons reach the root of the lung, which structure will be the most anterior in the anatomical plane?
Your Answer: Pulmonary artery
Correct Answer: Phrenic nerve
Explanation:The lung root contains two nerves, with the phrenic nerve positioned in the most anterior location and the vagus nerve situated in the most posterior location.
Anatomy of the Lungs
The lungs are a pair of organs located in the chest cavity that play a vital role in respiration. The right lung is composed of three lobes, while the left lung has two lobes. The apex of both lungs is approximately 4 cm superior to the sternocostal joint of the first rib. The base of the lungs is in contact with the diaphragm, while the costal surface corresponds to the cavity of the chest. The mediastinal surface contacts the mediastinal pleura and has the cardiac impression. The hilum is a triangular depression above and behind the concavity, where the structures that form the root of the lung enter and leave the viscus. The right main bronchus is shorter, wider, and more vertical than the left main bronchus. The inferior borders of both lungs are at the 6th rib in the mid clavicular line, 8th rib in the mid axillary line, and 10th rib posteriorly. The pleura runs two ribs lower than the corresponding lung level. The bronchopulmonary segments of the lungs are divided into ten segments, each with a specific function.
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This question is part of the following fields:
- Respiratory System
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Question 39
Correct
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A 10-year-old boy comes to the clinic with his mother. He complained of ear pain during the night, but there is no discharge, hearing loss, or other symptoms. Upon examination, he has no fever. The pinna of his ear appears red and swollen, and pressing on the tragus causes pain. Otoscopy reveals a healthy tympanic membrane, but the external auditory canal is inflamed. The external auditory canal consists of a cartilaginous outer part and a bony inner part. Which bone does the bony external canal pass through?
Your Answer: Temporal bone
Explanation:The temporal bone is the correct answer. It contains the bony external auditory canal and middle ear, which are composed of a cartilaginous outer third and a bony inner two-thirds. The temporal bone articulates with the parietal, occipital, sphenoid, zygomatic, and mandible bones.
The sphenoid bone is a complex bone that articulates with 12 other bones. It is divided into four parts: the body, greater wings, lesser wings, and pterygoid plates.
The zygomatic bone is located on the anterior and lateral aspects of the face and articulates with the frontal, sphenoid, temporal, and maxilla bones.
The parietal bone forms the sides and roof of the cranium and articulates with the parietal on the opposite side, as well as the frontal, temporal, occipital, and sphenoid bones.
The occipital bone is situated at the rear of the cranium and articulates with the temporal, sphenoid, parietals, and the first cervical vertebrae.
The patient’s symptoms of ear pain, erythematous pinna and external auditory canal, and tender tragus on palpation are consistent with otitis externa, which has numerous possible causes. The patient is not febrile and has no loss of hearing or dizziness.
Anatomy of the Ear
The ear is divided into three distinct regions: the external ear, middle ear, and internal ear. The external ear consists of the auricle and external auditory meatus, which are innervated by the greater auricular nerve and auriculotemporal branch of the trigeminal nerve. The middle ear is the space between the tympanic membrane and cochlea, and is connected to the nasopharynx by the eustachian tube. The tympanic membrane is composed of three layers and is approximately 1 cm in diameter. The middle ear is innervated by the glossopharyngeal nerve. The ossicles, consisting of the malleus, incus, and stapes, transmit sound vibrations from the tympanic membrane to the inner ear. The internal ear contains the cochlea, which houses the organ of corti, the sense organ of hearing. The vestibule accommodates the utricule and saccule, which contain endolymph and are surrounded by perilymph. The semicircular canals, which share a common opening into the vestibule, lie at various angles to the petrous temporal bone.
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This question is part of the following fields:
- Respiratory System
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Question 40
Incorrect
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A father brings his 5-year-old daughter to the GP with a 72-hour history of left ear pain. She has had a cough with coryzal symptoms for the past four days. She has no past medical history, allergies or current medications, and she is up-to-date with her vaccinations. Her temperature is 38.5ÂșC. No abnormality is detected on examination of the oral cavity. Following otoscopy, what is the most likely causative pathogen for her diagnosis of otitis media?
Your Answer: influenzae A
Correct Answer: Streptococcus pneumoniae
Explanation:Otitis media is primarily caused by bacteria, with viral URTIs often preceding the infection. The majority of cases are secondary to bacterial infections, with the most common culprit being…
Acute otitis media is a common condition in young children, often caused by bacterial infections following viral upper respiratory tract infections. Symptoms include ear pain, fever, and hearing loss, and diagnosis is based on criteria such as the presence of a middle ear effusion and inflammation of the tympanic membrane. Antibiotics may be prescribed in certain cases, and complications can include perforation of the tympanic membrane, hearing loss, and more serious conditions such as meningitis and brain abscess.
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This question is part of the following fields:
- Respiratory System
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Question 41
Correct
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A 67-year-old man visits the respiratory clinic for spirometry testing to investigate possible COPD. The clinician observes that his breathing appears to be shallow even at rest.
What specific lung volume would accurately describe the clinician's observation?Your Answer: Tidal volume (TV)
Explanation:Understanding Lung Volumes in Respiratory Physiology
In respiratory physiology, lung volumes can be measured to determine the amount of air that moves in and out of the lungs during breathing. The diagram above shows the different lung volumes that can be measured.
Tidal volume (TV) refers to the amount of air that is inspired or expired with each breath at rest. In males, the TV is 500ml while in females, it is 350ml.
Inspiratory reserve volume (IRV) is the maximum volume of air that can be inspired at the end of a normal tidal inspiration. The inspiratory capacity is the sum of TV and IRV. On the other hand, expiratory reserve volume (ERV) is the maximum volume of air that can be expired at the end of a normal tidal expiration.
Residual volume (RV) is the volume of air that remains in the lungs after maximal expiration. It increases with age and can be calculated by subtracting ERV from FRC. Speaking of FRC, it is the volume in the lungs at the end-expiratory position and is equal to the sum of ERV and RV.
Vital capacity (VC) is the maximum volume of air that can be expired after a maximal inspiration. It decreases with age and can be calculated by adding inspiratory capacity and ERV. Lastly, total lung capacity (TLC) is the sum of vital capacity and residual volume.
Physiological dead space (VD) is calculated by multiplying tidal volume by the difference between arterial carbon dioxide pressure (PaCO2) and end-tidal carbon dioxide pressure (PeCO2) and then dividing the result by PaCO2.
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This question is part of the following fields:
- Respiratory System
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Question 42
Incorrect
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An 85-year-old woman visits her doctor with a complaint of worsening breathlessness in the past 6 months. She has been smoking 10 cigarettes a day for the last 40 years. The doctor suspects that she may have chronic obstructive pulmonary disease. What is one of the mechanisms by which smoking damages the lungs and leads to emphysema?
Your Answer: Basal cell metaplasia
Correct Answer: Inactivation of alpha-1 antitrypsin
Explanation:The function of alpha-1 antitrypsin is to inhibit elastase. However, smoke has a negative impact on this protein in the lungs, resulting in increased activity of elastases and the breakdown of elastic tissue, which leads to emphysema.
Contrary to popular belief, smoke actually activates polymorphonuclear leucocytes, which contributes to the development of emphysema.
Mucous gland hyperplasia, basal cell metaplasia, and basement membrane thickening are all examples of how smoke affects the lungs to cause chronic bronchitis, not emphysema.
COPD, or chronic obstructive pulmonary disease, can be caused by a variety of factors. The most common cause is smoking, which can lead to inflammation and damage in the lungs over time. Another potential cause is alpha-1 antitrypsin deficiency, a genetic condition that can result in lung damage. Additionally, exposure to certain substances such as cadmium (used in smelting), coal, cotton, cement, and grain can also contribute to the development of COPD. It is important to identify and address these underlying causes in order to effectively manage and treat COPD.
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This question is part of the following fields:
- Respiratory System
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Question 43
Incorrect
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A 49-year-old patient presents to the rheumatology clinic with weight loss, fever, and night sweats. The individual is also experiencing shortness of breath. The following blood test results are obtained:
- Hemoglobin (Hb): 140 g/l
- Platelets: 192 * 109/l
- White cell count (WCC): 5.3 * 109/l
- Creatinine: 154 umol/l
- Urea: 9 mmol/l
- cANCA positive
The white cell differential count is reported as normal. What is the most likely diagnosis?Your Answer: Goodpasture's syndrome
Correct Answer: Granulomatosis with polyangiitis
Explanation:The most likely diagnosis for this patient is granulomatosis with polyangiitis, as indicated by the presence of cANCA and the involvement of multiple organs including the lungs, skin, kidneys, and upper respiratory tract. This condition is known to cause inflammation in the glomeruli, leading to renal impairment. Churg-Strauss disease and Alport’s syndrome are unlikely due to normal eosinophil levels and cANCA positivity, respectively. Goodpasture’s syndrome is also unlikely as the patient does not present with haematuria or haemoptysis.
Granulomatosis with Polyangiitis: An Autoimmune Condition
Granulomatosis with polyangiitis, previously known as Wegener’s granulomatosis, is an autoimmune condition that affects the upper and lower respiratory tract as well as the kidneys. It is characterized by a necrotizing granulomatous vasculitis. The condition presents with various symptoms such as epistaxis, sinusitis, nasal crusting, dyspnoea, haemoptysis, and rapidly progressive glomerulonephritis. Other symptoms include a saddle-shape nose deformity, vasculitic rash, eye involvement, and cranial nerve lesions.
To diagnose granulomatosis with polyangiitis, doctors perform various investigations such as cANCA and pANCA tests, chest x-rays, and renal biopsies. The cANCA test is positive in more than 90% of cases, while the pANCA test is positive in 25% of cases. Chest x-rays show a wide variety of presentations, including cavitating lesions. Renal biopsies reveal epithelial crescents in Bowman’s capsule.
The management of granulomatosis with polyangiitis involves the use of steroids, cyclophosphamide, and plasma exchange. Cyclophosphamide has a 90% response rate. The median survival rate for patients with this condition is 8-9 years.
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This question is part of the following fields:
- Respiratory System
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Question 44
Incorrect
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A 20-year-old male arrives at the emergency department with a sudden worsening of his asthma symptoms. He is experiencing difficulty in speaking and breathing, with cyanosis of the lips and a respiratory rate of 33 breaths per minute. He reports feeling lightheaded. Although his airways are open, his chest sounds are faint upon auscultation. The patient is administered oxygen, nebulized salbutamol, and intravenous aminophylline.
What is the mechanism of action of aminophylline?Your Answer: Antagonises the inflammatory effects of histamine by binding to histamine receptors
Correct Answer: Binds to adenosine receptors and blocks adenosine-mediated bronchoconstriction
Explanation:Aminophylline works by binding to adenosine receptors and preventing adenosine-induced bronchoconstriction. This mode of action is different from antihistamines like loratadine, which is an incorrect option. Theophylline, a shorter acting form of aminophylline, competitively inhibits type III and type IV phosphodiesterase enzymes responsible for breaking down cyclic AMP in smooth muscle cells, leading to possible bronchodilation. Additionally, theophylline binds to the adenosine A2B receptor and blocks adenosine-mediated bronchoconstriction. In inflammatory conditions, theophylline activates histone deacetylase, which prevents the transcription of inflammatory genes that require histone acetylation for transcription to begin. Therefore, the last three options are incorrect. (Source: Drugbank)
Aminophylline infusions are utilized to manage acute asthma and COPD. In patients who have not received xanthines (theophylline or aminophylline) before, a loading dose of 5 mg/kg is administered through a slow intravenous injection lasting at least 20 minutes. For the maintenance infusion, 1g of aminophylline is mixed with 1 litre of normal saline to create a solution of 1 mg/ml. The recommended dose is 500-700 mcg/kg/hour, or 300 mcg/kg/hour for elderly patients. It is important to monitor plasma theophylline concentrations.
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This question is part of the following fields:
- Respiratory System
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Question 45
Correct
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A 27-year-old woman is expecting her first baby. During routine midwife appointments, it was discovered that she has hypertension and proteinuria, which are signs of pre-eclampsia. To prevent respiratory distress syndrome, a complication of prematurity caused by inadequate pulmonary surfactant production, she will require steroid doses before induction of preterm labor. Which cell type is being targeted by corticosteroids in this patient?
Your Answer: Type 2 pneumocytes
Explanation:Types of Pneumocytes and Their Functions
Pneumocytes are specialized cells found in the lungs that play a crucial role in gas exchange. There are two main types of pneumocytes: type 1 and type 2. Type 1 pneumocytes are very thin squamous cells that cover around 97% of the alveolar surface. On the other hand, type 2 pneumocytes are cuboidal cells that secrete surfactant, a substance that reduces surface tension in the alveoli and prevents their collapse during expiration.
Type 2 pneumocytes start to develop around 24 weeks gestation, but adequate surfactant production does not take place until around 35 weeks. This is why premature babies are prone to respiratory distress syndrome. In addition, type 2 pneumocytes can differentiate into type 1 pneumocytes during lung damage, helping to repair and regenerate damaged lung tissue.
Apart from pneumocytes, there are also club cells (previously termed Clara cells) found in the bronchioles. These non-ciliated dome-shaped cells have a varied role, including protecting against the harmful effects of inhaled toxins and secreting glycosaminoglycans and lysozymes. Understanding the different types of pneumocytes and their functions is essential in comprehending the complex mechanisms involved in respiration.
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This question is part of the following fields:
- Respiratory System
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Question 46
Correct
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A 49-year-old man comes to the clinic with recent onset of asthma and frequent nosebleeds. Laboratory results reveal elevated eosinophil counts and a positive pANCA test.
What is the probable diagnosis?Your Answer: Eosinophilic granulomatosis with polyangiitis (EGPA)
Explanation:The presence of adult-onset asthma, eosinophilia, and a positive pANCA test strongly suggests a diagnosis of eosinophilic granulomatosis with polyangiitis (EGPA) in this patient.
Although GPA can cause epistaxis, the absence of other characteristic symptoms such as saddle-shaped nose deformity, haemoptysis, renal failure, and positive cANCA make EGPA a more likely diagnosis.
Polyarteritis Nodosa, Temporal Arteritis, and Toxic Epidermal Necrolysis have distinct clinical presentations that do not match the symptoms exhibited by this patient.
Eosinophilic Granulomatosis with Polyangiitis (Churg-Strauss Syndrome)
Eosinophilic granulomatosis with polyangiitis (EGPA), previously known as Churg-Strauss syndrome, is a type of small-medium vessel vasculitis that is associated with ANCA. It is characterized by asthma, blood eosinophilia (more than 10%), paranasal sinusitis, mononeuritis multiplex, and pANCA positivity in 60% of cases.
Compared to granulomatosis with polyangiitis, EGPA is more likely to have blood eosinophilia and asthma as prominent features. Additionally, leukotriene receptor antagonists may trigger the onset of the disease.
Overall, EGPA is a rare but serious condition that requires prompt diagnosis and treatment to prevent complications.
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This question is part of the following fields:
- Respiratory System
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Question 47
Correct
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A 25-year-old woman presents to the Emergency department with sudden onset of difficulty breathing. She has a history of asthma but is otherwise healthy. Upon admission, she is observed to be breathing rapidly, using her accessory muscles, and is experiencing cold and clammy skin. Upon chest auscultation, widespread wheezing is detected.
An arterial blood gas analysis reveals:
pH 7.46
pO2 13 kPa
pCO2 2.7 kPa
HCO3- 23 mmol/l
Which aspect of the underlying disease is affected in this patient?Your Answer: Forced Expiratory Volume
Explanation:It is probable that this individual is experiencing an acute episode of asthma. Asthma is a condition that results in the constriction of the airways, known as an obstructive airway disease. Its distinguishing feature is its ability to be reversed. The forced expiratory volume is the most impacted parameter in asthma and other obstructive airway diseases.
Understanding Lung Volumes in Respiratory Physiology
In respiratory physiology, lung volumes can be measured to determine the amount of air that moves in and out of the lungs during breathing. The diagram above shows the different lung volumes that can be measured.
Tidal volume (TV) refers to the amount of air that is inspired or expired with each breath at rest. In males, the TV is 500ml while in females, it is 350ml.
Inspiratory reserve volume (IRV) is the maximum volume of air that can be inspired at the end of a normal tidal inspiration. The inspiratory capacity is the sum of TV and IRV. On the other hand, expiratory reserve volume (ERV) is the maximum volume of air that can be expired at the end of a normal tidal expiration.
Residual volume (RV) is the volume of air that remains in the lungs after maximal expiration. It increases with age and can be calculated by subtracting ERV from FRC. Speaking of FRC, it is the volume in the lungs at the end-expiratory position and is equal to the sum of ERV and RV.
Vital capacity (VC) is the maximum volume of air that can be expired after a maximal inspiration. It decreases with age and can be calculated by adding inspiratory capacity and ERV. Lastly, total lung capacity (TLC) is the sum of vital capacity and residual volume.
Physiological dead space (VD) is calculated by multiplying tidal volume by the difference between arterial carbon dioxide pressure (PaCO2) and end-tidal carbon dioxide pressure (PeCO2) and then dividing the result by PaCO2.
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This question is part of the following fields:
- Respiratory System
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Question 48
Incorrect
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A 65-year-old woman comes to the clinic complaining of fever and productive cough for the past two days. She spends most of her time at home watching TV and rarely goes outside. She has no recent travel history. The patient has a history of gastroesophageal reflux disease but has not been compliant with medication and follow-up appointments. Upon physical examination, crackles are heard on the left lower lobe, and her sputum is described as 'red-currant jelly.'
What is the probable causative organism in this case?Your Answer: Streptococcus pneumoniae
Correct Answer: Klebsiella pneumoniae
Explanation:The patient’s history of severe gastro-oesophageal reflux disease (GORD) suggests that she may have aspiration pneumonia, particularly as she had not received appropriate treatment for it. Aspiration of gastric contents is likely to occur in the right lung due to the steep angle of the right bronchus. Klebsiella pneumoniae is a common cause of aspiration pneumonia and is known to produce ‘red-currant jelly’ sputum.
Mycoplasma pneumoniae is a cause of atypical pneumonia, which typically presents with a non-productive cough and clear lung sounds on auscultation. It is more common in younger individuals.
Burkholderia pseudomallei is the causative organism for melioidosis, a condition that is transmitted through exposure to contaminated water or soil, and is more commonly found in Southeast Asia. However, given the patient’s sedentary lifestyle and lack of travel history, it is unlikely to be the cause of her symptoms.
Streptococcus pneumoniae is the most common cause of pneumonia, but it typically produces yellowish-green sputum rather than the red-currant jelly sputum seen in Klebsiella pneumoniae infections. It also presents with fever, productive cough, and crackles on auscultation.
Understanding Klebsiella Pneumoniae
Klebsiella pneumoniae is a type of bacteria that is commonly found in the gut flora of humans. However, it can also cause various infections such as pneumonia and urinary tract infections. It is more prevalent in individuals who have alcoholism or diabetes. Aspiration is a common cause of pneumonia caused by Klebsiella pneumoniae. One of the distinct features of this type of pneumonia is the production of red-currant jelly sputum. It usually affects the upper lobes of the lungs.
The prognosis for Klebsiella pneumoniae infections is not good. It often leads to the formation of lung abscesses and empyema, which can be fatal. The mortality rate for this type of infection is between 30-50%.
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This question is part of the following fields:
- Respiratory System
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Question 49
Incorrect
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A 56-year-old man has been diagnosed with small cell lung carcinoma. The tumor measures 4 centimeters in its largest dimension and is not invading any surrounding structures. However, there are metastases in the ipsilateral hilar lymph nodes, and no distant metastases have been found. What is the TNM score for this patient, considering the primary tumor (T), regional lymph nodes (N), and distant metastases (M)?
Your Answer: T2 N2 M0
Correct Answer: T2 N1 M0
Explanation:It is crucial to have knowledge about the TNM system for staging lung cancer. The absence of distant metastases eliminates one of the options immediately (as M must be 0).
The size and invasion of the tumor are significant factors:
– T1 is less than 3 cm
– T2 is between 3 cm and 7 cm
– T3 is more than 7 cm and/or involves invasion of the chest wall, parietal pleura, diaphragm, phrenic nerve, mediastinal pleura, or parietal pericardium
– T4 can be any size but involves invasion of other structuresTo differentiate between N1 and N2, remember that N1 involves ipsilateral hilar or peribronchial lymph nodes, while N2 involves ipsilateral mediastinal and/or subcarinal lymph nodes.
Small Cell Lung Cancer: Characteristics and Management
Small cell lung cancer is a type of lung cancer that usually develops in the central part of the lungs and arises from APUD cells. This type of cancer is often associated with the secretion of hormones such as ADH and ACTH, which can cause hyponatremia and Cushing’s syndrome, respectively. In addition, ACTH secretion can lead to bilateral adrenal hyperplasia and hypokalemic alkalosis due to high levels of cortisol. Patients with small cell lung cancer may also experience Lambert-Eaton syndrome, which is characterized by antibodies to voltage-gated calcium channels causing a myasthenic-like syndrome.
Management of small cell lung cancer depends on the stage of the disease. Patients with very early stage disease may be considered for surgery, while those with limited disease typically receive a combination of chemotherapy and radiotherapy. Patients with more extensive disease are offered palliative chemotherapy. Unfortunately, most patients with small cell lung cancer are diagnosed with metastatic disease, making treatment more challenging.
Overall, small cell lung cancer is a complex disease that requires careful management and monitoring. Early detection and treatment can improve outcomes, but more research is needed to better understand the underlying mechanisms of this type of cancer.
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This question is part of the following fields:
- Respiratory System
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Question 50
Correct
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A 24-year-old man is being evaluated at the respiratory clinic for possible bronchiectasis. He has a history of recurrent chest infections since childhood and has difficulty maintaining a healthy weight. Despite using inhalers, he has not experienced any significant improvement. Genetic testing has been ordered to investigate the possibility of cystic fibrosis.
What is the typical role of the cystic fibrosis transmembrane conductance regulator?Your Answer: Chloride channel
Explanation:The chloride channel, specifically a cyclic-AMP regulated chloride channel, is the correct answer. Cystic fibrosis can be caused by various mutations, but they all affect the same gene, the cystic fibrosis transmembrane conductance regulator gene. This gene encodes a chloride channel that, when dysfunctional, results in increased viscosity of secretions and the development of cystic fibrosis.
Understanding Cystic Fibrosis
Cystic fibrosis is a genetic disorder that causes thickened secretions in the lungs and pancreas. It is an autosomal recessive condition that occurs due to a defect in the cystic fibrosis transmembrane conductance regulator gene (CFTR), which regulates a chloride channel. In the UK, 80% of CF cases are caused by delta F508 on chromosome 7, and the carrier rate is approximately 1 in 25.
CF patients are at risk of colonization by certain organisms, including Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia (previously known as Pseudomonas cepacia), and Aspergillus. These organisms can cause infections and exacerbate symptoms in CF patients. It is important for healthcare providers to monitor and manage these infections to prevent further complications.
Overall, understanding cystic fibrosis and its associated risks can help healthcare providers provide better care for patients with this condition.
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This question is part of the following fields:
- Respiratory System
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Question 51
Correct
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A 55-year-old man presents to his doctor with complaints of vertigo, which worsens when he rolls over in bed. The doctor diagnoses him with benign paroxysmal positional vertigo.
What treatment options are available to alleviate the symptoms of this condition?Your Answer: Epley manoeuvre
Explanation:The Epley manoeuvre is a treatment for BPPV, while the Dix-Hallpike manoeuvre is used for diagnosis. The Epley manoeuvre aims to move fluid in the inner ear to dislodge otoliths, while the Dix-Hallpike manoeuvre involves observing the patient for nystagmus when swiftly lowered from a sitting to supine position. Tinel’s sign is positive in those with carpal tunnel syndrome, where tapping the median nerve over the flexor retinaculum causes paraesthesia. The Trendelenburg test is used to assess venous valve competency in patients with varicose veins.
Benign paroxysmal positional vertigo (BPPV) is a common cause of vertigo that occurs suddenly when there is a change in head position. It is more prevalent in individuals over the age of 55 and is less common in younger patients. Symptoms of BPPV include dizziness and vertigo, which can be accompanied by nausea. Each episode typically lasts for 10-20 seconds and can be triggered by rolling over in bed or looking upwards. A positive Dix-Hallpike manoeuvre, which is indicated by vertigo and rotatory nystagmus, can confirm the diagnosis of BPPV.
Fortunately, BPPV has a good prognosis and usually resolves on its own within a few weeks to months. Treatment options include the Epley manoeuvre, which is successful in around 80% of cases, and vestibular rehabilitation exercises such as the Brandt-Daroff exercises. While medication such as Betahistine may be prescribed, it tends to have limited effectiveness. However, it is important to note that around half of individuals with BPPV may experience a recurrence of symptoms 3-5 years after their initial diagnosis.
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This question is part of the following fields:
- Respiratory System
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Question 52
Incorrect
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What is the accurate embryonic source of the stapes?
Your Answer: Fifth pharyngeal arch
Correct Answer: Second pharyngeal arch
Explanation:The stapes, which is a cartilaginous element in the ear, originates from the ectoderm covering the outer aspect of the second pharyngeal arch. This strip of ectoderm is located lateral to the metencephalic neural fold. Reicherts cartilage, which extends from the otic capsule to the midline on each side, is responsible for the formation of the stapes. The cartilages of the first and second pharyngeal arches articulate superior to the tubotympanic recess, with the malleus, incus, and stapes being formed from these cartilages. While the malleus is mostly formed from the first arch, the stapes is most likely to arise from the second arch.
The Development and Contributions of Pharyngeal Arches
During the fourth week of embryonic growth, a series of mesodermal outpouchings develop from the pharynx, forming the pharyngeal arches. These arches fuse in the ventral midline, while pharyngeal pouches form on the endodermal side between the arches. There are six pharyngeal arches, with the fifth arch not contributing any useful structures and often fusing with the sixth arch.
Each pharyngeal arch has its own set of muscular and skeletal contributions, as well as an associated endocrine gland, artery, and nerve. The first arch contributes muscles of mastication, the maxilla, Meckel’s cartilage, and the incus and malleus bones. The second arch contributes muscles of facial expression, the stapes bone, and the styloid process and hyoid bone. The third arch contributes the stylopharyngeus muscle, the greater horn and lower part of the hyoid bone, and the thymus gland. The fourth arch contributes the cricothyroid muscle, all intrinsic muscles of the soft palate, the thyroid and epiglottic cartilages, and the superior parathyroids. The sixth arch contributes all intrinsic muscles of the larynx (except the cricothyroid muscle), the cricoid, arytenoid, and corniculate cartilages, and is associated with the pulmonary artery and recurrent laryngeal nerve.
Overall, the development and contributions of pharyngeal arches play a crucial role in the formation of various structures in the head and neck region.
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This question is part of the following fields:
- Respiratory System
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Question 53
Incorrect
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A 25-year-old man who is an avid cyclist has been admitted to the hospital with a severe asthma attack. He is currently in the hospital for two days and is able to speak in complete sentences. His bedside oxygen saturation is at 98%, and he has a heart rate of 58 bpm, blood pressure of 110/68 mmHg, and a respiratory rate of 14 bpm. He is not experiencing any fever. Upon physical examination, there are no notable findings. The blood gas results show a PaO2 of 5.4 kPa (11.3-12.6), PaCO2 of 6.0 kPa (4.7-6.0), pH of 7.38 (7.36-7.44), and HCO3 of 27 mmol/L (20-28). What could be the possible explanation for these results?
Your Answer: Pulmonary embolism
Correct Answer: Venous sample
Explanation:Suspecting Venous Blood Sample with Low PaO2 and Good Oxygen Saturation
A low PaO2 level accompanied by a good oxygen saturation reading may indicate that the blood sample was taken from a vein rather than an artery. This suspicion is further supported if the patient appears to be in good health. It is unlikely that a faulty pulse oximeter is the cause of the discrepancy in readings. Therefore, it is important to consider the possibility of a venous blood sample when interpreting these results. Proper identification of the type of blood sample is crucial in accurately diagnosing and treating the patient’s condition.
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This question is part of the following fields:
- Respiratory System
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Question 54
Correct
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A 25-year-old female presents to the emergency department with complaints of shortness of breath that started 2 hours ago. She has no medical history. The results of her arterial blood gas (ABG) test are as follows:
Normal range
pH: 7.49 (7.35 - 7.45)
pO2: 12.2 (10 - 14)kPa
pCO2: 3.4 (4.5 - 6.0)kPa
HCO3: 22 (22 - 26)mmol/l
BE: +2 (-2 to +2)mmol/l
Her temperature is 37ÂșC, and her pulse is 98 beats/minute and regular. Based on this information, what is the most likely diagnosis?Your Answer: Anxiety hyperventilation
Explanation:The patient is exhibiting symptoms and ABG results consistent with respiratory alkalosis. However, it is important to conduct a thorough history and physical examination to rule out any underlying pulmonary pathology or infection. Based on the patient’s history, anxiety-induced hyperventilation is the most probable cause of her condition.
Respiratory Alkalosis: Causes and Examples
Respiratory alkalosis is a condition that occurs when the blood pH level rises above the normal range due to excessive breathing. This can be caused by various factors, including anxiety, pulmonary embolism, CNS disorders, altitude, and pregnancy. Salicylate poisoning can also lead to respiratory alkalosis, but it may also cause metabolic acidosis in the later stages. In this case, the respiratory centre is stimulated early, leading to respiratory alkalosis, while the direct acid effects of salicylates combined with acute renal failure may cause acidosis later on. It is important to identify the underlying cause of respiratory alkalosis to determine the appropriate treatment. Proper management can help prevent complications and improve the patient’s overall health.
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This question is part of the following fields:
- Respiratory System
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Question 55
Correct
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A 56-year-old woman comes to the clinic complaining of a persistent cough and increased production of sputum over the past year. She also reports feeling fatigued and experiencing shortness of breath. The patient mentions having had four chest infections in the last 12 months, all of which were treated with antibiotics. She has no personal or family history of lung issues and has never smoked.
The healthcare provider suspects that bronchiectasis may be the underlying cause of her symptoms and orders appropriate tests.
Which test is most likely to provide a definitive diagnosis?Your Answer: High-resolution computerised tomography
Explanation:Bronchiectasis can be diagnosed through various methods, including chest radiography, histopathology, and pulmonary function tests.
Chest radiography can reveal thickened bronchial walls, cystic lesions with fluid levels, collapsed areas with crowded pulmonary vasculature, and scarring, which are characteristic features of bronchiectasis.
Histopathology, which is a more invasive investigation often done through autopsy or surgery, can show irreversible dilation of bronchial airways and bronchial wall thickening.
However, high-resolution computerised tomography is a more favorable imaging technique as it is less invasive than histopathology.
Pulmonary function tests are commonly used to diagnose bronchiectasis, but they should be used in conjunction with other investigations as they are not sensitive or specific enough to provide sufficient diagnostic evidence on their own. An obstructive pattern is the most common pattern encountered, but a restrictive pattern is also possible.
Understanding the Causes of Bronchiectasis
Bronchiectasis is a condition characterized by the permanent dilation of the airways due to chronic inflammation or infection. There are various factors that can lead to this condition, including post-infective causes such as tuberculosis, measles, pertussis, and pneumonia. Cystic fibrosis, bronchial obstruction caused by lung cancer or foreign bodies, and immune deficiencies like selective IgA and hypogammaglobulinaemia can also contribute to bronchiectasis. Additionally, allergic bronchopulmonary aspergillosis (ABPA), ciliary dyskinetic syndromes like Kartagener’s syndrome and Young’s syndrome, and yellow nail syndrome are other potential causes. Understanding the underlying causes of bronchiectasis is crucial in developing effective treatment plans for patients.
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This question is part of the following fields:
- Respiratory System
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Question 56
Correct
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A 57-year-old woman arrives at the emergency department complaining of difficulty breathing. She has a medical history of idiopathic interstitial lung disease. Upon examination, her temperature is 37.1ÂșC, oxygen saturation is 76% on air, heart rate is 106 beats per minute, respiratory rate is 26 breaths per minute, and blood pressure is 116/60 mmHg.
What pulmonary alteration would take place in response to her low oxygen saturation?Your Answer: Pulmonary artery vasoconstriction
Explanation:Hypoxia causes vasoconstriction in the pulmonary arteries, which can lead to pulmonary artery hypertension in patients with chronic lung disease and chronic hypoxia. Diffuse bronchoconstriction is not a response to hypoxia, but may cause hypoxia in conditions such as acute asthma exacerbation. Hypersecretion of mucus from goblet cells is a characteristic finding in chronic inflammatory lung diseases, but is not a response to hypoxia. Pulmonary artery vasodilation occurs around well-ventilated alveoli to optimize oxygen uptake into the blood.
The Effects of Hypoxia on Pulmonary Arteries
When the partial pressure of oxygen in the blood decreases, the pulmonary arteries undergo vasoconstriction. This means that the blood vessels narrow, allowing blood to be redirected to areas of the lung that are better aerated. This response is a natural mechanism that helps to improve the efficiency of gaseous exchange in the lungs. By diverting blood to areas with more oxygen, the body can ensure that the tissues receive the oxygen they need to function properly. Overall, hypoxia triggers a physiological response that helps to maintain homeostasis in the body.
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This question is part of the following fields:
- Respiratory System
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Question 57
Incorrect
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A 16-year-old girl presents to the Emergency department with her mother. The mother reports that her daughter has been experiencing worsening breathlessness and facial puffiness for the past 30 minutes. Apart from eczema, the girl has been healthy and is currently taking oral contraceptives. On examination, the girl appears to be in distress, with laboured breathing and stridor but no wheezing. What is the probable cause of her breathlessness?
Your Answer: Pulmonary embolism
Correct Answer: Angio-oedema
Explanation:Noisy Breathing and Atopy in Adolescents
The presence of noisy breathing in an adolescent may indicate the possibility of stridor, which can be caused by an allergic reaction even in an otherwise healthy individual. The history of atopy, or a tendency to develop allergic reactions, further supports the diagnosis of angio-oedema. The sudden onset of symptoms also adds to the likelihood of this diagnosis.
While asthma is a possible differential diagnosis, it typically presents with expiratory wheezing. However, if the chest is silent, it may indicate a severe and life-threatening form of asthma. Therefore, it is important to consider all possible causes of noisy breathing and atopy in adolescents to ensure prompt and appropriate treatment.
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This question is part of the following fields:
- Respiratory System
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Question 58
Incorrect
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A 50-year-old female presents to her GP with complaints of shortness of breath and weakness during mild-moderate exercise. She reports that these episodes have been getting progressively worse and now often result in dizziness. The patient has no significant medical history but was a previous smoker for 15 years, smoking 15 cigarettes per day. Spirometry testing reveals a restrictive lung pattern. What is the most probable diagnosis?
Your Answer: Chronic obstructive pulmonary disease (COPD)
Correct Answer: Myasthenia gravis
Explanation:Myasthenia gravis can result in a restrictive pattern of lung disease due to weakness of the respiratory muscles, which causes difficulty in breathing air in. Asthma and COPD are incorrect as they cause an obstructive pattern on spirometry, with asthma being characterized by small bronchiole obstruction from inflammation and increased mucus production, and COPD causing small airway inflammation and emphysema that restricts outward airflow. Alpha-1 antitrypsin deficiency also leads to an obstructive pattern, as it results in pulmonary tissue degradation and panlobular emphysema.
Understanding the Differences between Obstructive and Restrictive Lung Diseases
Obstructive and restrictive lung diseases are two distinct categories of respiratory conditions that affect the lungs in different ways. Obstructive lung diseases are characterized by a reduction in the flow of air through the airways due to narrowing or blockage, while restrictive lung diseases are characterized by a decrease in lung volume or capacity, making it difficult to breathe in enough air.
Spirometry is a common diagnostic tool used to differentiate between obstructive and restrictive lung diseases. In obstructive lung diseases, the ratio of forced expiratory volume in one second (FEV1) to forced vital capacity (FVC) is less than 80%, indicating a reduced ability to exhale air. In contrast, restrictive lung diseases are characterized by an FEV1/FVC ratio greater than 80%, indicating a reduced ability to inhale air.
Examples of obstructive lung diseases include chronic obstructive pulmonary disease (COPD), chronic bronchitis, and emphysema, while asthma and bronchiectasis are also considered obstructive. Restrictive lung diseases include intrapulmonary conditions such as idiopathic pulmonary fibrosis, extrinsic allergic alveolitis, and drug-induced fibrosis, as well as extrapulmonary conditions such as neuromuscular diseases, obesity, and scoliosis.
Understanding the differences between obstructive and restrictive lung diseases is important for accurate diagnosis and appropriate treatment. While both types of conditions can cause difficulty breathing, the underlying causes and treatment approaches can vary significantly.
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This question is part of the following fields:
- Respiratory System
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Question 59
Incorrect
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A 35-year-old woman presents to the medical assessment unit with sudden onset shortness of breath. She reports no cough or fever and has no other associated symptoms. She recently returned from a hiking trip in France and takes the oral contraceptive pill but no other regular medications. She smokes 10 cigarettes a day but drinks no alcohol. On examination, she is tachypnoeic and tachycardic with an elevated JVP. Her calves are soft and non-tender with no pitting oedema. Initial blood tests show a positive D-dimer and elevated CRP. What is the appropriate treatment for this patient?
Your Answer: Intravenous unfractionated heparin
Correct Answer: Low molecular weight heparin
Explanation:Treatment for Suspected Pulmonary Embolism
When a patient presents with risk factors for pulmonary embolism (PE) such as recent travel and oral contraceptive pill use, along with symptoms like tachypnea, tachycardia, and hypoxia, it is important to consider the possibility of a significant PE. In such cases, treatment with low molecular weight heparin should be given promptly to prevent further complications. A low-grade fever is also common in venothromboembolic disease. Elevated JVP signifies significant right heart strain due to a significant PE, but maintained blood pressure is a positive sign.
The most common ECG finding in PE is an isolated sinus tachycardia, while the CXR may be clear, but prominent pulmonary arteries reflect pulmonary hypertension due to clot load in the pulmonary tree. A D-dimer test is recommended if the Wells score for PE is less than 4.
According to NICE guidelines on venous thromboembolic diseases, low molecular weight heparin is the appropriate initial treatment for suspected PE. It is important not to delay treatment to await CTPA unless it can be performed immediately. There is no evidence of pneumonia to warrant IV antibiotics. Unfractionated heparin may be considered for patients with an eGFR of less than 30, high risk of bleeding, or those undergoing thrombolysis, but this is not the case with this patient. Thrombolysis is not indicated unless there is haemodynamic instability, even in suspected large PEs.
In summary, prompt treatment with low molecular weight heparin is crucial in suspected cases of PE, and other treatment options should be considered based on individual patient factors.
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This question is part of the following fields:
- Respiratory System
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Question 60
Incorrect
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Which one of the following is true regarding the phrenic nerves?
Your Answer: They are derived from spinal roots C 2,3,4
Correct Answer: They both lie anterior to the hilum of the lungs
Explanation:The phrenic nerves, located in the anterior region of the lung’s hilum, play a crucial role in keeping the diaphragm functioning properly. These nerves have both sensory and motor functions, and any issues in the sub diaphragmatic area may result in referred pain in the shoulder.
The Phrenic Nerve: Origin, Path, and Supplies
The phrenic nerve is a crucial nerve that originates from the cervical spinal nerves C3, C4, and C5. It supplies the diaphragm and provides sensation to the central diaphragm and pericardium. The nerve passes with the internal jugular vein across scalenus anterior and deep to the prevertebral fascia of the deep cervical fascia.
The right phrenic nerve runs anterior to the first part of the subclavian artery in the superior mediastinum and laterally to the superior vena cava. In the middle mediastinum, it is located to the right of the pericardium and passes over the right atrium to exit the diaphragm at T8. On the other hand, the left phrenic nerve passes lateral to the left subclavian artery, aortic arch, and left ventricle. It passes anterior to the root of the lung and pierces the diaphragm alone.
Understanding the origin, path, and supplies of the phrenic nerve is essential in diagnosing and treating conditions that affect the diaphragm and pericardium.
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This question is part of the following fields:
- Respiratory System
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