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Question 1
Correct
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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: 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 2
Correct
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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: 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 3
Incorrect
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A 45-year-old businessman is admitted to the emergency department with suspected pneumonia following a lower respiratory tract infection. The patient had returned to the UK three days ago from a business trip to China. He reports experiencing a productive cough and feeling extremely fatigued and short of breath upon waking up. He has no significant medical history and is a non-smoker and non-drinker.
He is taken for a chest X-ray, where he learns that several of his colleagues who were on the same business trip have also been admitted to the emergency department with similar symptoms. The X-ray shows opacification in the right middle and lower zones, indicating consolidation. Initial blood tests reveal hyponatraemia and lymphopenia. Based on his presentation and X-ray findings, he is diagnosed with pneumonia.
Which organism is most likely responsible for causing his pneumonia?Your Answer: Streptococcus pneumoniae
Correct Answer: Legionella pneumophila
Explanation:If multiple individuals in an air conditioned space develop pneumonia, Legionella pneumophila should be considered as a possible cause. Legionella pneumophila is often associated with hyponatremia and lymphopenia. Haemophilus influenzae is a frequent cause of lower respiratory tract infections in patients with COPD. Klebsiella pneumoniae is commonly found in patients with alcohol dependence. Pneumocystis jiroveci is typically observed in HIV-positive patients and is characterized by a dry cough and desaturation during exercise.
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 4
Incorrect
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A 65-year-old man with uncontrolled diabetes complains of severe otalgia and headaches. During examination, granulation tissue is observed in the external auditory meatus. What is the probable causative agent of the infection?
Your Answer:
Correct Answer: Pseudomonas aeruginosa
Explanation:The primary cause of malignant otitis externa is typically Pseudomonas aeruginosa. Symptoms of this condition include intense pain, headaches, and the presence of granulation tissue in the external auditory meatus. Individuals with diabetes mellitus are at a higher risk for developing this condition.
Malignant Otitis Externa: A Rare but Serious Infection
Malignant otitis externa is a type of ear infection that is uncommon but can be serious. It is typically found in individuals who are immunocompromised, with 90% of cases occurring in diabetics. The infection starts in the soft tissues of the external auditory meatus and can progress to involve the soft tissues and bony ear canal, eventually leading to temporal bone osteomyelitis.
Key features in the patient’s history include diabetes or immunosuppression, severe and persistent ear pain, temporal headaches, and purulent otorrhea. In some cases, patients may also experience dysphagia, hoarseness, and facial nerve dysfunction.
Diagnosis is typically done through a CT scan, and non-resolving otitis externa with worsening pain should be referred urgently to an ENT specialist. Treatment involves intravenous antibiotics that cover pseudomonal infections.
In summary, malignant otitis externa is a rare but serious infection that requires prompt diagnosis and treatment. Patients with diabetes or immunosuppression should be particularly vigilant for symptoms and seek medical attention if they experience persistent ear pain or other related symptoms.
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This question is part of the following fields:
- Respiratory System
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Question 5
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:
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 6
Incorrect
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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:
Correct 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 7
Incorrect
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A 38-year-old man has been admitted to the ICU through the ED with reduced consciousness and cyanosis. Despite an oxygen saturation of 94% in the ED, both peripheral and central cyanosis were present. Arterial blood gas monitoring revealed significant hypoxia, but no evidence of methaemoglobin. The suspected diagnosis is carbon monoxide poisoning, and the patient is intubated and ventilated to prevent further leftward shift of the oxygen dissociation curve. What factors can cause this shift in the oxygen dissociation curve?
Your Answer:
Correct Answer: Hypocapnia
Explanation:The oxygen dissociation curve can be shifted to the left by low pCO2, which increases haemoglobin’s affinity for oxygen and makes it less likely to release oxygen to the tissues. In contrast, acidosis, hypercapnia, and hyperthermia cause a right shift of the curve, making it easier for oxygen to be released to the tissues. Raised levels of 2,3-diphosphoglycerate also shift the curve to the right by inhibiting oxygen binding to haemoglobin.
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 8
Incorrect
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A 59-year-old man comes to see his GP complaining of vertigo that has been going on for three days. He also reports experiencing left-sided ear pain and a change in his sense of taste, as well as constant ringing in his left ear. He took paracetamol on his own, but the vertigo persisted, so he decided to seek medical attention.
During the examination, the doctor observes that the man has a drooping left face with involvement of the forehead. Upon otoscopic examination, vesicles are seen in the external auditory canal of the left ear. A neurological examination is performed, which is normal except for the left facial paralysis.
What is the appropriate treatment for this man's condition?Your Answer:
Correct Answer: Oral acyclovir and corticosteroids
Explanation:Ramsay Hunt syndrome is treated with a combination of oral acyclovir and corticosteroids. This condition is caused by the varicella zoster virus, as evidenced by the presence of vesicles on the left ear and involvement of the seventh and eighth cranial nerves. Symptoms include facial paralysis and hearing impairments. Treatment typically involves a seven to ten day course of oral acyclovir and a five day course of corticosteroids, such as prednisolone.
It is important to note that oseltamivir (tamiflu) is an antiviral used for influenzae, while chloroquine is typically used for malaria. Amoxicillin is an antibiotic and is not effective in treating viral infections. While corticosteroids can provide relief from inflammation, they are not the primary treatment for Ramsay Hunt syndrome when used alone.
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 9
Incorrect
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A 33-year-old male presents to the ED with coughing and wheezing following an episode of alcohol intoxication. Upon examination, decreased breath sounds are noted on one side. Imaging reveals a foreign body obstructing an airway structure. What is the most probable location for this foreign body to be lodged?
Your Answer:
Correct Answer: Right mainstem bronchus
Explanation:It is rare for a foreign object to become lodged in the left mainstem bronchus due to its greater angle compared to the right mainstem bronchus. A tracheal obstruction would cause reduced breath sounds bilaterally, not just on one side. The right superior lobar bronchus is also unlikely to be affected due to its angle and direction. Therefore, foreign bodies typically get stuck in the right mainstem bronchus in adults because of its wider diameter and lesser angle.
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 10
Incorrect
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As the pregnancy progresses, at what stage does the foetus typically begin producing surfactant?
A mother has been informed that she will have to deliver her baby prematurely due to complications in the pregnancy. To decrease the chances of neonatal distress syndrome, doctors have administered steroids to stimulate surfactant production in the foetus. They clarify that the foetus is already generating its own surfactant, and these steroids will enhance the process.Your Answer:
Correct Answer: Week 22
Explanation:Lung development in humans begins at week 4 with the formation of the respiratory diverticulum. By week 10, the lungs start to grow as tertiary bronchial buds form. Terminal bronchioles begin to form around week 18. The saccular stage of lung development, which marks the earliest viability for a human fetus, occurs at around 22-24 weeks when type 2 alveolar cells start producing surfactant. By week 30, the primary alveoli form as the mesenchyme surrounding the lungs becomes highly vascular.
The Importance of Pulmonary Surfactant in Breathing
Pulmonary surfactant is a substance composed of phospholipids, carbohydrates, and proteins that is released by type 2 pneumocytes. Its main component, dipalmitoyl phosphatidylcholine (DPPC), plays a crucial role in reducing alveolar surface tension. This substance is first detectable around 28 weeks and increases in concentration as the alveoli decrease in size. This helps prevent the alveoli from collapsing and reduces the muscular force needed to expand the lungs, ultimately decreasing the work of breathing. Additionally, pulmonary surfactant lowers the elastic recoil at low lung volumes, preventing the alveoli from collapsing at the end of each expiration. Overall, pulmonary surfactant is essential in maintaining proper lung function and preventing respiratory distress.
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This question is part of the following fields:
- Respiratory System
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Question 11
Incorrect
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A 35-year-old woman presents with sudden chest pain and difficulty breathing. She recently returned from a trip to Italy with her family. She has no significant medical history but takes oral contraceptives. On examination, her pulse is 100 bpm, temperature is 37°C, oxygen saturation is 95%, respiratory rate is 28/min, and blood pressure is 116/76 mmHg. Chest examination is unremarkable and chest x-ray is normal. What is the most appropriate diagnostic test to confirm the diagnosis?
Your Answer:
Correct Answer: CT pulmonary angiogram (CTPA)
Explanation:Diagnosis of Pulmonary Embolism in a Woman with Chest Pain and Dyspnoea
This woman is experiencing chest pain and difficulty breathing, with a rapid heart rate and breathing rate. However, there are no visible signs on chest examination and her chest x-ray appears normal. Despite having no fever, her oxygen levels are lower than expected for a healthy person. To rule out a pulmonary embolism, doctors must consider risk factors such as recent air travel and use of oral contraceptives.
The gold standard for diagnosing a pulmonary embolism is a CT pulmonary angiogram, as it can detect even large saddle embolus near the pulmonary arteries. While VQ scanning was previously used, it can miss these larger emboli. Additionally, doctors may perform Doppler ultrasounds of the venous system to check for deep vein thrombosis.
This presentation is not indicative of atypical pneumonia, such as Legionella, as the patient’s temperature would be expected to be high and chest signs would be present. Overall, a thorough evaluation is necessary to accurately diagnose and treat a pulmonary embolism in a patient with chest pain and dyspnoea.
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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 man visits his GP complaining of shortness of breath, haemoptysis, and unintentional weight loss over the past 3 months. The GP refers him to the respiratory clinic for suspected lung cancer, and further investigations reveal a stage 2 squamous cell carcinoma of the lung. What is the most frequently associated paraneoplastic phenomenon with this type of cancer?
Your Answer:
Correct Answer: Parathyroid hormone-related protein (PTHrP)
Explanation:The correct answer is PTHrP, which is a paraneoplastic syndrome often associated with squamous cell lung cancer. PTHrP is a protein that functions similarly to parathyroid hormone and can cause hypercalcaemia when secreted by cancer cells.
Acanthosis nigricans is another paraneoplastic phenomenon that is commonly associated with gastric adenocarcinoma. This condition causes hyperpigmentation of skin folds, such as the armpits.
The syndrome of inappropriate ADH secretion is often linked to small cell lung cancer. This condition involves the hypersecretion of ADH, which leads to dilutional hyponatraemia and its associated symptoms.
Carcinoid syndrome is a paraneoplastic syndrome that is typically associated with neuroendocrine tumours that have metastasised to the liver. This condition causes hypersecretion of serotonin and other substances, resulting in facial flushing, palpitations, and gastrointestinal upset.
Lung cancer can present with paraneoplastic features, which are symptoms caused by the cancer but not directly related to the tumor itself. Small cell lung cancer can cause the secretion of ADH and, less commonly, ACTH, which can lead to hypertension, hyperglycemia, hypokalemia, alkalosis, and muscle weakness. Lambert-Eaton syndrome is also associated with small cell lung cancer. Squamous cell lung cancer can cause the secretion of parathyroid hormone-related protein, leading to hypercalcemia, as well as clubbing and hypertrophic pulmonary osteoarthropathy. Adenocarcinoma can cause gynecomastia and hypertrophic pulmonary osteoarthropathy. Hypertrophic pulmonary osteoarthropathy is a painful condition involving the proliferation of periosteum in the long bones. Although traditionally associated with squamous cell carcinoma, some studies suggest that adenocarcinoma is the most common cause.
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This question is part of the following fields:
- Respiratory System
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Question 13
Incorrect
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An 80-year-old man with metastatic lung cancer arrives at the acute medical unit with sudden shortness of breath. A chest x-ray shows a malignant pleural effusion encasing the right lung. The medical registrar intends to perform a pleural tap to drain the effusion and send a sample to the lab. The registrar takes into account the effusion's position around the lung. What is the minimum level of the effusion in the mid-axillary line?
Your Answer:
Correct Answer: 10th rib
Explanation:The parietal pleura can be found at the 10th rib in the mid-axillary line, while the visceral pleura is closely attached to the lung tissue and can be considered as one. The location of the parietal pleura is more inferior than that of the visceral pleura, with the former being at the 8th rib in the midclavicular line and the 10th rib in the midaxillary line. The location of the parietal pleura in the scapular line is not specified.
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 14
Incorrect
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A 58-year-old man comes to the GP complaining of wheezing, coughing, and shortness of breath. He has a smoking history of 35 pack-years but has reduced his smoking recently.
The GP orders spirometry, which confirms a diagnosis of chronic obstructive pulmonary disease. The results also show an elevated functional residual capacity.
What is the method used to calculate this metric?Your Answer:
Correct Answer: Expiratory reserve volume + residual volume
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 15
Incorrect
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A 29-year-old man visits his primary care physician with complaints of a malodorous discharge from his right ear for the past 3 weeks. The patient also reports experiencing ear pain for the past 2 weeks and occasional mild dizziness. Upon examination, the skin around the ear and pinna appear normal, but the ear canal is filled with debris. After removing the debris, a small perforation and waxy debris are observed on the tympanic membrane.
The Rinne test indicates that bone conduction is better than air conduction on the right, and the Weber test shows sound lateralization to the right. The patient has no significant medical history and has never presented with an ear problem before.
What is the most likely condition based on this patient's clinical presentation?Your Answer:
Correct Answer: Cholesteatoma
Explanation:Cholesteatoma is a growth of non-cancerous squamous epithelium that can be observed as an ‘attic crust’ during otoscopy. This patient is displaying symptoms consistent with cholesteatoma, including ear discharge, earache, conductive hearing loss, and dizziness, which suggests that the inner ear has also been affected. It is important to distinguish cholesteatoma from otitis externa, as failure to diagnose cholesteatoma can lead to serious complications. Cholesteatoma can erode the ossicles bones, damage the inner ear and vestibulocochlear nerve, and even result in brain infections if it erodes through the skull bone.
Otitis externa is an inflammation of the outer ear canal that causes ear pain, which worsens with movement of the outer ear. It is often caused by the use of earplugs or swimming in unclean water. Otitis media is an inflammation of the middle ear that can lead to fluid accumulation and perforation of the tympanic membrane. It is common in children and often follows a viral upper respiratory tract infection. Myringitis is a condition associated with otitis media that causes small vesicles or cysts to form on the surface of the eardrum, resulting in severe pain and hearing impairment. It is caused by viral or bacterial infections and is treated with pain relief and antibiotics.
Understanding Cholesteatoma
Cholesteatoma is a benign growth of squamous epithelium that can cause damage to the skull base. It is most commonly found in individuals between the ages of 10 and 20 years old. Those born with a cleft palate are at a higher risk of developing cholesteatoma, with a 100-fold increase in risk.
The main symptoms of cholesteatoma include a persistent discharge with a foul odor and hearing loss. Other symptoms may occur depending on the extent of the growth, such as vertigo, facial nerve palsy, and cerebellopontine angle syndrome.
During otoscopy, a characteristic attic crust may be seen in the uppermost part of the eardrum.
Management of cholesteatoma involves referral to an ear, nose, and throat specialist for surgical removal. Early detection and treatment are important to prevent further damage to the skull base and surrounding structures.
In summary, cholesteatoma is a non-cancerous growth that can cause significant damage if left untreated. It is important to be aware of the symptoms and seek medical attention promptly if they occur.
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This question is part of the following fields:
- Respiratory System
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Question 16
Incorrect
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A 65-year-old male with a diagnosis of lung cancer presents with fatigue and lightheadedness. Upon examination, the following results are obtained:
Plasma sodium concentration 115 mmol/L (137-144)
Potassium 3.5 mmol/L (3.5-4.9)
Urea 3.2 mmol/L (2.5-7.5)
Creatinine 67 µmol/L (60-110)
What is the probable reason for his symptoms based on these findings?Your Answer:
Correct Answer: Syndrome of inappropriate ADH secretion
Explanation:Syndrome of Inappropriate ADH Secretion
Syndrome of inappropriate ADH secretion (SIADH) is a condition characterized by low levels of sodium in the blood. This is caused by the overproduction of antidiuretic hormone (ADH) by the posterior pituitary gland. Tumors such as bronchial carcinoma can cause the ectopic elaboration of ADH, leading to dilutional hyponatremia. The diagnosis of SIADH is one of exclusion, but it can be supported by a high urine sodium concentration with high urine osmolality.
Hypoadrenalism is less likely to cause hyponatremia, as it is usually associated with hyperkalemia and mild hyperuricemia. On the other hand, diabetes insipidus is a condition where the kidneys are unable to reabsorb water, leading to excessive thirst and urination.
It is important to diagnose and treat SIADH promptly to prevent complications such as seizures, coma, and even death. Treatment options include fluid restriction, medications to block the effects of ADH, and addressing the underlying cause of the condition.
In conclusion, SIADH is a condition that can cause low levels of sodium in the blood due to the overproduction of ADH. It is important to differentiate it from other conditions that can cause hyponatremia and to treat it promptly to prevent complications.
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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 19-year-old male is admitted with acute asthma. He has been treated with steroid, bronchodilators and 15 l/min of oxygen.
His pulse rate is 125/min, oxygen saturation 89%, respiratory rate 24/min, blood pressure 140/88 mmHg and he has a peak flow rate of 150 l/min. On auscultation of his chest, he has bilateral wheezes.
Arterial blood gas (ABG) result taken on 15 l/min oxygen shows:
pH 7.42 (7.36-7.44)
PaO2 8.4 kPa (11.3-12.6)
PaCO2 5.3 kPa (4.7-6.0)
Standard HCO3 19 mmol/L (20-28)
Base excess −4 (+/-2)
Oxygen saturation 89%
What is the most appropriate action for this man?Your Answer:
Correct Answer: Call ITU to consider intubation
Explanation:Urgent Need for Ventilation in Life-Threatening Asthma
This patient is experiencing life-threatening asthma with a dangerously low oxygen saturation level of less than 92%. Despite having a normal PaCO2 level, the degree of hypoxia is inappropriate and requires immediate consideration for ventilation. The arterial blood gas (ABG) result is consistent with the clinical presentation, making a venous blood sample unnecessary. Additionally, the ABG and bedside oxygen saturation readings are identical, indicating an arterialised sample.
It is crucial to note that in cases of acute asthma, reducing the amount of oxygen below the maximum available is not recommended. Hypoxia can be fatal and must be addressed promptly. Therefore, urgent intervention is necessary to ensure the patient’s safety and well-being.
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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 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:
Correct 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 19
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:
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 20
Incorrect
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What causes a cervical rib?
Your Answer:
Correct Answer: Elongation of the transverse processes of the 7th cervical vertebrae
Explanation:Cervical ribs are formed when the transverse process of the 7th cervical vertebrae becomes elongated, resulting in a fibrous band that connects to the first thoracic rib.
Cervical ribs are a rare anomaly that affects only 0.2-0.4% of the population. They are often associated with neurological symptoms and are caused by an anomalous fibrous band that originates from the seventh cervical vertebrae and may arc towards the sternum. While most cases are congenital and present around the third decade of life, some cases have been reported to occur following trauma. Bilateral cervical ribs are present in up to 70% of cases. Compression of the subclavian artery can lead to absent radial pulse and a positive Adsons test, which involves lateral flexion of the neck towards the symptomatic side and traction of the symptomatic arm. Treatment is usually only necessary when there is evidence of neurovascular compromise, and the traditional operative method for excision is a transaxillary approach.
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This question is part of the following fields:
- Respiratory System
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Question 21
Incorrect
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A 63-year-old man visits his GP complaining of worsening shortness of breath. He was diagnosed with COPD six years ago and has been frequently admitted to the emergency department due to lower respiratory tract infections, especially in the past year. He has a smoking history of 50 pack-years and currently smokes 20 cigarettes per day.
During the examination, the patient appears to be struggling to breathe even at rest and is in the tripod position. His heart rate is 78/min, blood pressure is 140/88 mmHg, oxygen saturation is 88% on air, respiratory rate is 26 breaths per minute, and temperature is 36.4ºC. His chest expansion is symmetrical, and breath sounds are equal throughout the lung fields.
Recent spirometry results show that his FEV1 was 47% a week ago, 53% a month ago, and 67% six months ago. What intervention would be most effective in slowing the decline of his FEV1?Your Answer:
Correct Answer: Smoking cessation
Explanation:Slowing the decrease in FEV1 in COPD can be most effectively achieved by quitting smoking.
The National Institute for Health and Care Excellence (NICE) updated its guidelines on the management of chronic obstructive pulmonary disease (COPD) in 2018. The guidelines recommend general management strategies such as smoking cessation advice, annual influenzae vaccination, and one-off pneumococcal vaccination. Pulmonary rehabilitation is also recommended for patients who view themselves as functionally disabled by COPD.
Bronchodilator therapy is the first-line treatment for patients who remain breathless or have exacerbations despite using short-acting bronchodilators. The next step is determined by whether the patient has asthmatic features or features suggesting steroid responsiveness. NICE suggests several criteria to determine this, including a previous diagnosis of asthma or atopy, a higher blood eosinophil count, substantial variation in FEV1 over time, and substantial diurnal variation in peak expiratory flow.
If the patient does not have asthmatic features or features suggesting steroid responsiveness, a long-acting beta2-agonist (LABA) and long-acting muscarinic antagonist (LAMA) should be added. If the patient is already taking a short-acting muscarinic antagonist (SAMA), it should be discontinued and switched to a short-acting beta2-agonist (SABA). If the patient has asthmatic features or features suggesting steroid responsiveness, a LABA and inhaled corticosteroid (ICS) should be added. If the patient remains breathless or has exacerbations, triple therapy (LAMA + LABA + ICS) should be offered.
NICE only recommends theophylline after trials of short and long-acting bronchodilators or to people who cannot use inhaled therapy. Azithromycin prophylaxis is recommended in select patients who have optimised standard treatments and continue to have exacerbations. Mucolytics should be considered in patients with a chronic productive cough and continued if symptoms improve.
Cor pulmonale features include peripheral oedema, raised jugular venous pressure, systolic parasternal heave, and loud P2. Loop diuretics should be used for oedema, and long-term oxygen therapy should be considered. Smoking cessation, long-term oxygen therapy in eligible patients, and lung volume reduction surgery in selected patients may improve survival in patients with stable COPD. NICE does not recommend the use of ACE-inhibitors, calcium channel blockers, or alpha blockers
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This question is part of the following fields:
- Respiratory System
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Question 22
Incorrect
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John, a 55-year-old man, arrives at the emergency department complaining of chest pain that is relieved by leaning forward. He also mentions that the pain spreads to his left shoulder. The diagnosis is pericarditis.
Which nerve is accountable for the referred pain in this case?Your Answer:
Correct Answer: Phrenic nerve
Explanation:The phrenic nerve provides motor innervation to the diaphragm and sensory innervation to the pleura and pericardium. Pericarditis can cause referred pain to the shoulder due to the supraclavicular nerves originating at C3-4. It is important to note that there are no pericardial nerves. The spinal accessory nerve innervates the trapezius and sternocleidomastoid muscles, while the trochlear nerve supplies the superior oblique muscle. Although the vagus nerve has various functions, it does not supply the pericardium.
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 23
Incorrect
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A 44-year-old heavy smoker presents with a productive cough and progressively worsening shortness of breath on exertion. The patient's spirometry results are forwarded to you in clinic for review.
Tidal volume (TV) = 400 mL.
Vital capacity (VC) = 3,300 mL.
Inspiratory capacity (IC) = 2,600 mL.
FEV1/FVC = 60%
Body plethysmography is undertaken, demonstrating a residual volume (RV) of 1,200 mL.
What is this patient's total lung capacity (TLC)?Your Answer:
Correct Answer: 4,500 mL
Explanation:To calculate the total lung capacity, one can add the vital capacity and residual volume. For example, if the vital capacity is 3300 mL and the residual volume is 1200 mL, the total lung capacity would be 4500 mL. It is important to note that tidal volume, inspiratory capacity, and the FEV1/FVC ratio are other measurements related to lung function. Residual volume refers to the amount of air left in the lungs after a maximal exhalation, while total lung capacity refers to the volume of air in the lungs after a maximal inhalation.
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 24
Incorrect
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A 25-year-old female patient visits your clinic complaining of hearing loss. According to her, her hearing has been declining for about two years, with her left ear being worse than the right. She struggles to hear her partner when he is on her left side. Additionally, she has been experiencing tinnitus in her left ear for a year. She mentions that her mother also has hearing difficulties and uses hearing aids on both ears. During the examination, the Rinne test shows a negative result on the left and a positive result on the right. On the other hand, the Weber test indicates that the sound is louder on the left. What is the probable impairment?
Your Answer:
Correct Answer: Conductive hearing loss on the left.
Explanation:Based on the results of the Weber and Rinne tests, the patient in the question is likely experiencing conductive hearing loss on the left side. The Weber test revealed that the patient hears sound better on the left side, which could indicate a conductive hearing loss or sensorineural hearing loss on the right side. However, the Rinne test was negative on the left side, indicating a conductive hearing loss. This is further supported by the patient’s reported symptoms of hearing loss in the left ear. This presentation, along with a family history of hearing loss, suggests a possible diagnosis of otosclerosis, a condition that affects the stapes bone and can lead to severe or total hearing loss.
Understanding the Different Causes of Deafness
Deafness can be caused by various factors, with ear wax, otitis media, and otitis externa being the most common. However, there are other conditions that can lead to hearing loss, each with its own characteristic features. Presbycusis, for instance, is age-related sensorineural hearing loss that often makes it difficult for patients to follow conversations. Otosclerosis, on the other hand, is an autosomal dominant condition that replaces normal bone with vascular spongy bone, causing conductive deafness, tinnitus, and a flamingo tinge in the tympanic membrane. Glue ear, also known as otitis media with effusion, is the most common cause of conductive hearing loss in children, while Meniere’s disease is characterized by recurrent episodes of vertigo, tinnitus, and sensorineural hearing loss. Drug ototoxicity, noise damage, and acoustic neuroma are other factors that can lead to deafness.
Understanding the different causes of deafness is crucial in diagnosing and treating the condition. By knowing the characteristic features of each condition, healthcare professionals can determine the appropriate interventions to help patients manage their hearing loss. It is also important for individuals to protect their hearing by avoiding exposure to loud noises and seeking medical attention when they experience any symptoms of hearing loss. With proper care and management, people with deafness can still lead fulfilling lives.
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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 26-year-old man has been experiencing a chronic cough and wheeze since starting a new job. He has noticed that his peak flow measurements are significantly reduced while at work but improve on the weekends. What substance is commonly linked to this type of asthma?
Your Answer:
Correct Answer: Isocyanates
Explanation:Occupational Asthma: Causes and Symptoms
Occupational asthma is a type of asthma that is caused by exposure to certain chemicals in the workplace. Patients may experience worsening asthma symptoms while at work or notice an improvement in symptoms when away from work. The most common cause of occupational asthma is exposure to isocyanates, which are found in spray painting and foam moulding using adhesives. Other chemicals associated with occupational asthma include platinum salts, soldering flux resin, glutaraldehyde, flour, epoxy resins, and proteolytic enzymes.
To diagnose occupational asthma, it is recommended to measure peak expiratory flow at work and away from work. If there is a significant difference in peak expiratory flow, referral to a respiratory specialist is necessary. Treatment may include avoiding exposure to the triggering chemicals and using medications to manage asthma symptoms. It is important for employers to provide a safe working environment and for employees to report any concerns about potential exposure to harmful chemicals.
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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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A 26-year-old man presents to the emergency department with a feeling of food stuck in his throat. He experienced this sensation 2 hours ago after consuming fish at a nearby seafood restaurant. The patient reports no breathing difficulties. Upon laryngoscopy, a fish bone is found lodged in the left piriform recess. While removing the fish bone, a nerve located deep to the mucosa covering the recess is damaged.
Which function is most likely to be affected in this individual?Your Answer:
Correct Answer: Cough reflex
Explanation:Foreign objects lodged in the piriform recess can cause damage to the internal laryngeal nerve, which is located just beneath a thin layer of mucosa covering the recess. This nerve plays a crucial role in the cough reflex, as it carries sensory information from the area above the vocal cords. Attempts to remove foreign objects from the piriform recess can also lead to nerve damage.
Other functions, such as mastication, the pharyngeal reflex, salivation, and taste sensation, are mediated by different nerves and are not directly related to the piriform recess or the internal laryngeal nerve.
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 27
Incorrect
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A 10-year-old boy is recuperating the day after a tonsillectomy. His parents report that he hasn't had anything to eat for 6 hours prior to the surgery and he is feeling famished. However, he is declining any attempts to consume food or water. There are no prescribed medications or known drug allergies listed on his medical records.
What would be the most appropriate first step to take?Your Answer:
Correct Answer: Prescribe analgesia and encourage oral intake
Explanation:Effective pain management is crucial after a tonsillectomy to promote the consumption of food and fluids.
Prescribing analgesics and encouraging oral intake is the best course of action. This will alleviate pain and enable the patient to eat and drink, which is essential for a speedy recovery.
Starting maintenance fluids or partial nutritional feeds, obtaining IV access, or waiting for two hours before reviewing the patient are not the most appropriate options. Analgesia should be the primary consideration to facilitate oral fluid therapy and promote healing.
Tonsillitis and Tonsillectomy: Complications and Indications
Tonsillitis is a condition that can lead to various complications, including otitis media, peritonsillar abscess, and, in rare cases, rheumatic fever and glomerulonephritis. Tonsillectomy, the surgical removal of the tonsils, is a controversial procedure that should only be considered if the person meets specific criteria. According to NICE, surgery should only be considered if the person experiences sore throats due to tonsillitis, has five or more episodes of sore throat per year, has been experiencing symptoms for at least a year, and the episodes of sore throat are disabling and prevent normal functioning. Other established indications for a tonsillectomy include recurrent febrile convulsions, obstructive sleep apnoea, stridor, dysphagia, and peritonsillar abscess if unresponsive to standard treatment.
Despite the benefits of tonsillectomy, the procedure also carries some risks. Primary complications, which occur within 24 hours of the surgery, include haemorrhage and pain. Secondary complications, which occur between 24 hours to 10 days after the surgery, include haemorrhage (most commonly due to infection) and pain. Therefore, it is essential to weigh the benefits and risks of tonsillectomy before deciding to undergo the procedure.
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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 72-year-old woman is brought to the stroke unit with a suspected stroke. She has a medical history of hypertension, type II diabetes, and hypothyroidism. Additionally, she experienced a myocardial infarction 4 years ago. Upon arrival, the patient exhibited a positive FAST result and an irregular breathing pattern. An urgent brain CT scan was performed and is currently under review. What region of the brainstem is responsible for regulating the fundamental breathing rhythm?
Your Answer:
Correct Answer: Medulla oblongata
Explanation:The medullary rhythmicity area in the medullary oblongata controls the basic rhythm of breathing through its inspiratory and expiratory neurons. During quiet breathing, the inspiratory area is active for approximately 2 seconds, causing the diaphragm and external intercostals to contract, followed by a period of inactivity lasting around 3 seconds as the muscles relax and there is elastic recoil. Additional brainstem regions can be stimulated to regulate various aspects of breathing, such as extending inspiration in the apneustic area (refer to the table below).
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 29
Incorrect
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A 65-year-old woman comes to the COPD clinic complaining of increasing breathlessness over the past 3 months. She is currently receiving long-term oxygen therapy at home.
During the examination, the patient's face appears plethoric, but there is no evidence of dyspnea at rest.
The patient's FEV1/FVC ratio remains unchanged at 0.4, and her peak flow is 50% of the predicted value. However, her transfer factor is unexpectedly elevated.
What could be the possible cause of this unexpected finding?Your Answer:
Correct Answer: Polycythaemia
Explanation:The transfer factor is typically low in most conditions that impair alveolar diffusion, except for polycythaemia, asthma, haemorrhage, and left-to-right shunts, which can cause an increased transfer of carbon monoxide. In this case, the patient’s plethoric facies suggest polycythaemia as the cause of their increased transfer factor. It’s important to note that exacerbations of COPD, pneumonia, and pulmonary fibrosis typically result in a low transfer factor, not an increased one.
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 30
Incorrect
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What is the accurate embryonic source of the stapes?
Your Answer:
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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