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  • Question 1 - A 55-year-old man is admitted to the ICU after emergency surgery for an...

    Incorrect

    • A 55-year-old man is admitted to the ICU after emergency surgery for an abdominal aortic aneurysm. He presents with abdominal pain and diarrhea and is in a critical condition. Despite the absence of peritonism, which of the following arterial blood gas patterns is most likely to be observed?

      Your Answer: pH 7.30, pO2 9.2 pCO2 4.8, Base excess -2, lactate 1

      Correct Answer: pH 7.20, pO2 9.0, pCO2 3.5, Base excess -10, Lactate 8

      Explanation:

      It is probable that this individual is experiencing metabolic acidosis as a result of a mesenteric infarction.

      Disorders of Acid-Base Balance

      The acid-base nomogram is a useful tool for categorizing the various disorders of acid-base balance. Metabolic acidosis is the most common surgical acid-base disorder, characterized by a reduction in plasma bicarbonate levels. This can be caused by a gain of strong acid or loss of base, and is classified according to the anion gap. A normal anion gap indicates hyperchloraemic metabolic acidosis, which can be caused by gastrointestinal bicarbonate loss, renal tubular acidosis, drugs, or Addison’s disease. A raised anion gap indicates lactate, ketones, urate, or acid poisoning. Metabolic alkalosis, on the other hand, is usually caused by a rise in plasma bicarbonate levels due to a loss of hydrogen ions or a gain of bicarbonate. It is mainly caused by problems of the kidney or gastrointestinal tract. Respiratory acidosis is characterized by a rise in carbon dioxide levels due to alveolar hypoventilation, while respiratory alkalosis is caused by hyperventilation resulting in excess loss of carbon dioxide. These disorders have various causes, such as COPD, sedative drugs, anxiety, hypoxia, and pregnancy.

    • This question is part of the following fields:

      • Respiratory System
      35.4
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  • Question 2 - A 26-year-old man has been experiencing a chronic cough and wheeze since starting...

    Incorrect

    • 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: Organophosphates (insecticides)

      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.

    • This question is part of the following fields:

      • Respiratory System
      3.7
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  • Question 3 - A 15-year-old boy presents to his GP with a painless swelling in his...

    Correct

    • A 15-year-old boy presents to his GP with a painless swelling in his neck. The mass is located centrally just below the hyoid bone and does not cause any difficulty in swallowing or breathing. Upon examination, the GP notes that the mass moves with protrusion of the tongue and with swallowing. The GP diagnoses the boy with a benign thyroglossal cyst, which is caused by a persistent thyroglossal duct, and advises surgical removal. Where is the thyroglossal duct attached to the tongue?

      Your Answer: Foramen cecum

      Explanation:

      The thyroglossal duct connects the thyroid gland to the tongue via the foramen caecum during embryonic development. The terminal sulcus, median sulcus, palatoglossal arch, and epiglottis are not connected to the thyroid gland.

      Understanding Thyroglossal Cysts

      Thyroglossal cysts are named after the thyroid and tongue, which are the two structures involved in their development. During embryology, the thyroid gland develops from the floor of the pharynx and descends into the neck, connected to the tongue by the thyroglossal duct. The foramen cecum is the point of attachment of the thyroglossal duct to the tongue. Normally, the thyroglossal duct atrophies, but in some people, it may persist and give rise to a thyroglossal duct cyst.

      Thyroglossal cysts are more common in patients under 20 years old and are usually midline, between the isthmus of the thyroid and the hyoid bone. They move upwards with protrusion of the tongue and may be painful if infected. Understanding the embryology and presentation of thyroglossal cysts is important for proper diagnosis and treatment.

    • This question is part of the following fields:

      • Respiratory System
      5.2
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  • Question 4 - A 67-year-old man is admitted to the acute stroke unit following a haemorrhagic...

    Incorrect

    • A 67-year-old man is admitted to the acute stroke unit following a haemorrhagic stroke. Three days after admission he complains of pain and swelling in the left calf. A Doppler ultrasound shows large DVT with extension into the upper leg. Given his recent stroke, anticoagulation is contraindicated, however, there is a significant risk of him developing a pulmonary embolus. The decision is made to insert an inferior vena cava (IVC) filter. The registrar inserting the filter is fairly junior, he plans to insert this just above the renal veins, however, asks the consultant if there are any landmarks he can use to guide him. The consultant advises him if he reaches the diaphragm he has gone too far!

      At which vertebral level would the diaphragm be encountered when inserting an IVC filter?

      Your Answer:

      Correct Answer: T8

      Explanation:

      The point at which the inferior vena cava passes through the diaphragm is being asked in this question. The correct answer is T8, which is where the IVC crosses the diaphragm through the caval opening. The IVC is formed by the joining of the left and right common iliac veins at around L5.

      In patients who are at high risk of pulmonary embolus and for whom anticoagulation is not effective or contraindicated, an IVC filter can be used. This filter is usually inserted above the renal veins, but it can be placed at any level, including the superior vena cava, if necessary.

      The other options provided in the question, T6, T10, and T11, are not associated with any significant structures. The oesophagus passes through the diaphragm with the vagal trunk at T10.

      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.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 5 - A 27-year-old man with a history of epilepsy is admitted to the hospital...

    Incorrect

    • A 27-year-old man with a history of epilepsy is admitted to the hospital after experiencing a tonic-clonic seizure. He is currently taking sodium valproate as his only medication. A venous blood gas is obtained immediately.

      What are the expected venous blood gas results for this patient?

      Your Answer:

      Correct Answer: Low pH, high lactate, low SaO2

      Explanation:

      Acidosis shifts the oxygen dissociation curve to the right, which enhances oxygen delivery to the tissues by causing more oxygen to dissociate from Hb. postictal lactic acidosis is a common occurrence in patients with tonic-clonic seizures, and it is typically managed by monitoring for spontaneous resolution. During a seizure, tissue hypoxia can cause lactic acidosis. Therefore, a venous blood gas test for this patient should show low pH, high lactate, and low SaO2.

      If the venous blood gas test shows a high pH, normal lactate, and low SaO2, it would not be consistent with postictal lactic acidosis. This result indicates alkalosis, which can be caused by gastrointestinal losses, renal losses, or Cushing syndrome.

      A high pH, normal lactate, and normal SaO2 would also be inconsistent with postictal lactic acidosis because tissue hypoxia would cause an increase in lactate levels.

      Similarly, low pH, high lactate, and normal SaO2 would not be expected in postictal lactic acidosis because acidosis would shift the oxygen dissociation curve to the right, decreasing the oxygen saturation of haemoglobin.

      Finally, normal pH, normal lactate, and normal SaO2 are unlikely to be found in this patient shortly after a seizure. However, if the venous blood gas test was taken days after the seizure following an uncomplicated clinical course, these findings would be more plausible.

      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.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 6 - A 27-year-old man is undergoing respiratory spirometry. He performs a maximal inhalation followed...

    Incorrect

    • A 27-year-old man is undergoing respiratory spirometry. He performs a maximal inhalation followed by a maximal exhalation. Which of the following measurements will most accurately depict this process?

      Your Answer:

      Correct Answer: Vital capacity

      Explanation:

      The maximum amount of air that can be breathed in and out within one minute is known as maximum voluntary ventilation.

      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.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 7 - A 55-year-old man presents to his GP complaining of vertigo, describing a sensation...

    Incorrect

    • A 55-year-old man presents to his GP complaining of vertigo, describing a sensation of the room spinning around him. He reports that the symptoms are exacerbated when he rolls over in bed. The GP suspects that otoliths in the semicircular canals of the inner ear may be the cause. What diagnostic test could the GP perform to confirm this suspicion?

      Your Answer:

      Correct Answer: Dix-Hallpike manoeuvre

      Explanation:

      Benign paroxysmal positional vertigo (BPPV) is suspected based on the patient’s history. To confirm the diagnosis, the Dix-Hallpike manoeuvre can be performed, which involves quickly moving the patient from a sitting to supine position and observing for nystagmus.

      If BPPV is confirmed, the Epley manoeuvre can be used for treatment. This manoeuvre aims to dislodge otoliths by promoting fluid movement in the inner ear’s semicircular canals.

      Carpal tunnel syndrome can be diagnosed by a positive Tinel’s sign. This involves tapping the median nerve over the flexor retinaculum, causing paraesthesia in the median nerve’s distribution.

      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.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 8 - A 23-year-old woman comes to your clinic complaining of difficulty hearing her partner...

    Incorrect

    • 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:

      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.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 9 - A 54-year-old man complains of facial pain and discomfort during meals. He has...

    Incorrect

    • A 54-year-old man complains of facial pain and discomfort during meals. He has been experiencing halitosis and a dry mouth. Additionally, he has a lump under his left mandible. What is the probable underlying diagnosis?

      Your Answer:

      Correct Answer: Stone impacted in Whartons duct

      Explanation:

      The signs are indicative of sialolithiasis, which usually involves the formation of stones in the submandibular gland and can block Wharton’s duct. Stensen’s duct, on the other hand, is responsible for draining the parotid gland.

      Diseases of the Submandibular Glands

      The submandibular glands are responsible for producing mixed seromucinous secretions, which can range from more serous to more mucinous depending on parasympathetic activity. These glands secrete approximately 800-1000ml of saliva per day, with parasympathetic fibers derived from the chorda tympani nerves and the submandibular ganglion. However, several conditions can affect the submandibular glands.

      One such condition is sialolithiasis, which occurs when salivary gland calculi form in the submandibular gland. These stones are usually composed of calcium phosphate or calcium carbonate and can cause colicky pain and postprandial swelling of the gland. Sialography is used to investigate the site of obstruction and associated stones, with impacted stones in the distal aspect of Wharton’s duct potentially removed orally. However, other stones and chronic inflammation may require gland excision.

      Sialadenitis is another condition that can affect the submandibular glands, usually as a result of Staphylococcus aureus infection. This can cause pus to leak from the duct and erythema to be noted. A submandibular abscess may develop, which is a serious complication as it can spread through other deep fascial spaces and occlude the airway.

      Finally, submandibular tumors can also affect these glands, with only 8% of salivary gland tumors affecting the submandibular gland. Of these, 50% are malignant, usually adenoid cystic carcinoma. Diagnosis usually involves fine needle aspiration cytology, with imaging using CT and MRI. Due to the high prevalence of malignancy, all masses of the submandibular glands should generally be excised.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 10 - A 25-year-old male patient complains of sore throat, malaise, and fatigue for the...

    Incorrect

    • A 25-year-old male patient complains of sore throat, malaise, and fatigue for the past 5 days. During the examination, a significant peritonsillar abscess is observed. What is the probable causative organism responsible for this infection?

      Your Answer:

      Correct Answer: Streptococcus pyogenes

      Explanation:

      Streptococcal organisms are the most frequent cause of bacterial tonsillitis, which can lead to quinsy.

      Understanding Acute Tonsillitis

      Acute tonsillitis is a condition that is characterized by pharyngitis, fever, malaise, and lymphadenopathy. It is caused by bacterial infections in over half of all cases, with Streptococcus pyogenes being the most common organism. The tonsils become swollen and may have yellow or white pustules. It is important to note that infectious mononucleosis may mimic the symptoms of acute tonsillitis.

      Treatment for bacterial tonsillitis involves the use of penicillin-type antibiotics. Failure to treat bacterial tonsillitis may result in the formation of a local abscess known as quinsy.

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      • Respiratory System
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  • Question 11 - Cystic fibrosis is caused by a mutation in the CFTR gene. On which...

    Incorrect

    • Cystic fibrosis is caused by a mutation in the CFTR gene. On which chromosome is this gene located?

      Your Answer:

      Correct Answer: Chromosome 7

      Explanation:

      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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      • Respiratory System
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  • Question 12 - A 26-year-old man is brought to the emergency department after being rescued at...

    Incorrect

    • A 26-year-old man is brought to the emergency department after being rescued at sea following a sailing accident. He is currently unresponsive with a Glasgow Coma Score of 9 (E2 V3 M4).

      His vital signs include a heart rate of 110 beats per minute, blood pressure of 110/76 mmHg, oxygen saturation of 93%, and temperature of 34.8 ºC. An ECG is unremarkable and venous blood indicates type 2 respiratory failure. The patient's oxygen dissociation curve shows a leftward shift.

      What is the cause of the leftward shift in this 26-year-old patient's oxygen dissociation curve?

      Your Answer:

      Correct Answer: Hypothermia

      Explanation:

      The only answer that causes a leftward shift in the oxygen dissociation curve is hypothermia. When tissues undergo aerobic respiration, they generate heat, which changes the shape of the haemoglobin molecule and reduces its affinity for oxygen. This results in the release of oxygen at respiring tissues. In contrast, lower temperatures in the lungs cause a leftward shift in the oxygen dissociation curve, which increases the binding of oxygen to haemoglobin.

      Hypercapnia is not the correct answer because it causes a rightward shift in the oxygen dissociation curve. Hypercapnia lowers blood pH, which changes the shape of haemoglobin and reduces its affinity for oxygen.

      Hypoxaemia is not the correct answer because the partial pressure of oxygen does not affect the oxygen dissociation curve. The partial pressure of oxygen does not change the affinity of haemoglobin for oxygen.

      Increased concentration of 2,3-diphosphoglycerate (2,3-DPG) is not the correct answer because higher concentrations of 2,3-DPG reduce haemoglobin’s affinity for oxygen, causing a right shift in the oxygen dissociation curve.

      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.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 13 - Which one of the following is not a typical feature of central chemoreceptors...

    Incorrect

    • Which one of the following is not a typical feature of central chemoreceptors in the regulation of respiration?

      Your Answer:

      Correct Answer: They are stimulated primarily by venous hypercapnia

      Explanation:

      Arterial carbon dioxide stimulates them, but it takes longer to reach equilibrium compared to the carotid peripheral chemoreceptors. They are not as responsive to acidity because of the blood-brain barrier.

      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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      • Respiratory System
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  • Question 14 - A 57-year-old man comes to his GP complaining of worsening shortness of breath...

    Incorrect

    • A 57-year-old man comes to his GP complaining of worsening shortness of breath during physical activity over the past year. He has never smoked and reports no history of occupational exposure to asbestos, dust, or fumes. His BMI is calculated to be 40 kg/m². Upon examination, there is decreased chest expansion bilaterally, but the lungs are clear upon auscultation. The GP orders spirometry, which reveals a decreased expiratory reserve volume.

      Can you provide the definition of this particular lung volume?

      Your Answer:

      Correct Answer: Maximum volume of air that can be expired at the end of a normal tidal expiration

      Explanation:

      The expiratory reserve volume refers to the maximum amount of air that can be exhaled after a normal breath out. It is important to note that this volume can be reduced in conditions that limit lung expansion, such as obesity and ascites. Obesity, in particular, can cause a restrictive pattern on spirometry, where the FEV1/FVC ratio is ≥0.8. Other restrictive lung conditions include idiopathic pulmonary fibrosis, pleural effusion, ascites, and neuromuscular disorders that limit chest expansion. On the other hand, obstructive disorders like asthma and COPD lead to a FEV1/FVC ratio of <0.7, limiting the amount of air that can be exhaled in one second. It is essential to understand the different lung volumes and capacities, including inspiratory reserve volume, tidal volume, expiratory reserve volume, residual volume, inspiratory capacity, vital capacity, functional residual capacity, and total lung capacity. 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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      • Respiratory System
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  • Question 15 - A 72-year-old man with thyroid cancer is hospitalized for dyspnea. What is the...

    Incorrect

    • A 72-year-old man with thyroid cancer is hospitalized for dyspnea. What is the most appropriate test to evaluate potential compression of the upper respiratory tract?

      Your Answer:

      Correct Answer: Flow volume loop

      Explanation:

      Understanding Flow Volume Loops

      A flow volume loop is a graphical representation of the amount of air that a person can inhale and exhale over time. It is often described as a triangle on top of a semi-circle. This loop is useful in assessing the compression of the upper airway, which can be caused by various conditions such as asthma, chronic obstructive pulmonary disease (COPD), and sleep apnea.

      To interpret a flow volume loop, the vertical axis represents the flow rate, while the horizontal axis represents the volume of air. The loop starts at the bottom left corner, where the person begins to inhale. As the person inhales, the flow rate increases, creating the upward slope of the triangle. At the top of the triangle, the person reaches their maximum inhalation volume.

      The person then begins to exhale, creating the downward slope of the triangle. The flow rate decreases as the person exhales, until they reach their maximum exhalation volume, represented by the semi-circle. The loop then returns to the starting point, completing one full cycle.

      Overall, flow volume loops are a valuable tool in diagnosing and monitoring respiratory conditions. By analyzing the shape and size of the loop, healthcare professionals can identify abnormalities in lung function and determine the appropriate treatment plan.

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  • Question 16 - A 35-year-old patient has been experiencing breathing difficulties for the past year. He...

    Incorrect

    • 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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  • Question 17 - A 9-month-old girl is brought to the emergency department by her mother due...

    Incorrect

    • A 9-month-old girl is brought to the emergency department by her mother due to difficulty in breathing. The mother reports that her daughter has been restless, with a runny nose, feeling warm and a dry cough for the past 4 days. However, the mother is now quite worried because her daughter has not eaten since last night and her breathing seems to have worsened throughout the morning.

      During the examination, the infant has a respiratory rate of 70/min, heart rate of 155/min, oxygen saturation of 92% and a temperature of 37.9ºC. The infant shows signs of nasal flaring and subcostal recession while breathing. On auscultation, widespread wheezing is heard. The infant is admitted, treated with humidified oxygen via nasal cannula and discharged home after 2 days.

      What is the probable causative agent of this infant's illness?

      Your Answer:

      Correct Answer: Respiratory syncytial virus

      Explanation:

      Bronchiolitis typically presents with symptoms such as coryza and increased breathing effort, leading to feeding difficulties in children under one year of age. The majority of cases of bronchiolitis are caused by respiratory syncytial virus, while adenovirus is a less frequent culprit. On the other hand, croup is most commonly caused by parainfluenza virus.

      Understanding Bronchiolitis

      Bronchiolitis is a condition that is characterized by inflammation of the bronchioles. It is a serious lower respiratory tract infection that is most common in children under the age of one year. The pathogen responsible for 75-80% of cases is respiratory syncytial virus (RSV), while other causes include mycoplasma and adenoviruses. Bronchiolitis is more serious in children with bronchopulmonary dysplasia, congenital heart disease, or cystic fibrosis.

      The symptoms of bronchiolitis include coryzal symptoms, dry cough, increasing breathlessness, and wheezing. Fine inspiratory crackles may also be present. Children with bronchiolitis may experience feeding difficulties associated with increasing dyspnoea, which is often the reason for hospital admission.

      Immediate referral to hospital is recommended if the child has apnoea, looks seriously unwell to a healthcare professional, has severe respiratory distress, central cyanosis, or persistent oxygen saturation of less than 92% when breathing air. Clinicians should consider referring to hospital if the child has a respiratory rate of over 60 breaths/minute, difficulty with breastfeeding or inadequate oral fluid intake, or clinical dehydration.

      The investigation for bronchiolitis involves immunofluorescence of nasopharyngeal secretions, which may show RSV. Management of bronchiolitis is largely supportive, with humidified oxygen given via a head box if oxygen saturations are persistently < 92%. Nasogastric feeding may be needed if children cannot take enough fluid/feed by mouth, and suction is sometimes used for excessive upper airway secretions.

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  • Question 18 - A 35-year-old female presents with recurrent episodes of severe vertigo that have been...

    Incorrect

    • A 35-year-old female presents with recurrent episodes of severe vertigo that have been disabling. She experiences these episodes multiple times a day, with each one lasting for about 10-20 minutes. Along with the vertigo, she also experiences ringing in both ears, nausea, and vomiting. She has noticed a change in her hearing in both ears, with difficulty hearing at times and normal hearing at other times. Additionally, she reports increased pressure in her ears. During the examination, you notice a painless rash behind her ear that has been present for many years.

      What is the most likely diagnosis?

      Your Answer:

      Correct Answer: Meniere’s disease

      Explanation:

      Suspect Meniere’s disease in a patient presenting with vertigo, tinnitus, and fluctuating sensorineural hearing loss. Acoustic neuroma would present with additional symptoms such as facial numbness and loss of corneal reflex. Herpes Zoster Oticus (Ramsey Hunt syndrome) would present with facial palsy and a painless rash. Vestibular neuronitis would have longer episodes of vertigo, nausea, and vomiting, but no hearing loss. Benign paroxysmal positional vertigo would have brief episodes of vertigo after sudden head movements.

      Meniere’s disease is a condition that affects the inner ear and its cause is unknown. It is more commonly seen in middle-aged adults but can occur at any age and affects both men and women equally. The condition is characterized by the excessive pressure and progressive dilation of the endolymphatic system. The main symptoms of Meniere’s disease are recurrent episodes of vertigo, tinnitus, and sensorineural hearing loss. Vertigo is usually the most prominent symptom, but patients may also experience a sensation of aural fullness or pressure, nystagmus, and a positive Romberg test. These episodes can last from minutes to hours and are typically unilateral, but bilateral symptoms may develop over time.

      The natural history of Meniere’s disease is that symptoms usually resolve in the majority of patients after 5-10 years. However, most patients will be left with some degree of hearing loss, and psychological distress is common. ENT assessment is required to confirm the diagnosis, and patients should inform the DVLA as the current advice is to cease driving until satisfactory control of symptoms is achieved. Acute attacks can be managed with buccal or intramuscular prochlorperazine, and admission to the hospital may be required. Prevention strategies include the use of betahistine and vestibular rehabilitation exercises, which may be beneficial.

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  • Question 19 - A 26-year-old man has been referred to ENT by his doctor as he...

    Incorrect

    • A 26-year-old man has been referred to ENT by his doctor as he has swallowed a small chicken bone that feels stuck in his throat. During laryngoscopy, a chicken bone is observed lodged in the piriform recess. Which of the following nerves is most likely to be affected by the chicken bone?

      Your Answer:

      Correct Answer: Internal laryngeal nerve

      Explanation:

      When foreign objects get stuck in the piriform recess, particularly sharp items like bones from fish or chicken, they can harm the internal laryngeal nerve that lies beneath the mucous membrane in that area. Retrieving these objects also poses a risk of damaging the internal laryngeal nerve. However, the other nerves are not likely to be impacted.

      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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  • Question 20 - Sophie, a 4-year-old patient with Down's syndrome, is brought to the general practitioner...

    Incorrect

    • 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:

      Correct 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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  • Question 21 - A 49-year-old woman of African descent visits her primary care physician with concerns...

    Incorrect

    • A 49-year-old woman of African descent visits her primary care physician with concerns about a lump in her neck that has been present for a week. She reports no significant increase in size and denies any pain or difficulty swallowing. The patient has no notable medical history, except for a visit to the eye doctor last year for a red-eye that required treatment with topical steroid drops. During the examination, the doctor observes some red, tender nodules on the patient's shin, which the patient says come and go and do not cause much discomfort. A chest x-ray reveals bilateral hilar lymphadenopathy with no other significant findings. What is typically linked to this patient's condition?

      Your Answer:

      Correct Answer: Elevated angiotensin-converting enzyme levels

      Explanation:

      Sarcoidosis is likely in this patient based on their symptoms and examination findings, including a neck lump, tender nodules on the shin, and a history of red-eye. Bilateral lymphadenopathy on chest X-ray further supports the diagnosis, as does the presence of elevated angiotensin-converting enzyme levels, which are commonly seen in sarcoidosis. Hypercalcemia, fatigue, and uveitis are also associated with sarcoidosis, while exposure to silica is not supported by this patient’s presentation.

      Investigating Sarcoidosis

      Sarcoidosis is a disease that does not have a single diagnostic test, and therefore, diagnosis is mainly based on clinical observations. Although ACE levels may be used to monitor disease activity, they are not reliable in diagnosing sarcoidosis due to their low sensitivity and specificity. Routine blood tests may show hypercalcemia and a raised ESR.

      A chest x-ray is a common investigation for sarcoidosis and may reveal different stages of the disease. Stage 0 is normal, stage 1 shows bilateral hilar lymphadenopathy (BHL), stage 2 shows BHL and interstitial infiltrates, stage 3 shows diffuse interstitial infiltrates only, and stage 4 shows diffuse fibrosis. Other investigations, such as spirometry, may show a restrictive defect, while a tissue biopsy may reveal non-caseating granulomas. However, the Kveim test, which involves injecting part of the spleen from a patient with known sarcoidosis under the skin, is no longer performed due to concerns about cross-infection.

      In addition, a gallium-67 scan is not routinely used to investigate sarcoidosis. CT scans may also be used to investigate sarcoidosis, and they may show diffuse areas of nodularity predominantly in a peribronchial distribution with patchy areas of consolidation, particularly in the upper lobes. Ground glass opacities may also be present, but there are no gross reticular changes to suggest fibrosis.

      Overall, investigating sarcoidosis involves a combination of clinical observations, blood tests, chest x-rays, and other investigations such as spirometry and tissue biopsy. CT scans may also be used to provide more detailed information about the disease.

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  • Question 22 - A 25-year-old patient is undergoing routine pulmonary function testing to assess her chronic...

    Incorrect

    • A 25-year-old patient is undergoing routine pulmonary function testing to assess her chronic condition. The results are compared to a standardised predicted value and presented in the table below:

      FEV1 75% of predicted
      FVC 70% of predicted
      FEV1/FVC 105%

      What is the probable condition that this patient is suffering from, which can account for the above findings?

      Your Answer:

      Correct Answer: Neuromuscular disorder

      Explanation:

      The patient’s pulmonary function tests indicate a restrictive pattern, as both FEV1 and FVC are reduced. This suggests a possible neuromuscular disorder, as all other options would result in an obstructive pattern on the tests. Asthma, bronchiectasis, and COPD are unlikely diagnoses for a 20-year-old and would not match the test results. Pneumonia may affect the patient’s ability to perform the tests, but it is typically an acute condition that requires immediate treatment with antibiotics.

      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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  • Question 23 - A 38-year-old woman visits her GP with a solitary, painless tumour in her...

    Incorrect

    • A 38-year-old woman visits her GP with a solitary, painless tumour in her left cheek. Upon further examination, she is diagnosed with pleomorphic adenoma. What is the recommended management for this condition?

      Your Answer:

      Correct Answer: Surgical resection

      Explanation:

      Surgical resection is the preferred treatment for pleomorphic adenoma, a benign tumor of the parotid gland that may undergo malignant transformation. Chemotherapy and radiotherapy are not effective in managing this condition. Additionally, salivary stone removal is not relevant to the treatment of pleomorphic adenoma.

      Understanding Pleomorphic Adenoma

      Pleomorphic adenoma, also known as a benign mixed tumour, is a non-cancerous growth that commonly affects the parotid gland. This type of tumour usually develops in individuals aged 40 to 60 years old. The condition is characterized by the proliferation of epithelial and myoepithelial cells of the ducts, as well as an increase in stromal components. The tumour is slow-growing, lobular, and not well encapsulated.

      The clinical features of pleomorphic adenoma include a gradual onset of painless unilateral swelling of the parotid gland. The swelling is typically movable on examination rather than fixed. The management of pleomorphic adenoma involves surgical excision. The prognosis is generally good, with a recurrence rate of 1-5% with appropriate excision (parotidectomy). However, recurrence may occur due to capsular disruption during surgery. If left untreated, pleomorphic adenoma may undergo malignant transformation, occurring in 2-10% of adenomas observed for long periods. Carcinoma ex-pleomorphic adenoma is the most common type of malignant transformation, occurring most frequently as adenocarcinoma.

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  • Question 24 - What causes a cervical rib? ...

    Incorrect

    • 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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  • Question 25 - During a schoolyard brawl a boy is hit in the chest. The stick...

    Incorrect

    • During a schoolyard brawl a boy is hit in the chest. The stick passes through the posterior mediastinum (from left to right). Which one of the following structures is least likely to be injured?

      Your Answer:

      Correct Answer: Arch of the azygos vein

      Explanation:

      The azygos vein’s arch is located within the middle mediastinum.

      The mediastinum is the area located between the two pulmonary cavities and is covered by the mediastinal pleura. It extends from the thoracic inlet at the top to the diaphragm at the bottom. The mediastinum is divided into four regions: the superior mediastinum, middle mediastinum, posterior mediastinum, and anterior mediastinum.

      The superior mediastinum is the area between the manubriosternal angle and T4/5. It contains important structures such as the superior vena cava, brachiocephalic veins, arch of aorta, thoracic duct, trachea, oesophagus, thymus, vagus nerve, left recurrent laryngeal nerve, and phrenic nerve. The anterior mediastinum contains thymic remnants, lymph nodes, and fat. The middle mediastinum contains the pericardium, heart, aortic root, arch of azygos vein, and main bronchi. The posterior mediastinum contains the oesophagus, thoracic aorta, azygos vein, thoracic duct, vagus nerve, sympathetic nerve trunks, and splanchnic nerves.

      In summary, the mediastinum is a crucial area in the thorax that contains many important structures and is divided into four regions. Each region contains different structures that are essential for the proper functioning of the body.

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  • Question 26 - A 65-year-old man is having a coronary artery bypass surgery. Which structure would...

    Incorrect

    • A 65-year-old man is having a coronary artery bypass surgery. Which structure would typically need to be divided during the median sternotomy procedure?

      Your Answer:

      Correct Answer: Interclavicular ligament

      Explanation:

      During a median sternotomy, the interclavicular ligament is typically cut to allow access. However, it is important to avoid intentionally cutting the pleural reflections, as this can lead to the accumulation of fluid in the pleural cavity and require the insertion of a chest drain. The pectoralis major muscles may also be encountered, but if the incision is made in the midline, they should not need to be formally divided. It is crucial to be mindful of the proximity of the brachiocephalic vein and avoid injuring it, as this can result in significant bleeding.

      Sternotomy Procedure

      A sternotomy is a surgical procedure that involves making an incision in the sternum to access the heart and great vessels. The most common type of sternotomy is a median sternotomy, which involves making a midline incision from the interclavicular fossa to the xiphoid process. The fat and subcutaneous tissues are then divided to the level of the sternum, and the periosteum may be gently mobilized off the midline. However, it is important to avoid vigorous periosteal stripping. A bone saw is used to divide the bone itself, and bleeding from the bony edges of the cut sternum is stopped using roller ball diathermy or bone wax.

      Posteriorly, the reflections of the parietal pleura should be identified and avoided, unless surgery to the lung is planned. The fibrous pericardium is then incised, and the heart is brought into view. It is important to avoid the left brachiocephalic vein, which is an important posterior relation at the superior aspect of the sternotomy incision. More inferiorly, the thymic remnants may be identified. At the inferior aspect of the incision, the abdominal cavity may be entered, although this is seldom troublesome.

      Overall, a sternotomy is a complex surgical procedure that requires careful attention to detail and a thorough understanding of the anatomy of the chest and heart. By following the proper techniques and precautions, surgeons can safely access the heart and great vessels to perform a variety of life-saving procedures.

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  • Question 27 - A 63-year-old man visits his GP complaining of worsening shortness of breath. He...

    Incorrect

    • 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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  • Question 28 - A 50-year-old man suffers a closed head injury and experiences a decline in...

    Incorrect

    • A 50-year-old man suffers a closed head injury and experiences a decline in consciousness upon arrival at the hospital. To monitor his intracranial pressure, an ICP monitor is inserted. What is the normal range for intracranial pressure?

      Your Answer:

      Correct Answer: 7 - 15mm Hg

      Explanation:

      The typical range for intracranial pressure is 7 to 15 mm Hg, with the brain able to tolerate increases up to 24 mm Hg before displaying noticeable clinical symptoms.

      Understanding the Monro-Kelly Doctrine and Autoregulation in the CNS

      The Monro-Kelly doctrine governs the pressure within the cranium by considering the skull as a closed box. The loss of cerebrospinal fluid (CSF) can accommodate increases in mass until a critical point is reached, usually at 100-120ml of CSF lost. Beyond this point, intracranial pressure (ICP) rises sharply, and pressure will eventually equate with mean arterial pressure (MAP), leading to neuronal death and herniation.

      The central nervous system (CNS) has the ability to autoregulate its own blood supply through vasoconstriction and dilation of cerebral blood vessels. However, extreme blood pressure levels can exceed this capacity, increasing the risk of stroke. Additionally, metabolic factors such as hypercapnia can cause vasodilation, which is crucial in ventilating head-injured patients.

      It is important to note that the brain can only metabolize glucose, and a decrease in glucose levels can lead to impaired consciousness. Understanding the Monro-Kelly doctrine and autoregulation in the CNS is crucial in managing intracranial pressure and preventing neurological damage.

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  • Question 29 - A 43-year-old woman comes to the respiratory clinic for an outpatient appointment. She...

    Incorrect

    • 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 37.2ºC. A gas transfer test is performed, and her transfer factor is found to be low.

      What is the most likely diagnosis?

      Your Answer:

      Correct 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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  • Question 30 - A 23-year-old woman comes to your clinic with a complaint of ear pain...

    Incorrect

    • 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:

      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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