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  • Question 1 - A 60-year-old man visits his GP with worries about his hearing in recent...

    Correct

    • A 60-year-old man visits his GP with worries about his hearing in recent months. He has difficulty understanding conversations in noisy environments and his spouse has commented on his need for the television to be turned up to maximum volume.

      During the examination, the GP conducts some basic tests and finds:

      Rinne's Test - Air conduction > bone conduction in both ears
      Weber's Test - Lateralises to the left ear

      What can be inferred from these test results?

      Your Answer: Left sensorineural hearing loss

      Explanation:

      The patient has left sensorineural hearing loss, as indicated by the normal Rinne result (air conduction > bone conduction bilaterally) and abnormal Weber result (lateralising to the unaffected ear). In contrast, if the patient had conductive hearing loss, Rinne’s test would show bone conduction > air conduction, and Weber’s test would localise to the worse ear in bilateral conductive hearing loss or the affected ear in unilateral conductive hearing loss. For right sensorineural hearing loss, Rinne’s test would be normal, but Weber’s test would localise to the left ear.

      Rinne’s and Weber’s Test for Differentiating Conductive and Sensorineural Deafness

      Rinne’s and Weber’s tests are used to differentiate between conductive and sensorineural deafness. Rinne’s test involves placing a tuning fork over the mastoid process until the sound is no longer heard, then repositioning it just over the external acoustic meatus. A positive test indicates that air conduction (AC) is better than bone conduction (BC), while a negative test indicates that BC is better than AC, suggesting conductive deafness.

      Weber’s test involves placing a tuning fork in the middle of the forehead equidistant from the patient’s ears and asking the patient which side is loudest. In unilateral sensorineural deafness, sound is localized to the unaffected side, while in unilateral conductive deafness, sound is localized to the affected side.

      The table below summarizes the interpretation of Rinne and Weber tests. A normal result indicates that AC is greater than BC bilaterally and the sound is midline. Conductive hearing loss is indicated by BC being greater than AC in the affected ear and AC being greater than BC in the unaffected ear, with the sound lateralizing to the affected ear. Sensorineural hearing loss is indicated by AC being greater than BC bilaterally, with the sound lateralizing to the unaffected ear.

      Overall, Rinne’s and Weber’s tests are useful tools for differentiating between conductive and sensorineural deafness, allowing for appropriate management and treatment.

    • This question is part of the following fields:

      • Respiratory System
      34.9
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  • Question 2 - A 60-year-old diabetic patient presents to the clinic with a chief complaint of...

    Incorrect

    • A 60-year-old diabetic patient presents to the clinic with a chief complaint of hearing loss. After conducting a Webber’s and Rinne’s test, the following results were obtained:

      - Webber’s test: lateralizes to the left ear
      - Rinne’s test (left ear): bone conduction > air conduction
      - Rinne’s test (right ear): air conduction > bone conduction

      Based on these findings, what is the probable cause of the patient's hearing loss?

      Your Answer: Diabetic sensory neuropathy

      Correct Answer: Otitis media with effusion

      Explanation:

      The Weber test lateralises to the side with bone conduction > air conduction, indicating conductive hearing loss on that side. The options given include acoustic neuroma (sensorineural hearing loss), otitis media with effusion (conductive hearing loss), temporal lobe epilepsy (no conductive hearing loss), and Meniere’s disease (vertigo, tinnitus, and fluctuating hearing loss). The correct answer is otitis media with effusion.

      Rinne’s and Weber’s Test for Differentiating Conductive and Sensorineural Deafness

      Rinne’s and Weber’s tests are used to differentiate between conductive and sensorineural deafness. Rinne’s test involves placing a tuning fork over the mastoid process until the sound is no longer heard, then repositioning it just over the external acoustic meatus. A positive test indicates that air conduction (AC) is better than bone conduction (BC), while a negative test indicates that BC is better than AC, suggesting conductive deafness.

      Weber’s test involves placing a tuning fork in the middle of the forehead equidistant from the patient’s ears and asking the patient which side is loudest. In unilateral sensorineural deafness, sound is localized to the unaffected side, while in unilateral conductive deafness, sound is localized to the affected side.

      The table below summarizes the interpretation of Rinne and Weber tests. A normal result indicates that AC is greater than BC bilaterally and the sound is midline. Conductive hearing loss is indicated by BC being greater than AC in the affected ear and AC being greater than BC in the unaffected ear, with the sound lateralizing to the affected ear. Sensorineural hearing loss is indicated by AC being greater than BC bilaterally, with the sound lateralizing to the unaffected ear.

      Overall, Rinne’s and Weber’s tests are useful tools for differentiating between conductive and sensorineural deafness, allowing for appropriate management and treatment.

    • This question is part of the following fields:

      • Respiratory System
      7.1
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  • Question 3 - Cystic fibrosis is caused by a mutation in the CFTR gene. On which...

    Correct

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

      Your 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.

    • This question is part of the following fields:

      • Respiratory System
      51
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  • Question 4 - An 87-year-old man with a history of interstitial lung disease is admitted with...

    Incorrect

    • An 87-year-old man with a history of interstitial lung disease is admitted with fever, productive cough, and difficulty breathing. His inflammatory markers are elevated, and a chest x-ray reveals focal patchy consolidation in the right lung. He requires oxygen supplementation as his oxygen saturation level is 87% on room air. What factor causes a decrease in haemoglobin's affinity for oxygen?

      Your Answer: Decrease in carbon dioxide

      Correct Answer: Increase in temperature

      Explanation:

      What effect does pyrexia have on 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
      15.5
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  • Question 5 - You are on call for the pediatric ward at night and are urgently...

    Incorrect

    • You are on call for the pediatric ward at night and are urgently called to a child who is choking on a piece of hot dog visible in their oropharynx. The child is in extremis with saturations of 87% and there is no effective cough.

      What is the most appropriate immediate management for this pediatric patient?

      Your Answer: Cricothyroidotomy

      Correct Answer: Back blows

      Explanation:

      Resuscitation Council (UK) Recommendations for Choking Emergencies

      When faced with a choking emergency, the Resuscitation Council (UK) recommends a specific course of action. If the patient is able to cough effectively, encourage them to do so. If not, but they are conscious, try five back blows followed by five abdominal thrusts (Heimlich manoeuvre) and repeat if necessary. However, if the patient becomes unconscious, begin CPR immediately. It is important to note that a finger sweep is no longer recommended as it can push the obstruction further into the airway. Additionally, high flow oxygen is necessary for breathing, but nasopharyngeal airways will not help in this situation. Removal with forceps is also not recommended as it can be hazardous. If the Heimlich manoeuvre fails, a cricothyroidotomy should be considered. While this procedure is recommended in the US and UK, it is not encouraged in some countries like Australia due to the risk of internal injury from over-vigorous use.

    • This question is part of the following fields:

      • Respiratory System
      151.1
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  • Question 6 - A 26-year-old male is brought to the emergency department by his mother. He...

    Incorrect

    • 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: Loperamide

      Correct Answer: Ciprofloxacin

      Explanation:

      Terbinafine is frequently prescribed for the treatment of fungal nail infections as an antifungal medication.

      Theophylline and its Poisoning

      Theophylline is a naturally occurring methylxanthine that is commonly used as a bronchodilator in the management of asthma and COPD. Its exact mechanism of action is still unknown, but it is believed to be a non-specific inhibitor of phosphodiesterase, resulting in an increase in cAMP. Other proposed mechanisms include antagonism of adenosine and prostaglandin inhibition.

      However, theophylline poisoning can occur and is characterized by symptoms such as acidosis, hypokalemia, vomiting, tachycardia, arrhythmias, and seizures. In such cases, gastric lavage may be considered if the ingestion occurred less than an hour prior. Activated charcoal is also recommended, while whole-bowel irrigation can be performed if theophylline is in sustained-release form. Charcoal hemoperfusion is preferable to hemodialysis in managing theophylline poisoning.

    • This question is part of the following fields:

      • Respiratory System
      123.2
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  • Question 7 - A senior citizen who has been a lifelong smoker visits the respiratory clinic...

    Incorrect

    • A senior citizen who has been a lifelong smoker visits the respiratory clinic for a check-up on his emphysema. What alterations in his lung function test results would you anticipate?

      Your Answer:

      Correct Answer: Increased residual volume and reduced vital capacity

      Explanation:

      Emphysema causes an increase in residual volume, leading to a decrease in vital capacity. This is due to damage to the alveolar walls, which results in the formation of large air sacs called bullae. The lungs lose their compliance, making it difficult to fully exhale and causing air to become trapped in the bullae. As a result, the total volume that can be exhaled is reduced, leading to a decrease in vital 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.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 8 - A 75-year-old man visits his doctor complaining of weight loss and feeling full...

    Incorrect

    • A 75-year-old man visits his doctor complaining of weight loss and feeling full quickly. During the abdominal examination, the doctor notices a swollen lymph node in the left supraclavicular region. The doctor suspects that this could be a sign of gastric cancer with the spread of tumor emboli through the thoracic duct as it ascends from the abdomen into the mediastinum. Can you name the two other structures that pass through the diaphragm along with the thoracic duct?

      Your Answer:

      Correct Answer: Aorta and azygous vein

      Explanation:

      The point at which the aorta, thoracic duct, and azygous vein cross the diaphragm is at T12, specifically at the aortic opening. This is also where the oesophageal branches of the left gastric veins, the vagal trunk, and the oesophagus pass through the diaphragm, at the oesophageal opening located at T10. The left phrenic nerve and sympathetic trunk have their own separate openings in the diaphragm. A lymph node in the left supraclavicular fossa, known as Virchow’s node, is a characteristic sign of early gastric carcinoma.

      Structures Perforating the Diaphragm

      The diaphragm is a dome-shaped muscle that separates the thoracic and abdominal cavities. It plays a crucial role in breathing by contracting and relaxing to create negative pressure in the lungs. However, there are certain structures that perforate the diaphragm, allowing them to pass through from the thoracic to the abdominal cavity. These structures include the inferior vena cava at the level of T8, the esophagus and vagal trunk at T10, and the aorta, thoracic duct, and azygous vein at T12.

      To remember these structures and their corresponding levels, a helpful mnemonic is I 8(ate) 10 EGGS AT 12. This means that the inferior vena cava is at T8, the esophagus and vagal trunk are at T10, and the aorta, thoracic duct, and azygous vein are at T12. Knowing these structures and their locations is important for medical professionals, as they may need to access or treat them during surgical procedures or diagnose issues related to them.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 9 - A 65-year-old male with a diagnosis of lung cancer presents with fatigue and...

    Incorrect

    • 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 ”mol/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.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 10 - A 24-year-old man is being evaluated at the respiratory clinic for possible bronchiectasis....

    Incorrect

    • A 24-year-old man is being evaluated at the respiratory clinic for possible bronchiectasis. He has a history of recurrent chest infections since childhood and has difficulty maintaining a healthy weight. Despite using inhalers, he has not experienced any significant improvement. Genetic testing has been ordered to investigate the possibility of cystic fibrosis.

      What is the typical role of the cystic fibrosis transmembrane conductance regulator?

      Your Answer:

      Correct Answer: Chloride channel

      Explanation:

      The chloride channel, specifically a cyclic-AMP regulated chloride channel, is the correct answer. Cystic fibrosis can be caused by various mutations, but they all affect the same gene, the cystic fibrosis transmembrane conductance regulator gene. This gene encodes a chloride channel that, when dysfunctional, results in increased viscosity of secretions and the development of cystic fibrosis.

      Understanding Cystic Fibrosis

      Cystic fibrosis is a genetic disorder that causes thickened secretions in the lungs and pancreas. It is an autosomal recessive condition that occurs due to a defect in the cystic fibrosis transmembrane conductance regulator gene (CFTR), which regulates a chloride channel. In the UK, 80% of CF cases are caused by delta F508 on chromosome 7, and the carrier rate is approximately 1 in 25.

      CF patients are at risk of colonization by certain organisms, including Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia (previously known as Pseudomonas cepacia), and Aspergillus. These organisms can cause infections and exacerbate symptoms in CF patients. It is important for healthcare providers to monitor and manage these infections to prevent further complications.

      Overall, understanding cystic fibrosis and its associated risks can help healthcare providers provide better care for patients with this condition.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 11 - During a radical neck dissection, at what age would division of which of...

    Incorrect

    • During a radical neck dissection, at what age would division of which of the following fascial layers expose the ansa cervicalis?

      Your Answer:

      Correct Answer: Pretracheal fascia

      Explanation:

      To access the ansa cervicalis, one must cut through the pretracheal fascia on the posterolateral side of the thyroid gland. This nerve is located in front of the carotid sheath. However, it should be noted that the pre vertebral fascia is situated further back and cannot be reached by dividing the investing layer of fascia.

      The ansa cervicalis is a nerve that provides innervation to the sternohyoid, sternothyroid, and omohyoid muscles. It is composed of two roots: the superior root, which branches off from C1 and is located anterolateral to the carotid sheath, and the inferior root, which is derived from the C2 and C3 roots and passes posterolateral to the internal jugular vein. The inferior root enters the inferior aspect of the strap muscles, which are located in the neck, and should be divided in their upper half when exposing a large goitre. The ansa cervicalis is situated in front of the carotid sheath and is an important nerve for the proper functioning of the neck muscles.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 12 - A 49-year-old patient presents to the rheumatology clinic with weight loss, fever, and...

    Incorrect

    • 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:

      Correct Answer: Granulomatosis with polyangiitis

      Explanation:

      The most likely diagnosis for this patient is granulomatosis with polyangiitis, as indicated by the presence of cANCA and the involvement of multiple organs including the lungs, skin, kidneys, and upper respiratory tract. This condition is known to cause inflammation in the glomeruli, leading to renal impairment. Churg-Strauss disease and Alport’s syndrome are unlikely due to normal eosinophil levels and cANCA positivity, respectively. Goodpasture’s syndrome is also unlikely as the patient does not present with haematuria or haemoptysis.

      Granulomatosis with Polyangiitis: An Autoimmune Condition

      Granulomatosis with polyangiitis, previously known as Wegener’s granulomatosis, is an autoimmune condition that affects the upper and lower respiratory tract as well as the kidneys. It is characterized by a necrotizing granulomatous vasculitis. The condition presents with various symptoms such as epistaxis, sinusitis, nasal crusting, dyspnoea, haemoptysis, and rapidly progressive glomerulonephritis. Other symptoms include a saddle-shape nose deformity, vasculitic rash, eye involvement, and cranial nerve lesions.

      To diagnose granulomatosis with polyangiitis, doctors perform various investigations such as cANCA and pANCA tests, chest x-rays, and renal biopsies. The cANCA test is positive in more than 90% of cases, while the pANCA test is positive in 25% of cases. Chest x-rays show a wide variety of presentations, including cavitating lesions. Renal biopsies reveal epithelial crescents in Bowman’s capsule.

      The management of granulomatosis with polyangiitis involves the use of steroids, cyclophosphamide, and plasma exchange. Cyclophosphamide has a 90% response rate. The median survival rate for patients with this condition is 8-9 years.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 13 - A patient is being anaesthetised for a minor bowel surgery. Sarah, a second...

    Incorrect

    • A patient is being anaesthetised for a minor bowel surgery. Sarah, a second year medical student is present and is asked to assist the anaesthetist during intubation. The anaesthetist inserts a laryngoscope in the patient's mouth and asks Sarah to identify the larynx.

      Which one of the following anatomical landmarks corresponds to the position of the structure being identified by the student?

      Your Answer:

      Correct Answer: C3-C6

      Explanation:

      The larynx is located in the front of the neck, specifically at the level of the vertebrae C3-C6. This area also includes important anatomical landmarks such as the Atlas and Axis vertebrae (C1-C2), the thyroid cartilage (C5), and the pulmonary hilum (T5-T7).

      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.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 14 - Which one of the following does not cause a normal anion gap acidosis?...

    Incorrect

    • Which one of the following does not cause a normal anion gap acidosis?

      Your Answer:

      Correct Answer: Uraemia

      Explanation:

      Normal Gap Acidosis can be remembered using the acronym HARDUP, which stands for Hyperalimentation/hyperventilation, Acetazolamide, and R (which is currently blank).

      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
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  • Question 15 - A father brings his 9-year-old daughter to your general practice, as he is...

    Incorrect

    • A father brings his 9-year-old daughter to your general practice, as he is worried about her hearing. He notices that he has to repeat himself when talking to her, and thinks she is often 'in her own little world'. During the examination, the Rinne test is positive on the left and negative on the right. What conclusions can be drawn from this?

      Your Answer:

      Correct Answer: Can not tell if both sides are affected.

      Explanation:

      The Rinne and Weber tests are used to diagnose hearing loss. The Rinne test involves comparing air and bone conduction, with a positive result indicating a healthy or sensorineural loss and a negative result indicating a conductive loss. The Weber test involves placing a tuning fork on the forehead and determining if the sound is symmetrical or louder on one side, with a conductive loss resulting in louder sound on the affected side and a sensorineural loss resulting in louder sound on the non-affected side. When used together, these tests can provide more information about the type and affected side of hearing loss.

      Rinne’s and Weber’s Test for Differentiating Conductive and Sensorineural Deafness

      Rinne’s and Weber’s tests are used to differentiate between conductive and sensorineural deafness. Rinne’s test involves placing a tuning fork over the mastoid process until the sound is no longer heard, then repositioning it just over the external acoustic meatus. A positive test indicates that air conduction (AC) is better than bone conduction (BC), while a negative test indicates that BC is better than AC, suggesting conductive deafness.

      Weber’s test involves placing a tuning fork in the middle of the forehead equidistant from the patient’s ears and asking the patient which side is loudest. In unilateral sensorineural deafness, sound is localized to the unaffected side, while in unilateral conductive deafness, sound is localized to the affected side.

      The table below summarizes the interpretation of Rinne and Weber tests. A normal result indicates that AC is greater than BC bilaterally and the sound is midline. Conductive hearing loss is indicated by BC being greater than AC in the affected ear and AC being greater than BC in the unaffected ear, with the sound lateralizing to the affected ear. Sensorineural hearing loss is indicated by AC being greater than BC bilaterally, with the sound lateralizing to the unaffected ear.

      Overall, Rinne’s and Weber’s tests are useful tools for differentiating between conductive and sensorineural deafness, allowing for appropriate management and treatment.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 16 - A 25-year-old man is shot in the chest during a robbery. The right...

    Incorrect

    • A 25-year-old man is shot in the chest during a robbery. The right lung is lacerated and is bleeding. An emergency thoracotomy is performed. The surgeons place a clamp over the hilum of the right lung. Which one of the following structures lies most anteriorly at this level?

      Your Answer:

      Correct Answer: Phrenic nerve

      Explanation:

      At this location, the phrenic nerve is situated in front. The vagus nerve runs in front and then curves backwards just above the base of the left bronchus, releasing the recurrent laryngeal nerve as it curves.

      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.

    • This question is part of the following fields:

      • Respiratory System
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  • Question 17 - A 75-year-old man visits his doctor complaining of a productive cough that has...

    Incorrect

    • A 75-year-old man visits his doctor complaining of a productive cough that has lasted for 5 days. He has also been feeling generally unwell and has had a fever for the past 2 days. The doctor suspects a bacterial respiratory tract infection and orders a blood panel, sputum microscopy, and culture. What is the most likely abnormality to be found in the blood results?

      Your Answer:

      Correct Answer: Neutrophils

      Explanation:

      Neutrophils are typically elevated during an acute bacterial infection, while eosinophils are commonly elevated in response to parasitic infections and allergies. Lymphocytes tend to increase during acute viral infections and chronic inflammation. IgE levels are raised in cases of allergic asthma, malaria, and type 1 hypersensitivity reactions. Anti-CCP antibody is a diagnostic tool for Rheumatoid arthritis.

      Pneumonia is a common condition that affects the alveoli of the lungs, usually caused by a bacterial infection. Other causes include viral and fungal infections. Streptococcus pneumoniae is the most common organism responsible for pneumonia, accounting for 80% of cases. Haemophilus influenzae is common in patients with COPD, while Staphylococcus aureus often occurs in patients following influenzae infection. Mycoplasma pneumoniae and Legionella pneumophilia are atypical pneumonias that present with dry cough and other atypical symptoms. Pneumocystis jiroveci is typically seen in patients with HIV. Idiopathic interstitial pneumonia is a group of non-infective causes of pneumonia.

      Patients who develop pneumonia outside of the hospital have community-acquired pneumonia (CAP), while those who develop it within hospitals are said to have hospital-acquired pneumonia. Symptoms of pneumonia include cough, sputum, dyspnoea, chest pain, and fever. Signs of systemic inflammatory response, tachycardia, reduced oxygen saturations, and reduced breath sounds may also be present. Chest x-ray is used to diagnose pneumonia, with consolidation being the classical finding. Blood tests, such as full blood count, urea and electrolytes, and CRP, are also used to check for infection.

      Patients with pneumonia require antibiotics to treat the underlying infection and supportive care, such as oxygen therapy and intravenous fluids. Risk stratification is done using a scoring system called CURB-65, which stands for confusion, respiration rate, blood pressure, age, and is used to determine the management of patients with community-acquired pneumonia. Home-based care is recommended for patients with a CRB65 score of 0, while hospital assessment is recommended for all other patients, particularly those with a CRB65 score of 2 or more. The CURB-65 score also correlates with an increased risk of mortality at 30 days.

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  • Question 18 - A 78-year-old man comes to the emergency department complaining of increasing difficulty in...

    Incorrect

    • A 78-year-old man comes to the emergency department complaining of increasing difficulty in breathing over the past two days. He has a medical history of squamous cell lung cancer.

      Upon examination, the trachea is observed to have shifted towards the left side, with dull percussion and absence of breath sounds throughout the left chest.

      What is the probable diagnosis?

      Your Answer:

      Correct Answer: Left lung collapse

      Explanation:

      When a lung collapses, it can cause the trachea to shift towards the affected side, and there may be dullness on percussion and reduced breath sounds throughout the lung field. This is because the decrease in pressure on the affected side causes the mediastinum and trachea to move towards it.

      A massive pleural effusion, on the other hand, would cause widespread dullness and absent breath sounds, but it would push the trachea away from the affected side due to increased pressure.

      Pneumonia typically only affects one lung zone, so there would not be widespread dullness or absent breath sounds throughout the hemithorax. It also does not usually affect the position of the mediastinum or trachea.

      Pneumothorax would be hyperresonant on percussion, not dull, and it may push the trachea away from the affected side in severe cases, but this is more common in tension pneumothoraces that occur after trauma.

      A lobectomy may cause the trachea to shift towards the same side as the surgery due to decreased pressure, but it would not cause dullness or absent breath sounds throughout the lung fields.

      Understanding White Lung Lesions on Chest X-Rays

      When examining a chest x-ray, white shadowing in the lungs can indicate a variety of conditions. These may include consolidation, pleural effusion, collapse, pneumonectomy, specific lesions such as tumors, or fluid accumulation such as pulmonary edema. In cases where there is a complete white-out of one side of the chest, it is important to assess the position of the trachea. If the trachea is pulled towards the side of the white-out, it may indicate pneumonectomy, lung collapse, or pulmonary hypoplasia. If the trachea is pushed away from the white-out, it may indicate pleural effusion, a large thoracic mass, or a diaphragmatic hernia. Other signs of a positive mass effect may include leftward bowing of the azygo-oesophageal recess and splaying of the ribs on the affected side. Understanding the potential causes of white lung lesions on chest x-rays can aid in accurate diagnosis and treatment.

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  • Question 19 - Which of the following paraneoplastic manifestations is the LEAST frequent in individuals diagnosed...

    Incorrect

    • Which of the following paraneoplastic manifestations is the LEAST frequent in individuals diagnosed with squamous cell lung carcinoma?

      Your Answer:

      Correct Answer: Lambert-Eaton syndrome

      Explanation:

      Small cell lung cancer is strongly associated with Lambert-Eaton syndrome, while squamous cell lung cancer is more commonly associated with paraneoplastic features such as PTHrp, clubbing, and HPOA.

      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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  • Question 20 - A 75-year-old man presents with a 2-month history of progressive shortness of breath...

    Incorrect

    • A 75-year-old man presents with a 2-month history of progressive shortness of breath and a recent episode of coughing up blood in the morning. He has also experienced significant weight loss of over 12 lbs and loss of appetite. Upon physical examination, conjunctival pallor is noted. The patient has a 30 pack year history of smoking. A chest x-ray reveals a mediastinal mass and ipsilateral elevation of the right diaphragm. What structure is being compressed by the mediastinal mass to explain these findings?

      Your Answer:

      Correct Answer: Phrenic nerve

      Explanation:

      Lung cancer can cause the hemidiaphragm on the same side to rise due to pressure on the phrenic nerve. Haemoptysis is a common symptom of lung cancer, along with significant weight loss and a history of smoking. A chest x-ray can confirm the presence of a mediastinal mass, which is likely to be lung cancer.

      A rapidly expanding lung mass can cause compression of surrounding structures, leading to complications. For example, an apical tumor can compress the brachial plexus, causing sensory symptoms in the arms or Erb’s or Klumpke’s palsies. Compression of the cervical sympathetic chain can cause Horner’s syndrome, which includes meiosis, anhidrosis, ptosis, and enophthalmos.

      A mediastinal mass can also compress the recurrent laryngeal nerve as it winds around the aortic arch, resulting in hoarseness of voice or aphonia. Superior vena caval syndrome is a medical emergency that can cause swelling of the face, neck, upper chest, and arms, as well as the development of collaterals on the chest wall. Malignancy is the most common cause, but non-malignant causes can include an aortic aneurysm, fibrosing mediastinitis, or iatrogenic factors.

      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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  • Question 21 - 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 37.2ÂșC. 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 22 - A 29-year-old man visits his primary care physician with complaints of a malodorous...

    Incorrect

    • 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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  • Question 23 - 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.

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  • Question 24 - A 33-year-old male presents to the ED with coughing and wheezing following an...

    Incorrect

    • 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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  • Question 25 - A 58-year-old man comes to the GP complaining of wheezing, coughing, and shortness...

    Incorrect

    • 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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  • Question 26 - A 30-year-old female complains of weakness, weight gain, and cold intolerance. You suspect...

    Incorrect

    • A 30-year-old female complains of weakness, weight gain, and cold intolerance. You suspect hypothyroidism. What vocal change would you anticipate to have occurred, increasing the probability of this potential diagnosis?

      Your Answer:

      Correct Answer: Hoarse voice

      Explanation:

      Hoarseness is a symptom that can be caused by hypothyroidism.

      When a patient presents with hoarseness, it can be difficult to determine the underlying cause. However, if the hoarseness is accompanied by other symptoms commonly associated with hypothyroidism, it can help narrow down the diagnosis.

      The reason for the voice change in hypothyroidism is due to the thickening of the vocal cords caused by the accumulation of mucopolysaccharide. This substance, also known as glycosaminoglycans, is found throughout the body in mucus and joint fluid. When it builds up in the vocal cords, it can lower the pitch of the voice. The thyroid hormone plays a role in preventing this buildup.

      Hoarseness can be caused by various factors such as overusing the voice, smoking, viral infections, hypothyroidism, gastro-oesophageal reflux, laryngeal cancer, and lung cancer. It is important to investigate the underlying cause of hoarseness, and a chest x-ray may be necessary to rule out any apical lung lesions.

      If laryngeal cancer is suspected, it is recommended to refer the patient to an ENT specialist through a suspected cancer pathway. This referral should be considered for individuals who are 45 years old and above and have persistent unexplained hoarseness or an unexplained lump in the neck. Early detection and treatment of laryngeal cancer can significantly improve the patient’s prognosis.

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  • Question 27 - As the pregnancy progresses, at what stage does the foetus typically begin producing...

    Incorrect

    • 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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  • Question 28 - A 25-year-old man presents to the Emergency department with acute onset of shortness...

    Incorrect

    • A 25-year-old man presents to the Emergency department with acute onset of shortness of breath during a basketball game. He reports no history of trauma and is typically healthy. Upon examination, he appears tall and lean, and respiratory assessment reveals reduced breath sounds and hyper-resonant percussion notes on the right side. The trachea remains centrally located. A chest x-ray confirms a diagnosis of a collapsed lung due to a right-sided pneumothorax. What is the reason for the lung's failure to re-expand?

      Your Answer:

      Correct Answer: Increase in intrapleural pressure

      Explanation:

      The process of lung expansion relies on the negative pressure in the intrapleural space between the visceral and parietal pleura, which is present throughout respiration. This negative pressure pulls the lung towards the chest wall, allowing it to expand. However, if air enters the intrapleural space, the negative pressure is lost and the lung cannot fully reinflate. It is important to note that the intrapleural space is a potential space between the pleural surfaces, and there is typically no actual space present under normal circumstances.

      Management of Pneumothorax: BTS Guidelines

      Pneumothorax is a condition where air accumulates in the pleural space, causing the lung to collapse. The British Thoracic Society (BTS) has published guidelines for the management of spontaneous pneumothorax, which can be primary or secondary. Primary pneumothorax occurs without any underlying lung disease, while secondary pneumothorax is associated with lung disease.

      The BTS recommends that patients with a rim of air less than 2 cm and no shortness of breath may be discharged, while those with a larger rim of air or shortness of breath should undergo aspiration or chest drain insertion. For secondary pneumothorax, patients over 50 years old with a rim of air greater than 2 cm or shortness of breath should undergo chest drain insertion. Aspiration may be attempted for those with a rim of air between 1-2 cm, but chest drain insertion is recommended if aspiration fails.

      Patients with iatrogenic pneumothorax, which is caused by medical procedures, have a lower likelihood of recurrence than those with spontaneous pneumothorax. Observation is usually sufficient, but chest drain insertion may be required in some cases. Ventilated patients and those with chronic obstructive pulmonary disease (COPD) may require chest drain insertion.

      Patients with pneumothorax should be advised to avoid smoking to reduce the risk of further episodes. They should also be aware of restrictions on air travel and scuba diving. The CAA recommends a waiting period of two weeks after successful drainage before air travel, while the BTS advises against scuba diving unless the patient has undergone bilateral surgical pleurectomy and has normal lung function and chest CT scan postoperatively.

      In summary, the BTS guidelines provide a comprehensive approach to the management of pneumothorax, taking into account the type of pneumothorax and the patient’s individual circumstances. Early intervention and appropriate follow-up can help prevent complications and improve outcomes.

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  • Question 29 - 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 ÂșC. 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.

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  • Question 30 - A 70-year-old man with lung cancer is having a left pneumonectomy. The left...

    Incorrect

    • A 70-year-old man with lung cancer is having a left pneumonectomy. The left main bronchus is being divided. Which thoracic vertebrae is located behind this structure?

      Your Answer:

      Correct Answer: T6

      Explanation:

      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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SESSION STATS - PERFORMANCE PER SPECIALTY

Respiratory System (3/6) 50%
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