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EDIC Part I study materials
EDIC Part I study resources

EDIC Part I practice questions

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Question 1Acute Kidney Injury

A 68-year-old man is admitted with acute decompensated heart failure and a serum creatinine that has risen from 1.0 to 1.9 mg/dL over three days. His urine sodium is 12 mmol/L, urine osmolality is 520 mOsm/kg, and FENa is 0.4%. Which mechanism best explains his acute kidney injury?

  1. Postrenal obstruction at the level of the bladder outlet
  2. Acute interstitial nephritis from a drug-induced hypersensitivity reaction
  3. Acute tubular necrosis from ischemic injury with loss of concentrating ability
  4. Prerenal azotemia from reduced effective circulating volume with intact tubular reabsorption Correct answer.

Explanation

In cardiorenal physiology, reduced effective circulating volume triggers avid sodium and water reabsorption, producing a low urine sodium, high urine osmolality, and FENa below 1%. These indices indicate functional prerenal azotemia rather than established tubular damage. Intact tubular function is what allows the urine to be concentrated and sodium-poor.

Question 2Acute Kidney Injury

Which KDIGO criterion defines stage 1 acute kidney injury by serum creatinine alone?

  1. Increase to 2.0 to 2.9 times baseline within 7 days
  2. Increase of at least 0.3 mg/dL within 48 hours or 1.5 to 1.9 times baseline within 7 days Correct answer.
  3. Increase to 3.0 times baseline or more within 7 days
  4. Initiation of renal replacement therapy regardless of creatinine

Explanation

KDIGO stage 1 AKI is defined by a creatinine rise of at least 0.3 mg/dL within 48 hours or a rise to 1.5 to 1.9 times baseline within the prior 7 days. Stage 2 requires 2.0 to 2.9 times baseline, and stage 3 requires 3.0 times baseline, creatinine of 4.0 mg/dL or more, or initiation of renal replacement therapy.

Question 3Acute Kidney Injury

A 54-year-old woman with cirrhosis and tense ascites develops oliguria after large-volume paracentesis without albumin replacement. Blood pressure falls from 118/70 to 92/58 mmHg. Which initial management step is most appropriate?

  1. High-dose furosemide to mobilize ascites
  2. Immediate initiation of intermittent hemodialysis
  3. Intravenous fluid challenge with crystalloid and reassessment of hemodynamics Correct answer.
  4. Oral potassium supplementation alone

Explanation

This is prerenal AKI from post-paracentesis circulatory dysfunction, driven by reduced effective circulating volume. The first step is restoring intravascular volume with crystalloid, or albumin in the cirrhosis context, and reassessing perfusion and urine output. Dialysis is reserved for refractory complications such as hyperkalemia or volume overload.

Question 4Acute Kidney Injury

Fractional excretion of sodium (FENa) is calculated using which formula?

  1. (Urine Na x Plasma creatinine) / (Plasma Na x Urine creatinine) x 100 Correct answer.
  2. (Urine Na x Urine creatinine) / (Plasma Na x Plasma creatinine) x 100
  3. (Urine Na / Plasma Na) x 100
  4. (Plasma Na x Plasma creatinine) / (Urine Na x Urine creatinine) x 100

Explanation

FENa expresses the fraction of filtered sodium that is excreted, so it compares sodium clearance with creatinine clearance. The formula is urine sodium times plasma creatinine divided by plasma sodium times urine creatinine, multiplied by 100 to give a percentage. A value below 1% suggests sodium-avid prerenal physiology.

Question 5Acute Kidney Injury

Which finding is most characteristic of hepatorenal syndrome in a patient with advanced cirrhosis?

  1. Bilateral enlarged kidneys with perinephric stranding on imaging
  2. Eosinophiluria with sterile pyuria
  3. Urine sodium below 10 mmol/L with no improvement after albumin challenge and absence of shock Correct answer.
  4. Urine sodium above 40 mmol/L with muddy brown casts

Explanation

Hepatorenal syndrome is a functional renal failure in cirrhosis characterized by intense sodium avidity, urine sodium typically below 10 mmol/L, and failure to respond to albumin challenge in the absence of shock or nephrotoxins. The diagnosis is one of exclusion after other causes are eliminated.

Question 6Acute Kidney Injury

A patient receiving gentamicin for four days develops non-oliguric AKI with a creatinine rise from 0.9 to 2.4 mg/dL. Urinalysis shows granular casts and FENa of 3.2%. Which mechanism is most likely?

  1. Aminoglycoside-induced acute tubular necrosis Correct answer.
  2. Acute glomerulonephritis
  3. Contrast-induced nephropathy
  4. Prerenal azotemia from sepsis

Explanation

Aminoglycosides accumulate in proximal tubular cells and cause direct tubular toxicity, typically after several days of therapy. The findings of granular casts and a FENa above 2% support established tubular injury rather than a prerenal state. Non-oliguric presentations are common with aminoglycoside toxicity.

Question 7Acute Kidney Injury

Which urinalysis finding most strongly supports acute tubular necrosis over prerenal azotemia?

  1. White blood cell casts
  2. Hyaline casts
  3. Muddy brown granular casts Correct answer.
  4. Broad waxy casts

Explanation

Muddy brown granular casts reflect sloughed tubular epithelial cells and indicate established tubular injury, supporting acute tubular necrosis. Hyaline casts are nonspecific and can occur in normal concentrated urine. White cell casts suggest interstitial nephritis or pyelonephritis, and broad waxy casts indicate chronic kidney disease.

Question 8Acute Kidney Injury

A 72-year-old man with benign prostatic hyperplasia presents with anuria, a palpable bladder, and creatinine of 4.1 mg/dL. Which initial intervention is most appropriate?

  1. Dopamine infusion to improve renal perfusion
  2. Urethral catheterization for bladder decompression Correct answer.
  3. Nephrotoxic drug review alone without drainage
  4. Intravenous furosemide to stimulate urine output

Explanation

Anuria with a palpable bladder indicates acute postrenal obstruction at the bladder outlet, most likely from prostatic enlargement. Prompt bladder decompression with urethral catheterization relieves the obstruction and allows post-obstructive diuresis monitoring. Identifying and relieving the obstruction is the definitive first step.

Question 9Acute Kidney Injury

Which statement about contrast-associated acute kidney injury is accurate?

  1. Serum creatinine peaks within 6 hours of contrast exposure
  2. Risk is reduced by volume expansion with isotonic crystalloid before and after contrast administration Correct answer.
  3. Risk is highest with low-osmolar nonionic contrast agents
  4. Prophylactic N-acetylcysteine reliably prevents contrast-associated AKI

Explanation

Peri-procedural volume expansion with isotonic saline is the best-supported preventive measure for contrast-associated AKI. N-acetylcysteine has not been shown to reliably prevent the injury in large trials. Creatinine typically rises at 48 to 72 hours, and low-osmolar agents carry lower risk than high-osmolar agents.

Question 10Acute Kidney Injury

A patient with AKI has a potassium of 6.9 mmol/L with peaked T waves and widening of the QRS complex. Which intervention should be given first to stabilize the myocardium?

  1. Intravenous furosemide
  2. Intravenous calcium gluconate Correct answer.
  3. Intravenous regular insulin with dextrose
  4. Oral sodium polystyrene sulfonate

Explanation

When hyperkalemia produces electrocardiographic changes, intravenous calcium salts are given first to stabilize the cardiac membrane, acting within minutes without lowering potassium. Insulin with dextrose, beta-agonists, and potassium removal follow to shift and eliminate potassium. Calcium does not reduce the serum potassium concentration itself.

Question 11Acute Kidney Injury

Which parameter is used to define the oliguric threshold in AKI staging by urine output?

  1. Urine output less than 1.0 mL/kg/h for 2 hours
  2. Urine output less than 2.0 mL/kg/h for 4 hours
  3. Urine output less than 0.3 mL/kg/h for 24 hours only
  4. Urine output less than 0.5 mL/kg/h for 6 to 12 hours Correct answer.

Explanation

KDIGO stage 1 AKI by urine output is less than 0.5 mL/kg/h for 6 to 12 hours. Stage 2 is less than 0.5 mL/kg/h for 12 hours or more, and stage 3 includes less than 0.3 mL/kg/h for 24 hours or anuria for 12 hours. These thresholds standardize the oliguric definition across stages.

Question 12Acute Kidney Injury

A 45-year-old woman started on vancomycin and piperacillin-tazobactam ten days ago develops fever, a maculopapular rash, and creatinine rising from 0.8 to 2.6 mg/dL. Urinalysis shows sterile pyuria and eosinophiluria. Which diagnosis is most likely?

  1. Prerenal azotemia from fever
  2. Post-streptococcal glomerulonephritis
  3. Acute tubular necrosis from vancomycin
  4. Drug-induced acute interstitial nephritis Correct answer.

Explanation

Fever, rash, sterile pyuria, and eosinophiluria after exposure to beta-lactam or vancomycin therapy are classic for drug-induced acute interstitial nephritis. The temporal relationship and hypersensitivity features support an allergic tubulointerstitial process. Withdrawal of the culprit drug is the cornerstone of management.

Question 13Acute Kidney Injury

Which statement about renal replacement therapy initiation in AKI is most consistent with current evidence?

  1. Early initiation consistently reduces mortality in critically ill patients with AKI
  2. Renal replacement therapy should be started whenever creatinine exceeds 2.0 mg/dL
  3. Intermittent hemodialysis is contraindicated in hemodynamically unstable patients
  4. Early initiation in the absence of urgent indications does not improve survival compared with a watchful waiting strategy Correct answer.

Explanation

Large randomized trials have not shown a survival benefit from early renal replacement therapy in the absence of urgent indications such as refractory hyperkalemia, acidosis, volume overload, or uremic complications. A watchful waiting approach with prompt initiation when indications arise is reasonable. Urgent indications, not a fixed creatinine threshold, guide timing.

Question 14Acute Kidney Injury

Which of the following is the most appropriate initial fluid strategy for a patient with septic shock and early AKI?

  1. Rapid infusion of hydroxyethyl starch to achieve a central venous pressure target
  2. Balanced crystalloid resuscitation guided by dynamic measures of fluid responsiveness Correct answer.
  3. Hypertonic saline to increase serum sodium
  4. Restriction of all intravenous fluids until creatinine improves

Explanation

Balanced crystalloids with resuscitation guided by dynamic indices of fluid responsiveness support perfusion while limiting unnecessary fluid accumulation. Hydroxyethyl starch increases the risk of kidney injury and should be avoided. Fluid restriction in early septic shock would worsen hypoperfusion.

Question 15Acute Kidney Injury

A patient with AKI on day 4 of admission has persistent oliguria, a creatinine that has plateaued at 3.8 mg/dL, refractory metabolic acidosis, and pulmonary edema despite diuretics. Which next step is most appropriate?

  1. Increase the furosemide dose further
  2. Initiate renal replacement therapy Correct answer.
  3. Give a fluid bolus to improve renal perfusion
  4. Start a low-dose dopamine infusion

Explanation

Refractory volume overload, severe metabolic acidosis, and persistent oliguria are accepted urgent indications for renal replacement therapy. Continuing diuretics in the face of pulmonary edema risks further harm. Vasoactive dopamine and additional fluid would not address the failure of renal excretory function.

Question 16Acute Kidney Injury

A 60-year-old man with AKI has a serum sodium of 118 mmol/L, serum glucose of 90 mg/dL, and no hyperlipidemia. Which statement about his hyponatremia is correct?

  1. The low sodium is most likely spurious because glucose is normal
  2. A measured serum osmolality is needed to exclude pseudohyponatremia and assess true hypo-osmolality Correct answer.
  3. Hyponatremia in AKI is always due to sodium loss from tubular injury
  4. Rapid correction to a sodium of 135 mmol/L within 6 hours is the goal

Explanation

True hypo-osmolality should be confirmed with a measured serum osmolality, because pseudohyponatremia from hyperproteinemia or hyperlipidemia can produce a spuriously low sodium. In AKI, impaired free water excretion commonly causes dilutional hyponatremia. Correction must be gradual to avoid osmotic demyelination.

Question 17Acute Kidney Injury

A patient with AKI attributed to prerenal azotemia has been treated with intravenous fluids, but creatinine continues to rise and urine output falls. Which finding would most strongly suggest a transition to intrinsic acute tubular necrosis?

  1. Rising FENa above 2% with muddy brown granular casts Correct answer.
  2. Blood urea nitrogen-to-creatinine ratio rising above 20
  3. Urine sodium falling to 8 mmol/L
  4. Urine osmolality rising to 600 mOsm/kg

Explanation

A shift from a sodium-avid prerenal profile to a FENa above 2% with muddy brown granular casts signals established tubular injury, indicating the process is no longer purely prerenal. A low urine sodium, concentrated urine, and a high BUN-to-creatinine ratio are features of prerenal physiology. Recognizing the transition guides fluid management and prognostication.

Question 18Acute Respiratory Failure

A 62-year-old man with severe community-acquired pneumonia has a PaO2 of 55 mmHg on room air. By the Berlin definition, which PaO2/FiO2 threshold must be met to classify his hypoxaemia as moderate acute respiratory distress syndrome?

  1. 100 to 200 mmHg with positive end-expiratory pressure of at least 5 cmH2O Correct answer.
  2. 200 to 300 mmHg with positive end-expiratory pressure of at least 5 cmH2O
  3. 50 to 100 mmHg with positive end-expiratory pressure of at least 5 cmH2O
  4. Below 50 mmHg with positive end-expiratory pressure of at least 5 cmH2O

Explanation

The Berlin definition grades ARDS by the PaO2/FiO2 ratio measured with positive end-expiratory pressure of at least 5 cmH2O: mild is 200 to 300, moderate is 100 to 200, and severe is below 100 mmHg. The ratio must be calculated on ventilated or CPAP-supported patients with bilateral opacities not fully explained by cardiac failure.

Question 19Acute Respiratory Failure

Which arterial blood gas finding is most characteristic of acute hypercapnic respiratory failure in a patient with an acute exacerbation of chronic obstructive pulmonary disease?

  1. PaO2 60 mmHg with PaCO2 38 mmHg and pH 7.40
  2. PaO2 80 mmHg with PaCO2 45 mmHg and pH 7.36
  3. PaO2 90 mmHg with PaCO2 30 mmHg and pH 7.50
  4. PaO2 55 mmHg with PaCO2 70 mmHg and pH 7.28 Correct answer.

Explanation

Acute hypercapnic respiratory failure is defined by a PaCO2 above 50 mmHg together with acidaemia, reflecting alveolar hypoventilation that outstrips renal compensation. The combination of hypoxaemia, hypercapnia and respiratory acidosis is typical of a severe COPD exacerbation.

Question 20Acute Respiratory Failure

A patient with acute respiratory failure is breathing oxygen through a Venturi mask set to deliver 35% oxygen. What is the main clinical advantage of this device over a simple nasal cannula?

  1. It humidifies gas to body temperature and full saturation
  2. It allows precise measurement of tidal volume during spontaneous breathing
  3. It can generate positive end-expiratory pressure of 10 cmH2O
  4. It delivers a relatively constant inspired oxygen fraction regardless of the patient's inspiratory flow Correct answer.

Explanation

A Venturi (air-entrainment) mask mixes oxygen with room air at a fixed ratio, so the delivered FiO2 remains stable even when the patient's peak inspiratory flow varies. This makes it useful when a predictable oxygen concentration is required, for example in COPD at risk of hypercapnia.

Question 21Acute Respiratory Failure

Which finding on a plain chest radiograph most supports a diagnosis of cardiogenic pulmonary oedema rather than non-cardiogenic acute respiratory distress syndrome?

  1. Hyperinflation with flattened hemidiaphragms and a narrow mediastinum
  2. Cardiomegaly with bilateral perihilar alveolar opacities and pleural effusions Correct answer.
  3. Unilateral lobar consolidation with air bronchograms
  4. Patchy peripheral opacities with normal cardiac silhouette and no effusions

Explanation

Cardiogenic oedema typically produces an enlarged cardiac silhouette, perihilar bat-wing alveolar shadowing, upper-lobe blood diversion and pleural effusions. Non-cardiogenic ARDS more often shows diffuse opacities with a normal heart size and no effusions.

Question 22Acute Respiratory Failure

A patient with acute hypoxaemic respiratory failure is started on high-flow nasal oxygen therapy. Which physiological effect best explains the improvement in oxygenation seen with this device?

  1. Direct alveolar recruitment achieved by pressures above 30 cmH2O
  2. Reversal of intrapulmonary shunt by abolishing hypoxic pulmonary vasoconstriction
  3. Complete elimination of the patient's work of breathing
  4. Delivery of a stable high FiO2 with a modest positive end-expiratory pressure effect and dead-space washout Correct answer.

Explanation

High-flow nasal cannula provides a heated, humidified flow that meets inspiratory demand, giving a stable high FiO2 while generating a small positive end-expiratory pressure effect and washing out nasopharyngeal dead space. It reduces work of breathing but does not abolish it or eliminate shunt.

Question 23Acute Respiratory Failure

A 70-year-old woman with Guillain-Barre syndrome is being monitored for impending respiratory failure. Which bedside measurement is the most useful early indicator of respiratory muscle fatigue?

  1. Peripheral oxygen saturation measured continuously
  2. Peak cough flow measured once on admission
  3. Serum bicarbonate concentration
  4. Vital capacity trending downward on serial measurement Correct answer.

Explanation

Serial vital capacity is the classic bedside measure of respiratory muscle strength in neuromuscular disease; a falling vital capacity signals fatigue before gas exchange deteriorates. Oxygen saturation can remain normal until collapse because hypoxaemia is a late finding in hypoventilation.

Question 24Acute Respiratory Failure

A patient with severe acute respiratory distress syndrome is considered for prone positioning. Which statement best reflects the evidence supporting this intervention?

  1. Prone positioning is indicated only when the PaO2/FiO2 ratio exceeds 300 mmHg
  2. Prone positioning for at least 12 to 16 hours daily reduces mortality in moderate-to-severe ARDS Correct answer.
  3. Prone positioning improves oxygenation but has no effect on mortality
  4. Prone positioning should be limited to 4 hours daily to avoid pressure injuries

Explanation

A landmark randomised trial showed that prolonged prone positioning, around 16 hours per day, reduced mortality in patients with moderate-to-severe ARDS. The benefit is attributed to recruitment of dorsal lung regions and more uniform ventilation-perfusion distribution.

Question 25Acute Respiratory Failure

A 55-year-old man with acute pancreatitis develops respiratory failure. His PaO2/FiO2 ratio is 150 mmHg on positive end-expiratory pressure of 8 cmH2O, and chest imaging shows bilateral opacities. Echocardiography shows normal ventricular function and there is no evidence of volume overload. Which diagnosis is most consistent with these findings?

  1. Severe community-acquired pneumonia with lobar consolidation
  2. Pulmonary embolism with right ventricular failure
  3. Acute cardiogenic pulmonary oedema
  4. Moderate acute respiratory distress syndrome of extrapulmonary origin Correct answer.

Explanation

The Berlin criteria are met: acute onset, bilateral opacities, a ratio between 100 and 200 mmHg on positive end-expiratory pressure, and respiratory failure not fully explained by cardiac failure. Pancreatitis is a recognised extrapulmonary trigger of ARDS, which often produces more uniform opacities than a primary pulmonary cause.

Question 26Acute Respiratory Failure

A patient with an acute exacerbation of COPD has a pH of 7.22 and PaCO2 of 68 mmHg despite controlled oxygen therapy. Which intervention is most appropriate next?

  1. Increasing the inspired oxygen concentration to 100%
  2. Intravenous sodium bicarbonate to correct the acidosis
  3. Immediate tracheal intubation and mechanical ventilation
  4. Non-invasive ventilation with bilevel positive airway pressure Correct answer.

Explanation

Non-invasive ventilation is the first-line ventilatory support for hypercapnic COPD exacerbations with respiratory acidosis, reducing intubation and mortality. Controlled oxygen should be maintained to a target saturation, not increased to 100%, and bicarbonate is not indicated for acute respiratory acidosis.

Question 27Acute Respiratory Failure

Which ventilator strategy has been shown to reduce mortality in patients with acute respiratory distress syndrome?

  1. Permissive hypercapnia avoided by increasing respiratory rate to normalise PaCO2
  2. Low tidal volume ventilation of about 6 mL/kg predicted body weight with plateau pressure below 30 cmH2O Correct answer.
  3. Routine use of high tidal volumes with zero end-expiratory pressure
  4. High tidal volume of 12 mL/kg to improve carbon dioxide clearance

Explanation

Lung-protective ventilation using tidal volumes near 6 mL/kg predicted body weight and limiting plateau pressure to 30 cmH2O or less reduces ventilator-induced lung injury and mortality. Permissive hypercapnia is accepted rather than aggressively corrected.

Question 28Acute Respiratory Failure

A patient is admitted with acute hypoxaemic respiratory failure and a history of heart failure. Which test is most useful for distinguishing cardiogenic pulmonary oedema from ARDS at the bedside?

  1. Serum amylase and lipase
  2. Bedside echocardiography combined with natriuretic peptide measurement Correct answer.
  3. Sputum Gram stain
  4. Serial blood cultures

Explanation

Echocardiography assesses ventricular function and filling pressures, while natriuretic peptides support a hydrostatic cause when elevated. Together they help separate cardiogenic oedema from ARDS, in which cardiac function is typically normal and peptides are not markedly raised.

Question 29Acute Respiratory Failure

A patient with acute respiratory failure has a chest radiograph showing a large right-sided pleural effusion with mediastinal shift to the left and hypotension. What is the most appropriate immediate management?

  1. Diuretic therapy with careful fluid balance
  2. Urgent decompression, initially by needle thoracocentesis or chest drain Correct answer.
  3. Broad-spectrum antibiotics alone
  4. Non-invasive ventilation with bilevel positive airway pressure

Explanation

A large effusion causing mediastinal shift and haemodynamic compromise suggests tension physiology, most often a tension hydrothorax or haemothorax, and requires urgent drainage. Medical therapy alone will not relieve the compressive effect on the heart and great vessels.

Question 30Acute Respiratory Failure

In a patient with acute respiratory distress syndrome, which finding best indicates that the respiratory failure is not solely due to left atrial hypertension?

  1. A history of hypertension treated with two agents
  2. Bilateral pleural effusions on computed tomography
  3. A pulmonary artery occlusion pressure of 15 mmHg with normal ventricular function on echocardiography Correct answer.
  4. A brain natriuretic peptide level of 1200 pg/mL

Explanation

The Berlin definition requires that respiratory failure not be fully explained by cardiac failure or fluid overload, which is supported by objective assessment such as a normal pulmonary artery occlusion pressure and normal ventricular function. Bilateral effusions and a hypertension history are non-specific and do not exclude a hydrostatic component.

Question 31Acute Respiratory Failure

A patient with acute respiratory failure is receiving mechanical ventilation and develops a sudden rise in peak airway pressure with a reduced tidal volume. Which cause should be considered first?

  1. A decrease in the patient's metabolic rate
  2. Progressive resolution of the underlying pneumonia
  3. A gradual increase in lung compliance
  4. A blocked or displaced endotracheal tube Correct answer.

Explanation

A sudden increase in peak airway pressure with falling delivered volume points to an obstruction or displacement of the artificial airway, such as mucus plugging, biting, or tube migration. Immediate assessment includes passing a suction catheter and checking tube position.

Question 32Acute Respiratory Failure

A patient with severe acute respiratory distress syndrome has refractory hypoxaemia despite lung-protective ventilation and prone positioning. Venovenous extracorporeal membrane oxygenation is being considered. Which statement best describes its role?

  1. It should be used only when the PaO2/FiO2 ratio is above 300 mmHg
  2. It provides gas exchange support while the lungs recover, and is considered when conventional measures fail in potentially reversible disease Correct answer.
  3. It is a definitive treatment that replaces mechanical ventilation permanently
  4. It is indicated primarily for isolated right ventricular failure

Explanation

Venovenous ECMO supports oxygenation and carbon dioxide removal in severe but potentially reversible respiratory failure when conventional ventilation and adjuncts fail. It is a bridge to recovery or transplantation, not a permanent replacement for the lungs.

Question 33Acute Respiratory Failure

A patient with acute respiratory failure has a PaO2 of 60 mmHg while receiving 60% oxygen by Venturi mask. Which calculation gives the PaO2/FiO2 ratio, and how should it be interpreted?

  1. 360 mmHg, indicating normal oxygenation
  2. 100 mmHg, indicating severe impairment of oxygenation Correct answer.
  3. 60 mmHg, indicating normal oxygenation
  4. 36 mmHg, indicating mild impairment

Explanation

The ratio is calculated by dividing PaO2 by the fractional inspired oxygen, so 60 divided by 0.60 equals 100 mmHg. A ratio of 100 mmHg represents severe impairment of oxygenation and, in the appropriate clinical context, severe ARDS.

Question 34Acute Respiratory Failure

A patient with acute respiratory failure is being assessed for weaning from mechanical ventilation. Which combination of findings best predicts successful extubation?

  1. Negative inspiratory force weaker than minus 15 cmH2O
  2. Rapid shallow breathing index above 150 with copious secretions
  3. PaO2/FiO2 ratio of 120 mmHg on positive end-expiratory pressure of 12 cmH2O
  4. Rapid shallow breathing index below 105 with adequate cough and minimal secretions Correct answer.

Explanation

A rapid shallow breathing index below about 105 breaths per minute per litre, together with a strong cough and manageable secretions, predicts extubation success. A high index, low ratio, high support, or weak inspiratory force all predict failure.

Question 35Anaesthesia & Peri-operative Medicine

A patient with a documented anaphylactic reaction to rocuronium is scheduled for surgery requiring neuromuscular blockade. Which neuromuscular blocking agent is most appropriate, given that cross-reactivity between aminosteroid and benzylisoquinolinium agents is low?

  1. Rocuronium
  2. Vecuronium
  3. Pancuronium
  4. Cisatracurium Correct answer.

Explanation

Cisatracurium is a benzylisoquinolinium compound, a structurally distinct class from the aminosteroid agents rocuronium, vecuronium and pancuronium, so cross-sensitivity is uncommon. When a patient has confirmed aminosteroid allergy, switching to a benzylisoquinolinium relaxant is the standard strategy. Sugammadex does not prevent the allergic reaction and is not a substitute for avoiding the culprit drug.

Question 36Anaesthesia & Peri-operative Medicine

During rapid sequence induction in a hypovolaemic trauma patient, which induction agent is preferred because it best preserves haemodynamic stability?

  1. Etomidate
  2. Ketamine Correct answer.
  3. Thiopentone
  4. Propofol

Explanation

Ketamine is a dissociative agent that increases sympathetic outflow and preserves or raises blood pressure, making it useful in hypovolaemic or shocked patients. Propofol and thiopentone cause significant vasodilatation and myocardial depression, and etomidate, while haemodynamically stable, does not provide the same sympathetic support. The choice must still be titrated to effect to avoid excessive hypertension in the injured patient.

Question 37Anaesthesia & Peri-operative Medicine

A 70 kg patient requires a sugammadex dose to reverse deep rocuronium blockade (post-tetanic count 1-2). What dose is recommended?

  1. 16 mg/kg
  2. 4 mg/kg
  3. 8 mg/kg Correct answer.
  4. 2 mg/kg

Explanation

Sugammadex dosing is graded to depth of blockade: 2 mg/kg for moderate block (train-of-four count 1-2), 4 mg/kg for deep block (post-tetanic count 1-2) and 16 mg/kg for immediate reversal after a rocuronium rapid sequence induction. Deep blockade therefore requires 4 mg/kg, not 2 mg/kg. Choosing the correct dose avoids inadequate reversal and re-curarisation.

Question 38Anaesthesia & Peri-operative Medicine

Which volatile anaesthetic is most strongly associated with triggering malignant hyperthermia?

  1. Halothane Correct answer.
  2. Isoflurane
  3. Desflurane
  4. Sevoflurane

Explanation

All volatile anaesthetics can trigger malignant hyperthermia, but halothane is historically the most potent trigger and the classic agent associated with the syndrome. In modern practice sevoflurane and desflurane are the most commonly implicated simply because they are widely used. The key clinical point is that any volatile agent plus succinylcholine should be avoided in susceptible patients.

Question 39Anaesthesia & Peri-operative Medicine

A patient with severe aortic stenosis is undergoing induction of anaesthesia. Maintenance of which physiological parameter is most critical to avoid myocardial ischaemia?

  1. Heart rate above 100 beats per minute
  2. Increased myocardial contractility
  3. Reduction of preload to lower wall stress
  4. Systemic vascular resistance and diastolic perfusion pressure Correct answer.

Explanation

In severe aortic stenosis the hypertrophied left ventricle depends on adequate diastolic coronary perfusion pressure and is very sensitive to afterload reduction. Vasodilatation or hypotension can cause dangerous falls in coronary flow and ischaemia, so systemic vascular resistance and diastolic pressure must be maintained. Tachycardia is poorly tolerated because it shortens diastolic filling and coronary perfusion time.

Question 40Anaesthesia & Peri-operative Medicine

Which agent is the first-line treatment for bronchospasm during anaphylaxis under anaesthesia?

  1. Intramuscular adrenaline Correct answer.
  2. Intravenous salbutamol
  3. Nebulised ipratropium
  4. Intravenous hydrocortisone

Explanation

Intramuscular adrenaline is the first-line treatment for anaphylaxis because it reverses vasodilatation, reduces mucosal oedema and bronchodilates. It should be given early into the anterolateral thigh at 0.5 mg (0.5 mL of 1:1000) in adults. Bronchodilators and steroids are adjuncts, not initial therapy.

Question 41Anaesthesia & Peri-operative Medicine

A patient with chronic kidney disease (eGFR 20 mL/min/1.73 m2) requires neuromuscular blockade. Which agent is preferred because its elimination is organ-independent?

  1. Vecuronium
  2. Rocuronium
  3. Pancuronium
  4. Atracurium Correct answer.

Explanation

Atracurium undergoes Hofmann degradation and ester hydrolysis, so its clearance is largely independent of renal and hepatic function. This makes it the relaxant of choice in renal failure, where aminosteroid agents accumulate and prolong blockade. Cisatracurium shares this property and is an equally valid alternative.

Question 42Anaesthesia & Peri-operative Medicine

Which preoperative fasting interval is currently recommended for clear fluids in adults before elective surgery?

  1. 2 hours Correct answer.
  2. 8 hours
  3. 4 hours
  4. 6 hours

Explanation

Current guidance permits clear fluids up to 2 hours before induction of anaesthesia in adults, because gastric emptying of clear liquids is rapid. Light meals require 6 hours and fatty or fried meals require 8 hours. Prolonged clear-fluid fasting is discouraged as it causes dehydration and patient discomfort without reducing aspiration risk.

Question 43Anaesthesia & Peri-operative Medicine

A patient receiving long-term lithium therapy is scheduled for major surgery. Which perioperative risk requires particular attention?

  1. Hyperkalaemia caused by volatile agents
  2. Increased metabolism of propofol requiring higher doses
  3. Enhanced neuromuscular blockade and lithium toxicity with dehydration Correct answer.
  4. Reduced seizure threshold requiring higher anaesthetic doses

Explanation

Lithium has a narrow therapeutic index and is renally excreted, so dehydration, blood loss and diuretics can precipitate toxicity. It also prolongs the action of depolarising and non-depolarising neuromuscular blockers, so neuromuscular monitoring is essential. Many anaesthetists reduce or omit the dose on the morning of surgery after checking a lithium level.

Question 44Anaesthesia & Peri-operative Medicine

Which monitoring modality provides the earliest reliable warning of a venous air embolism during neurosurgery in the sitting position?

  1. Pulse oximetry
  2. Capnography
  3. Precordial Doppler Correct answer.
  4. Central venous pressure

Explanation

Precordial Doppler is the most sensitive monitor for detecting small volumes of venous air entrainment and typically changes before other parameters. A fall in end-tidal CO2 is a later and less sensitive sign, although it is widely used. Precordial Doppler is therefore the earliest warning, but it is non-specific and requires correlation with clinical signs.

Question 45Anaesthesia & Peri-operative Medicine

A patient with a history of suxamethonium-induced masseter spasm and hyperthermia requires general anaesthesia. Which technique is most appropriate?

  1. Isoflurane with succinylcholine
  2. Sevoflurane with succinylcholine
  3. Propofol with rocuronium and a trigger-free circuit Correct answer.
  4. Desflurane with succinylcholine

Explanation

Masseter spasm after succinylcholine may be an early sign of malignant hyperthermia susceptibility, so all trigger agents (volatile anaesthetics and succinylcholine) should be avoided. A total intravenous anaesthetic with propofol and a non-depolarising relaxant such as rocuronium is the standard safe approach. The circuit should be prepared trigger-free and dantrolene must be immediately available.

Question 46Anaesthesia & Peri-operative Medicine

Which local anaesthetic has the longest duration of action when used for peripheral nerve blockade?

  1. Chloroprocaine
  2. Mepivacaine
  3. Lidocaine
  4. Bupivacaine Correct answer.

Explanation

Bupivacaine is highly protein-bound and has the longest duration of action among common amide local anaesthetics, typically 8-12 hours for peripheral blocks. Lidocaine and mepivacaine are intermediate in duration, and chloroprocaine is short-acting. This property makes bupivacaine popular for postoperative analgesia in regional anaesthesia.

Question 47Anaesthesia & Peri-operative Medicine

A patient with severe pre-eclampsia requires anaesthesia for caesarean section. Which statement about spinal anaesthesia is correct?

  1. General anaesthesia is always preferred to avoid hypotension
  2. Epidural anaesthesia cannot be used in pre-eclampsia
  3. Spinal anaesthesia is safe with careful blood pressure control and vasopressor support Correct answer.
  4. Spinal anaesthesia is contraindicated because of the risk of seizures

Explanation

Spinal anaesthesia is widely used in severe pre-eclampsia and is generally preferred to general anaesthesia, which carries airway and hypertensive-response risks. The main concern is hypotension, which is managed with preload or co-load and prompt vasopressor therapy, often phenylephrine. Neuraxial techniques are not contraindicated in pre-eclampsia unless there is coagulopathy or another specific contraindication.

Question 48Anaesthesia & Peri-operative Medicine

Which of the following best describes the mechanism of action of tranexamic acid in reducing perioperative bleeding?

  1. Direct activation of antithrombin
  2. Inhibition of platelet cyclooxygenase
  3. Inhibition of plasminogen activation and fibrinolysis Correct answer.
  4. Reversal of heparin by binding to factor Xa

Explanation

Tranexamic acid is an antifibrinolytic that competitively blocks lysine-binding sites on plasminogen, preventing its conversion to plasmin and reducing clot breakdown. It does not activate antithrombin, inhibit platelet cyclooxygenase or reverse heparin. This mechanism underlies its use in trauma, cardiac and orthopaedic surgery.

Question 49Anaesthesia & Peri-operative Medicine

A patient is receiving a remifentanil infusion for awake fibreoptic intubation. Which statement about remifentanil is correct?

  1. It is primarily eliminated unchanged by the kidney
  2. It has a long duration of action requiring prolonged postoperative ventilation
  3. It is metabolised by plasma esterases and has a short context-insensitive half-time Correct answer.
  4. It has a context-sensitive half-time that increases markedly with prolonged infusion

Explanation

Remifentanil is an ester-linked opioid metabolised by non-specific plasma and tissue esterases, giving a context-insensitive half-time of about 3-5 minutes regardless of infusion duration. This makes it ideal for procedures requiring rapid titratability. It is not renally eliminated and does not cause prolonged postoperative respiratory depression.

Question 50Anaesthesia & Peri-operative Medicine

Which finding is the most reliable early sign of a tension pneumothorax during positive-pressure ventilation?

  1. Sudden rise in peak airway pressure with hypotension and reduced breath sounds Correct answer.
  2. Gradual decrease in end-tidal CO2 with bradycardia
  3. Increase in central venous pressure alone
  4. Wheezing on both lung fields

Explanation

Tension pneumothorax during positive-pressure ventilation presents with a sudden rise in peak inspiratory pressure, hypotension and unilateral absent breath sounds, often with tracheal deviation. Immediate needle decompression followed by chest drain is required. Waiting for late signs such as bradycardia or desaturation risks cardiac arrest.