DHA Critical Care Medicine exam questions

6 worked Critical Care Medicine practice questions

Original exam-style questions from the bank, spread across the blueprint domains. They are not real or recalled exam questions. Try each one, then open the answer for the rationale and reference. None of them appear in the free mock exam, so reading them will not spoil it.

1. Question 1 · Cardiovascular critical care

   A patient with acute type B aortic dissection has blood pressure 190/100 mmHg and heart rate 105 beats/min. What is the best initial approach?

   1. AIntravenous sodium nitroprusside first, then a beta-blocker if heart rate rises
   2. BOral amlodipine with a target systolic below 160 mmHg
   3. CIntravenous hydralazine with a target MAP of 110 mmHg
   4. DIntravenous beta-blocker first, aiming for heart rate about 60 and systolic 100 to 120 mmHg
   Show answer and explanation

   Correct answer: D. Intravenous beta-blocker first, aiming for heart rate about 60 and systolic 100 to 120 mmHg

   Beta-blockade comes first to reduce heart rate and the rate of rise of aortic pressure, then vasodilators are added if needed. Starting a vasodilator alone causes reflex tachycardia and increased shear stress on the aortic wall.

   Reference: ESC Guidelines on Aortic Diseases 2014

2. Question 2 · Haematology, gastrointestinal and nutrition

   A malnourished patient starts enteral feeding in the ICU. On day 2 she develops weakness and respiratory failure. Which electrolyte abnormality is the hallmark of refeeding syndrome?

   1. AHypophosphataemia
   2. BHypernatraemia
   3. CHypercalcaemia
   4. DHyperkalaemia
   Show answer and explanation

   Correct answer: A. Hypophosphataemia

   Refeeding drives phosphate, potassium and magnesium into cells, and hypophosphataemia is the hallmark, causing muscle weakness and respiratory failure. Feeding should start slowly with electrolyte replacement and thiamine.

   Reference: NICE CG32 Nutrition Support for Adults

3. Question 3 · Neurocritical care

   A patient with traumatic brain injury has mean arterial pressure 80 mmHg and intracranial pressure 25 mmHg. What is the cerebral perfusion pressure?

   1. A105 mmHg
   2. B65 mmHg
   3. C55 mmHg
   4. D45 mmHg
   Show answer and explanation

   Correct answer: C. 55 mmHg

   CPP = MAP - ICP = 80 - 25 = 55 mmHg. This is below the recommended target of 60 to 70 mmHg, and the ICP is above the treatment threshold of 22 mmHg.

   Reference: Brain Trauma Foundation Guidelines, 4th ed. 2016

4. Question 4 · Renal, metabolic, fluids and electrolytes

   A patient has pH 7.12, bicarbonate 10 mmol/L and PaCO2 32 mmHg. Using Winter's formula, what is the best interpretation?

   1. AMetabolic acidosis with appropriate respiratory compensation
   2. BMetabolic acidosis with an additional respiratory alkalosis
   3. CMetabolic acidosis with an additional respiratory acidosis
   4. DPrimary respiratory acidosis with renal compensation
   Show answer and explanation

   Correct answer: C. Metabolic acidosis with an additional respiratory acidosis

   Expected PaCO2 = 1.5 x 10 + 8 = 23 plus or minus 2 mmHg. A measured PaCO2 of 32 mmHg is higher than expected, so there is a concurrent respiratory acidosis, for example from fatigue or sedation.

   Reference: Marino's The ICU Book, 4th ed.

5. Question 5 · Respiratory failure and mechanical ventilation

   A 180 cm tall man with ARDS weighs 110 kg. Using lung-protective ventilation at 6 mL/kg predicted body weight, what tidal volume is closest to correct?

   1. A660 mL
   2. B450 mL
   3. C540 mL
   4. D360 mL
   Show answer and explanation

   Correct answer: B. 450 mL

   Male predicted body weight = 50 + 0.91 x (180 - 152.4), about 75 kg, so 6 mL/kg gives about 450 mL. Using actual body weight (110 kg) gives 660 mL, a common and harmful error.

   Reference: ARDSNet ARMA Trial, NEJM 2000

6. Question 6 · Respiratory failure and mechanical ventilation

   A patient with ARDS has PaO2/FiO2 of 110 mmHg after 24 hours of optimised lung-protective ventilation with adequate PEEP. What intervention has been shown to reduce mortality in this group?

   1. AProne positioning for at least 16 hours per day
   2. BRoutine high-frequency oscillatory ventilation
   3. CInhaled nitric oxide for 7 days
   4. DHigh-dose methylprednisolone from day 14
   Show answer and explanation

   Correct answer: A. Prone positioning for at least 16 hours per day

   In patients with PaO2/FiO2 below 150 mmHg, early prolonged prone positioning reduced mortality in the PROSEVA trial. Inhaled nitric oxide improves oxygenation transiently but has not improved survival, and high-frequency oscillation showed harm or no benefit.

   Reference: PROSEVA Trial, NEJM 2013