Intravenous Anaesthetic Agents (Propofol, Ketamine, Etomidate, Barbiturates) MCQs

Anaesthesia · 36 free questions with answers & explanations.

1. Propofol infusion syndrome (PRIS) is a rare but lethal complication of prolonged high-dose propofol infusion. The pathophysiology involves:
2. Ketamine produces dissociative anaesthesia by acting as a non-competitive antagonist at which receptor, and what unique haemodynamic profile does this produce?
3. A single induction dose of etomidate (0.3 mg/kg IV) causes transient adrenocortical suppression. The specific enzyme inhibited is:
4. Thiopentone sodium is contraindicated in patients with variegate porphyria because it:
5. Dexmedetomidine is increasingly used for procedural sedation and ICU analgosedation. Its primary mechanism of action is:
6. Propofol infusion syndrome (PRIS) occurs most commonly with high-dose, prolonged infusions. Which metabolic abnormality is the hallmark of PRIS that distinguishes it from simple propofol toxicity?
7. Ketamine produces dissociative anaesthesia primarily by acting at which receptor, and which feature of its pharmacology explains the unique preservation of laryngeal reflexes?
8. Etomidate is chosen over propofol for induction in a haemodynamically unstable trauma patient. Which mechanism accounts for its superior cardiovascular stability?
9. Context-sensitive half-time explains why propofol's recovery is faster than thiopentone after prolonged infusions. What does 'context-sensitive' refer to in this pharmacokinetic concept?
10. A patient undergoing electroconvulsive therapy (ECT) needs an IV induction agent that produces brief, reliable unconsciousness while least suppressing seizure threshold and duration. Which agent is most appropriate?
11. Propofol infusion syndrome (PRIS) is a rare but fatal complication. Which metabolic derangement is the most characteristic biochemical marker and what is the minimum infusion rate below which PRIS risk is acceptably low?
12. Ketamine produces dissociative anaesthesia by its primary action on which receptor system, and which co-administered drug most effectively prevents emergence reactions?
13. Etomidate is selected for induction in a haemodynamically unstable trauma patient. Which unique side effect of etomidate mandates particular concern in septic patients requiring prolonged ICU care?
14. Context-sensitive half-life is used to predict recovery from continuous IV infusion. After a 4-hour propofol infusion at anaesthetic doses, what is the approximate context-sensitive half-life?
15. A patient receiving a prolonged propofol infusion (>48 h at >4 mg/kg/h) for ICU sedation develops metabolic acidosis, rhabdomyolysis, lipemic serum, and bradyarrhythmia resistant to atropine. The most likely diagnosis and its pathophysiological basis is:
16. Etomidate inhibits adrenal steroidogenesis even after a single induction dose. The specific enzyme blocked is:
17. Ketamine produces 'dissociative anaesthesia' through its primary receptor mechanism. Which additional receptor interaction MOST accounts for its bronchodilatory effect?
18. Thiopentone has a shorter clinical duration of action (10–15 min) after a single bolus despite its long elimination half-life (11 hours). This is best explained by:
19. A 45-year-old patient on propofol infusion at 6 mg/kg/hr for 72 hours in ICU develops metabolic acidosis, bradycardia refractory to atropine, lipaemic plasma, and elevated CK. The most likely diagnosis and the underlying mechanism involve:
20. Etomidate causes adrenocortical suppression lasting 4–8 hours after a single induction dose. Which enzyme does it inhibit?
21. A trauma patient arrives in haemorrhagic shock (HR 130, BP 70/40 mmHg). Ketamine is chosen for induction. In this patient's adrenergically depleted state, what direct myocardial effect of ketamine would be most likely to manifest?
22. Thiopentone produces unconsciousness at a lower total body dose in elderly patients due to pharmacokinetic changes. The primary reason for this altered dose requirement is:
23. Propofol infusion syndrome (PRIS) is a rare but lethal complication. Which clinical scenario carries the HIGHEST risk for PRIS?
24. Etomidate is preferred as an induction agent in a haemodynamically unstable patient. Which receptor mechanism best explains its cardiovascular stability?
25. Propofol infusion syndrome (PRIS) is a rare but lethal complication. Which combination of features should trigger immediate suspicion of PRIS?
26. Etomidate is the induction agent of choice for haemodynamically unstable patients. Its disadvantage for repeated dosing or prolonged infusion is:
27. A mechanically ventilated ICU patient receiving propofol infusion at 5 mg/kg/h for 72 hours develops new-onset metabolic acidosis (pH 7.18, lactate 8 mmol/L), lipemic plasma, rhabdomyolysis, and bradycardia. What is the diagnosis and management?
28. Etomidate is the induction agent of choice in haemodynamically unstable patients. However, a single induction dose causes adrenocortical suppression lasting approximately how long?
29. Which intravenous anaesthetic agent produces 'dissociative anaesthesia' characterised by profound analgesia, amnesia, and cataleptic state without loss of airway reflexes, and what is its primary mechanism?
30. A 35-year-old patient with status asthmaticus requires emergency anaesthesia for mechanical ventilation. The MOST appropriate induction agent is:
31. Propofol infusion syndrome (PRIS) is a potentially lethal complication in ICU patients receiving prolonged high-dose propofol. The earliest metabolic indicator of PRIS is:
32. Etomidate is preferred for rapid sequence induction in a haemodynamically unstable trauma patient. The primary concern with its use in the ICU setting is:
33. A 70-year-old patient on long-term phenytoin therapy requires induction of anaesthesia. The dose of thiopentone required is likely to be:
34. Which property of ketamine is responsible for the dissociative anaesthesia it produces?
35. Thiopentone produces anaesthesia in 'one arm-brain circulation time' (approximately 30–45 seconds). What accounts for the rapid termination of effect after a single induction dose?
36. Remifentanil is an ultra-short-acting opioid used in TIVA. Which metabolic pathway accounts for its extremely short duration of action and why is it unique among opioids?