Muscle Relaxants (Depolarizing and Non-Depolarizing) MCQs

Anaesthesia · 31 free questions with answers & explanations.

1. A patient with a 6-hour history of bowel obstruction requires rapid sequence intubation. Suxamethonium (1.5 mg/kg) is administered. At what serum potassium level would this dose be absolutely contraindicated due to risk of fatal hyperkalaemia?
2. A patient receiving vecuronium has a train-of-four (TOF) ratio of 0.4 on peripheral nerve stimulator with a supramaximal stimulus. What does this indicate about residual neuromuscular blockade?
3. Sugammadex reverses rocuronium-induced neuromuscular blockade by which unique mechanism?
4. Phase II block (dual block) following suxamethonium is characterised by which pattern on peripheral nerve stimulator?
5. Mivacurium is the only non-depolarising muscle relaxant metabolised by plasma cholinesterase. Its duration of action in a patient with dibucaine number of 20 would be:
6. Which train-of-four (TOF) ratio value is considered the clinical threshold for adequate neuromuscular recovery, above which residual block-related adverse respiratory events are unlikely?
7. Sugammadex reverses rocuronium and vecuronium by which pharmacological mechanism, and at what dose is it used for immediate reversal of rocuronium after high-dose intubating dose?
8. A patient with pseudocholinesterase deficiency receives succinylcholine. Which phase of neuromuscular block will be prolonged, and what is the safest management strategy?
9. Neostigmine used for reversal of non-depolarizing block must always be accompanied by glycopyrrolate or atropine. Which specific adverse effect of neostigmine necessitates this?
10. Rocuronium 1.2 mg/kg is used for rapid sequence induction. Which reversal agent can specifically reverse even this high-dose rocuronium, and at what dose?
11. Train-of-four (TOF) monitoring is used to assess neuromuscular block. A TOF ratio of 0.6 corresponds to which clinical finding?
12. A patient with renal failure requires neuromuscular blockade for a 3-hour abdominal procedure. Which agent is MOST appropriate given its organ-independent elimination?
13. Succinylcholine is given to a patient and the anaesthetist observes that instead of the typical brief fasciculations and paralysis, the patient shows prolonged paralysis for 45 minutes. Which enzyme deficiency best explains this?
14. A patient given succinylcholine 1.5 mg/kg for rapid sequence intubation develops generalised muscular rigidity, inability to open the mouth, and hyperthermia within 5 minutes. Volatile anaesthetic was not used. The MOST likely diagnosis and explanation is:
15. Cisatracurium is preferred over atracurium in patients with hepatic and renal failure. The primary reason is:
16. Sugammadex reverses rocuronium blockade by encapsulation. When administered after rocuronium for a 'cannot intubate, cannot oxygenate' scenario with a dose of 16 mg/kg, the minimum time before rocuronium can be safely re-administered to re-paralise the patient is approximately:
17. The train-of-four (TOF) ratio at the adductor pollicis is used to assess neuromuscular recovery. A TOF ratio of 0.9 is considered the threshold for safe extubation. However, even at TOF ratio ≥0.9, residual neuromuscular blockade may be demonstrated at the:
18. A patient with a 3-day-old 40% TBSA burn is given succinylcholine for rapid sequence intubation. Thirty seconds later, the cardiac monitor shows peaked T waves followed by ventricular fibrillation. The mechanism responsible is:
19. Rocuronium 1.2 mg/kg achieves conditions comparable to succinylcholine for rapid sequence intubation. When sugammadex is given at the end of surgery, what is the mechanism by which rocuronium block is reversed?
20. During train-of-four (TOF) monitoring, a patient shows a TOF ratio of 0.7 after neostigmine reversal. The anaesthetist plans to extubate. Which clinical deficit is MOST likely to be present at this TOF ratio?
21. A patient with myasthenia gravis undergoing thymectomy receives atracurium. Compared to a healthy patient, the expected sensitivity of this patient to atracurium is:
22. Train-of-four (TOF) monitoring shows a TOF ratio of 0.7 after vecuronium administration for a 2-hour laparoscopy. The patient is extubated uneventfully but develops clinical signs of residual neuromuscular blockade (RNMB) in the PACU. What TOF ratio is the currently accepted threshold below which clinically significant RNMB and risk of postoperative pulmonary complications exist?
23. Rocuronium-induced neuromuscular block of 1.2 mg/kg (RSI dose) can be reversed by sugammadex at a dose of:
24. A patient receives vecuronium for neuromuscular blockade. At end of surgery, TOF (train-of-four) ratio is 0.6. The anaesthetist administers neostigmine 2.5 mg + glycopyrrolate 0.5 mg. Why is neostigmine NOT fully reliable for reversal when TOF <0.9, and what is the safer alternative?
25. Phase II block (dual block) occurs with succinylcholine under which circumstance, and how does it differ from Phase I block on TOF stimulation?
26. A patient in the emergency department requires rapid sequence intubation. Succinylcholine 1.5 mg/kg IV is given. Which of the following is a CONTRAINDICATION to its use?
27. A 50-year-old patient receives rocuronium 0.6 mg/kg for intubation. At the end of surgery, train-of-four (TOF) ratio is 0.6 at the adductor pollicis. The BEST reversal agent combination is:
28. Phase II block (dual block) can occur with succinylcholine when it is used as:
29. A patient with myasthenia gravis requires abdominal surgery. Which neuromuscular blocking agent strategy is MOST appropriate?
30. Mivacurium is the only non-depolarizing muscle relaxant that can be reversed by:
31. Phase II block can occur after large or repeated doses of succinylcholine. Which of the following accurately describes a Phase II block compared to Phase I block?