Paper I — 2021 May (Supplementary) (2010 Scheme) — Q2
3 min read
Paper I
2021 May (Supplementary) (2010 Scheme) · 40 marks · 120 min
Question
Read the clinical problem and answer the following questions: A 50 years old man was
administered succinylcholine for endotracheal intubation. The patient developed
prolonged muscle paralysis and apnea. (2+2+2)
What could be the cause of apnea in this patient
How will you treat the apnea
Name two muscle relaxants that you can use in this patient in future
Q26 marksEssays
Answer
Cause of apnoea
This is “scoline apnoea” — succinylcholine is normally rapidly hydrolysed by plasma pseudocholinesterase, giving it a short duration of action. This patient likely has a genetically determined atypical or deficient form of plasma pseudocholinesterase, which hydrolyses succinylcholine very slowly, grossly prolonging the depolarizing neuromuscular block and causing sustained respiratory muscle paralysis and apnoea
Treatment of the apnoea
Continue mechanical ventilation/assisted respiration and maintain sedation/anaesthesia until neuromuscular function recovers spontaneously (may take hours)
Do NOT give further muscle relaxants or anticholinesterase reversal agents (ineffective/potentially worsening for depolarizing block)
Confirm diagnosis with a dibucaine number test; fresh frozen plasma (source of normal pseudocholinesterase) may be considered in severe/prolonged cases
Counsel the patient/family regarding the genetic trait for future anaesthetic exposures
Two muscle relaxants for future use
Atracurium (non-depolarizing, eliminated by Hofmann elimination — independent of pseudocholinesterase)
Vecuronium/Rocuronium (non-depolarizing, hepatically eliminated — not dependent on plasma pseudocholinesterase)
