A patient with pseudocholinesterase deficiency receives succinylcholine. Which phase of neuromuscular block will be prolonged, and what is the safest management strategy?

• A Phase II (desensitization) block; reverse with neostigmine immediately
• B Phase I block; administer fresh frozen plasma to replenish pseudocholinesterase urgently
• C Phase I (depolarization) block; maintain sedation and ventilatory support until spontaneous recovery; neostigmine is contraindicated ✓
• D Phase II block; reverse with sugammadex 16 mg/kg

Explanation

Pseudocholinesterase (butyrylcholinesterase) normally hydrolyses succinylcholine rapidly in plasma before it reaches the NMJ in significant amounts; deficiency prolongs apnoea from Phase I (depolarizing) block, sometimes for hours. Neostigmine is contraindicated because it inhibits cholinesterase further, prolonging apnoea. Sugammadex does not encapsulate succinylcholine (it is not an aminosteroid). Management is sedation and controlled ventilation until spontaneous recovery. FFP contains pseudocholinesterase but is not routinely recommended. Dibucaine number quantifies the degree of enzyme inhibition.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.