<prompt> After suxamethonium 50mg, apnea persists for one hour --treatment with cholnesterase is indicatedProbably an atypical cholinesterase is presentTreatment with stored blood is indicatedApnea may be due to low serum potassium concentration  <response>: Suxamethonium is a depolarising muscle relaxant used to rapidly gain optimal intubating conditions. It is normally metabolised within 5 minutes by plasma cholinesterase. Some patients lack this enzyme or have an altered enzyme that does not metabolise the suxamethonium as rapidly. These patients may remain paralysed for a prolonged period after a standard dose of suxamethonium and rely on renal elimination. This condition is often referred to as suxamethonium apnea 