Suxamethonium apnoea masked by tetrahydroaminacrine.

A case is reported of a patient who was given THA with suxamethonium and who demonstrated a prolonged apnoea. This patient was later shown to have a variant cholinesterase enzyme. The different techniques of THA and suxamethonium administration are discussed and it is suggested that an initial dose of suxamethonium should precede a THA-suxamethonium combination in order to try and avoid a prolonged apnoea.