Prolonged mivacurium neuromuscular blockade in a newborn.

Mivacurium is a short acting non-depolarising neuromuscular blocking agent. Short duration of action is due to a rapid hydrolysis by plasma cholinesterase (CHe). The duration of neuromuscular blockade can be prolonged by an abnormal variant of CHe. We report a case of a newborn with neuromuscular blockade for a duration of 8 hours following mivacurium 0.2 mg.kg(-1), CHe activity values were not contributive for the diagnosis. The diagnosis was obtained with molecular study showing the new-born homozygocity. The whole family was heterozygous. This case emphasises the lack of precision of CHe activity measurement during the first 6 months of life. (C) 1998 Elsevier, Paris.