[Prolonged neuromuscular block after administration of mivacurium caused by plasma psueudocholinesterase deficiency].

Mivacurium is a new neuromuscular blocking agent with a short acting time of about 30 min, due to a fast hydrolysis by pseudocholinesterases. This metabolism carries a risk for prolonged neuromuscular block in case of an acquired or congenital pseudocholinesterase deficiency. We report the case of a 75-year-old woman who experienced a neuromuscular block prolonged for 10 h after a single dose of 0.35 mg.kg-1 of mivacurium, because of a major pseudocholinesterase (1800 UI.L-1, normal value: 5400-13200 UI.L-1). The likely cause was a congenital deficiency by a homozygote genetic mutation, as usual causes of an acquired deficiency had been eliminated.