[Plasma cholinesterase variations as a result of prolonged neuromuscular blockade. Review and problems encountered in two cases of prolonged neuromuscular blockade after muscle relaxation with succinylcholine as compared to mivacurium].

Succinylcholine and mivacurium are degraded more slowly in patients with a qualitatively or quantitatively reduced plasma cholinesterase and are therefore known for inducing a prolonged postoperative apnea. Perioperative laboratory screening even including plasma cholinesterase activity testing will not prevent this due to a possible aberration only in the qualitative cholinesterase activity. This is illustrated by introducing two cases reports of prolonged apnea after administration of mivacurium or succinylcholine. The pathophysiology of plasma cholinesterase is reviewed including genetically determined variants and the degradation pathways of mivacurium and succinylcholine. Only extensive laboratory chemical tests are sufficient to prevent this possible complication. Due to the rare incidence there is no evidence for recommending these laboratory investigations in all patients. Once prolonged apnea occurs following the administration of mivacurium or succinylcholine the best choice is ongoing ventilation combined with a sufficient sedation.