Prolonged neuromuscular block due to cholinesterase depletion by plasmapheresis

Plasmapheresis is a well-known therapeutic procedure for several medical conditions in which removal of circulating antibodies or albumin-bound toxins is desired. Circulating plasma cholinesterase enzyme levels are also depleted with plasmapheresis. This action causes patients to be susceptible to prolonged neuromuscular blockade when neuromuscular blocking drugs that are metabolized by this enzyme are used. We describe a case of prolonged neuromuscular blockade following succinylcholine and mivacurium administration in a 24-year-old renal transplant patient undergoing repeated plasmapheresis for recurrence of focal segmental glomerulosclerosis and acute vascular rejection. Serum and plasma cholinesterase levels were less than 20% of normal at the time of the event. The patient had spontaneous recovery after 12 hours of conservative supportive care. She tolerated a similar procedure uneventfully two weeks later when she was not taking plasmapheresis. Anesthesiologists should be aware of plasmapheresis as a mechanism for plasma cholinesterase depletion when using neuromuscular blocking drugs that are metabolized by this enzyme.