CUMULATIVE REDUCTION IN SERUM-CHOLINESTERASE FOLLOWING REPEATED THERAPEUTIC PLASMA-EXCHANGE

Study Objective: To investigate the magnitude of serum cholinesterase reduction following repeated therapeutic plasma exchange in patients w ith neuromuscular disease. Design: Serum cholinesterase activity was m easured immediately before and after each plasma exchange in open-labe l fashion and then analyzed using an analysis of variance model. Setti ng: Inpatient neurology and allergy and immunology clinics at a univer sity-affiliated hospital. Patients: 50 consecutive patients with neuro muscular disease. Interventions: All patients underwent repeated thera peutic plasma exchange, with each subject receiving up to a maximum of six plasma exchanges. Measurements and Main Results: Serum cholineste rase activity was determined spectrophotometrically. Analysis of varia nce revealed a significant reduction in serum cholinesterase following each therapeutic plasma exchange (p < 0.0001), a significant and cons istent reduction across the six treatments (p < 0.0001), and a signifi cant interaction between (before versus after exchange) and treatment number (p < 0.0001). Mean serum cholinesterase before repeated therape utic plasma exchange was 4817 U/L, but it decreased to a mean of 929 U /L following six plasma exchanges. Conclusions: There is a significant reduction in serum cholinesterase following repeated therapeutic plas ma exchange. It is suggested that drugs metabolized by serum cholinest erase (e.g., succinylcholine, mivacurium) be used with caution in the period immediately following repeated therapeutic plasma exchange.