STUDY OBJECTIVE: To investigate the magnitude of serum cholinesterase reduction following repeated therapeutic plasma exchange in patients with neuromuscular disease. DESIGN: Serum cholinesterase activity was measured immediately before and after each plasma exchange in open-label fashion and then analyzed using an analysis of variance model. SETTING: Inpatient neurology and allergy and immunology clinics at a university-affiliated hospital. PATIENTS: 50 consecutive patients with neuromuscular disease. INTERVENTIONS: All patients underwent repeated therapeutic plasma exchange, with each subject receiving up to a maximum of six plasma exchanges. MEASUREMENTS AND MAIN RESULTS: Serum cholinesterase activity was determined spectrophotometrically. Analysis of variance revealed a significant reduction in serum cholinesterase following each therapeutic plasma exchange (p < 0.0001), a significant and consistent reduction across the six treatments (p < 0.0001), and a significant interaction between (before versus after exchange) and treatment number (p < 0.0001). Mean serum cholinesterase before repeated therapeutic 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 plasma exchange. It is suggested that drugs metabolized by serum cholinesterase (e.g., succinylcholine, mivacurium) be used with caution in the period immediately following repeated therapeutic plasma exchange.
STUDY OBJECTIVE: To investigate the magnitude of serum cholinesterase reduction following repeated therapeutic plasma exchange in patients with neuromuscular disease. DESIGN: Serum cholinesterase activity was measured immediately before and after each plasma exchange in open-label fashion and then analyzed using an analysis of variance model. SETTING: Inpatient neurology and allergy and immunology clinics at a university-affiliated hospital. PATIENTS: 50 consecutive patients with neuromuscular disease. INTERVENTIONS: All patients underwent repeated therapeutic plasma exchange, with each subject receiving up to a maximum of six plasma exchanges. MEASUREMENTS AND MAIN RESULTS: Serum cholinesterase activity was determined spectrophotometrically. Analysis of variance revealed a significant reduction in serum cholinesterase following each therapeutic plasma exchange (p < 0.0001), a significant and consistent reduction across the six treatments (p < 0.0001), and a significant interaction between (before versus after exchange) and treatment number (p < 0.0001). Mean serum cholinesterase before repeated therapeutic 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 plasma exchange. It is suggested that drugs metabolized by serum cholinesterase (e.g., succinylcholine, mivacurium) be used with caution in the period immediately following repeated therapeutic plasma exchange.