Correlation of plasma cholinesterase activity and duration of action of succinylcholine during pregnancy.

Correlation between plasma cholinesterase activity and duration of neuromuscular blockade following succinylcholine (SCh) was studied in 30 healthy women undergoing laparoscopic tubal coagulation and 20 pregnany women indergoing elective repeat cesarean section. All patients received N2O-thiopental anesthesia. Cholinesterase activity in nonpregnant patients was significantly greater than in pregnant patients. Time to 90 percent recovery of control twitch height following 40 or 80 mg/m2 BSA of SCh was not significantly different in pregnant versus nonpregnant patients. There also was no correlation between plasma cholinesterase activity and duration of paralysis from SCh. The authors conclude that pregnant patients have lower cholinesterase activity, but prolonged neuromuscular blockade from SCh should not occur unless the patient is grossly overdosed with SCh. Routine use of a peripheral nerve stimulator is recommended to avoid such overdosage.