EXTENDED DURATION OF ACTION OF ROCURONIUM IN POSTPARTUM PATIENTS

We studied the time course of action of a single bolus of 600 mu g/kg rocuronium given during anesthesia with propofol, fentanyl, and nitrou s oxide was studied in 12 nonpregnant and 12 postpartum patients. Neur omuscular effects were quantified by recording the indirectly evoked t witch response of the adductor pollicis muscle after ulnar nerve stimu lation. In all patients, the trachea was intubated 60 s after administ ration of rocuronium. Onset time was similar in both groups (nonpregna nt: 91 +/- 28 s vs. postpartum: 95 +/- 30 s), with the time to 25% twi tch recovery being significantly longer (P < 0.001) in the postpartum patients (31.1 +/- 3.6 min) compared with the nonpregnant group (24.9 +/- 4.0 min). The time required for recovery from 25% to 75% of the co ntrol twitch response after reversal with neostigmine and atropine was significantly longer (P = 0.003) in postpartum (4.8 +/- 0.9 min) than in nonpregnant patients (3.2 +/- 0.6 min). These data suggest that pr egnancy-induced changes result in prolonged effects of rocuronium in p ostpartum patients.