Comparison of cisatracurium-induced neuromuscular blockade between immediate postpartum and nonpregnant patients

Study Objective: To evaluate and compare cisatracurium-induced neuromuscula r blockade and intubating conditions between immediate postpartum (PP) and nonpregnant (NP) patients. Design: Prospective control study Settings: University Hospital Center Patients: 44 ASA physical status I and II patients: 22 immediate postpartum (PP) patients (< 48 hours after delivery) scheduled for elective postpartu m tubal ligation and 22 nonpregnant (NP) patients (> 40 weeks from prior pr egnancy) scheduled for elective gynecological procedures. Interventions: General anesthesia was induced intravenously (IV) with thiop ental sodium 5 mg/kg, fentanyl 2.0 to 3.0 ug/kg, midazolam 0.015 to 0.025 m g/kg, and cisatracurium 0.2 mg/kg. Evoked electromyographic responses of th e adductor pollicis muscle were obtained by supra-maximal train-of-four sti mulation of the ulnar nerve every ten seconds via surface electrodes at the wrist. Intubation was attempted at 90 s after completion of cisatracurium administration and again at 120 seconds if the first attempt was unsuccessf ul. The intubating anesthesiologist assessed the intubating conditions with four variables: jaw relaxation, vocal cord immobility and exposure, patien t/diaphragmatic movement, and overall intubating impression. Intraoperative anesthetic was maintained with 30 % oxygen, 70 % nitrous oxide, and 1 % en d-tidal isoflurane, as tolerated. Patient temperature was maintained at 35. 5 degrees to 37.5 degrees Celsius (C), and end-tidal carbon dioxide at 30 t o 36 mmHg. Measurements and Main Results: The mean onset times to 50%, 90%, and maxima l T-1 depression and mean time to 25% T-1 recovery in the PP group (68 +/- 19 sec, 110 +/- 26 sec, 147 +/- 32 sec, 60 +/- 6 min) were significantly le ss than those in the NP group (80 +/- 17 sec, 131 +/- 28 sec, 181 +/- 44 se c, 69 +/- 12 min), respectively (p < 0.05). All patients were successfully intubated on the first attempt at 90 seconds. 91% of the NP group and 81% o f the PP group had excellent overall intubating conditions. Conclusions: This is the first published control study to compare the effec ts of cisatracurium between NP and PP patients. The results suggest that th e mean onset time and clinical duration of cisatracurium are significantly shorter in immediate postpartum patients than those in nonpregnant female p atients. (C) 2001 by Elsevier Science Inc.