For anesthesia in cesarean section N2O and low concentrations of inhalation anesthetics are regarded as the anesthetic agent of choice. But a low level of anesthesia frequently leads to increased maternal hemodynamic responses and awareness. The effects of a 3 µg/kg fentanyl bolus injection after umbilical cord clamping was evaluated in 20 full-term parturients, scheduled for elective cesarean section, versus to 20 parturients without fentanyl.

The forty parturients (ASA physical status 1, 2) scheduled for cesarean section were randomized to either a N2O-enflurane (E group) or a N2O-enflurane-fentanyl (F group). Thiopental sodium (4 mg/kg) and succinylcholine (1.5 mg/kg) were administered intravenously for the induction and endotracheal intubation. Anesthesia was maintained with 50% N2O and 1% enflurane in oxygen until delivery. After delivery, the intravenous injection of 0.5 mg/kg of atracurium was administered, controlled ventilation was applied to maintain PetCO2 at 30 to 35 mmHg with N2O (3 L/min) and O2 (1.5 L/min). Immediately after clamping the umbilical cord, 3 µg/kg of fentanyl (F group only) was administered. Heart rate, blood pressure, awareness, recovery time, postoperative complication and recall were evaluated.

Heart rate values at 10 and 20 min after umbilical cord clamping and 5 min after extubation, and mean arterial pressure at 5, 10 and 20 min after umbilical cord clamping in group F were found to be significantly lower than in group E.

We conclude that N2O-enflurane-fentanyl at 3 µg/kg is clinically satisfactory in anesthesia for cesarean section, having no adverse effects on the mother.