Maternal and Neonatal Effects of Remifentanil at Induction of General Anesthesia for Cesarean Delivery

Abstract

Use of remifentanil during general anesthesia for cesarean delivery has been described, but its maternal and neonatal effects have not been investigated by a controlled study. In a randomized, double-blind, controlled study, patients undergoing elective cesarean delivery received an intravenous bolus of 1 microg/kg remifentanil (n = 20) or saline (n = 20) immediately before induction of general anesthesia. The authors compared maternal hemodynamic changes and neonatal condition and measured plasma concentrations of remifentanil. The maximum increase in systolic arterial pressure from baseline after induction was smaller in the remifentanil group (median, 9 [range, -17 to 31] mmHg) compared with the control group (42 [6-73] mmHg, median difference, 33 mmHg; 95% confidence interval of difference, 23-45 mmHg; P < 0.0001). Maximum recorded values were smaller in the remifentanil group compared with the control group for systolic and mean arterial pressure and maternal heart rate. Apgar scores and time to sustained respiration were similar between groups. Two neonates in the remifentanil group were considered clinically depressed at birth and were given a single dose of naloxone. Remifentanil crossed the placenta with an umbilical venous/maternal arterial concentration ratio of 0.73 (SD, 0.17) and an umbilical arterial/umbilical venous concentration ratio of 0.60 (0.23). A single bolus of 1 microg/kg remifentanil effectively attenuated hemodynamic changes after induction and tracheal intubation. However, remifentanil crosses the placenta and may cause mild neonatal depression and thus should be used for clear maternal indications when adequate facilities for neonatal resuscitation are available.