Remifentanil for cesarean section under general anesthesia: effects on maternal stress hormone secretion and neonatal...

Remifentanil may attenuate maternal hemodynamic response during cesarean section under general anesthesia, but could cause transient but significant neonatal depression. We investigated the effect of low-dose remifentanil on maternal neuroendocrine response and fetal wellbeing.

Forty-two ASA I-II parturients undergoing cesarean section at term under general anesthesia were randomized to receive either fentanyl after delivery (n=21, group C) or remifentanil bolus 0.5 microg/kg before induction followed by a continuous infusion at 0.15 microg x kg(-1)min(-1) until peritoneal incision, then restarted after delivery (n=21, group R). Maternal heart rate and blood pressure, and epinephrine, norepinephrine, adrenocorticotropic hormone (ACTH), and growth hormone levels were measured at baseline, uterine incision, and the end of surgery. Remifentanil was measured in maternal and umbilical arterial and venous blood. One- and 5-minute Apgar scores and umbilical arterial and venous pH were recorded.

ACTH was significantly higher in group C at uterine incision (P<0.01). No significant differences were observed in hemodynamics, catecholamines or growth hormone. Apgar scores at 1 (P<0.05) and 5 min (P<0.01) were significantly higher in group C. Mean umbilical pH values were within normal range but significantly higher in group C. Three neonates in group R required intubation but recovered at 5 min without naloxone. Mean+/-SD maternal remifentanil concentration was 1.67+/-1.04 ng/mL.

Remifentanil administration before peritoneal incision partially reduced the hormonal stress response. Maternal benefits must be weighed against transitory but significant neonatal respiratory depression. Neonatal resuscitation facilities are mandatory when remifentanil is used.