ORIGINAL ARTICLE
Remifentanil for cesarean section under general anesthesia: effects on maternal stress hormone secretion and neonatal well-being: a randomized trial

https://doi.org/10.1016/j.ijoa.2008.01.002Get rights and content

Abstract

Background

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.

Methods

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 μg/kg before induction followed by a continuous infusion at 0.15 μg·kg−1min−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.

Results

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.

Conclusions

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.

Introduction

Regional anesthesia is preferred for cesarean section because of reduced maternal mortality.1 However, general anesthesia may be indicated if regional anesthesia fails or is contraindicated, or for emergency delivery. In a recent meta-analysis, general anesthesia was shown to be associated with transient neonatal sedation and essentially benign effects on neonatal acid-base balance.2

The neuroendocrine stress response to surgery appears less well controlled with general than with regional anesthesia.3 The use of systemic opioids obtunds the hormonal stress response during lower abdominal procedures under general anesthesia.4 However, during cesarean section opioid administration is usually avoided until after delivery to reduce the risk of neonatal depression.[5], [6] If opioid administration before delivery is thought to be advantageous, remifentanil with its fast onset and rapid metabolism appears to be a suitable agent. It provides hemodynamic stability in patients undergoing cesarean section under general anesthesia,7 and has been successfully used in cases of maternal cardiac disease,[8], [9] neurological conditions, preeclampsia and liver disease.[10], [11], [12] However, previous studies showed that the use of remifentanil to control the hemodynamic response to intubation and surgery is associated with transitory but significant neonatal depression.[7], [13] Since this effect could be dose-dependent,14 the aim of our study was to investigate whether administration of low-dose remifentanil could control the neuroendocrine response at cesarean section under general anesthesia without adverse effect on the neonate.

Section snippets

Methods

The study was designed as a randomized, controlled, single-blind trial. Anesthetists and pediatricians were not blinded to anesthetic technique. Approval from the local research ethics committee was obtained and written informed consent was given by all patients who participated in the study.

Forty-two ASA I-II women with singleton term pregnancy scheduled for elective cesarean section were enrolled. All patients had absolute or relative contraindications to regional anesthesia. Exclusion

Results

Forty-two women were recruited to and completed the study. Maternal height, weight, gestational age, and neonatal weight were similar in the two groups (Table 1). Indications for general anesthesia are also presented in Table 1.

There were no significant differences between the groups in heart rate or blood pressure at any time (Figure 1, Figure 2).

Maternal hormone concentrations for the three sampling times are given in Table 2. Norepinephrine (P <0.001 in group C and P <0.0001 in group R) and

Discussion

Remifentanil, administered as a 0.5-μg/kg bolus before induction followed by an infusion of 0.15 μg·kg−1min−1 until peritoneal incision, partially obtunded the neuroendocrine response to surgery with a decrease in ACTH rise. However, this was at the expense of transient neonatal depression, with Apgar scores significantly lower in babies whose mothers had received remifentanil, although all scores improved to ⩾8 within 5 min. Neonatal respiratory depression has previously been reported

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      Six remifentanil studies investigated the requirement for post-delivery BVM and showed no difference (RR 1.45; 95%CI 0.88 to 2.39; I2=0%; P=0.71).10,16,20,22,25,26 Similarly there was no significant difference in neonatal intubation rate with remifentanil (RR 1.34; 95%CI 0.67 to 2.68; I2=0%; P=0.97)10,16,18,20,22,25,26 or alfentanil (RR 1.65; 95%CI 0.60 to 4.56; I2=0%; P=0.69).9,15 There was no increase in NICU admission with remifentanil (RR 0.95; 95%CI 0.77 to 1.19; I2=0%; P=0.67).10,22,25

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