Effect of Fentanyl Added to Bupivacaine for Intrathecal Injection on the Outcome of Neonates Delivered by Caesarean Section under Spinal Anaesthesia.

Abstract

Background: Addition of fentanyl to 0.5% hyperbaric bupivacaine for subarachnoid block (SAB) enhances the efficacy of bupivacaine and enables the use of reduced doses of the two drugs, thereby minimising their adverse effects. However, fentanyl may cross the placenta and cause chest wall rigidity, cardiovascular and respiratory depression in the foetus, resulting in poor neonatal outcome.

Objectives: This study aimed to determine and compare the effects of 20 and 25 µg fentanyl added to 10 mg 0.5% hyperbaric bupivacaine on the outcome of neonates delivered by caesarean section under SAB.

Materials and methods: Ninety-nine pregnant women, aged 18-45 years and American Society of Anaesthesiologists I and II, were randomly divided into three equal groups: group A, group B, and group C. Each group received 2 mL (10 mg) 0.5% hyperbaric bupivacaine, and in addition, group A received 0.5 mL normal saline, group B received 0.4 mL (20 µg) fentanyl + 0.1 mL normal saline, whereas group C received 0.5 mL (25 µg) fentanyl. Following delivery, the newborn babies' Apgar scores, Neurological and Adaptive Capacity Scores (NACS), umbilical cord arterial blood gas, peripheral oxygen saturation (SpO₂), and pulse rate were assessed.

Results: The mean Apgar scores at 1 and 5 min and the mean NACS at 15 min and 2 h were significantly lower in the fentanyl/bupivacaine groups compared with the bupivacaine only group (P < 0.001). The mean pH and SpO₂/PR of the neonates were within normal neonatal range but decreased from group A to group C (P < 0.05).

Conclusions: Neonates whose mothers received bupivacaine only had better outcomes than those who received bupivacaine/fentanyl combination, whereas those who received 20 µg fentanyl had better outcomes than those who received 25 µg.