Effects of intrathecally administered fentanyl on duration of analgesia in patients undergoing spinal anaesthesia for elective caesarean section.

BACKGROUND: Intrathecal opioids have gained popularity in obstetrics; they augment the analgesia produced by local anaesthetic agents. The aim of this study is to determine the duration of analgesia following addition of fentanyl to bupivacaine during elective Caesarean section.

METHOD: This is a prospective randomized study comparing the effect of addition of 25 microg of fentanyl to 2.5 mls of 0.5% hyperbaric bupivacaine intrathecally on sixty healthy women of American Society ofAnaesthesiologist (ASA) physical status I scheduled for elective Caesarean section at the UCH, Ibadan. Patients were randomized to group B, n=30 and group FB, n=30. Maternal heart rate, blood pressure, respiratory rate, sensory level, motor block, pain score (NRS) and side effects were observed every 2 minutes for first 15 minutes, then at 5 minutes interval for the remainder of the operation. Thereafter at 30 minutes interval until the first complaint of pain.

RESULTS: Complete analgesia (time from injection of intrathecal drug to first report of pain) lasted longer in group FB (240 +/- 29 minutes) than group B (99 +/- 12 minutes) with a p-value of 0.002. The duration of effective analgesia (time from injection of intrathecal drug to first request for analgesic) in group FB (276 +/- 26 minutes) while group B was (121 +/- 10 minutes) with a p-value of 0.001. Both were statistically significant.

CONCLUSION: We conclude that the addition of 25 microg of fentanyl to bupivacaine intrathecally for elective Caesarean section increases the duration of complete and effective analgesia thereby reducing the need for early postoperative use of analgesics.