The effect of adding magnesium sulphate to epidural bupivacaine and fentanyl in elective caesarean section using combined spinal-epidural anaesthesia: a prospective double blind randomised study.

BACKGROUND

Combined spinal-epidural anaesthesia is commonly used for elective caesarean section. Intrathecal injection produces rapid onset with minimal doses of local anaesthetic and epidural administration can be used to prolong the block. Our study examined the effects of adding magnesium sulphate to epidural bupivacaine and fentanyl in patients undergoing elective caesarean section using combined spinal-epidural anaesthesia.

METHODS

Women ASA physical status I or II at term were recruited. All received 2 mL intrathecal 0.5% hyperbaric bupivacaine, 10 mL epidural 0.25% plain bupivacaine with fentanyl 100 μg, and were randomly allocated to receive either 10 mL of epidural 0.9% sodium chloride or 10 mL epidural 5% magnesium sulphate. The quality of surgical anaesthesia, incidence of hypotension, Apgar scores, intraoperative pain assessment, onset of postoperative pain, sedation scores and side effects were recorded in the postoperative period.

RESULTS

Ninety women were recruited. There was no difference in the time taken for the block to reach T4 sensory level, time to reach the highest level of sensory block, time interval between first neuraxial injection and onset of surgery between the groups. Women who received magnesium had greater motor block and muscle relaxation (P<0.05). Apgar scores were 7 or more in almost all neonates in both groups. There was no significant difference in the incidence of hypotension, nausea and vomiting and duration of motor blockade between the groups. Women who received magnesium showed less shivering and later onset of post operative pain (P<0.05).

CONCLUSION

The addition of magnesium to epidural bupivacaine and fentanyl in women undergoing elective caesarean section with combined spinal-epidural anaesthesia improved intraoperative conditions and the quality of postoperative analgesia.