Epidural volume extension via a combined spinal–epidural is the enhancement of a small-dose intrathecal block by an epidural injection of physiological saline solution. We evaluated the effect of epidural volume extension on the combined spinal–epidural technique of providing spinal anaesthesia for Caesarean section with hyperbaric or plain 0.5% bupivacaine.

Patients (n = 240) with height >163 cm received 9 mg and patients <163 cm received 8 mg of bupivacaine. Each study drug was combined with 20 μg fentanyl. Using the combined spinal–epidural technique, Group A (n = 60) received hyperbaric bupivacaine, and Group B (n = 60) received hyperbaric bupivacaine and 10 mL saline epidurally 5 min after subarachnoid injection. Group C (n = 60) received plain bupivacaine and Group D (n = 60) received plain bupivacaine and 10 mL saline epidurally 5 min after subarachnoid injection. An anaesthetist blinded to the anaesthetic solution injected examined the level of analgesia by the pinprick method and motor block with the modified Bromage scale for 30 min after subarachnoid injection, during the intraoperative period and subsequently every 15 min for 135 min during the recovery period.

Time to reach a sensory block at T4 was significantly shorter in Groups C and D than in Groups A (P = 0.003 and 0.017) and B (P = 0.006 and 0.048), respectively. During the intraoperative period, sensory block levels were significantly higher in Group C than in Group A. Recovery was similar in all groups; only onset was faster in Groups C and D.

There was no effect of epidural volume extension on the profile of spinal anaesthesia with the combined spinal–epidural technique for Caesarean section using hyperbaric or plain bupivacaine.