The advantages of epidural anesthesia for Caesarean section are well documented. However, its disadvantages include a slow onset time, which preclude its use for urgent procedures. The object of this clinical trial was to ascertain if a useful reduction in onset time may be obtained by fentanyl supplementation versus plain ropivacaine.

Twenty healthy women scheduled for Caesarean section were allocated randomly to receive 20 ml of 0.75% ropivacaine with normal saline 1 ml (group 1) or 20 ml of 0.75% ropivacaine with fentanyl 50 mcg (group 2) via a epidural catheter inserted 3 cm into the epidural space, identified by the loss of resistance technique using a midline approach at the L3-4 interspace. After insertion of the catheter, and with the patient supine, a test dose of 3 ml of the solution was given, and then the remainder was injected at a rate of 10 ml/min. The time for sensory block to develop at T8 by loss of cold discrimination using an alcohol sponge was defined as the onset time. Onset of block was timed from the end of the last injection. If a sensory block of T6 or higher was not present at 30 min, 5 ml of 2% lidocaine mixed with 0.5 ml of 8.4% sodium bicarbonate were administered until an adequate height of block had been achieved. After surgery had started and discomfort was felt, 50 mcg of i.v. fentanyl was administered repeatedly after delivery. Side effects (hypotension, nausea/vomiting, shivering, bradycardia, respiratory depression) during surgery were recorded, and the upper limit of sensory analgesia to the alcohol sponge was determined.

The onset time was 8.7 ± 4.3 min in group 1 and 11.9 ± 5.4 min in group 2, respectively. No significant difference was evident between the two groups in terms of onset time to the sensory block to T8. The number of patients that required supplementary analgesia and experiencing side effects was similar. The maximum upper level observed in any patient was C6 in group 1 and C4 in group 2.

The combined use of ropivacaine and fentanyl did not reduce sensory onset or produce an unnecessarily extended sensory block level.