Giving phenylephrine alone by infusion at cesarean delivery was associated with a lower incidence of fetal acidosis and maternal nausea and vomiting than giving ephedrine alone. There was no advantage to combining phenylephrine and ephedrine because it increased nausea and vomiting, and it did not further improve fetal blood gas values, compared with giving phenylephrine alone.

We have examined the effect of extradual injection of 0.5% bupivacaine or normal saline on the progression of spinal anaesthesia in 28 patients undergoing Caesearean section. Three groups were studied. Subarachnoid anaesthesia was established in all patients. Group A (n = 10), the control, received no extradural injection for 20 min. Group B (n = 9) received extradural bupivacaine 10 ml and group C (n = 9) received extradual saline 10 ml 5 min after the subarachnoid injection. Sensory levels were compared at 5-min intervals and extension of the block was found to be similar in groups B and C and significantly faster than the control (P < 0.05). The quality of anaesthesia and incidence of adverse effects was similar for all three groups. We conclude that the mechanism of extension of spinal anaesthesia by extradural injection of local anaesthesia is largely a volume effect.

This study provides evidence that intravenous phenylephrine can decrease rostral spread of spinal anesthesia in pregnancy, compared with intravenous ephedrine. Further work is required to investigate possible mechanisms and to assess its clinical significance.

We have examined the hypothesis that intrathecal fentanyl at operation can increase postoperative i.v. morphine requirements. We studied 60 patients undergoing Caesarean section. All received intrathecal 0.5% plain bupivacaine 2 ml combined with either fentanyl 0.5 ml (25 g) (group F) (n:30) or normal saline 0.5 ml (group S) (n:30). In addition, 10 ml of an extradural solution (fentanyl 1 ml (50 g) combined with 0.5% bupivacaine 9 ml) was administered after delivery. Extradural solution was only given before delivery if the intrathecal injection failed to produce a block above T6 or the patient required further analgesia. Postoperative analgesia was provided with i.v. morphine patient-controlled analgesia. At operation, intrathecal fentanyl reduced the need to administer extradural solution before delivery, increased the anaesthetist's satisfaction with analgesia and reduced nausea, but increased pruritus. Up to 6 h after delivery there was no difference in postoperative morphine requirements or pain scores. Between 6 h and 23 h there was a 63% increase in morphine requirements in group F. We consider the most likely explanation for this finding to be that intrathecal fentanyl induced acute spinal opioid tolerance.

In this randomized, double-blind study of 60 patients, we have assessed the analgesic efficacy of extradural bupivacaine and extradural fentanyl, either alone or in combination, after Caesarean section. Patients received 0.1% bupivacaine (group B), fentanyl 4 micrograms ml-1 (group F) or 0.05% bupivacaine combined with fentanyl 2 micrograms ml-1 (group BF) by patient-controlled extradural analgesia (PCEA). Adding fentanyl to bupivacaine reduced the dose of bupivacaine by up to 68%, improved analgesia at rest and decreased PCEA use. Motor and sensory block were decreased, but there was more pruritus. Overall patient satisfaction was increased. Adding bupivacaine to fentanyl reduced the dose of fentanyl by up to 57% without altering pain scores or PCEA use. Sensory block increased but pruritus did not decrease. Bupivacaine 0.05% produced clinically significant leg weakness in three patients. Overall patient satisfaction was not altered. There was a significant additive analgesic effect between 0.05% bupivacaine and fentanyl but no clinical benefit was demonstrated from using the combination compared with fentanyl alone for this group of postoperative patients.