Intrathecal alfentanil with and without bupivacaine for analgesia in labour.

Combined spinal-epidural (CSE) for analgesia in labour is widely used as a method of providing pain relief while minimising motor blockade. Aiming to further reduce the associated motor weakness, we investigated the use of alfentanil alone as the initial intrathecal injection in a double-blind study. Thirty women were randomly allocated to receive either alfentanil 0.25 mg with bupivacaine 2.5 mg intrathecally, or alfentanil 0.25 mg in the same volume. Onset of analgesia did not differ significantly between groups but duration was significantly longer in those receiving alfentanil-bupivacaine (mean 55 min vs. 40 min; p < 0.05). Quality of analgesia was satisfactory for all women, although the cumulative analgesia scores were significantly lower in the women receiving the alfentanil-bupivacaine mixture (p = 0.003). More women in the alfentanil-bupivacaine group developed both a sensory level (15/15 vs. 6/15; p < 0.01) and sympathetic block (12/15 vs. 4/15; p < 0.01). Sixty per cent of women receiving the alfentanil-bupivacaine mixture demonstrated an impaired ability to straight leg raise compared with none of the women in the alfentanil-saline group (p < 0.01). The incidence of adverse effects in mother and fetus was similar in both groups. We conclude that intrathecal alfentanil 0.25 mg alone as part of a CSE technique provides rapid analgesia of satisfactory quality without detectable motor blockade.