We have studied postoperative analgesia and unwanted side effects of a single dose of a mixture of morphine and sufentanil administered extradurally with the effects produced by extradural injection of each opioid alone in 64 patients after Caesarean delivery. The patients were allocated randomly to receive morphine 4 mg (n = 21), sufentanil 50 μg (n = 22) or morphine 2 mg with sufentanil 25 μg (n = 21) via an extradural catheter in a double-blind design. Intensity of pain was measured using a linear visual analogue scale. Compared with the effect produced by morphine alone, the morphine-sufentanil combination produced more rapid onset of pain relief (19 (SD 5) min vs 79 (23) min for a 75% reduction of pain; P < 0.01), whereas the duration and quality of analgesia assessed during 12 h was similar for these two groups. In contrast, patients receiving sufentanil alone required significantly more supplementary analgesia 4 h after administration than with morphine alone or morphine combined with sufentanil. There were no significant changes in cardiorespiratory variables in any group. Side effects consisted mainly of pruritus and nausea and did not differ between groups, with the exception of early and transient dizziness which was observed only in patients given sufentanil either alone or in combination with morphine. We conclude that a single extradural injection of morphine and sufentanil combines the short onset time produced by sufentanil and the long duration of analgesia attributable to morphine, thus providing excellent and prolonged analgesia after Caesarean deliver
