[Minimal dosages of fentanyl and sufentanil with bupivacaine for epidural analgesia in labor].
To estimate the minimal dosages of fentanyl and sufentanil in combination with 0.0625% W/V bupivacaine for epidural analgesia in labor. Forty-six pregnant women with full term gestation who requested epidural analgesia in labor were enrolled in this up-down sequential allocation study. Ten mL of fentanyl or sufentanil in combination of 0.0625% W/V bupivacaine was injected into the L2-3 epidural space of the women when their cervical dilated at about 2-4 cm. The effectiveness and side effects of the analgesia were observed in the following 30 minutes. The initial dose for the first study participant was set at 100 microg for fentanyl and 20 microg for sufentanil, respectively. The subsequent doses for the next study participants were determined by the response of the previous participants (testing interval, 5 microg for fentanyl and 1 microg for sufentanil). The minimum analgesic dose (MAD) of fentanyl or sufentanil was calculated using Dixon-Massey method. The MAD was 65.9 microg for fentanyl and 15.3 microg for sufentanil with 0.0625% W/V bupivacaine for epidural analgesia in labor. There were no significant differences in analgesia equality and side effects between fentanyl and sufentanil. When combined with 0.0625% W/V bupivacaine for epidural analgesia in labor, the minimum analgesic dose is 65.9 microg for fentanyl and 15.3 microg for sufentanil.