Determination of the analgesic dose-response relationship for epidural fentanyl and sufentanil with bupivacaine 0.125% in laboring patients

Study Objective: To establish the analgesic effective doses as defined as a visual analog pain scale (VAS) of at least 10 for 95% of parturients (ED95 ) receiving either epidural fentanyl or sufentanil with bupivacaine 0.125% for labor analgesia. Design: Double-blind, randomized controlled study. Setting: Two tertiary-care teaching hospitals. Patients: 100 female patients, at full-term pregnancy, in active early labo r (<5 cm carvical dilation) and requesting obstetric anesthesia services fo r labor analgesia. Interventions: Patients were randomized and equally dist ributed to receive one of ten epidural dosing regimens of bupivacaine 0.125 % alone ol with either fentanyl 25, 50, 75, or 100 mu g or sufentanil 5, 1 0, 15, 20, ol 25 mu g in a 10-ml bolus after a 3-ml test dose of bupivacain e 0.25%. Measurements and Main Results: VAS scores were obtained from each parturien t using a 10-cm plastic VAS slide rule at times 0, 1, 5, 10, 15, 20, 25, an d 30 minutes, and then again when the patient requested additional analgesi a. Analgesia duration and demographic and obstetric data also were obtained . Using a log-probit dose-responce analysis, analgesic success as defined a s a VAS of at least 10 with each opioid dose was plotted and an ED, value o f 8 mu g and 50 mu g was Established for sufentanil and fetanyl, respective ly, in bupivacaine 0.125 %. No statistical difference was detected for anal gesic duration or incidence of side effects between analgesic groups. Conclusions: Epidural analgesia with fentanyl and sufentanil in bupivacaine 0.125 % behaves in a close-response fashion allowing for the determination of equipotent dose of each. (C) 1998 by Elsevier Science Inc.