Figure 1. Duration of analgesia (time to first request for additional analgesia). Groups differed significantly (analysis of variance, P < 0.05). *Fentanyl-bupivacaine 2.5 group significantly different from fentanyl-only and fentanyl-bupivacaine 1.25 groups, P < 0.001. See text for description of groups (mean +/- SD).