Figure 2. Onset of analgesia (mean, SD). Data points are slightly offset for clarity, as are x and y axes. Groups differed significantly from each other (analysis of variance, P < 0.01). *At 2.5 min, fentanyl-bupivacaine 2.5 and fentanyl-bupivacaine 1.25 groups, P < 0.05 vs. fentanyl-only group; and fentanyl-bupivacaine 2.5 group, P < 0.05 vs. group fentanyl-bupivacaine 1.25. **At 5.0 min, fentanyl-bupivacaine 2.5 and fentanyl-bupivacaine 1.25 groups, P < 0.05 vs. fentanyl-only group.