Extended perineural analgesia after hip and knee replacement when buprenorphine-clonidine-dexamethasone is added to bupivacaine: Preliminary report from a randomized clinical trial

Abstract

Objective. We tested the hypothesis that buprenorphine-clonidine-dexamethasone (BCD) extends perineural analgesia compared with plain bupivacaine (BPV) nerve blocks used for hip and knee replacement surgery. Design. Prospective, parallel-arms, randomized, double-blind trial. Setting. A single veterans' hospital. Subjects. Seventyeight veterans scheduled for total hip or knee replacement with plans for spinal as the primary anesthetic. Methods. Participants underwent nerve/plexus blocks at L2-L4 and L4-S3 in advance of hip or knee joint replacement surgery. Patients were randomized to receive BPV-BCD or plain BPV in a 4:1 allocation ratio. Patients answered four block duration questions (listed below). Time differences between treatments were analyzed using the t test. Results. Significant (P<0.001) prolongation of the time parameters was reported by patients after the BPV-BCD blocks (N=62) vs plain BPV (N=16). The time until start of postoperative pain was 26 vs 11 hours (mean difference = 15 hours, 95% CI = 8 to 21). The time until no pain relief from the blocks was 32 vs 15 hours (mean difference = 17 hours, 95% CI = 10 to 24). The time until the numbness wore off was 37 vs 21 hours (mean difference = 16 hours, 95% CI = 8 to 23). The time until the worst postoperative pain was 39 vs 20 hours (mean difference = 19 hours, 95% CI = 11 to 27). Conclusions. BPV-BCD provided 26-39 hours of perineural analgesia in the L2-L4 and L4-S3 nerve distributions after hip/knee replacement surgery, compared with 11-21 hours for plain BPV.