Extended femoral nerve sheath block after total hip arthroplasty: continuous versus patient-controlled techniques

We assessed the efficacy of patient-controlled analgesia (PCA) techniques for extended femoral nerve sheath block after total hip arthroplasty. Forty-five patients were divided into three groups of 15. Over 48 h, all patients received 0.125% bupivacaine with clonidine 1 microg/mL and sufentanil 0.1 microg/mL via a femoral nerve sheath catheter as a continuous infusion at 10 mL/h in Group 1, as PCA boluses only of 10 mL/h in Group 2, or as PCA boluses of 5 mL per 30 min in Group 3. Pain scores, sensory block, supplemental analgesia, bupivacaine consumption, side effects, and satisfaction scores were recorded. Pain scores at rest and supplemental analgesia were comparable in the three groups. At 48 h, pain relief on movement was significantly better in Group 3 than in Group 1 (P = 0.01). Bupivacaine consumption was significantly less in Groups 2 and 3 than in Group 1 (P < 0.001). Side effects were comparable in the three groups. Satisfaction scores were significantly higher in Group 3 than in the other groups (P < 0.01). We conclude that, to maintain extended femoral nerve sheath block after total hip arthroplasty, PCA techniques reduce the local anesthetic consumption without compromise in patient satisfaction or visual analog scale scores. Of the two PCA techniques tested, PCA boluses (5 mL per 30 min) of 0.125% bupivacaine with clonidine 1 microg/mL and sufentanil 0.1 microg/mL are associated with the smallest local anesthetic consumption and the most patient satisfaction.