Lumbar plexus block reduces pain and blood loss associated with total hip arthroplasty

Background: The usefulness of peripheral nerve blockade in the anesthetic m anagement of hip surgery has not been clearly established. Because sensory afferents from the hip include several branches of the lumbar plexus, the a uthors hypothesized that a lumbar plexus block could reduce pain from a maj or hip procedure. Methods: In a double-blind prospective trial, 60 patients undergoing total hip arthroplasty were randomized to receive general anesthesia with (plexus group, n = 30) or without (control group, n = 30) a posterior lumbar plexu s block. The block was performed after induction using a nerve stimulator, and 0.4 ml/kg bupivacaine, 0.5%, with epinephrine was injected. General ane sthesia was standardized, and supplemental fentanyl was administered per he modynamic guidelines. Postoperative pain and patient-controlled intravenous morphine use were serially assessed for 48 h. Results: The proportion of patients receiving supplemental fentanyl intraop eratively was more than 3 times greater in the control group (20 of 30 vs. 6 of 29, P = 0.001). In the postanesthesia care unit, a greater than fourfo ld reduction in pain scores was observed in the plexus group (visual analog ue scale [VAS] pain score at arrival 1.3 +/- 2 vs. 5.6 +/- 3, P < 0.001), a nd "rescue" morphine boluses (administered if VAS > 3) were administered 10 times less frequently (in 2 of 28 vs. in 22 of 29 patients, P < 0.0001). P ain scores and morphine consumption remained significantly lower in the ple xus group until 6 h after randomization (VAS at 6 h, 1.4 +/- 1.3 vs. 2.4 +/ - 1.4, P = 0.007; cumulative morphine at 6 h, 5.6 +/- 4.7 vs. 12.6 +/- 7.5 mg, P < 0.0001). Operative and postoperative (48 h) blood loss was modestly decreased in the treated group. Epidural-like distribution of anesthesia o ccurred in 3 of 28 plexus group patients, but no other side-effects were no ted. Conclusions: Posterior lumbar plexus block provides effective analgesia for total hip arthroplasty, reducing intra- and postoperative opioid requireme nts, Moreover, blood loss during and after the procedure is diminished. Epi dural anesthetic distribution should be anticipated in a minority of cases.