Clonidine and analgesic duration after popliteal fossa nerve blockade: randomized, double-blind, placebo-controlled study.

BACKGROUND: We tested the hypothesis that 100 microg clonidine added to 0.375% bupivacaine would prolong the duration of analgesia from popliteal fossa nerve blockade.

METHODS: Ninety-nine patients scheduled for hospital admission after foot or ankle surgery entered this randomized, double-blind, placebo-controlled trial. Patients received a popliteal fossa block (nerve stimulator technique, via the posterior approach) using 30 mL 0.375% bupivacaine, with epinephrine. Patients were randomized to receive no clonidine, 100 microg clonidine IM, or 100 microg clonidine with bupivacaine for the popliteal block. Patients also received a combined spinal-epidural anesthetic, a saphenous nerve block, and postoperative IV patient-controlled analgesia. The primary outcome was patient-reported duration of analgesia.

RESULTS: Duration of analgesia was statistically longer in the block clonidine group (18 +/- 6 h for clonidine with bupivacaine vs 14 +/- 7 h for IM clonidine and 15 +/- 7 h for control, P = 0.016 for control vs clonidine with bupivacaine). Pain scores, analgesic use, and side effects attributable to pain management were similar among groups.

CONCLUSIONS: Clonidine significantly prolongs the analgesic duration after popliteal fossa nerve blockade with bupivacaine.