Distal tourniquet or leg position after injection enhances the efficacy of sciatic nerve blockade by the popliteal approach.

Abstract

In this study, we hypothesized that leg positioning and distal tourniquet application, when compared with neutral positioning of the leg, alters the efficacy of sciatic nerve block performed by the double-stimulation technique. Ninety randomized, consecutive, ASA physical status I to III patients undergoing foot and ankle surgery with a popliteal fossa block (using a double-stimulation technique with the patient in prone position) were prospectively studied. Patients were randomized to have the blocked leg either kept in a neutral position immediately after the patient was turned supine (group 1), flexed 45 degrees at the thigh and maintained in that position for 15 minutes (group 2), or have a distal tourniquet applied with the leg in a neutral position and inflated during injection of the local anesthetic with the patient supine (group 3). A standardized local anesthetic mixture containing 15 mL of 2% prilocaine and 15 mL of 0.5% levobupivacaine was used in all study groups. The onset times for sensory and motor blocks were shorter, and the time to recovery of blocks was longer, postprocedure in both group 2 and 3. Similar beneficial effects might be reached with the application of a distal tourniquet during injection or elevating the patient's leg turned supine immediately after sciatic nerve block with a popliteal approach by a double-injection technique. We suggest that using the leg-up position or application of a distal tourniquet for sciatic nerve block may lead to a more proximal distribution of the local anesthetic and may result in a faster onset of sensory and motor blocks as well as longer duration of blockade.