Comparative study between combined sciatic-femoral nerve block, via a single skin injection, and spinal block anesthesia for unilateral surgery of the lower limb.

BACKGROUND AND OBJECTIVES Unilateral spinal anesthesia has advantages when used in outpatient basis. The objective of the present study was to compare unilateral spinal anesthesia with combined sciatic-femoral nerve block in unilateral orthopedic surgeries in outpatients. METHODS Sixty patients were randomly divided into two groups of 30 patients to receive 6 mg of hyperbaric or hypobaric bupivacaine (RQ group) in left lateral decubitus, or 800 mg of 1.6% lidocaine with epinephrine on sciatic and femoral nerves (CFI group) in dorsal decubitus. A 150-mm needle connected to a neurostimulator, inserted in the middle point between both classical approaches, was used for the nerve block, with the injection of 15 mL on the femoral nerve and 35 mL on the sciatic nerve. The time for the blockades and their duration were evaluated. After twenty minutes, patients were evaluated regarding the sensorial and motor blockades. RESULTS Time for performance of spinal anesthesia was substantially lower than for combined sciatic-femoral nerve block. Unilateral blockade was achieved in 90% of the patients in the RQ group, and 100% in the CFI group. Bradycardia or hypotension was not observed. CONCLUSIONS This study concluded that combined sciatic-femoral nerve block is technically easy to perform and it can be an alternative for unilateral blockade of the lower limbs. Unilateral spinal anesthesia with low doses of bupivacaine resulted in shorter time to perform it, lower number of attempts, and earlier recovery than combined sciatic-femoral nerve block, but with the same efficacy.