Abstract

Sixty patients receiving spinal anesthesia were tested in a double-blind study. The patients were given a subarachnoid injection of either 2 ml of hyperbaric bupivacaine 0.5%, hyperbaric lidocaine 5%, or hyperbaric mepivacaine 4%. Thirty of the patients were placed in the side position for 15 minutes to achieve spinal hemianalgesia. Thirty patients were moved to the supine horizontal position immediately after the sub-arachnoid injection. Six patients lying 45 minutes in the side position were also studied. Pinprick analgesia and motor block were tested during induction, surgery, and recovery. No spinal hemianalgesias were achieved. All anesthetics, however, produced satisfactory surgical conditions. Sensory analgesia achieved an average maximum level of T5-T6 with all solutions. Motor block was complete in the dependent leg after 15 minutes in the side position. Incomplete motor block in the nondependent leg was observed in one lidocaine patient and in six bupivacaine patients. Otherwise the differences in the spinal anesthetic properties between the different solutions were unexpectedly small. The plasma concentrations of all three drugs were nontoxic. No severe complications occurred. The most common complaint was backache in 14 of 60 patients.