Abstract

Plain 0.5% bupivacaine and hyperbaric 0.5% tetracaine were compared for spinal anesthesia in 40 patients undergoing operation of lower extremities. Lumbar puncture was performed with a 22 gauge spinal needle with the patient in the lateral recumbent position. The third lumbar interspace was chosen for the puncture, when a free flow of clear CSF was obtained, the local anesthetic solution (2.5 ml of 0.5% bupivacaine or 2.0 ml of hyperbaric 0.5% tetracaine) was injected at a rate of 0.1ml/sec without barbotage. After injection of anesthetics, clinical features were observed and compared between the two groups. The results were as follows: 1. The two groups were well matched for age, sex, height and weight. 2. In both groups, sensory block to T₁₂ dermatome was obtained within 4 minutes, mean maximal level of analgesia was T₆₋₇, and the mean time for maximal level was around 20 minutes. 3. The onset times of motor block were similar in both groups and complete motor block was obtained in all cases within 20 minutes. 4. The duration of analgesia above the T₁₂ dermatome was 3 hours, postoperative analgesia was 7 hours. These value were significantly prolonged than those of the tetracaine group (p<0.05). 5. The changes in systolic pressure in the bupivacaine group were significantly less than those of the tetracaine group (p<0.05). 6. The complications after spinal anesthesia were headache, numbness, urinary retention and backpain, and were no significant difference in both groups. From the obtained results, we concluded that plain 0.5% bupivacaine was a relatively satisfactory agent for spinal anesthesia for operation of lower extremities. The time of onset, height of block and the complications of postoperative period were similar in both groups. The advantages of plain 0.5% bupivacaine were less hypotension and long duration of analgesia.

• Keywords: Spinal anesthesia;Bupivacaine;Tetracaine;