Hypotension in spinal anesthesia a comparison of tetracaine and bupivacaine

Two spinal anesthetic formulations, bupivacaine 0.75% without dextrose (22.5 mg), and tetracaine, 0.5% in 5% dextrose (15 mg), were compared in a double-blind study of 60 patients undergoing orthopedic surgery. Injections were made with the patients in the lateral recumbent position after which they were turned supine and horizontal. A statistically significantly greater fall in mean systolic and diastolic blood pressure was found in the tetracaine group. Also, the maximum decrease in systolic blood pressure was statistically significantly more profound in the tetracaine group (24.7 ± 2.3%) than In the bupivacaine group (15.2 ± 1.7%). The mean upper level of analgesia at time for maximum decrease in systolic blood pressure was approximately T4 and T6. No differences were found between the groups with regard to changes in heart rate. One patient in the bupivacaine group developed postlumbar puncture headache.