Abstract

Isobaric (dextrose-free) bupivacaine 0.5% (15 mg) and hyperbaric lidocaine 5% (90 mg) were compared in a double-blind study of 40 patients who had urological surgery under spinal anesthesia. After the injection, the patients remained in the sitting position for 2 minutes before being placed in the lithotomy position (37 patients) or supine horizontal position (3 patients). With both drugs, T10 level of analgesia was reached within 8 minutes, although it took 20-25 minutes to achieve maximum cephalad level of analgesia (T6-8). Duration of analgesia was significantly longer for bupivacaine in the T12-S5 segments. Onset time to complete motor blockade of the lower limbs was significantly shorter for lidocaine: 6 minutes versus 12 minutes for bupivacaine. The motor blockade was complete in 19 of 20 patients in the bupivacaine group and in 17 of 20 patients in the lidocaine group. Duration of complete motor blockade was significantly longer for bupivacaine. Cardiovascular changes were minimal and no significant differences between the groups were found. In one patient a severe headache developed and another patient got bronchospasm.