Although lidocaine seems to be one of the most suitable spinal anesthetics for ambulatory surgery, the safety of lidocaine for spinal anesthesia has been called into question by report of transient neurologic toxicity. So diluted bupivacaine with opioids or adrenergic receptor agonist can replace spinal lidocaine, but delayed awakening, pruritis, intraoperative weak motor block are unsolved problems. This study explored the possibility of solving the unmerited problem to mix bupivacaine and plain lidocaine in spinal anesthesia for transurethral surgery.

Fifty patients presented for transurethral resection of bladder or prostate. The duration was expected to less one hour. All patients were randomized to two groups receiving the following spinal anesthetics: Group I (7.5 mg bupivacaine), 1.5 ml of 0.5% spinal bupivacaine in 8% dextrose + 0.6 ml saline; Group II (7.5 mg bupivacaine + 6 mg lidocaine), 1.5 ml of 0.5% spinal bupivacaine in 8% dextrose + 0.6 ml 1% plain lidocaine. The sensory and motor block level were checked via pinprick test and modified Bromage score.

The highest level of sensory block was not different in group I and group II [median (range): T8 (T5-T9) vs. T8 (T5-T10)]. Onset time to peak block was similar in both groups (11 ± 2 vs. 11 ± 4 min). Time to two-segment regression (49 ± 10 vs. 42 ± 10 min; P < 0.05), L1 regression (139 ± 27 vs. 113 ± 24 min; P < 0.01), S2 regression (200 ± 41 vs. 158 ± 38 min; P < 0.01) were significantly reduced in group II. No clinical evidence of transient neurologic toxicity was found. Modified Bromage score to evaluate for motor block was not different at the same sensory block level.

Bupivacaine and lidocaine mixture as spinal anesthetics provided the combination of adequate depth of anesthesia and rapid recovery.