COMPARISON OF 5-PERCENT WITH DEXTROSE, 1.5-PERCENT WITH DEXTROSE, AND1.5-PERCENT DEXTROSE-FREE LIDOCAINE SOLUTIONS FOR SPINAL-ANESTHESIA IN HUMAN VOLUNTEERS

The use of lidocaine in concentrations less than 5% for spinal anesthe sia may be advantageous but has not been carefully studied. Lidocaine 50 mg (1.5% with dextrose and 1.5% dextrose-free) was administered to eight volunteers in a randomized, double blind, cross-over fashion. Al l of these subjects had previously received 5% lidocaine with dextrose using the same experimental protocol. Sensory analgesia was assessed with pinprick, transcutaneous electrical stimulation (TES) equivalent to surgical incision, and duration of tolerance of pneumatic thigh tou rniquet. Motor block was assessed with isometric force dynamometry. Pe ak dermatomal level was the highest and duration until regression of p inprick the longest with the 5% solution (P < 0.05). Duration of toler ance to TES was increased (33 +/- 10 min) with the 5% solution (P < 0. 04). Duration of tolerance to tourniquet pain was increased (11 +/- 3 min) with the 5% solution (P < 0.02). Duration of motor block was incr eased (45 +/- 9 min) with the 5% and the 1.5% without dextrose solutio ns (P < 0.04). Time to void was increased (33 +/- 5 min) with the 5% s olution (P < 0.03). In conclusion, the use of different solutions of l idocaine for spinal anesthesia results in significant differences in s ensory and motor block and time until recovery of micturition.