The effect of intravenous lidocaine infusion on subarachnoid anesthesia in patients undergoing total knee replacement: a randomised controlled trial.

Abstract

Intravenous lidocaine is a non-opioid analgesic adjunct for perioperative pain relief. The aim of our study was to explore whether concurrent administration of intravenous lidocaine prolongs the duration of sensory block during total knee replacement (TKR) under spinal anaesthesia. This prospective randomized double blind controlled trial was conducted on 28 patients (14 in lidocaine group and 14 in the control group) undergoing unilateral TKR under spinal anesthesia. In the lidocaine group, intravenous lidocaine 1.5mg·kg-1 followed by an infusion of 1.5mg·kg-1·h-1 was administered intraoperatively after spinal anesthesia. The primary outcome was the duration of sensory block of spinal anesthesia. Secondary outcomes included onset time of sensory and motor block, duration of motor block, time to first postoperative analgesic, postoperative visual analog scale (VAS) scores and postoperative analgesia requirement in 24h after surgery. The duration of sensory and motor block was longer in the lidocaine group (Mean ± SD; 112.50 ± 5.80min versus 78.21 ± 9.12min;p < 0.001 and 237.14 ± 9.14min versus 215.00 ± 10.12min;p < 0.001, respectively). Time to requirement of first rescue analgesia was 184.29 ± 9.38min in the lidocaine group and 127.14 ± 23.35min in the control group (p < 0.001). VAS scores were lower in the lidocaine group at 4, 8, 12 and 24h after surgery (p < 0.00001, p < 0.00001, p < 0.00006, p = 0.032, respectively). Requirement of additional analgesia in the first 24h was higher in the control group. There were no clinical signs to suggest lidocaine toxicity in any patient. During unilateral TKR under spinal anaesthesia, concurrent use of intravenous lidocaine prolonged sensory block and reduced postoperative analgesic requirements.