PURPOSE: 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. METHODS: 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 1.5 mg·kg RESULTS: The duration of sensory and motor block was longer in the lidocaine group (Mean ± SD
112.50 ± 5.80 min versus 78.21 ± 9.12 min
p <
0.001 and 237.14 ± 9.14 min versus 215.00 ± 10.12 min
p <
0.001, respectively). Time to requirement of first rescue analgesia was 184.29 ± 9.38 min in the lidocaine group and 127.14 ± 23.35 min in the control group (p <
0.001). VAS scores were lower in the lidocaine group at 4, 8, 12 and 24 h after surgery (p <
0.00001, p <
0.00001, p <
0.00006, p = 0.032, respectively). Requirement of additional analgesia in the first 24 h was higher in the control group. There were no clinical signs to suggest lidocaine toxicity in any patient. CONCLUSION: During unilateral TKR under spinal anaesthesia, concurrent use of intravenous lidocaine prolonged sensory block and reduced postoperative analgesic requirements.