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−1 followed by an infusion of 1.5 mg·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 24 h after surgery."

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."

Excerpts

It has been suggested that intravenous (IV) lidocaine prevents the depolarization of neurons of damaged or dysfunctional nerves and reduces or prevents neo-proliferation of active sodium channels in these nerves. Lidocaine reduces the sensitivity and activity of spinal cord neurons thereby decreasing central sensitization and also decreases N-methyl-D-aspartate receptor-mediated post-synaptic depolarization. All these pharmacological effects result in significant analgesic, anti-hyperalgesic, anti-inflammatory and neuroprotective properties.

Koppert et al. suggested that perioperatively administered low dose IV lidocaine reduces pain during surgery by blocking impulses mediated by mechano-insensitive nociceptors, thereby preventing the development of central sensitization and hyperalgesia.

In 2019, Khezri et al. reported that IV lidocaine given as a supplementary agent in patients undergoing caesarean section under spinal anesthesia prolonged the duration of the sensory and motor blockade of spinal anesthesia and delayed the first analgesic request by patients without any hemodynamic disturbance or respiratory depression.

While the pain during and after caesarean section has visceral and somatic components, the pain during and after TKR is a somatic pain. Different nerve fibres may have varying susceptibility to neural blockade by lidocaine. Also, while there are plenty of studies on the beneficial effects of lidocaine infusion in the perioperative period, there is a paucity of studies assessing the effect of IV lidocaine infusion on the duration of sensory blockade of spinal anesthesia. Hence, we aimed to study the effect of IV lidocaine on the characteristics of subarachnoid block and analgesic requirements in patients undergoing TKR.

We found a significant prolongation of the sensory and motor block of spinal anesthesia when IV lidocaine was administered to patients undergoing unilateral TKR under spinal anesthesia. Intraoperative infusion of lidocaine also led to lower BIS values and a significantly reduced requirement of intraoperative midazolam. In the postoperative period, the pain scores were lower in the lidocaine group at 4, 8, 12 and 24 h after surgery. The time to requirement of first postoperative rescue analgesia was longer in the lidocaine group and the overall requirement of additional analgesia in the first 24 h was also significantly lower.

Lidocaine may have special benefits in the elderly population as it does not cause hemodynamic instability or any respiratory depression and causes a mild degree of sedation.

Although there was an associated prolongation of the duration of motor block in the lidocaine group, the mean duration was 237.14 ± 9.14 min which may not be clinically relevant as it will not delay ambulation after TKR.

Patients presenting for TKR are older, often have multiple comorbidities, may be on anticoagulant therapy, and may have other contraindications to epidural analgesia or regional nerve blocks. In such patients, the use of an IV lidocaine infusion may prove to be a valuable non opioid adjunct for perioperative analgesia if used with safety and within the prescribed dose ranges to prevent lidocaine toxicity.

Citation

Kodkani, A., Bhalotra, A.R., Singh, R. et al. The effect of intravenous lidocaine infusion on subarachnoid anesthesia in patients undergoing total knee replacement: a randomised controlled trial. J Anesth (2024). https://doi.org/10.1007/s00540-024-03430-5

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