Lidocaine infusion adjunct to total intravenous anesthesia reduces the total dose of propofol during intraoperative neurophysiological monitoring

Total intravenous anesthesia (TIVA) with propofol and opioids is frequently utilized for spinal surgery where somatosensory evoked potentials (SSEP) and motor evoked potentials (tcMEP) are monitored. Lidocaine infusions can contribute to antinociception and unconsciousness, thus allowing for a reduction in the total dose of propofol. We examined our recent experience with lidocaine infusions to quantify this effect. After institutional review board approval, we conducted a retrospective review of propofol usage in propofol-opioid TIVA (with and without lidocaine) for spine cases monitored with SSEP and tcMEP over a 7 months period. The propofol infusion rate, cortical amplitudes of the SSEP (median nerve, posterior tibial nerve), amplitudes and stimulation voltage of the tcMEP (adductor pollicis brevis, tibialis anterior) were evaluated. The savings of propofol and sufentanil were estimated based on utilization in 50 milliliter (ml) bottles and 5 ml ampules, respectively. 129 cases were evaluated. Propofol infusion rates were reduced with lidocaine infusion from an average of 115-99 μg/kg/min (p = 0.00038) and sufentanil infusions from an average of 0.36-0.29 μg/kg/h (p = 0.0059). This reduction in propofol infusion was also seen when the cases were divided into anterior cervical, posterior cervical, or posterior thoraco-lumbar procedures. No significant differences in the cortical SSEP or tcMEP amplitudes or the tcMEP stimulation voltages used were observed. No complications were associated with the use of the lidocaine infusion. The total estimated drug savings included 104 50 ml bottles of propofol and 5 5 ml ampules of sufentanil. These cases indicate that a lidocaine infusion can be effectively utilized in spine surgery with SSEP and tcMEP monitoring as a means to reduce propofol and sufentanil usage without a negative effect on the monitoring.