A Preliminary Study of Volatile Agents or Total Intravenous Anesthesia for Neurophysiological Monitoring During Posterior Spinal Fusion in Adolescents With Idiopathic Scoliosis

Study Design. A prospective randomized controlled trial. Objective. The purpose of this study was to prospectively compare the efficacy of neurophysiological monitoring during general anesthesia with either a total intravenous technique or with the volatile anesthetic agent, desflurane. Summary of Background Data. A total intravenous anesthetic technique is generally chosen when neurophysiological monitoring is used as it has been shown to facilitate such monitoring. Despite this, with prolonged infusions of propofol, prolonged awakening times may be seen, which may impact the time required for postoperative neurological assessment or more importantly result in significant delays, should a wake-up test become necessary. To date, there are no prospective trials comparing intravenous techniques with a volatile agent-based anesthetic technique and its effects on neurophysiological monitoring. Methods. This prospective study compares somatosensory evoked potential and motor evoked potential monitoring during posterior spinal fusion in 30 adolescents. The patients were randomized to receive a total intravenous technique with propofol-remifentanil or a volatile agent-based technique with desflurane-remifentanil. Results. The groups were similar with regard to age, weight, height, body mass index, Cobb angle, and distribution of Lenke classifications. No differences were noted in anesthesia time, surgery time, intraoperative fluids, or estimated blood loss between the 2 groups. Time to eye opening, time to following commands, and time to tracheal extubation were shorter in the volatile anesthesia group than the total intravenous anesthesia group. No clinically significant difference was noted in the amplitude or latency of somatosensory evoked potential monitoring. Although statistically significantly greater voltage amplitude was required to generate a motor evoked potential, the voltage amount was within a clinically acceptable range. Conclusion. Our data demonstrate that a volatile agent-based anesthetic regimen is feasible even during neurophysiological monitoring. Advantages include a more rapid awakening and the feasibility of a rapid wake-up test (<5 min) in the event that irreversible changes in neurophysiological monitoring are noted.