Comparison between effect of desflurane/remifentanil and propofol/remifentanil anesthesia on somatosensory evoked potential monitoring during scoliosis surgery-A randomized controlled trial.

Hasan, M Shahnaz; Tan, Jin-Keat; Chan, Chris Yin Wei; Kwan, Mun Keong; Karim, Fathil Syafiq Abdul; Goh, Khean-Jin

BACKGROUND Drugs used in anesthesia can affect somatosensory evoked potential (SSEP) monitoring, which is used routinely for intraoperative monitoring of spinal cord integrity during spinal surgery. OBJECTIVE The objective of this study was to determine whether combined total intravenous anesthesia (TIVA) technique with propofol/remifentanil is associated with less SSEP suppression when compared to combined volatile agent desflurane/remifentanil anesthesia during corrective scoliosis surgery at a comparable depth of anesthesia. DESIGN It is a randomized controlled trial. SETTING The study was conducted at the Single tertiary University Hospital during October 2014 to June 2015. PATIENTS Patients who required SSEP and had no neurological deficits, and were of American Society of Anesthesiologist I and II physical status, were included. Patients who had sensory or motor deficits preoperatively and significant cardiovascular and respiratory disease were excluded. A total of 72 patients were screened, and 67 patients were randomized and allocated to two groups: 34 in desflurane/remifentanil group and 33 in TIVA group. Four patients from desflurane/remifentanil group and three from TIVA group were withdrawn due to decrease in SSEP amplitude to <0.3 µV after induction of anesthesia. Thirty patients from each group were analyzed. INTERVENTIONS Sixty-seven patients were randomized to receive TIVA or desflurane/remifentanil anesthesia. MAIN OUTCOME MEASURES The measurements taken were the amplitude and latency of SSEP monitoring at five different time points during surgery: before and after the induction of anesthesia, at skin incision, at pedicle screw insertion, and at rod insertion. RESULTS Both anesthesia techniques, TIVA and desflurane/remifentanil, resulted in decreased amplitude and increased latencies of both cervical and cortical peaks. The desflurane/remifentanil group had a significantly greater reduction in the amplitude ( p = 0.004) and an increase in latency ( p = 0.002) of P40 compared with the TIVA group. However, there were no differences in both amplitude ( p = 0.214) and latency ( p = 0.16) in cervical SSEP between the two groups. CONCLUSIONS Compared with TIVA technique, desflurane/remifentanil anesthesia caused more suppression in cortical SSEP, but not in cervical SSEP, at a comparable depth of anesthesia.