Effects of inhalation of different concentrations of sevoflurane combined anesthesia on somatosensory evoked potentials in adolescent patients undergoing scoliosis surgery

Abstract

Objective To investigate the effects of inhalation of different concentrations of sevoflurane combined anesthesia on somatosensory evoked potentials (SEPs) in the adolescent patients undergoing scoliosis surgery.Methods Forty-five adolescent patients of both sexes,aged 12-17 yr,with body mass index of 15-23 kg/m2,undergoing scoliosis surgery under general anesthesia,were randomly divided into 3 groups ( n =15 each):low concentration sevoflurane group ( group S1 ),moderate concentration sevoflurane group ( group S2 ) and high concentration sevoflurane group (group S3 ).Anesthesia was induced with fentanyl 4 μg/kg,midazolam 0.03 mg/kg,propofol 2.0 mg/kg,and rocuronium 0.6 mg/kg.The patients were endotracheal intubated and mechanically ventilated.Anesthesia was maintained with propofol infusion at 8 mg· kg-1 · h-1 and remifentanil infusion at 0.25 mg· kg-1 ·min-1.After beginning of the surgery,1.8％,4.0％ and 6.0％ sevoflurane were inhaled for 10 min in groups S1-3 respectively,SEPs were measured by stimulating the posterior tibial nerve and significant SEP suppression was detected and recorded.The wave P40 latency,wave P40-N50 amplitude,and time for P40 waveform changes were recorded before sevoflurane inhalation (baseline) and at 10 min of sevoflurane inhalation,and the time for recovery of P40 waveform was recorded after sevoflurane inhalation was stopped.The prolonged percentage of P40 latency and decreased percentage of P40-N50 amplitude were calculated.Results The rates of significant SEP suppression were 80％,100％ and 100％ in groups S1,S2 and S3 respectively ( P ＞ 0.05).Compared with group S1,the prolonged percentage of P40 latency and decreased percentage of P40-N50 amplitude were significantly increased,the time for P40 waveform changes was significantly shortened,and the time for recovery of P40 waveform was significantly prolonged in groups S2 and group S3 ( P ＜ 0.05).Compared with group S2,the decreased percentage of P40-N50 amplitude was significantly increased,the time for P40 waveform changes was significantly shortened,and the time for recovery of P40 waveform was significantly prolonged in group S3 ( P ＜ 0.05).Conclusion 1.8％,4.0％ and 6.0％ sevofiurane combined anesthesia can suppress SEPs in the adolescent patients undergoing scoliosis surgery,and they are not suitable for the surgeries requiring SEP monitoring. Key words: Anesthetics, inhalation; Evoked potentials, somatosensory; Monitoring, intraoperative; Adolescent