Effects of duration of surgery flash-induced visual evoked potentials in patients undergoing spinal surgery in prone position

Abstract

Objective To investigate the effects of duration of surgery on flash-induced visual evoked potentials (VEP) in patients undergoing spinal surgery in prone position.Methods Eighty-two ASA Ⅰ or Ⅱ patients of both sexes aged 20-76 yr weighing 43-96 kg undergoing spinal surgery in prone position were divided into 3 groups according to the duration of surgery:group S≤2 h ( n =34) ; group M 2-4 h ( n =38) and group L≥4 h ( n =10).VEP was monitored using protektor VEP monitoring device (Xltek Co.,Canada).The latency,amplitude and recovery time of wave P100 were recorded before and 10 min after induction of anesthesia and at the end of surgery.Results Compared with group S,the amplitude of wave P1000 was significantly decreased at the end of surgery in group M,the lantency of wave P100 was significantly prolonged,while the amplitude of wave P100 was decreased at the end of surgery in group L ( P ＜ 0.05).Compared with group M,the lantency of wave P100 was significantly prolonged,while the amplitude of wave P100 was decreased at the end of surgery in group L ( P ＜ 0.05).Compared with groups S and M,the recovery time of wave P100 was significantly prolonged in group L ( P ＜0.05).There was no significant difference in the recovery time of wave P100 between groups S and M ( P ＞ 0.05).Conclusion Duration of surgery (≥4 h) can affect flash-induced VEP,the longer the duration,the stronger the effects. Key words: Time; Surgical procedures,operative, Evoked potentials, visual; Spine