Effect of propofol dose changes on intraoperative somatosensory and motor evoked potentials monitoring

English Keywords:Intravenous anaesthesia  Propofol  Somatosensory evoked potential  Motor evoked potential  Intraoperative monitoring  Scoliosis surgery

English Abstract:

  【Abstract】 Objectives: To investigate the effect of propofol dose changes on somatosensory evoked potential(SEP) and motor evoked potential(MEP). Methods: Twenty patients with idiopathic scoliosis received surgical treatment with propofol intravenous anaesthesia, and multimodality intraoperative neurophysiologic monitoring was reviewed. The changes of SEP and MEP in responding to dose increase were recorded during induction of anaesthesia, and the changes in responding to dose decrease were recorded during closure procedure. Dose-increase delay and dose-decrease delay periods were measured accordingly. Results: The change of propofol dose did not produce significant change in latency of SEP (36.1±2.6ms vs 36.2±2.3ms, P>0.05) and MEP (27.0±1.5ms vs 27.1±1.6ms, P>0.05). The increase of propofol dose significantly decreased the amplitude of SEP (1.91±0.53μV vs 1.37±0.55μV, P<0.001) and MEP (175.7±134μV vs 127±81μV, P<0.001), while the decrease of propofol dose significantly increased the amplitude of SEP (1.26±0.64μV vs 1.50±0.56μV, P<0.005) and MEP (143±100μV vs 169±133μV, P<0.005). However, there was lag effect of SEP and MEP changes in responding to dose change of propofol. The dose-increase delay period was 18.5±6.5min in SEP and 10.5±3.6min in MEP respectively, while dose-decrease delay period was 29.6±10.6min in SEP and 13.5±6.3min in MEP respectively, there were statistically differences between two groups(P<0.05). Conclusions: The dose of propofol increase may produce a faster decrease of SEP and MEP. On the contrary, the dose decrease will cause a increase of SEP and MEP. In addition, MEP is more sensitive to dose changes of anesthetic than SEP.