Appropriate degree of neuromuscular block for monitoring abnormal muscle response during microvascular decompression / 中华麻醉学杂志

ABSTRACT

Objective:To determine the appropriate degree of neuromuscular block (NMB) for abnormal muscle response (AMR) monitoring during microvascular decompression.Methods:Fifty American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients of both sexes, aged 20-64 yr, with body mass index≤30 kg/m 2, who were diagnosed with facial spasm before surgery, scheduled for elective microvascular decompression, were selected.Anesthesia was induced with midazolam 0.05-0.10 mg/kg, sufentanil 0.3-0.5 μg/kg and propofol 1.5-2.5 mg/kg. After patients lost consciousness, electrophysiological monitoring was performed, the zygomatic branch of the facial nerve was stimulated, and the baseline of AMR was recorded in the mental muscle.NMB was monitored with TOF-Watch SX monitor.After rocuronium 0.6 mg/kg was intravenously injected, the amplitude and latency of AMR were measured at different degrees of NMB (100%, 75%, 50% and 25%). The amplitude reservation ratio (the ratio of the amplitude of AMR monitored to the baseline value) was calculated.Linear correlation of the amplitude reservation ratio or latency of AMR with the degree of NMB was analyzed.The criteria for determining the appropriate degree of NMB in AMR monitoring were 1.amplitude reservation ratio of AMR≥50%; 2.no body movement during electrical stimulatation of facial nerve. Results:No patients had any body movement during electrical stimulation performed at different degrees of NMB.The amplitude reservation ratio ( Y) was negatively correlated with the degree of NMB ( X) ( r=-0.943, t=-42.73, P<0.001), the linear regression equation of the interaction between the degree of NMB ( X) and the amplitude reservation ratio (Y) was Y=90.36-0.894 7 X, and the coefficient of determination R2 was 0.8804 ( F=1825.41, P<0.001). The amplitude reservation ratio ( Y) was positively correlated with the degree of NMB ( X) ( r=0.879, t=28.67, P<0.001) in the latency period, the linear regression equation of the interaction between the degree of NMB ( X) and the latency ( Y) was Y=10.77+ 0.074 3 X, and the coefficient of determination R2 was 0.7681 ( F=821.30, P<0.001). The estimated appropriate degree of NMB for AMR monitoring during microvascular decompression was 25%-45%. Conclusions:The appropriate degree of NMB for AMR monitoring during microvascular decompression was 25%-45%.