脑电双频指数监测在重症加强治疗病房机械通气患者镇静中的应用

Application of the bispectral index monitor in mechanical ventilation in patients under sedation in the intensive care unit

目的 探讨脑电双频指数（BIS）实时监测在重症加强治疗病房（ICU）机械通气患者镇静中应用的可行性。方法 选取30例术后机械通气患者，静脉注射咪唑安定或异丙酚达到合理镇静，采用盲法对患者每隔5min分别记录1次Ramsay镇静分级评分及BIS。比较Ramsay镇静分级评分对应BIS中位数的总体差异，分析BIS结果与Ramsay镇静分级评分的相关性。计算BIS的敏感度和约登（Youden）指数，确定BIS监测的敏感度和特异度。结果 随镇静深度的加深，BIS明显降低，Ramsay分级评分对应的BIS中位数之间差异有显著性（P〈0．01）；BIS与Ramsay分级评分呈负相关（r=-0．794，P〈0．01）；Ramsay分级评分2～5分（为合理镇静）时对应的BIS中位数的95％可信区间（参考值范围）为61～84；当BIS值为81时，BIS监测从镇静合理到镇静不足的Youden指数和敏感度最高；Ramsay分级评分为6分（为镇静过度）时对应的BIS中位数的95％可信区间为48～58。结论 BIS监测与Ramsay镇静分级具有良好的相关性，能实时、客观地监测ICU机械通气患者的镇静状态，并指导镇静治疗。

Objective To evaluate bispectral index （BIS） technology in postoperative patients under sedation undergoing mechanical ventilation according to Ramsay sedation scales in intensive care unit （ICU）. Methods Thirty posto-perative patients on mechanical ventilation were sedated with midazolam or propofol intravenously. All patients were evaluated for their levels of sedation by using BIS and the Ramsay scale simultaneously every 5 minutes with blind method. The total differences of median BIS in each sedation scale were compared. The BIS measurements and the corresponding Ramsy scale measurements were selected for analyzing the correlations. The sensitivity of BIS and Youden index were calculated, and the sensitivity and specificity of BIS were identified. Results The median BIS corresponding to each Ramsay scale decreased significantly along with the increasing of sedation depth. There were significant differences of median BIS in each Ramsay sedation scale （P〈0. 001）. BIS was negatively correlated with Ramsay scale, and the r value was -0. 794 （P〈0.01）. When the patient was optimally sedated （Ramsay scale 2 -5 scores）, the corresponding median BIS 95% confident interval （CI） were 61 -84. The sensitivity and Youden index of BIS value with optimal or under sedation were the highest when BIS= 81. The 95% CI of median BIS were 48- 58 when Ramsay scale was 6 scores. Conclusion BIS measurements evaluated in clinically relevant ranges compare favorably with Ramsay scale. BIS may be best used to identify and prevent over or under sedation of mechanical ventilated patients in the ICU.