影响机械通气患者撤机后果的因素分析

Study on weaning outcome of patients with mechanical ventilation

目的 研究自动适应性支持通气(ASV)和双水平气道正压通气(BiPAP)两种通气模式对撤机后果的影响,并比较常规撤机指标对机械通气患者撤机的预测价值.方法 60例需机械通气的患者随机分两组:ASV组(n=27)和BiPAP组(n=33).床旁监测呼吸频率(RR)、潮气量(VT)、分钟通气量(VE)、阻力(R)、顺应性(C);在自主呼吸试验30 min时分别测定RR、VT并计算浅快呼吸指数(RSB).结果 两组平均带机时间分别为ASV(5.9±2.4)d;BiPAP(6.6±3.0)d.与BiPAP组相比,ASV组患者RSB较低[(68±19)次/(min·L)vs(80±22)次/(min·L),P＜0.05],VT较高[(387±73)ml vs(339±64)ml,P＜0.05)],而撤机成功率无显著性提高(81.5% vs 78.8%,P＞0.05).以撤机后果作为因变量进行Logistic回归分析显示:只有RSB与机械通气时间(DMV)是回归模型中有显著性的两个指标.常规撤机指标RSB、RR、VE和VT的ROC曲线显示RSB的曲线下面积最大.结论 ASV和BiPAP是两种较好的通气模式,二者具有相似的撤机后果.ASV在预防浅快呼吸和操作简单两方面优于BiPAP.RSB在预测撤机后果上优于常规撤机指标,对呼吸机撤离有一定指导意义.

Objective To compare respective effects between adaptive support ventilation (ASV) and biphasic positive airway pressure (BiPAP). The outcome of weaning from mechanical ventilation was compared between the traditional predictors. Methods Sixty patients with respiratory failure were randomly assigned to two weaning techaniques :ASV( n = 27) and BiPAP( n = 33). RR,VT,VE,R, C were measured in 60 cases with mechanical ventilation at the bedside. RR, VT were measured after 30 min of a spontaneous breathing trial and calculated rapid - shallow breathing index ( RSB ). Results The median duration of mechanical ventilation was (5.9 ± 2.4 ) days for ASV and ( 6.6 ± 3.0 ) days for BiPAP. Compared to BiPAP, during ASV patients had lower RSB [( 68 ± 19 ) bpm/L vs ( 80 ± 22 )bpm/L, P ＜0.05)]and higher VT[(387 ±73)ml vs(339 ±64)ml, P ＜0.05)] and no significant increasing in the rate of successful weaning(81.5% vs 78.8% , P ＞0.05). To perform logistic regression analysis with the weaning outcome as the dependent variable, RSB and DMV were the only two significant variables in the model. Area under the ROC curve of RSB was bigger than the other traditional predictors including RR, VT and VE. Conclusions ASV and BiPAP are two of better ventilatory modes and have similartary weaning outcome. ASV is superior to BiPAP in improving RSB and easily to be controlled by clinician. RSB is superior totraditional predictors in predicting weaning outcomes.