目的 探索在压力支持通气(pressure support ventilation,PSV)模式下,通过压力监测设备获得肌肉压力指数(reference measurement of inspiratory muscle pressure index on experimental condition,PMIref)和通过呼吸机屏幕获得PMI(simple measurement of PMI from the ventilator,PMIvent)的一致性,PMIvent与吸气努力的相关性,以及PMI评价低吸气努力的预测价值.方法 本研究纳入2022 年6 月至2023 年6 月间22 例使用PSV模式的成年急性呼吸衰竭患者,将压力支持(support pressure,PS)水平从20 cmH2 O到 2 cmH2 O(1 cmH2 O=0.098 kPa)进行滴定,每个PS水平进行吸气末保持和呼气末保持,记录流量、气道压和食道压信号,计算PMIref、PMIvent和食道-压力时间乘积(esophageal pressure-time product,PTPes).采用Bland-Altman检验分析PMIvent与PMIref的一致性,采用决定系数(R2)评估 PMI 与吸气努力之间的相关性,采用受试者工作特征(receiver operating characteristic,ROC)曲线的方法评估PMI检测低努力的诊断效能,根据约登指数确定最佳临界值.结果 PMIvent和PMIref之间的残差(95%一致性区间)为 0.18(-0.44～0.80).PMIref 和 PTPes/min 显著相关(患者间 R2 = 0.61,患者内 R2 = 0.80),PMIvent与 PTPes/min显著相关(患者间R2=0.62,患者内R2=0.81).对于临界值PTPes<50 cmH2 O·s·min-1时,PMIvent的ROC曲线下面积(area under the curve,AUC)为0.93(0.89,0.96),最佳临界值为-0.77 cmH2 O.结论 通过呼吸机获得的PMIvent可以有效替代实验条件下测量的PMIref.PMIvent和PMIref都与吸气努力显著相关,具有预测低吸气努力的潜在价值.
The feasibility and validity of inspiratory muscle pressure index to assess inspiratory effort
Objective To explore the correlation of simple measurement of inspiratory muscle pressure index from the ventilator(PMIvent)and reference measurement of inspiratory muscle pressure index on experimental condition(PMIref),the relationship between PMIvent and inspiratory effort,and further to determine the clinical feasibility and validity of PMI for assessing inspiratory effort during pressure support ventilation(PSV).Methods Adult acute respiratory failure patients undergoing mechanical ventilation were screened daily and enrolled 24 h after switching to PSV mode.Baseline ventilators were set according to the principle of keeping tidal volume/predicted body weight(VT/PBW)at 6-8 mL/kg and respiratory rate(RR)at 20-30 breaths/min and the decision of the responsible ICU physician.A downward support pressure(PS)titration was conducted from 20 cmH2O to 2 cmH2O.Three end-inspiratory holdings(EIO)and three end-expiratory holdings(EEO)were performed.PMIvent was calculated as the difference between plateau pressure(Pplat)within 2 s after EIO and the airway peak pressure(Ppeak)at EIO.PMIref was calculated as the difference between Pplat at one cardiac cycle after EIO and Ppeak at EIO.Flow,airway pressure(Paw),and esophageal pressure(Pes)signals were displayed continuously and saved.PMIref,PMIvent and esophageal pressure time product per breath(PTPes)were measured.PTPes per minute was calculated as the product of PTPes and RR.The"normal"range of PTPes per minute was defined as 50 to 200 cmH2O·s·min-1.The accuracy of PMIvent compared to PMIref was assessed with a Bland-Altman plot.The correlation between PMI and inspiratory effort was evaluated as the coefficient of determination(R2).The ability of PMI to detect high/low effort was assessed using the area under the receiver operating characteristics curve(ROC AUC).The optimal cut-off values were selected based on the Youden index.Results The accuracy and precision of PMIvent compared to PMIref showed a low bias(0.18)with smaller 95%limits of agreements(-0.44,0.80).PMIref was significantly related to the PTPes per minute(between-patients R2=0.61,within-patients R2=0.80,respectively).PMIvent was also related to the PTPes per minute(between-patients R2=0.62,within-patients R2=0.81).For a cut-off PTPes<50 cmH2O·s·min-1,PMIvent showed an ROC AUC of 0.93[0.89,0.96],and the best threshold was-0.77 cmH2O.Conclusion PMIvent can effectively replace PMIref.Like PMIref,PMIvent was significantly related to inspiratory effort and had the potential value to predict low inspiratory effort.
mechanical ventilationinspiratory effortpressure muscle indexesophageal pressure time product
NETL
NSTL
万方数据
维普
