Data_Sheet_1_Calculation of Transpulmonary Pressure From Regional Ventilation Displayed by Electrical Impedance Tomography in Acute Respiratory Distress Syndrome.pdf

Transpulmonary driving pressure (DPL) corresponds to the cyclical stress imposed on the lung parenchyma during tidal breathing and, therefore, can be used to assess the risk of ventilator-induced lung injury (VILI). Its measurement at the bedside requires the use of esophageal pressure (Peso), which is sometimes technically challenging. Recently, it has been demonstrated how in an animal model of ARDS, the transpulmonary pressure (PL) measured with Peso calculated with the absolute values method (PL = Paw—Peso) is equivalent to the transpulmonary pressure directly measured using pleural sensors in the central-dependent part of the lung. We hypothesized that, since the PL derived from Peso reflects the regional behavior of the lung, it could exist a relationship between regional parameters measured by electrical impedance tomography (EIT) and driving PL (DPL). Moreover, we explored if, by integrating airways pressure data and EIT data, it could be possible to estimate non-invasively DPL and consequently lung elastance (EL) and elastance-derived inspiratory PL (PI). We analyzed 59 measurements from 20 patients with ARDS. There was a significant intra-patient correlation between EIT derived regional compliance in regions of interest (ROI1) (r = 0.5, p = 0.001), ROI2 (r = −0.68, p < 0.001), and ROI3 (r = −0.4, p = 0.002), and DPL. A multiple linear regression successfully predicted DPL based on respiratory system elastance (Ers), ideal body weight (IBW), roi1%, roi2%, and roi3% (R2 = 0.84, p < 0.001). The corresponding Bland-Altmann analysis showed a bias of −1.4e-007 cmH2O and limits of agreement (LoA) of −2.4–2.4 cmH2O. EL and PI calculated using EIT showed good agreement (R2 = 0.89, p < 0.001 and R2 = 0.75, p < 0.001) with the esophageal derived correspondent variables. In conclusion, DPL has a good correlation with EIT-derived parameters in the central lung. DPL, PI, and EL can be estimated with good accuracy non-invasively combining information coming from EIT and airway pressure.

跨肺驱动压（Transpulmonary driving pressure, DPL）指潮式呼吸过程中施加于肺实质的周期性应力，可用于评估呼吸机相关性肺损伤（Ventilator-induced lung injury, VILI）的发生风险。床旁测量该指标需依托食管压（Esophageal pressure, Peso），但该操作有时存在技术难度。近期有研究证实，在急性呼吸窘迫综合征（ARDS）动物模型中，采用绝对值法计算食管压所得的跨肺压（计算公式为PL = 气道压Paw — 食管压Peso），与直接采用肺中央依赖区胸膜传感器测得的跨肺压（PL）具有等效性。我们提出假说：由食管压推导得到的跨肺压可反映肺部的区域力学特性，因此电阻抗断层成像（Electrical Impedance Tomography, EIT）测得的区域参数与跨肺驱动压（DPL）之间可能存在相关性。此外，本研究探讨了整合气道压数据与EIT数据，能否无创估算跨肺驱动压，进而推导肺弹性（Lung elastance, EL）及弹性衍生吸气相跨肺压（PI）。本研究分析了20例急性呼吸窘迫综合征患者的59组测量数据。结果显示，各感兴趣区（ROI）的EIT推导区域顺应性与跨肺驱动压均存在显著的患者内相关性：ROI1相关系数r=0.5，p=0.001；ROI2相关系数r=-0.68，p<0.001；ROI3相关系数r=-0.4，p=0.002。基于呼吸系统弹性（Respiratory system elastance, Ers）、理想体重（Ideal Body Weight, IBW）及ROI1%、ROI2%、ROI3%的多元线性回归模型可有效预测跨肺驱动压（决定系数R²=0.84，p<0.001）。对应的布兰德-奥特曼分析显示，其偏差为-1.4×10^-7 cmH₂O，一致性界限为-2.4~2.4 cmH₂O。通过EIT计算得到的肺弹性与弹性衍生吸气相跨肺压，与基于食管压推导的对应指标均具有良好的一致性（肺弹性：R²=0.89，p<0.001；弹性衍生吸气相跨肺压：R²=0.75，p<0.001）。综上，跨肺驱动压与肺中央区域的EIT推导参数具有良好相关性。结合EIT与气道压信息，可无创且高精度地估算跨肺驱动压、弹性衍生吸气相跨肺压及肺弹性。