LAUSR

Abstract Congenital Diaphragmatic Hernia (CDH) is a serious newborn defect requiring mechanical ventilation. Initial ventilation settings should take into account the severity of lungs inhomogeneity (LI), but it is not assessed in everyday clinical practice. We present a new LI index that can be easily determined at the bedside. It is based on a comparison of resistive-elastic properties of lungs and defined as a ratio of time constants T1.T2−1 of gas flows in both lungs (T1 = R1·C1, T2 = R2·C2). We hypothesised that T1.T2−1 index increase causes a rise of lungs impedance (Z) and requires elevation of peak inspiratory pressure (PIP), mean airway pressure (MAP), and work of breathing (WOB). Infant hybrid (numerical-physical) respiratory simulator and a ventilator were used to simulate conventional ventilation of homogeneous and inhomogeneous lungs, and to measure PIP, MAP and WOB. A high correlation was found between Z, WOB, PIP, MAP and the T1.T2−1 index (r = 0.9, P