Extravascular lung water and pulmonary vascular permeability index may inadvertently delay the identification of acute respiratory distress syndrome

colleagues [1] reported a multicenter cohort study that showed pulmonary vascular permeability index (PVPI) to be a practical diagnostic parameter to recognize acute lung injury/acute respiratory distress syndrome (ALI/ ARDS) in pulmonary edema. Th eir study deserves to be appreciated. Th e transpulmonary thermodilution technique allows an accurate bedside estimation of increased pulmonary vascular permeability, which is the physiopathologic hallmark of ALI/ARDS [2], facilitating the validity of diagnosis. However, the specifi c quantitative diagnostic parameter perhaps inadvertently compromises the eff ort to identify ARDS early. Firstly, the relatively limited availability of PiCCO probably restricts the comprehensive application of PVPI. Secondly, some patients with mild ARDS may manifest only mild hypoxemia, which requires only non-invasive mechanical ventilation. In this case, it seems cumbersome to obtain extravascular lung water index (EVLWI) and PVPI for diagnosis. To do that, in fact, hinders rapid recognition of mild ARDS to some extent. Th irdly, the cutoff of EVLWI (≥10 mL/kg) exhibited low sensitivity (63%) [3], as did the PVPI cutoff in this study. Th us, EVLWI and PVPI are combined into a diagnostic composite to achieve optimum sensitivity and specifi city by altering the threshold of each parameter. Nevertheless, we are more hopeful of establishing the stratifi cation criteria, which keep the composite of EVLWI and PVPI as a standard for confi rming a diagnosis of ARDS, while American-European Consensus Conference criteria or the Berlin defi nition is treated as a selection criterion to quickly screen for patients with hypoxemia in clinical practice.