How Useful is Extravascular Lung Water Measurement in Managing Lung Injury in Intensive Care Unit?

Context: The primary goal of septic shock management is optimization of organ perfusion, often at the risk of overloading the interstitium and causing pulmonary edema. The conventionally used end points of resuscitation do not generally include volumetric parameters such as extravascular lung water index (EVLWI) and pulmonary vascular permeability index (PVPI). Aims: This study aimed to assess the prognostic value of EVLWI and PVPI by calculating their correlation with the severity of lung injury. Settings and Design: This prospective observational study included twenty mechanically ventilated critically ill patients with Acute Physiology and Chronic Health Evaluation score (APACHE II) >20. Subjects and Methods: EVLWI and PVPI were measured using transpulmonary thermodilution, and simultaneously, PaO2:FiO2 ratio, alveolar-arterial gradient of oxygen (AaDO2), and chest radiograph scores from two radiologists were obtained. Statistical Analysis: The correlation of EVLWI and PVPI with chest radiograph scores, PaO2:FiO2 ratio, and AaDO2 were calculated. The inter-observer agreement between the two radiologists was tested using kappa test. Results: EVLWI and PVPI correlated modestly with PaO2:FiO2 (r = −0.32, P = 0.0004; r = −0.39, P = 0.0001). There was a better correlation of EVLWI and PVPI with PaO2:FiO2 ratio (r = −0.71, P < 0.0001; r = −0.58, P = 0.0001) in the acute respiratory distress syndrome (ARDS) subgroup. The EVLWI values correlated significantly with corresponding chest radiograph scores (r = 0.71, P < 0.0001 for observer 1 and r = 0.68, P < 0.0001 for observer 2). Conclusions: EVLWI and PVPI may have a prognostic significance in the assessment of lung injury in septic shock patients with ARDS. Further research is required to reveal the usefulness of EVLWI as an end point of fluid resuscitation in the management of septic shock with ARDS.