Correlation of severity classification of acute respiratory distress syndrome by the Berlin definition with extra vascular lung water index and pulmonary vascular permeability index

Abstract

To explore the correlation of severity classification of acute respiratory distress syndrome (ARDS) by the Berlin definition with extra vascular lung water index (EVLWI) and pulmonary vascular permeability index (PVPI). A total of 70 cases with ARDS at intensive care unit of our hospital from July 2012 to July 2014 were divided into three groups of mild (n = 20), moderate (n = 30) and severe (n = 20) according to the Berlin definition. The scores of acute physiology and chronic health evaluation (APACHE) II and sequential organ failure assessment (SOFA) within 24 h of admission were recorded. And the values of EVLWI and PVPI of three groups from Day 1-4 were monitored by pulse indicator continuous cardiac output (PiCCO). Receiver operating characteristic (ROC) curve was drawn for these parameters and the area under curve was compared. Meanwhile blood gas was analyzed and oxygenation index (OI) calculated. And the correlations of EVLWI and PVPI with OI were analyzed. Comparisons of EVLWI, PVPI and OI were made for three groups at different timepoints: As the severity of ARDS aggravated, EVLWI and PVPI of three groups increased significantly at any timepoint while OI decreased sharply (P < 0.05). EVLWI and PVPI declined gradually from Day 1-4 in mild ARDS group (P < 0.05), PVPI declined dramatically (P < 0.05) while EVLWI showed no obvious change in moderate ARDS group (P > 0.05). There was no sharp decline of EVLWI or PVPI in severe ARDS group (P > 0.05). And OI increased significantly from Day 1-4 in three groups (P < 0.01). The area under ROC curve (AUC) for PVPI in evaluating the prognosis of three groups was 0.594, 0.643, 0.723 and 0.816 respectively. PVPI > 2.95 at Day 4 of admission was used as the best threshold value for judging prognosis. And the sensitivity was 70% and specificity 92%. OI had negative correlation with EVLWI and PVPI in three groups from Day 1-4 [(r = -0.685, P = 0.000) and (r = -0.631, P = 0.000)]. Both EVLWI and PVPI reflect adequately the severity of ARDS by the Berlin definition. And the dynamic trend of PVPI is superior to that of EVLWI.