Lung Ultrasound Prediction Model for Acute Respiratory Distress Syndrome: A Multicenter Prospective Observational Study.

Rationale: Lung ultrasound (LUS) is a promising tool for diagnosis of acute respiratory distress syndrome (ARDS), but adequately sized studies with external validation are lacking. 

Objectives: To develop and validate a data-driven LUS score for diagnosis of ARDS and compare its performance to chest radiography (CXR). 

Methods: This multicenter prospective observational study included invasively ventilated ICU patients who were divided into a derivation and validation cohort. Three raters scored ARDS according to the Berlin criteria resulting in classification of 'certain no ARDS', 'certain ARDS' when experts agreed or 'uncertain ARDS' when evaluations conflicted. Uncertain cases were classified in a consensus meeting. Results of a 12-region LUS exam were used in a logistic regression model to develop the LUS-ARDS score. 

Measurements and Main Results: 324 (16% certain ARDS) and 129 (34% certain ARDS) patients were included in the derivation cohort and the validation cohort, respectively. Using ARDS diagnosis by the expert panel as the reference test, the LUS-ARDS score, including the left and right LUS aeration score and antero-lateral pleural line abnormalities, had an area under the receiver operating characteristics (ROC) curve of 0.90 (CI:0.85-0.95) in certain patients of the derivation cohort and 0.80 (CI:0.72-0.87) in all patients of the validation cohort. Within patients who had imaging gold standard chest computed tomography available, diagnostic accuracy of eight independent CXR readers followed the ROC curve of the LUS-ARDS score. 

Conclusions: The LUS-ARDS score can accurately diagnose ARDS, also after external validation. The LUS-ARDS score may be a useful adjunct to diagnosis of ARDS after further validation as it had comparable performance to the current practice with experienced CXR readers, but more objectifiable diagnostic accuracy at each cut-off.