Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol.
BACKGROUND
This study assesses the potential of lung ultrasonography to diagnose acute respiratory failure.


METHODS
This observational study was conducted in university-affiliated teaching-hospital ICUs. We performed ultrasonography on consecutive patients admitted to the ICU with acute respiratory failure, comparing lung ultrasonography results on initial presentation with the final diagnosis by the ICU team. Uncertain diagnoses and rare causes (frequency<2%) were excluded. We included 260 dyspneic patients with a definite diagnosis. Three items were assessed: artifacts (horizontal A lines or vertical B lines indicating interstitial syndrome), lung sliding, and alveolar consolidation and/or pleural effusion. Combined with venous analysis, these items were grouped to assess ultrasound profiles.


RESULTS
Predominant A lines plus lung sliding indicated asthma (n=34) or COPD (n=49) with 89% sensitivity and 97% specificity. Multiple anterior diffuse B lines with lung sliding indicated pulmonary edema (n=64) with 97% sensitivity and 95% specificity. A normal anterior profile plus deep venous thrombosis indicated pulmonary embolism (n=21) with 81% sensitivity and 99% specificity. Anterior absent lung sliding plus A lines plus lung point indicated pneumothorax (n=9) with 81% sensitivity and 100% specificity. Anterior alveolar consolidations, anterior diffuse B lines with abolished lung sliding, anterior asymmetric interstitial patterns, posterior consolidations or effusions without anterior diffuse B lines indicated pneumonia (n=83) with 89% sensitivity and 94% specificity. The use of these profiles would have provided correct diagnoses in 90.5% of cases.


CONCLUSIONS
Lung ultrasound can help the clinician make a rapid diagnosis in patients with acute respiratory failure, thus meeting the priority objective of saving time.
Lichtenstein
Daniel A
DA
Service de Réanimation Médicale, Hôpital Ambroise-Paré, F-92100 Boulogne, Faculté Paris-Ouest, France. dlicht@free.fr
Mezière
Gilbert A
GA
D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001249:Asthma / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000000981:diagnostic imaging; D011030:Pneumothorax / Q000000981:diagnostic imaging; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging; D011654:Pulmonary Edema / Q000000981:diagnostic imaging; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging; D012131:Respiratory Insufficiency / Q000000981:diagnostic imaging*; D012680:Sensitivity and Specificity; D014463:Ultrasonography