Chest
Volume 134, Issue 1, July 2008, Pages 117-125
Journal home page for Chest

Original Research
Critical Care Medicine
Relevance of Lung Ultrasound in the Diagnosis of Acute Respiratory Failure*: The BLUE Protocol

https://doi.org/10.1378/chest.07-2800Get rights and content

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.

Section snippets

Materials and Methods

This was an observational study conducted in university-affiliated hospitals over 4 years investigating 301 consecutive adult patients with acute respiratory failure. The official diagnosis was established in the hospitalization report using standardized tests by the ICU staff and not including lung ultrasound data (Table 1). Sixteen patients never received a definite diagnosis, 16 patients had several official diagnoses, and 9 patients had rare (ie, frequency < 2%) diagnoses. To simplify this

Results

This study included 260 patients with a definite diagnosis: 140 men and 120 women (mean age, 68 years; range, 22 to 91 years; SD, 16 years).

Discussion

Briefly, the B profile (anterior interstitial syndrome with lung sliding) indicated pulmonary edema. The B' profile (lung sliding abolished) indicated pneumonia. The A/B profile (asymmetric anterior interstitial syndrome) and the C profile (anterior consolidation) indicated pneumonia, as did the A profile plus PLAPS. The A profile plus venous thrombosis indicated pulmonary embolism. A normal profile indicated COPD/asthma.

These results correspond to physiopathologic patterns, particularly echoed

Conclusions

Lung ultrasound immediately provided diagnosis of acute respiratory failure in 90.5% of cases. It can therefore be added to the armamentarium of critical care.47 The additional value of saving time should provide prompter relief for these severely dyspneic patients.

Acknowledgment

So many people surrounded and helped this project, directly or not, that only a collective but warm thanks will be made in this space. Special thanks to François Jardin, who made this work possible.

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    This work was presented partly at the twenty-third ISICEM, Brussels, March 30, 2003.

    The authors have no conflicts of interest to disclose.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

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