A New Global Definition of Acute Respiratory Distress Syndrome

Abstract

Background: Since publication of the 2012 Berlin definition of acute respiratory distress syndrome (ARDS), several developments have supported the need for an expansion of the definition, including the use of high-flow nasal oxygen, the expansion of the use of pulse oximetry in place of arterial blood gases, the use of ultrasound for chest imaging, and the need for applicability in resource-limited settings. Methods: A consensus conference of 32 critical care ARDS experts was convened, had six virtual meetings (June 2021 to March 2022), and subsequently obtained input from members of several critical care societies. The goal was to develop a definition that would 1) identify patients with the currently accepted conceptual framework for ARDS, 2) facilitate rapid ARDS diagnosis for clinical care and research, 3) be applicable in resource-limited settings, 4) be useful for testing specific therapies, and 5) be practical for communication to patients and caregivers. Results: The committee made four main recommendations: 1) include high-flow nasal oxygen with a minimum flow rate of ⩾30 L/min; 2) use Pa_O2:Fi_O2 ⩽ 300 mm Hg or oxygen saturation as measured by pulse oximetry Sp_O2:Fi_O2 ⩽ 315 (if oxygen saturation as measured by pulse oximetry is ⩽97%) to identify hypoxemia; 3) retain bilateral opacities for imaging criteria but add ultrasound as an imaging modality, especially in resource-limited areas; and 4) in resource-limited settings, do not require positive end-expiratory pressure, oxygen flow rate, or specific respiratory support devices. Conclusions: We propose a new global definition of ARDS that builds on the Berlin definition. The recommendations also identify areas for future research, including the need for prospective assessments of the feasibility, reliability, and prognostic validity of the proposed global definition.

Keywords: ARDS; acute lung injury; pulmonary edema.

Figure 1.

Illustrative cases with patient descriptions, representative lung imaging, and oxygenation data for the three categories of acute respiratory distress syndrome (ARDS) in the global definition: intubated ARDS (top), nonintubated ARDS (middle), and ARDS in a resource-limited setting (bottom). Note the patient in the resource-limited setting can be identified using either ultrasound (bottom, demonstrating bilateral diffuse B-lines in nondependent areas of the lung) or chest radiography or computed tomography. Also, only the patient with intubated ARDS (top) meets criteria for the Berlin definition of ARDS. Arrow, endotracheal tube. COVID-19 = coronavirus disease; F = female; HFNO = high-flow nasal oxygen; M = male; P/F = Pa_O2:Fi_O2; S/F = Sp_O2:Fi_O2; Sp_O2 = oxygen saturation as measured by pulse oximetry. The OpenCriticalCare.org Project, Creative Commons SA-BY-NC for the patient drawings.