The rationale

In the decade since the Berlin Definition1 was published, several developments in the management and study of ARDS have prompted consideration of an expansion of the definition:

  • Non-invasive pulse oximetric methods for evaluating oxygenation criteria for ARDS have been validated and applied in observational studies and clinical trials2–6.

  • The use of high flow nasal oxygen (HFNO) to manage severe hypoxemic respiratory failure increased after the publication of the FLORALI trial in 20157, and its use became widespread during the COVID-19 pandemic8–10. Patients with acute hypoxemic respiratory failure who are managed with HFNO do not meet the Berlin definition of ARDS, which requires invasive or non-invasive mechanical ventilation with a minimum of 5 cmH2O of positive end-expiratory pressure (PEEP)11–13.

  • The Berlin Definition is problematic in resource-limited settings because chest radiography, arterial blood gas measurements, and mechanical ventilation are not always available. These limitations led to the proposed Kigali modification of the Berlin Definition for resource-limited settings14; however, the Kigali modification has not been formally incorporated into the current ARDS definition4.

  • Ultrasound imaging is increasingly used in critically ill patients with acute hypoxemic respiratory failure, sometimes supplanting traditional chest radiography15–17.


The goal

The definition should:

  1. Identify lung injury in ARDS as an acute inflammatory process that results in critical lung injury. Identify critical hypoxemia not primarily attributable to hydrostatic pulmonary edema (heart failure or fluid overload), airway disease, pulmonary embolism, or an acute exacerbation of an underlying pulmonary condition such as interstitial lung disease. Inflammation may be primarily confined to the lungs or complicated by multiorgan injury/failure, including shock.

  2. Facilitate early recognition and diagnosis of ARDS for early implementation of standard care and ability to compare outcomes.

  3. Be applicable with modifications in resource-limited settings.

  4. Be adapted or modified for testing of specific therapies.

  5. Allow for easy communication to patients and caregivers.



1.
Acute Respiratory Distress Syndrome: The Berlin Definition. JAMA 307, 2526–2533 (2012).
2.
Rice, T. W. et al. Comparison of the SpO2/FIO2 ratio and the PaO2/FIO2 ratio in patients with acute lung injury or ARDS. Chest 132, 410–417 (2007).
3.
Brown, S. M. et al. Nonlinear Imputation of Pao2/Fio2 From Spo2/Fio2 Among Patients With Acute Respiratory Distress Syndrome. Chest 150, 307–313 (2016).
4.
Vercesi, V. et al. External confirmation and exploration of the Kigali modification for diagnosing moderate or severe ARDS. Intensive Care Med 44, 523–524 (2018).
5.
Moss, M. et al. Early Neuromuscular Blockade in the Acute Respiratory Distress Syndrome. N Engl J Med 380, 1997–2008 (2019).
6.
Wick, K. D., Matthay, M. A. & Ware, L. B. Pulse oximetry for the diagnosis and management of acute respiratory distress syndrome. Lancet Respir Med 10, 1086–1098 (2022).
7.
Frat, J. P. et al. High-flow oxygen through nasal cannula in acute hypoxemic respiratory failure. N Engl J Med 372, 2185–2196 (2015).
8.
Ranieri, V. M. et al. High-Flow Nasal Oxygen for Severe Hypoxemia: Oxygenation Response and Outcome in Patients with COVID-19. Am J Respir Crit Care Med 205, 431–439 (2022).
9.
Gershengorn, H. B. et al. The Impact of High-Flow Nasal Cannula Use on Patient Mortality and the Availability of Mechanical Ventilators in COVID-19. Ann Am Thorac Soc 18, 623–631 (2021).
10.
Calligaro, G. L. et al. The utility of high-flow nasal oxygen for severe COVID-19 pneumonia in a resource-constrained setting: A multi-centre prospective observational study. EClinicalMedicine 28, 100570 (2020).
11.
Ferguson, N. D. et al. The Berlin definition of ARDS: an expanded rationale, justification, and supplementary material. Intensive Care Med 38, 1573–1582 (2012).
12.
Ware, L. B. Go with the Flow: Expanding the Definition of Acute Respiratory Distress Syndrome to Include High-Flow Nasal Oxygen. Am J Respir Crit Care Med 205, 380–382 (2022).
13.
Matthay, M. A., Thompson, B. T. & Ware, L. B. The Berlin definition of acute respiratory distress syndrome: should patients receiving high-flow nasal oxygen be included? Lancet Respir Med 9, 933–936 (2021).
14.
Riviello, E. D. et al. Hospital Incidence and Outcomes of the Acute Respiratory Distress Syndrome Using the Kigali Modification of the Berlin Definition. Am J Respir Crit Care Med 193, 52–59 (2016).
15.
Wooten, W. M., Shaffer, L. E. T. & Hamilton, L. A. Bedside Ultrasound Versus Chest Radiography for Detection of Pulmonary Edema: A Prospective Cohort Study. J Ultrasound Med 38, 967–973 (2019).
16.
Sachdev, A. et al. Chest sonography versus chest radiograph in children admitted to paediatric intensive care - A prospective study. Trop Doct 51, 296–301 (2021).
17.
Smit, M. R. et al. Lung Ultrasound Prediction Model for Acute Respiratory Distress Syndrome: A Multicenter Prospective Observational Study. Am J Respir Crit Care Med 207, 1591–1601 (2023).


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