Acute Respiratory Distress Syndrome (ARDS), marked by acute hypoxemia and bilateral pulmonary infiltrates, has undergone multiple definitions over the years. Challenges persist regarding the ARDS definitions, leading to various revisions. Through the Delphi study, the investigators aims to gather global opinions on the conceptual framework of ARDS, assess the utility of current and past definitions, and explore the role of subphenotyping. The diverse panel's collective expertise will contribute valuable insights for refining future ARDS definitions and enhancing clinical management.

Acute respiratory distress syndrome (ARDS), characterized by acute hypoxemia and bilateral pulmonary infiltrates that are not attributable to heart failure, has seen multiple definitions over the years. The primary purpose of a formal ARDS definition is to identify a homogenous cohort among patients with acute hypoxemic respiratory failure (AHRF), facilitating research, therapeutic trials, and prognostic assessment.

The validity of the conceptual framework of ARDS, however, has been challenged and uncertainties exist regarding the utility of ARDS definitions. Amongst other reasons, the lack of consensus on the conceptual model and diagnostic criteria have led to numerous revisions of the definition of ARDS. Furthermore, categorizing ARDS to assess treatment effects has had limited success, and subphenotypes have been proposed in part to address this issue.

The Delphi methodology has been used to generate expert consensus on components of the ARDS definition. Consensus process through a Delphi minimizes individual or professional dominance and peer pressure bias through a careful selection of experts, anonymous voting and monitoring attrition rates during Delphi rounds. A rigorous Delphi would be useful to assess the utility of the conceptual model of ARDS, past and current definitions of ARDS, and the value of categorisation of ARDS by means of subphenotyping.

Through this Delphi study, the investigators intend to assess the challenges in the conceptual framework of ARDS, past and current ARDS definitions, ongoing efforts in ARDS categorization and will develop consensus statements for future research in the definition and subphenotyping of ARDS.

Inclusion Criteria:

• At least 5 years of clinical experience as a staff member, with care for AHRF or ARDS patients or preclinical expertise (of more than 5 years) in AHRF or ARDS;
• At least 5 publications (original studies) as a leading or senior author or member of the steering committee of an observational study or a randomised controlled trial in AHRF or ARDS;

Exclusion Criteria:

• Not more than 25% of panellists from the previous or current definitions of ARDS (including the Berlin Definition of ARDS, the Kigali Modification of the Definition of ARDS, and the New Global Definition of ARDS)
• Not more than 70% of the panellists from each sex; and from each of high and low-middle-income countries

A diverse panel of 35 to 40 Panellists from different professional disciplines, such as Internal Medicine, Intensive Care Medicine, Respiratory Medicine, Anaesthesiology, and Physiology, with experience in the field of ARDS.

Anonymised reports of the Delphi rounds will be shared with original publication.