Importance  Venovenous extracorporeal membrane oxygenation (VV ECMO) is a resource-intensive, life-sustaining technology to support patients with severe refractory respiratory failure. Its precise indications and contraindications are not standardized, and expert opinions are frequently changing, leading to variation in why and to whom VV ECMO is offered.

Objective  To characterize the ways clinicians approach candidacy selection, the criteria considered, and the relative weight given to such variables.

Design, Setting, and Participants  This qualitative study conducted virtual semistructured interviews of clinicians between September and December 2024. Transcripts were qualitatively analyzed from January to June 2025 using both inductive and deductive approaches to thematic analysis and line-by-line consensus coding. Participants were physicians and ECMO coordinators from various urban, rural, public, and private medical centers in 9 countries.

Main Outcomes and Measures  Themes and subthemes that reflected clinicians’ experiences and views.

Results  A purposeful sample of 45 clinicians directly involved in ECMO candidacy selection were contacted, of whom 24 (19 males [79%]) enrolled. Among these 24 participants interviewed, 21 (88%) were physicians and 3 (12%) were ECMO center coordinators; 8 (33%) practiced outside of the US. Five main themes were identified: (1) clinicians vary in their interpretation and incorporation of patient age, body mass index, and time on mechanical ventilation when selecting VV ECMO candidates; (2) perceived contraindications to VV ECMO are often flexible depending on various ethical and social criteria; (3) cognitive biases and heuristics affect the VV ECMO decision-making process; (4) institutional and cultural contexts shape individual VV ECMO candidacy decisions; and (5) participants provided suggestions to improve consistency in VV ECMO candidacy selection.

Conclusions and Relevance  In this qualitative study, decisions to pursue VV ECMO for patients with severe respiratory failure were largely based on clinical judgments of suitability rather than objective guidelines. Variability in candidacy decision-making may lead to inconsistent or inequitable allocation.