The American Association for Thoracic Surgery (AATS) 2026 Expert Consensus Document: Guidelines for donor/recipient size-matching in lung transplantation

BACKGROUND: Donor to recipient size matching is an essential part of lung transplantation, with significant mismatch leading to worse patient outcomes. The current practice is based on limited data along with broadly accepted themes that have not been articulated in the form of objective and definitive guidelines. The objective of the American Association for Thoracic Surgery (AATS) Clinical Practice Standards Committee (CPSC) expert panel was to develop evidence- and expert-based recommendations for optimal donor to recipient lung allograft size matching based on review of the existing literature. METHODS: The AATS CPSC assembled an expert panel of 18 lung transplant surgeons from 15 centers who developed a consensus document of recommendations. The panel was divided into subgroups covering size-matching in (1) bilateral lung transplantation, (2) single lung transplantation, (3) lobar transplantation, (4) unique situations, and (5) management of complications following severe size mismatch. Following a focused literature review, each subgroup formulated recommendation statements for each subtopic, which were reviewed and further refined using a Delphi process until consensus was achieved on each final statement by the voting group. RESULTS: The expert panel achieved consensus on 20 recommendations for current best practices in donor and recipient size matching. These recommendations include utilization of a ratio of donor-to-recipient predicted total lung capacity between 0.8 to 1.2, with special considerations based on recipient pathology, single lung or lobar transplantation, and anatomic variations such as chest wall abnormalities or significant mediastinal shift. Furthermore, oversized allografts can be reduced in size via non-anatomic or anatomic resection in select cases when required. CONCLUSIONS: Consistent practice guidelines regarding donor to recipient size matching will be helpful and important to achieve optimal outcomes in lung transplantation. The recommendations described here provide guidance for professionals involved in the care of patients with end-stage lung disease considered for transplantation.