Bridging the Gap: A Comparative Analysis of Patients Requiring Mechanical Ventilation or ECMO as Bridge to Lung Transplant Between ERAS

A. Moin¹, S. Biswas Roy², A. Rybachok³, M. Shacker⁴, A. Arjuna⁵, J. Huang⁵, M. Smith⁵, R. Bremner^5
1Creighton University, Phoenix, Arizona ²Norton Thoracic Institute, Phoenix, Arizona ³Creighton University School of Medicine, Phoenix, Arizona ⁴Creighton University School of Medicine, San Jose, California ⁵Norton Thoracic Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona

Purpose: The newly implemented Composite Allocation Score (CAS) is predicted to reduce the median time to transplant for the sickest waitlisted patients as compared to Lung Allocation Score (LAS) era. We compared outcomes in lung transplant recipients (LTRs) who were bridged to lung transplantation using mechanical ventilation or ECMO between eras.

Methods: The United Network for Organ Sharing (UNOS) STAR file was queried for all adult LTRs bridged to transplant with MV or ECMO during the LAS era (January 1, 2007, to March 8, 2023) and the CAS era (March 9, 2023, to October 15, 2023). Baseline patient characteristics were reviewed and perioperative outcomes analyzed. Survival estimates were calculated using the Kaplan-Meier approach.

Results: 4,138 patients were included; 3,863 (MV-BTT: 2154, ECMO-BTT: 1709) in LAS era and 1,877 in CAS era. MV-BTT use was higher in LAS compared to CAS (LAS, 6.49%, CAS, 3.22%; p< 0.001), while ECMO-BTT was comparable between eras (LAS 5.15%, CAS 5.05%, p=0.86). Recipient age was higher for both MV (LAS 52, CAS 57 years, p=0.014) and ECMO BTT (LAS 50, CAS 54 years, p< 0.001) in CAS as compared to LAS. Median waitlist time was longer in LAS era for both MV (LAS, 17 days, CAS, 7 days, p< 0.001) and ECMO (LAS, 14 days, CAS, 9 days, p< 0.001), whereas median ischemic time was longer by an hour in CAS era (p < 0.001). Post-operative ECMO and dialysis rates were comparable between eras. Infection rates, acute rejection and graft failure post-transplant were higher in LAS than CAS. Survival at 30 days and 12 month was similar between eras. Waitlist withdrawal rate was lower for MV-BTT in CAS compared to LAS (LAS 36%, CAS 18%, p< 0.001); the trend was similar for MV waitlist mortality (LAS: 15%, CAS 7.6%, p 0.059). Waitlist mortality and withdrawal for ECMO-BTT did not differ significantly between eras, although rates were proportionally higher.

Conclusion: Elimination of geographic boundaries in the CAS era has increased rates of successful MV-BTT. The average recipient age for MV and ECMO BTT has increased and waitlist times have decreased in the CAS era. Although donor lungs are traveling longer distances, peri-operative outcomes are comparable to the LAS era. Long term outcome of candidates bridged with MV or ECMO in the CAS era remains to be seen.

Identify the source of the funding for this research project: There was no funding for this project.