Limited cumulative experience with ex vivo lung perfusion is associated with inferior outcomes after lung transplantation

Centralized Static Ex Vivo Lung Perfusion in the United States

BACKGROUND

Ex vivo lung perfusion (EVLP) may improve donor lung utilization but requires significant infrastructure and expertise. Centralized EVLP facilities may mitigate these requirements.

METHODS

From the United Network for Organ Sharing database, we identified 345 adults undergoing isolated, first-time lung transplantation using donor lungs perfused by static EVLP (March 1, 2018-December 31, 2022). Recipients of lungs perfused at centralized EVLP facilities (n = 165) were compared with recipients of lungs perfused at individual transplant centers (n = 180). Propensity score matching was used to create balanced groups for comparison.

RESULTS

Centralized EVLP facilities were increasingly used from 2018 to 2022 (35.3% vs 55.8%, P = .04) and were more likely used when the annual center volume of EVLP lung transplants was low. Compared with allografts placed on EVLP at individual transplant centers, those placed on EVLP at centralized facilities had longer median ischemic time (11.3 vs 9.6 hours, P < .001) and were less likely to come from donation after circulatory death donors (25.4% vs 39.5%, P = .003) or be used for double-lung transplant (73.3% vs 83.9%, P = .02). In 102 well-matched recipient pairs, 2-year survival was equivalent between those receiving allografts perfused at centralized facilities (77.9%; 95% CI, 68.0%-85.1%) vs individual transplant centers (77.7%; 95% CI, 67.8%-84.9%; P = .90). Multivariable Cox regression analysis also showed equivalent 2-year survival (adjusted hazard ratio, 1.02; 95% CI, 0.57-1.84; P = .95).

CONCLUSIONS

Transplanting lung allografts that underwent static EVLP at centralized facilities had similar outcomes compared with transplanting lungs perfused at individual transplant centers. The centralized model of clinical EVLP can potentially improve access to EVLP.

Thoracoabdominal Normothermic Regional Perfusion and Donation After Circulatory Death Lung Use

Importance

Donation after circulatory death (DCD) heart procurement has increased, but concerns remain about the effect of simultaneous heart and lung procurement, particularly with thoracoabdominal normothermic regional perfusion (TA-NRP), on the use of DCD lungs. Previous analyses exclude critical donor factors and organ nonuse, and rapidly rising DCD use may bias comparisons to historical controls.

Objective

To use validated risk-adjusted models to assess whether DCD heart procurement via TA-NRP and direct procurement is associated with lung use.

Design, Setting, and Participants

This retrospective cohort study involved adult DCD donors between January 1, 2019, and September 30, 2024, listed in the Scientific Registry of Transplant Recipients (SRTR). The SRTR deceased donor yield model was used to develop an observed to expected (O:E) yield ratio of lung use obtained through DCD among 4 cohorts: cardiac DCD donors vs noncardiac DCD donors and cardiac DCD donors undergoing TA-NRP vs direct procurement. Temporal trends in O:E ratios were analyzed with the Cochran-Armitage test.

Main Outcomes and Measures

The O:E ratios of DCD lung use.

Results

Among 24 431 DCD donors (15 878 [65.0%] male; median [IQR] age, 49.0 [37.0-58.0] years), 22 607 were noncardiac DCD (14 375 [63.6%] male; median [IQR] age, 51.0 [39.0-58.0] years) and 1824 were cardiac DCD (1503 [82.4%] male; median [IQR] age, 32.0 [26.0-38.0] years) donors; noncardiac DCD donors were more likely to be smokers (6873 [30.4%] vs 227 [12.4%]; P < .001). Among cardiac DCD donors, 325 underwent TA-NRP, while 712 underwent direct procurement. TA-NRP donors had shorter median (IQR) lung ischemic times (6.07 [4.38-9.56] hours vs 8.12 [6.16-12.00] hours; P < .001) and distances to recipient hospitals (222 [9-626] nautical miles vs 331 [159-521] nautical miles; P = .050) than direct procurement donors. Lung use was higher among cardiac DCD donations compared with noncardiac DCD donations (16.7% vs 4.4%, P < .001). Within the cardiac DCD cohort, lung use was similar between TA-NRP and direct procurement (19.1% vs 18.7%; P = .88) cohorts. Both noncardiac DCD and cardiac DCD donors had observed lung yields greater than expected (O:E, 1.29 [95% CI, 1.21-1.35] and 1.79 [95% CI, 1.62-1.96]; both P < .001), although cardiac DCD yield was significantly higher than noncardiac DCD yield (P < .001). Both TA-NRP and direct procurement lung yields were greater than expected (O:E, 2.00 [95% CI, 1.60-2.43] and 1.77 [95% CI, 1.52-1.99]; both P < .001) but were not significantly different from each other (P = .83). The O:E ratios did not change significantly over time across all cohorts. Among recipients, the TA-NRP cohort experienced significantly better 90-day mortality (0 of 62 vs 9 of 128 patients [7.0%]; P = .03) and overall survival (4 of 62 patients [6.5%] vs 21 of 128 patients [16.4%]; P = .04) rates compared with the direct procurement cohort.

Conclusions and Relevance

In this cohort study of DCD donors, concomitant heart procurement provided better-than-expected rates of lung use as assessed with validated O:E use ratios regardless of procurement technique. The findings also suggest a survival benefit with improved 90-day and overall survival rates for the TA-NRP cohort compared with the direct procurement cohort. Policies should be developed to maximize the benefits of these donations.

Impact of Ex Vivo Lung Perfusion on Inpatient Cost: A Propensity Score-Matched Analysis of the US Nationwide Healthcare Cost and Utilization Project Database

BACKGROUND

The goal of this study was to investigate the association between ex vivo lung perfusion (EVLP) use and inpatient hospitalization cost for lung transplantation in a nationwide sample.

METHODS

Lung transplantation patients in 2018-2020 Nationwide Readmissions Database (NRD) were grouped based on use of EVLP. The primary outcome was total inpatient hospitalization cost. 1:2 propensity score matching by EVLP status was performed followed by multivariable linear regression to determine the association between inpatient cost and EVLP while adjusting for pre-transplant hospital days, high volume EVLP center status, and propensity score.

RESULTS

There were 3902 lung transplants and 118 (3%) were recipients of EVLP lungs. Among EVLP patients, the median cost was $871 468 (IQR: $608 671-1 274 392), compared to $846 516 (IQR: $531 462-1 439 267, p = 0.871) among the total non-EVLP cohort. After 1:2 propensity score-matched cohort, recipients of EVLP lungs had longer median hospital length of stay (p = 0.046). In the multivariable model using the matched sample, increased cost was not associated with EVLP use (p = 0.783); however, high volume EVLP centers were associated with decreased cost (p = 0.018).

CONCLUSIONS

EVLP use was not associated with greater inpatient costs and may be favorable at high volume centers.

Disparities in lung transplantation in children

Lung transplantation is a recognized therapy for end-stage respiratory failure in children and young people. It is only available in selected countries and is limited by access to suitable organs. Data on disparities in access and outcomes for children undergoing lung transplantation are limited. It is clear from data from studies in adults, and from studies in other solid organ transplants in children, that systemic inequities exist in this field. While data relating specifically to pediatric lung transplantation are relatively sparse, professionals should be aware of the risk that healthcare systems may result in disparities in access and outcomes following lung transplantation in children.

Cost effectiveness of commercial portable ex vivo lung perfusion at a low-volume US lung transplant center

BACKGROUND

Portable ex vivo lung perfusion during lung transplantation is a resource-intensive technology. In light of its increasing use, we evaluated the cost-effectiveness of ex vivo lung perfusion at a low-volume lung transplant center in the USA.

METHODS

Patients listed for lung transplantation (2015-2021) in the United Network for Organ Sharing database were included. Quality-of-life was approximated by Karnofsky Performance Status scores 1-year post-transplant. Total transplantation encounter and 1-year follow-up costs accrued by our academic center for patients listed from 2018 to 2021 were obtained. Cost-effectiveness was calculated by evaluating the number of patients attaining various Karnofsky scores relative to cost.

RESULTS

Of the 13 930 adult patients who underwent lung transplant in the United Network for Organ Sharing database, 13 477 (96.7%) used static cold storage and 453 (3.3%) used ex vivo lung perfusion, compared to 30/58 (51.7%) and 28/58 (48.3%), respectively, at our center. Compared to static cold storage, median total costs at 1 year were higher for ex vivo lung perfusion ($918 000 vs. $516 000; p = 0.007) along with the cost of living 1 year with a Karnofsky functional status of 100 after transplant ($1 290 000 vs. $841 000). In simulated scenarios, each Karnofsky-adjusted life year gained by ex vivo lung perfusion was 1.00-1.72 times more expensive.

CONCLUSIONS

Portable ex vivo lung perfusion is not currently cost-effective at a low-volume transplant centers in the USA, being 1.53 times more expensive per Karnofsky-adjusted life year. Improving donor lung and/or recipient biology during ex vivo lung perfusion may improve its utility for routine transplantation.

Lung transplantation after ex vivo lung perfusion in high-risk recipients: A propensity-score matched analysis of a national database

PURPOSE

We report outcomes associated with ex vivo lung perfusion (EVLP) lungs in high-risk lung transplant recipients utilizing a national database.

METHODS

We performed a retrospective analysis of the United Network for Organ Sharing Database (January 1, 2018-March 31, 2024). High-risk status was defined as mean pulmonary arterial pressure >35 mm Hg, lung retransplantation, or bridge to transplant. In addition to univariable analysis, propensity-score matched analysis was performed on predictors of donor and recipient characteristics.

RESULTS

Risk of dying on the waitlist was significantly higher for high-risk candidates (hazard ratio, 1.69; 95% CI, 1.51-1.89; P < .001). Following matching, 203 EVLP cases were matched to 609 standard procurement recipients. The EVLP group was associated with higher rates of postoperative acute kidney injury requiring renal replacement therapy (27% vs 16%; P < .001), higher mortality on index admission (13% vs 8%; P = .04), and longer length of stay (29 vs 25 days; P = .006). EVLP modality was associated with survival time (P < .001) with portable EVLP having significantly shorter survival (2.7 years) relative to standard cases (4.7 years; P < .02). A subgroup analysis found that this survival effect was limited to bridge and retransplant recipients.

CONCLUSIONS

EVLP lungs were associated with higher rates of postoperative acute kidney injury and portable EVLP was associated with shorter survival in high-risk lung transplant recipients. However, given the high waitlist mortality in this candidate population, EVLP lungs should still be considered an alternative.

Pushing the Survival Bar Higher: Two Decades of Innovation in Lung Transplantation

Survival after lung transplantation has significantly improved during the last two decades. The refinement of the already existing extracorporeal life support (ECLS) systems, such as extracorporeal membrane oxygenation (ECMO), and the introduction of new techniques for donor lung optimization, such as ex vivo lung perfusion (EVLP), have allowed the extension of transplant indication to patients with end-stage lung failure after acute respiratory distress syndrome (ARDS) and the expansion of the donor organ pool, due to the better evaluation and optimization of extended-criteria donor (ECD) lungs and of donors after circulatory death (DCD). The close monitoring of anti-HLA donor-specific antibodies (DSAs) has allowed the early recognition of pulmonary antibody-mediated rejection (AMR), which requires a completely different treatment and has a worse prognosis than acute cellular rejection (ACR). As such, the standardization of patient selection and post-transplant management has significantly contributed to this positive trend, especially at high-volume centers. This review focuses on lung transplantation after ARDS, on the role of EVLP in lung donor expansion, on ECMO as a principal cardiopulmonary support system in lung transplantation, and on the diagnosis and therapy of pulmonary AMR.

How do we expand the lung donor pool?

PURPOSE OF REVIEW

Lung transplantation activity continues to be limited by the availability of timely quality donor lungs. It is apparent though that progress has been made. The steady evolution of clinical practice, combined with painstaking scientific discovery and innovation are described.

RECENT FINDINGS

There have been successful studies reporting innovations in the wider use and broader consideration of donation after circulatory death donor lungs, including an increasing number of transplants from each of the controlled, uncontrolled and medically assisted dying donor descriptive categories. Donors beyond age 70 years are providing better than expected long-term outcomes. Hepatitis C PCR positive donor lungs can be safely used if treated postoperatively with appropriate antivirals. Donor lung perfusion at a constant 10 degrees appears capable of significantly improving donor logistics and ex-vivo lung perfusion offers the potential of an ever-increasing number of novel donor management roles. Bioartificial and xenografts remain distant possibilities only at present.

SUMMARY

Donor lungs have proved to be surprisingly robust and combined with clinical, scientific and engineering innovations, the realizable lung donor pool is proving to be larger than previously thought.

Advances in lung transplantation: 60 years on

Lung transplantation is a well-established treatment for advanced lung disease, improving survival and quality of life. Over the last 60 years all aspects of lung transplantation have evolved significantly and exponential growth in transplant volume. This has been particularly evident over the last decade with a substantial increase in lung transplant numbers as a result of innovations in donor utilization procurement, including the use donation after circulatory death and ex-vivo lung perfusion organs. Donor lungs have proved to be surprisingly robust, and therefore the donor pool is actually larger than previously thought. Parallel to this, lung transplant outcomes have continued to improve with improved acute management as well as microbiological and immunological insights and innovations. The management of lung transplant recipients continues to be complex and heavily dependent on a tertiary care multidisciplinary paradigm. Whilst long term outcomes continue to be limited by chronic lung allograft dysfunction improvements in diagnostics, mechanistic understanding and evolutions in treatment paradigms have all contributed to a median survival that in some centres approaches 10 years. As ongoing studies build on developing novel approaches to diagnosis and treatment of transplant complications and improvements in donor utilization more individuals will have the opportunity to benefit from lung transplantation. As has always been the case, early referral for transplant consideration is important to achieve best results.

Epidemiology and Long-Term Outcomes in Thoracic Transplantation

Over the past five decades, outcomes for lung transplantation have significantly improved in the early post-operative period, such that lung transplant is now the gold standard treatment for end-stage respiratory disease. The major limitation that impacts lung transplant survival rates is the development of chronic lung allograft dysfunction (CLAD). CLAD affects around 50% of lung transplant recipients within five years of transplantation. We must also consider other factors impacting the survival rate such as the surgical technique (single versus double lung transplant), along with donor and recipient characteristics. The future is promising, with more research looking into ex vivo lung perfusion (EVLP) and bioengineered lungs, with the hope of increasing the donor pool and decreasing the risk of graft rejection.