Normothermic regional perfusion: Ethical issues in thoracic organ donation

Post-transplant survival after normothermic regional perfusion versus direct procurement and perfusion in donation after circulatory determination of death in heart transplantation

BACKGROUND

Since 2019, the annual transplantation rate of hearts donated following circulatory death (DCD) has increased significantly in the United States. The 2 major heart procurement techniques following circulatory death are direct procurement and perfusion (DPP) and normothermic regional perfusion (NRP). Post-transplant survival for heart recipients has not been compared between these 2 techniques.

METHODS

This observational study uses data on adult heart transplants from donors after circulatory death from January 1, 2019 to December 31, 2021 in the Scientific Registry of Transplant Recipients. We identified comparable transplant cases across procurement types using propensity-score matching and measured the association between procurement technique and 1-year post-transplant survival using Kaplan-Meier and Cox proportional hazards model stratefied by matching pairs.

RESULTS

Among 318 DCD heart transplants, 216 (68%) were procured via DPP, and 102 (32%) via NRP. Among 22 transplant centers that accepted circulatory-death donors, 3 used NRP exclusively, and 5 used both procurement techniques. After propensity-score matching on recipient and donor factors, there was no significant difference in 1-year post-transplant survival (93.1% for NRP vs 91.1% for DPP, p = 0.79) between procurement techniques.

CONCLUSIONS

NRP and DPP procurements are associated with similar 1-year post-transplant survival. If NRP is ethically permissible and improves outcomes for abdominal organs, it should be the preferred procurement technique for DCD hearts.

Cardiac organoids do not warrant additional moral scrutiny

Certain organoid subtypes are particularly sensitive. We explore whether moral intuitions about the heartbeat warrant unique moral consideration for newly advanced contracting cardiac organoids. Despite the heartbeat's moral significance in organ procurement and abortion discussions, we argue that this significance should not translate into moral implications for cardiac organoids.

Neither Ethical nor Prudent: Why Not to Choose Normothermic Regional Perfusion

In transplant medicine, the use of normothermic regional perfusion (NRP) in donation after circulatory determination of death raises ethical difficulties. NRP is objectionable because it restores the donor's circulation, thus invalidating a death declaration based on the permanent cessation of circulation. NRP's defenders respond with arguments that are tortuous and factually inaccurate and depend on introducing extraneous concepts into the law. However, results comparable to NRP's-more and higher-quality organs and more efficient allocation-can be achieved by removing organs from deceased donors and using normothermic machine perfusion (NMP) to support the organs outside the body, without jeopardizing confidence in transplantation's legal and ethical foundations. Given the controversy that NRP generates and the convoluted justifications made for it, we recommend a prudential approach we call "ethical parsimony," which holds that, in the choice between competing means of achieving a result, the ethically simpler one is to be preferred. This approach makes clear that policy-makers should favor NMP over NRP.

Advancing the Scientific Basis for Determining Death in Controlled Organ Donation After Circulatory Determination of Death

In controlled organ donation after circulatory determination of death (cDCDD), accurate and timely death determination is critical, yet knowledge gaps persist. Further research to improve the science of defining and determining death by circulatory criteria is therefore warranted. In a workshop sponsored by the National Heart, Lung, and Blood Institute, experts identified research opportunities pertaining to scientific, conceptual, and ethical understandings of DCDD and associated technologies. This article identifies a research strategy to inform the biomedical definition of death, the criteria for its determination, and circulatory death determination in cDCDD. Highlighting knowledge gaps, we propose that further research is needed to inform the observation period following cessation of circulation in pediatric and neonatal populations, the temporal relationship between the cessation of brain and circulatory function after the withdrawal of life-sustaining measures in all patient populations, and the minimal pulse pressures that sustain brain blood flow, perfusion, activity, and function. Additionally, accurate predictive tools to estimate time to asystole following the withdrawal of treatment and alternative monitoring modalities to establish the cessation of circulatory, brainstem, and brain function are needed. The physiologic and conceptual implications of postmortem interventions that resume circulation in cDCDD donors likewise demand attention to inform organ recovery practices. Finally, because jurisdictionally variable definitions of death and the criteria for its determination may impede collaborative research efforts, further work is required to achieve consensus on the physiologic and conceptual rationale for defining and determining death after circulatory arrest.

Donor heart refusal after circulatory death: An analysis of United Network for Organ Sharing refusal codes

Objective

Donor hearts procured after circulatory death (DCD) may significantly increase the number of hearts available for transplantation. The purpose of this study was to analyze current DCD and brain-dead donor (DBD) heart transplantation rates and characterize organ refusal using the most up-to-date United Network for Organ Sharing (UNOS) and Organ Procurement and Transplantation Network data.

Methods

We analyzed UNOS and Organ Procurement and Transplantation Network DBD and DCD candidate, transplantation, and demographic data from 2020 through 2022 and 2022 refusal code data to characterize DCD heart use and refusal. Subanalyses were performed to characterize DCD donor demographics and regional transplantation rate variance.

Results

DCD hearts were declined 3.37 times more often than DBD hearts. The most frequently used code for DCD refusal was neurologic function, related to concerns of a prolonged dying process and organ preservation. In 2022, 92% (1329/1452) of all DCD refusals were attributed to neurologic function. When compared with DBD, DCD donor hearts were more frequently declined as the result of prolonged warm ischemic time (odds ratio, 5.65; 95% confidence interval, 4.07-7.86) and other concerns over organ preservation (odds ratio, 4.06; 95% confidence interval, 3.33-4.94). Transplantation rate variation was observed between demographic groups and UNOS regions. DCD transplantation rates are currently experiencing second order polynomial growth.

Conclusions

DCD donor hearts are declined more frequently than DBD. DCD heart refusals result from concerns over a prolonged dying process and organ preservation. Heart transplantation rates may be substantially improved by ex situ hemodynamic assessment, adoption of normothermic regional perfusion guidelines, and quality initiatives.

Association of procurement technique with organ yield and cost following donation after circulatory death

Donation after circulatory death (DCD) could account for the largest expansion of the donor allograft pool in the contemporary era. However, the organ yield and associated costs of normothermic regional perfusion (NRP) compared to super-rapid recovery (SRR) with ex-situ normothermic machine perfusion, remain unreported. The Organ Procurement and Transplantation Network (December 2019 to June 2023) was analyzed to determine the number of organs recovered per donor. A cost analysis was performed based on our institution's experience since 2022. Of 43 502 donors, 30 646 (70%) were donors after brain death (DBD), 12 536 (29%) DCD-SRR and 320 (0.7%) DCD-NRP. The mean number of organs recovered was 3.70 for DBD, 3.71 for DCD-NRP (P < .001), and 2.45 for DCD-SRR (P < .001). Following risk adjustment, DCD-NRP (adjusted odds ratio 1.34, confidence interval 1.04-1.75) and DCD-SRR (adjusted odds ratio 2.11, confidence interval 2.01-2.21; reference: DBD) remained associated with greater odds of allograft nonuse. Including incomplete and completed procurement runs, the total average cost of DCD-NRP was $9463.22 per donor. By conservative estimates, we found that approximately 31 donor allografts could be procured using DCD-NRP for the cost equivalent of 1 allograft procured via DCD-SRR with ex-situ normothermic machine perfusion. In conclusion, DCD-SRR procurements were associated with the lowest organ yield compared to other procurement methods. To facilitate broader adoption of DCD procurement, a comprehensive understanding of the trade-offs inherent in each technique is imperative.

Twenty-four-hour Normothermic Ex Vivo Heart Perfusion With Low Flow Functional Assessment in an Adult Porcine Model

BACKGROUND

Cold static storage and normothermic ex vivo heart perfusion are routinely limited to 6 h. This report describes intermittent left atrial (LA) perfusion that allows cardiac functional assessment in a working heart mode.

METHODS

Using our adult porcine model, general anesthesia was induced and a complete cardiectomy was performed following cardioplegic arrest. Back-table instrumentation was completed and normothermic ex vivo heart perfusion (NEHP) was initiated in a nonworking heart mode (Langendorff). After 1 h of resuscitation and recovery, LA perfusion was initiated and the heart was transitioned to a coronary flow-only working heart mode for 30 min. Baseline working heart parameters were documented and the heart was returned to nonworking mode. Working heart assessments were performed for 30 min every 6 h for 24 h.

RESULTS

Twenty-four-hour NEHP on 9 consecutive hearts (280 ± 42.1 g) was successful and no significant differences were found between working heart parameters at baseline and after 24 h of perfusion. There was no difference between initial and final measurements of LA mean pressures (5.0 ± 3.1 versus 9.0 ± 6.5 mm Hg, P = 0.22), left ventricular systolic pressures (44.3 ± 7.2 versus 39.1 ± 9.0 mm Hg, P = 0.13), mean aortic pressures (30.9 ± 5.8 versus 28.1 ± 8.1 mm Hg, P = 0.37), and coronary resistance (0.174 ± 0.046 versus 0.173 ± 0.066 mL/min/g, P = 0.90). There were also no significant differences between lactate (2.4 ± 0.5 versus 2.6 ± 0.4 mmol/L, P = 0.17) and glucose (173 ± 75 versus 156 ± 70 mg/dL, P = 0.37).

CONCLUSIONS

A novel model using intermittent LA perfusion to create a coronary flow-only working heart mode for assessment of ex vivo cardiac function has been successfully developed.

Lung recovery utilizing thoracoabdominal normothermic regional perfusion during donation after circulatory death: The Colorado experience

Objective

Donation after circulatory death (DCD) procurement and transplantation after thoracoabdominal normothermic regional perfusion (TA-NRP) remains a novel technique to improve cardiac and hepatic allograft preservation but may be complicated by lung allograft pulmonary edema. We present a single-center series on early implementation of a lung-protective protocol with strategies to mitigate posttransplant pulmonary edema in DCD lung allografts after TA-NRP procurement.

Methods

Data from all lung transplantations performed using a TA-NRP procurement strategy from October 2022 to April 2023 are presented. Donor management consisted of key factors to reduce lung allograft pulmonary edema: aggressive predonation and early posttransplant diuresis, complete venous drainage at TA-NRP initiation, and early pulmonary artery venting upon initiation of systemic perfusion. Donor and recipient characteristics, procurement characteristics such as TA-NRP intervals, and 30-day postoperative outcomes were assessed.

Results

During the study period, 8 lung transplants were performed utilizing TA-NRP procurement from DCD donors. Donor ages ranged from 16 to 39 years and extubation time to declaration of death ranged from 10 to 90 minutes. Time from declaration to TA-NRP initiation was 7 to 17 minutes with TA-NRP perfusion times of 49 to 111 minutes. Median left and right allograft warm ischemia times were 55.5 minutes (interquartile range, 46.5-67.5 minutes) and 41.0 minutes (interquartile range, 39.0-53.0 minutes, respectively, with 2 recipients supported with cardiopulmonary bypass or venoarterial extracorporeal membrane oxygenation during implantation. No postoperative extracorporeal membrane oxygenation was required. There were no pulmonary-related deaths; however, 1 patient died from complications of severe necrotizing pancreatitis with a normal functioning allograft. All patients were extubated within 24 hours. Index intensive care unit length of stay ranged from 3 to 11 days with a hospital length of stay of 13 to 37 days.

Conclusions

Despite concern regarding quality of DCD lung allografts recovered using the TA-NRP technique, we report initial success using this procurement method. Implementation of strategies to mitigate pulmonary edema can result in acceptable outcomes following lung transplantation. Demonstration of short- and long-term safety and efficacy of this technique will become increasingly important as the use of TA-NRP for thoracic and abdominal allografts in DCD donors expands.

Normothermic regional perfusion for donation after circulatory death donors

PURPOSE OF REVIEW

This review is intended to provide an update on the logistics, technique, and outcomes associated with normothermic regional perfusion (NRP), as well as provide a discussion of the associated ethical issues.

RECENT FINDINGS

There has been renewed interest in utilizing NRP to increase quality and availability of organs from donation after circulatory death (DCD) donors. Our institution has increasing experience with thoraco-abdominal NRP (TA-NRP) in controlled DCD donors (cDCD), whereas abdominal NRP (A-NRP) has been used with success in both cDCD and uncontrolled DCD (uDCD). There is increasing evidence that NRP can be conducted in a practical and cost-efficient manner, and that the organ yield may be of better quality than standard direct procurement and perfusion (DPP).

SUMMARY

NRP is increasingly successful and will likely prove to be a superior method for cDCD recovery. However, before TA-NRP can be widely accepted the ethical debate surrounding this technique must be settled.

VIDEO ABSTRACT

http://links.lww.com/COOT/A11.

Protocol for a qualitative pilot study to explore ethical issues and stakeholder trust in the use of normothermic regional perfusion in organ donation in Canada

INTRODUCTION

The process of controlled organ donation after circulatory determination of death (cDCDD) results in ischaemic injury to organs and leads to poorer outcomes in organ recipients. Although not yet used in Canada, normothermic regional perfusion (NRP) is a perfusion technology used postmortem with cDCDD donors to selectively restore perfusion of oxygenated blood to target organs in situ, reversing ischaemic injury and improving organ viability and post-transplant outcomes. However, NRP poses significant ethical challenges. To preserve trust in deceased donation, these ethical challenges must be addressed to the satisfaction of Canadian stakeholders before NRP's implementation. This study will identify ethical issues pertaining to NRP and explore perspectives of NRP among key stakeholders. By developing an explanatory framework delineating how stakeholder perceptions of NRP's ethical implications impact trust in Canada's donation and transplantation systems, this study will inform the development of responsible policy on NRP's use in Canada.

METHODS AND ANALYSIS

This study includes two workstreams. Workstream 1 is a scoping review of medical and bioethical literature to identify ethical issues stemming from NRP. We will apply a common search string across Medline, PubMed (other than Medline) and Embase to identify relevant articles. We will identify grey literature through Google searches, websites of organ donation organisations and consultation with our research network. No date limits will be applied. All peer-reviewed publications, commentaries, editorials or documents that engage with ethical issues in NRP (or conceptual and empirical issues as they relate to these ethical issues) will be included. News articles, conference abstracts and publications not in English will be excluded. Workstream 2 consists of interviews with healthcare providers, institutional stakeholders, organ recipients and deceased donors' family members (n=24-36), as well as focus groups with healthcare providers involved in deceased donation and transplantation (n=20-32). Constructivist grounded theory methodology will guide data collection and analysis in workstream 2.

ETHICS AND DISSEMINATION

This study was approved by Western University's research ethics committee (Western REM; ID: 120001). All participants will be asked to provide written informed consent to participate. Findings will be shared with Canadian organ donation and transplantation organisations, presented at national conferences and published in medical journals.

Normothermic Regional Perfusion is an Emerging Cost-Effective Alternative in Donation After Circulatory Death (DCD) in Heart Transplantation

In donation after circulatory death (DCD) organ transplantation, normothermic regional perfusion (NRP) restores oxygenated blood flow following cardiac arrest and reverses warm ischemia. Recently, NRP has also been used to help recover DCD hearts in addition to the abdominal organs. While DCD donation has increased the number of abdominal organs and lungs pool, it has not been able to increase the number of heart transplants, despite the fact that it has the potential to increase the number of heart transplants by 15-30%. Thoracoabdominal normothermic regional perfusion makes heart transplantation feasible and permits assessing heart function before an organ procurement without affecting the preservation of abdominal organs. NRP can be used in two ways for DCD donor heart transplants: normothermic regional perfusion followed by machine perfusion (NRP-MP) and normothermic regional perfusion followed by static cold storage (NRP-SCS). Normothermic regional perfusion is an emerging technology, a cost-effective alternative in donation after circulatory death (DCD), and will increase the pool of donors in heart transplantation.