Marginal Lung Donors: A Diminishing Margin of Safety?

Donor blood cultures and outcomes after lung transplantation: a single-center report

BACKGROUND

Transplanting lungs from donors with positive blood cultures has not been shown to adversely affect survival. There is limited evidence for potential effects on other outcomes, such as hospital course, graft function, and transmission of infection.

METHODS

This retrospective cohort study included adult patients who underwent lung-only transplantation for the first time between March 2010 and December 2022. Outcomes of patients whose donors had positive blood cultures within 72 h of transplant were compared to patients whose donors had negative blood cultures.

RESULTS

Twenty-five (10.8%) of 232 donors had positive blood cultures, including a single, unexpected case with candidemia. The most commonly isolated bacteria were Enterobacter cloacae (n = 5), Klebsiella pneumoniae (n = 5), Acinetobacter baumannii (n = 3), Pseudomonas aeruginosa (n = 3), and Staphylococcus aureus (n = 3). Eleven donors had identical bacteria in their respiratory cultures. All patients who were transplanted from donors with positive blood cultures survived beyond 90 days. Positive donor blood cultures were not associated with longer hospital stay, in-hospital complications, acute cellular rejection, or the achievement of 80% predicted forced expiratory volume in the first second. Probable transmission of donor bacteremia occurred in only two cases (both with S. aureus). These two donors had positive respiratory cultures with the same organism.

CONCLUSION

The study did not find an increased risk of adverse events when transplanting lungs from donors with positive blood cultures. Allograft cultures may be more predictive of the risk of transmitting infections.

Donor respiratory multidrug-resistant bacteria and lung transplantation outcomes

RATIONALE

Respiratory culture screening is mandatory for all potential lung transplant donors. There is limited evidence on the significance of donor multidrug-resistant (MDR) bacteria on transplant outcomes. Establishing the safety of allografts colonized with MDR bacteria has implications for widening an already limited donor pool.

OBJECTIVES

We aimed to describe the prevalence of respiratory MDR bacteria among our donor population and to test for associations with posttransplant outcomes.

METHODS

This retrospective observational study included all adult patients who underwent lung-only transplantation for the first time at King Faisal Specialist Hospital & Research Centre in Riyadh from January 2015 through May 2022. The study evaluated donor bronchoalveolar lavage and bronchial swab cultures.

MAIN RESULTS

Sixty-seven of 181 donors (37%) had respiratory MDR bacteria, most commonly MDR Acinetobacter baumannii (n = 24), methicillin-resistant Staphylococcus aureus (n = 18), MDR Klebsiella pneumoniae (n = 8), MDR Pseudomonas aeruginosa (n = 7), and Stenotrophomonas maltophilia (n = 6). Donor respiratory MDR bacteria were not significantly associated with allograft survival or chronic lung allograft dysfunction (CLAD) in adjusted hazard models. Sensitivity analyses revealed an increased risk for 90-day mortality among recipients of allografts with MDR Klebsiella pneumoniae (n = 6 with strains resistant to a carbapenem and n = 2 resistant to a third-generation cephalosporin only) compared to those receiving culture-negative allografts (25.0% versus 11.1%, p = 0.04). MDR Klebsiella pneumoniae (aHR 3.31, 95%CI 0.95-11.56) and Stenotrophomonas maltophilia (aHR 5.35, 95%CI 1.26-22.77) were associated with an increased risk for CLAD compared to negative cultures.

CONCLUSION

Our data suggest the potential safety of using lung allografts with MDR bacteria in the setting of appropriate prophylaxis; however, caution should be exercised in the case of MDR Klebsiella pneumoniae.

Impact of Recruitment Maneuvers to Cover Adverse Effects of Donor Transfer

OBJECTIVES

Our aim was to investigate the negative effects of transferring brain-dead donors to the intensive care unit on the ratio of PaO₂ to inspired oxygen fraction and the benefits of recruitment maneuvers on its reversal.

MATERIALS AND METHODS

In this randomized trial, we assigned 30 brain-dead donors to an intervention group and a control group. After transfer to the intensive care unit, donors in the intervention group received a lung recruitment maneuver according to protocol for 1 hour, whereas the control group did not receive this intervention. Arterial blood gas was drawn before transfer, immediately aftertransfer, and 3 hours after transfer.

RESULTS

Before transfer to immediately after transfer, the PaO₂-to-inspired oxygen fraction ratio decreased from 281.30 ± 100.33 to 225.03 ± 95.72 mm Hg (P < .01). At 3 hours aftertransfer,the PaO₂-to-inspired oxygen fraction ratio in the intervention and control groups was 280.4 ± 120.4 and 213.4 ± 75.5 mm Hg (P = .017), respectively. The absolute difference in PaO₂-to-inspired oxygen fraction ratio from before to 3 hours after transfer was -16.9 ± 44.1 and 51.8 ± 61.4 mm Hg (P < .001), in the intervention and control groups,respectively. Increasing central venous pressure and/or transfer time further potentiated the decrease ofthe PaO₂-to-inspired oxygen fraction ratio.

CONCLUSIONS

The PaO₂-to-inspired oxygen fraction ratio decreased after transfer of brain-dead donors to the intensive care unit. This was partially reversible by standardized recruitment maneuvers.

An observational study of Donor Ex Vivo Lung Perfusion in UK lung transplantation: DEVELOP-UK

BACKGROUND

Many patients awaiting lung transplantation die before a donor organ becomes available. Ex vivo lung perfusion (EVLP) allows initially unusable donor lungs to be assessed and reconditioned for clinical use.

OBJECTIVE

The objective of the Donor Ex Vivo Lung Perfusion in UK lung transplantation study was to evaluate the clinical effectiveness and cost-effectiveness of EVLP in increasing UK lung transplant activity.

DESIGN

A multicentre, unblinded, non-randomised, non-inferiority observational study to compare transplant outcomes between EVLP-assessed and standard donor lungs.

SETTING

Multicentre study involving all five UK officially designated NHS adult lung transplant centres.

PARTICIPANTS

Patients aged ≥ 18 years with advanced lung disease accepted onto the lung transplant waiting list.

INTERVENTION

The study intervention was EVLP assessment of donor lungs before determining suitability for transplantation.

MAIN OUTCOME MEASURES

The primary outcome measure was survival during the first 12 months following lung transplantation. Secondary outcome measures were patient-centred outcomes that are influenced by the effectiveness of lung transplantation and that contribute to the health-care costs.

RESULTS

Lungs from 53 donors unsuitable for standard transplant were assessed with EVLP, of which 18 (34%) were subsequently transplanted. A total of 184 participants received standard donor lungs. Owing to the early closure of the study, a non-inferiority analysis was not conducted. The Kaplan-Meier estimate of survival at 12 months was 0.67 [95% confidence interval (CI) 0.40 to 0.83] for the EVLP arm and 0.80 (95% CI 0.74 to 0.85) for the standard arm. The hazard ratio for overall 12-month survival in the EVLP arm relative to the standard arm was 1.96 (95% CI 0.83 to 4.67). Patients in the EVLP arm required ventilation for a longer period and stayed longer in an intensive therapy unit (ITU) than patients in the standard arm, but duration of overall hospital stay was similar in both groups. There was a higher rate of very early grade 3 primary graft dysfunction (PGD) in the EVLP arm, but rates of PGD did not differ between groups after 72 hours. The requirement for extracorporeal membrane oxygenation (ECMO) support was higher in the EVLP arm (7/18, 38.8%) than in the standard arm (6/184, 3.2%). There were no major differences in rates of chest radiograph abnormalities, infection, lung function or rejection by 12 months. The cost of EVLP transplants is approximately £35,000 higher than the cost of standard transplants, as a result of the cost of the EVLP procedure, and the increased ECMO use and ITU stay. Predictors of cost were quality of life on joining the waiting list, type of transplant and number of lungs transplanted. An exploratory model comparing a NHS lung transplant service that includes EVLP and standard lung transplants with one including only standard lung transplants resulted in an incremental cost-effectiveness ratio of £73,000. Interviews showed that patients had a good understanding of the need for, and the processes of, EVLP. If EVLP can increase the number of usable donor lungs and reduce waiting, it is likely to be acceptable to those waiting for lung transplantation. Study limitations include small numbers in the EVLP arm, limiting analysis to descriptive statistics and the EVLP protocol change during the study.

CONCLUSIONS

Overall, one-third of donor lungs subjected to EVLP were deemed suitable for transplant. Estimated survival over 12 months was lower than in the standard group, but the data were also consistent with no difference in survival between groups. Patients receiving these additional transplants experience a higher rate of early graft injury and need for unplanned ECMO support, at increased cost. The small number of participants in the EVLP arm because of early study termination limits the robustness of these conclusions. The reason for the increased PGD rates, high ECMO requirement and possible differences in lung injury between EVLP protocols needs evaluation.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN44922411.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 85. See the NIHR Journals Library website for further project information.

Current Status and Future of Lung Donation in Korea

Lung transplantation is the only effective treatment option for patients with end-stage lung disease. However, donor organ shortage makes timely transplant not possible for all patients, especially in Korea. We investigated the number and utilization of donor lungs by retrospectively reviewing all donor organs registered in the Korea Network for Organ Sharing database from March 2012 to March 2016. The donors were stratified into 4 groups by donor acceptability criteria. A total of 1,304 donors were included. Of those, 295 brain-dead donors (22.6%) consented to lung donation. Among these consented donors, 168 donors (12.9%) were retrieved for lung transplant. Retrieval rate was very low compared with that of the kidney (93.9%), liver (86.3%), and heart (27.3%). The characteristics of utilized donor lungs were: mean age, 40.5 years (range: 18 to 63 years); mean partial pressure of oxygen, 356.5 mmHg; mean smoking history, 5.9 pack-years; and mean body mass index, 22.6 kg/m². The proportion of donors with acceptable condition of the transplanted lungs was only 39.3% (ideal 19, standard 47, marginal 70, unusable 32). Among brain-dead patients who denied to donate lungs (n = 1,009), 82 were potentially acceptable donors (ideal 19, standard 63), which was equal to half of actually transplanted lung donations. Many potential donor lungs, which are currently excluded, may be successfully used in lung transplantation in Korea. The available lung donors must be actively selected and managed to maximize the utilization of this precious resource.

Benefit of a single recruitment maneuver after an apnea test for the diagnosis of brain death

Introduction

Many potential lung transplants are lost because of hypoxemia during donor management. We hypothesized that the apnea test, necessary to confirm the diagnosis of brain death in potential lung donors, was involved in the decrease in the ratio of partial pressure of arterial O₂ to fraction of inspired O₂ (PaO₂/FiO₂) and that a single recruitment maneuver performed just after the apnea test can reverse this alteration.

Methods

In this case-control study, we examined the effectiveness of the recruitment maneuver with a comparison cohort of brain dead patients who did not receive the maneuver. Patients were matched one-to-one on the basis of initial PaO₂/FiO₂ and on the duration of mechanical ventilation before the apnea test. PaO₂/FiO₂ was measured before (T1), at the end (T2) and two hours after apnea test (T3).

Results

Twenty-seven patients were included in each group. The apnea test was associated with a significant decrease in PaO₂/FiO₂ from 284 ± 98 to 224 ± 104 mmHg (P < 0.001). The decrease in PaO₂/FiO₂ between T1 and T3 was significantly lower in the recruitment maneuver group than in the control group (-4 (-68-57) vs -61 (-110--18) mmHg, P = 0.02). The number of potential donors with PaO₂/FiO₂ > 300 mmHg decreased by 58% (95% CI: 28-85%) in the control group vs 0% (95% CI: 0-34%) in the recruitment maneuver group (P < 0.001).

Conclusions

The apnea test induced a decrease in PaO₂/FiO₂ in potential lung donors. A single recruitment maneuver performed immediately after the apnea test can reverse this alteration and may prevent the loss of potential lung donors.

Single-lung transplantation in a chronic pulmonary emphysema patient with a marginal donor who was ABO blood group nonidentical but compatible

Because the number of ideal brain-dead donors is limited, active use of marginal donors is currently one of the major issues discussed in regard to lung transplantation. We report a case in which the patient underwent single-lung transplantation for chronic pulmonary emphysema. The lung came from a marginal, ABO blood group nonidentical, compatible donor. Because the donor was marginal (pneumonia in the right lung and lobar atelectasis in both lungs), all recipient candidates with ABO blood group identical declined. Thus, a nonidentical, compatible recipient had a chance to receive a lung transplant. This 49-year-old man underwent single-lung transplantation for chronic pulmonary emphysema with severe respiratory failure. He had a good postoperative clinical course.

Organ transplantation: historical perspective and current practice

Over the course of the last century, organ transplantation has overcome major technical limitations to become the success it is today. The breakthroughs include developing techniques for vascular anastomoses, managing the immune response (initially by avoiding it with the use of identical twins and subsequently controlling it with chemical immunosuppressants), and devising preservation solutions that enable prolonged periods of ex vivo storage while preserving function. One challenge that has remained from the outset is to overcome the shortage of suitable donor organs. The results of organ transplantation continue to improve, both as a consequence of the above innovations and the improvements in peri- and postoperative management. This review describes some of the achievements and challenges of organ transplantation.

Optimizing post-transplant outcomes in lung transplantation

Lung transplant recipients are at risk of numerous complications, which range from early events, such as primary graft dysfunction, to late events, including opportunistic infection or graft loss caused by chronic rejection. Although lung transplantation is often the only therapeutic option that can improve quality of life and prolong survival for many forms of end-stage lung disease, survival following lung transplantation is significantly worse than survival following transplantation of other solid organs. Carefully choosing potential recipients for listing, maximizing the likelihood that donor organs will function well following implantation, appropriate use of immunosuppressive agents to prevent allograft rejection, prophylactic or pre-emptive strategies to prevent allograft infection and appropriate surveillance to detect significant complications are key to maximizing the likelihood of prolonged graft and patient survival while avoiding significant complications following lung transplantation. Post-transplant outcomes will be optimized by a team approach to comprehensive management of the lung transplantation recipient combined with vigilant surveillance to detect complications in a timely fashion.

[Logistic, technic and postoperative complications of lung and heart-lung transplantations]

In France, the "Agence de la biomédecine" distributes lung grafts. "Ideal" criteria for lung donor selection are not always respected, driven by the scarcity of suitable donor lungs (10% deaths while waiting). In single lung transplantation, three anastomoses are performed (bronchus near the lobar carina, pulmonary artery, left atrium). For double lung transplantation (twice as frequent around the world), two single lung transplantations are successively performed through two separate anterolateral thoracotomies, often without cardiopulmonary bypass. Heart lung transplantations are now rare (2% around the world). Postoperative mortality has improved (between 10 and 15%): less severe primary graft dysfunctions, treatable with ECMO, fewer bronchial complications, improvement in the diagnosis of hyperacute humoral rejection, improvement in antiviral prophylaxis.

The number of lung transplants can be safely doubled using extended criteria donors; a single-center review

Relaxing the standard lung donor criteria may significantly increase the reported 15% organ yield but post-transplant recipient outcome should be carefully monitored. Charts from all consecutive deceased organ donors within our hospital network were reviewed over a 2-year period. Reasons for lung refusals and number of lungs transplanted were analysed. Hospital outcome including early recipient survival was compared between standard- and extended criteria donors. Out of 283 referrals, 164 (58%) qualified as donor of any organ. The majority (65.9%) of these effective donors were declined for lung donation because of chest X-ray abnormalities (20%), age >70 years (13%), poor oxygenation (10%), or aspiration (9%). Out of 56 (34.1%) accepted lung donors, 50 transplants were performed at our center, 23 from standard criteria donors versus 27 from extended criteria donors. There were no significant differences in hospital outcome and in early survival between lung recipients from both donor groups. Lung acceptance rate (34.1%) in our donor network is 10-20% higher than reported figures. The number of lung transplants in our center doubled by accepting extended criteria donors. This policy did not negatively influence our results after lung transplantation.

Extended donor criteria in lung transplantation

PURPOSE OF REVIEW

Despite improvements in respiratory care and lung transplant organ allocation algorithms, waiting lists continue to grow worldwide. Attempts at improving organ donation rates have generally had little impact on the increase in the number of transplants performed. Improved use of the available pool of cadaveric organ donors, therefore, represents one of few immediately available strategies to alleviate organ shortages.

RECENT FINDINGS

The once-strict lung donor selection criteria have, of necessity, been relaxed and, in many instances, this situation has been to no apparent detrimental effect on posttransplant outcome. There is, however, some evidence that extension of donor acceptability in some respects leads to poorer early outcomes, mainly by increasing the rate of early graft dysfunction. The extension of selection criteria to allow the maximum number of safe lung transplants, coupled with aggressive and appropriate donor management is, therefore, of particular current relevance to the lung transplantation community.

SUMMARY

Although the available evidence for and against the commonly used lung donor selection criteria leaves many questions unanswered, it can help decrease the large number of uncertainties that be falls the practice of lung donor selection and recipient matching.

Lung transplantation from the non-heart beating donor

The inflated lung, with its unique tolerance of the absence of a circulation, is particularly suited to retrieval from the non-heart beating donor. Absence of some of the squeal of brain death may be a further potential advantage. This concept has been embraced by several centers around the world, with promising early results.

Lung transplantation in older patients?

OBJECTIVE

Age 65 years and older is generally considered a contraindication to lung transplantation. Our group has offered lung transplantation to select patients 65 years of age and older who lack other comorbid conditions. We sought to define the short- and medium-term outcome of lung transplantation in patients aged 65 years and older.

METHODS

We reviewed the records of our lung transplant recipients from March 2000 to September 2006. During this interval, 50 patients were 65 years or older at the time of transplantation. Fifty patients younger than 65 years were matched to the older cohort by means of propensity analysis. The demographics and perioperative and postoperative characteristics and survival of the 2 groups were compared.

RESULTS

Older patients were more likely to receive single-lung transplantation (older group: 76% vs younger group: 16%, P < .05) and nonstandard donor lungs (older group: 46% vs younger group: 28%, P = .06). The composite in-hospital morbidity rate was similar in the older and younger groups. There was no significant difference in the early oxygenation parameters, incidence of acute cellular rejection, or incidence of bronchiolitis obliterans syndrome between the 2 groups. The early survival of the older patients was 95.7% compared with 95.9% in the younger cohort (P = .73). The 1-year survival of the 2 groups was also similar (older group: 79.7% vs younger group: 91.2%, P = .16). The 3-year survival of the older and younger recipients was 73.6% and 74.2%, respectively (P = .64). There were 8 deaths in the older recipient group during the 1-month to 1-year posttransplantation interval, predominantly because of infections.

CONCLUSIONS

Lung transplantation can be performed in patients older than 65 years with acceptable clinical outcomes. The "increased" mortality of older patients between 1 month and 1 year after transplantation, predominantly from infectious causes, might be due to immunosenescence of older patients. This finding warrants adjustments in the immunosuppression protocol of older patients undergoing lung transplantation. The effect of offering lung transplantation to older patients on donor lung availability deserves further investigation.