Donor Hemodynamics as a Predictor of Outcomes After Kidney Transplantation From Donors After Cardiac Death

Antecedent Cardiac Arrest Status of Donation After Circulatory Determination of Death (DCDD) Kidney Donors and the Risk of Delayed Graft Function After Kidney Transplantation: A Cohort Study

BACKGROUND

The number of donors from donation after circulatory determination of death (DCDD) has increased by at least 4-fold over the past decade. This study evaluated the association between the antecedent cardiac arrest status of controlled DCDD donors and the risk of delayed graft function (DGF).

METHODS

Using data from the Australia and New Zealand Dialysis and Transplant, the associations between antecedent cardiac arrest status of DCDD donors before withdrawal of cardiorespiratory support, DGF, posttransplant estimated glomerular filtration rate (eGFR), and allograft loss were examined using adjusted logistic, linear mixed modeling, and cox regression, respectively. Among donors who experienced cardiac arrest, we evaluated the association between duration and unwitnessed status of arrest and DGF.

RESULTS

A total of 1173 kidney transplant recipients received DCDD kidneys from 646 donors in Australia between 2014 and 2019. Of these, 335 DCDD had antecedent cardiac arrest. Compared with recipients of kidneys from donors without antecedent cardiac arrest, the adjusted odds ratio (95% confidence interval) for DGF was 0.85 (0.65-1.11) among those with kidneys from donors with cardiac arrest. There was no association between antecedent cardiac arrest and posttransplant eGFR or allograft loss. The duration of cardiac arrest and unwitnessed status were not associated with DGF.

CONCLUSIONS

This focused analysis in an Australian population showed that the allograft outcomes were similar whether DCDD donors had experienced a prior cardiac arrest, with no associations between duration or unwitnessed status of arrest and risk of DGF. This study thus provides important reassurance to transplant programs and the patients they counsel, to accept kidneys from donors through the DCDD pathway irrespective of a prior cardiac arrest.

Can We Predict Kidney Graft Function and Graft Survival Using Hypothermic Machine Perfusion Parameters From Donors After Circulatory Death?

Background

Hypothermic machine perfusion (HMP) reduces renal injury in donation after circulatory death donors with a high Kidney Donor Profile Index (KDPI). This study aims to characterize the correlation between KDPI, HMP parameters, and donor vitals during the withdrawal period in predicting short- and long-term graft outcomes.

Methods

ANOVA with Tukey's honestly significant difference tests compared the relationship between average flow, average resistance, peak resistance, flow slope, and resistance slope on day 30, 1-y, and 3-y eGFR, and days of delayed graft function. Graft and recipient survival rates were assessed using Kaplan-Meier analysis.

Results

The data for 72 grafts were suitable for analysis. Kidneys with KDPI >50% had a significantly higher day 30, and 1-y posttransplant eGFR, if HMP average flow was >150 mL/min, or the average resistance was <0.15 mm Hg/mL/min, compared with kidneys with also KDPI >50% but had not achieved the same pump parameters. There were no significant differences in the Kaplan-Meier analysis, considering recipient or graft survival, regardless of the KPDI score with 3- or 5-y outcomes.

Conclusions

Use of average resistance and average flow from a HMP, in conjunction with KDPI, may be predictive of the short- and long-term function of donation after circulatory death kidney transplants.

Impact of Extraction Time During Donation After Circulatory Death Organ Procurement on Kidney Function After Transplantation in The Netherlands

Background

In The Netherlands, 60% of deceased-donor kidney offers are after donation after circulatory death. Cold and warm ischemia times are known risk factors for delayed graft function (DGF) and inferior allograft survival. Extraction time is a relatively new ischemia time. During procurement, cooling of the kidneys is suboptimal with ongoing ischemia. However, evidence is lacking on whether extraction time has an impact on DGF if all ischemic periods are included.

Methods

Between 2012 and 2018, 1524 donation after circulatory death kidneys were procured and transplanted in The Netherlands. Donation and transplantation-related data were obtained from the database of the Dutch Transplant Foundation. The primary outcome parameter was the incidence of DGF.

Results

In our cohort, extraction time ranged from 14 to 237 min, with a mean of 62 min (SD 32). In multivariate logistic regression analysis, extraction time was an independent risk factor for incidence of DGF (odds ratio per minute increase 1.008; 95% confidence interval, 1.003-1.013; P = 0.001). The agonal phase, hypoperfusion time, and anastomosis time were not independent risk factors for incidence of DGF.

Conclusions

Considering all known ischemic periods during the donation after the circulatory death process, prolonged kidney extraction time increased the risk of DGF after kidney transplantation.

Donation after circulatory death heart transplantation using normothermic regional perfusion:The NYU Protocol

Objective

This study aimed to evaluate the impact of cardiopulmonary bypass for thoraco-abdominal normothermic regional perfusion on the metabolic milieu of donation after cardiac death organ donors before transplantation.

Methods

Local donation after cardiac death donor offers are assessed for suitability and willingness to participate. Withdrawal of life-sustaining therapy is performed in the operating room. After declaration of circulatory death and a 5-minute observation period, the cardiac team performs a median sternotomy, ligation of the aortic arch vessels, and initiation of thoraco-abdominal normothermic regional perfusion via central cardiopulmonary bypass at 37 °C. Three sodium chloride zero balance ultrafiltration bags containing 50 mEq sodium bicarbonate and 0.5 g calcium carbonate are infused. Arterial blood gas measurements are obtained every 15 minutes after every zero balance ultrafiltration bag is infused, and blood is transfused as needed to maintain hemoglobin greater than 8 mg/dL. Cardiopulmonary bypass is weaned with concurrent hemodynamic and transesophageal echocardiogram evaluation of the donor heart. The remainder of the procurement, including the abdominal organs, proceeds in a similar controlled fashion as is performed for a standard donation after brain death donor.

Results

Between January 2020 and May 2022, 18 donation after cardiac death transplants using the thoraco-abdominal normothermic regional perfusion protocol were performed at our institution. The median donor age was 42.5 years (range, 20-51 years), and 88.9% (16/18) were male. The mean total donor cardiopulmonary bypass time was 88.8 ± 51.8 minutes. At the beginning of cardiopulmonary bypass, the average donor lactate was 9.4 ± 1.5 mmol/L compared with an average final lactate of 5.3 ± 2.7 mmol/L (P<.0001). The average beginning potassium was 6.5 ± 1.8 mmol/L compared with an average end potassium of 4.2 ± 0.4 mmol/L (P<.0001) . The average beginning hemoglobin was 6.8 ± 0.7 g/dL, and the average end hemoglobin was 8.2 ± 1.3 g/dL (P<.001) . On average, donation after cardiac death donors received transfusions of 2.3 ± 1.5 units of packed red blood cells. Of the 18 donors who underwent normothermic regional perfusion, all hearts were deemed suitable for recovery and successfully transplanted, a yield of 100%. Other organs successfully recovered and transplanted include kidneys (80.6% yield), livers (66.7% yield), and bilateral lungs (27.8% yield).

Conclusions

The use of cardiopulmonary bypass for thoraco-abdominal normothermic regional perfusion is a burgeoning option for improving the quality of organs from donation after cardiac death donors. Meticulous intraoperative management of donation after cardiac death donors with a specific focus on improving their metabolic milieu may lead to improved graft function in transplant recipients.

Ethical Issues Related to Donation and Transplantation of Donation After Circulatory Determination of Death Donors

With the continuing disparity between organ supply to match the increasing demand for kidney transplants in patients with renal failure, donation after the circulatory determination of death (DCDD) has become an important and increasing global source of kidneys for clinical use. The concern that the outcomes of controlled DCDD donor kidney transplants were inferior to those obtained from donors declared dead by neurologic criteria has largely diminished because large-scale registry and single-center reports consistently have reported favorable outcomes. For uncontrolled DCDD kidney transplants, outcomes are correspondingly acceptable, although there is a greater risk of primary nonfunction. The potential of DCDD remains unrealized in many countries because of the ethical concerns and resource implications in the utilization of these donor kidneys for transplantation. In this review, we discuss the origin and definitions of DCDD donors, and examine the long-term outcomes of transplants from DCDD donor kidneys. We discuss the controversies, challenges, and ethical and legal barriers in the acceptance of DCDD, including the complexities of implementing and sustaining controlled and uncontrolled DCDD donor programs. The lessons learned from global leaders will assist a wider international recognition, acceptance, and development of DCDD transplant programs that will noticeably facilitate and address the global shortages of kidneys for transplantation, and ensure the opportunity for people who had indicated their desires to become organ donors fulfill their final wishes.

Nonutilization of Kidneys From Donors After Circulatory Determinant of Death

Background.

The expansion of donation after circulatory determination of death (DCDD) programs and unmet demands for kidney transplantation indicate that there is a need to improve the efficiency and utilization of these organs.

Methods.

We studied all DCDD donors retrieved for kidney transplantation in Australia between 2014 and 2019 and determined the factors associated with nonutilization using least absolute shrinkage and selection operator and random forest models. Self-organizing maps were used to group these donors into clusters with similar characteristics and features associated with nonutilization were defined.

Results.

Of the 762 DCDD donors, 116 (15%) were not utilized for kidney transplantation. Of the 9 clusters derived from self-organizing map, 2 had the highest proportions of nonutilized kidneys. Factors for nonutilization (adjusted odds ratio [95% confidence interval], per SD increase) were duration from withdrawal of cardiorespiratory support till death (1.38 [1.16-1.64]), admission and terminal serum creatinine (1.43 [1.13-1.85]) and (1.41 [1.16-1.73]). Donor kidney function and duration of warm ischemia were the main factors for clinical decisions taken not to use kidneys from DCDD donors.

Conclusions.

Donor terminal kidney function and the duration of warm ischemia are the key factors for nonutilization of DCDD kidneys. Strategies to reduce the duration of warm ischemia and improve post-transplant recipient kidney function may reduce rates of nonutilization.

Kidney transplant outcome of expanded criteria donors after circulatory death

The increase in the number of patients on the kidney transplant waiting list has led to an attempt to increase the number of potential donors by incorporating candidates that previously would not have been considered optimal, including donors after cardiac death (DCD) and those with "expanded" criteria (ECD). Recipients of controlled DCD (cDCD) grafts suffer more delayed graft function (DGF), but have a long-term evolution comparable to those of brain-dead donors, which has allowed an increase in the number of cDCD transplants in different countries in recent years. In parallel, the use of cDCD with expanded criteria (cDCD/ECD) has increased in recent years in different countries, allowing the waiting list for kidney transplantation to be shortened. The use of these grafts, although associated with a higher frequency of DGF, offers similar or only slightly lower long-term graft survival than those of brain death donors with expanded criteria. Different studies have observed that cDCD/ECD graft recipients have worse kidney function than cDCD/standard and DBD/ECD. Mortality associated with cDCD/ECD graft transplantation mostly relates to the recipient age. Patients who receive a cDCD/≥60 graft have better survival than those who continue on the waiting list, although this fact has not been demonstrated in recipients of cDCD/>65 years. The use of this type of organ should be accompanied by the optimization of surgical times and the shortest possible cold ischemia.

Antemortem Heparin in Organ Donation After Circulatory Death Determination: A Systematic Review of the Literature

Donation after circulatory death determination frequently involves antemortem heparin administration to mitigate peri-arrest microvascular thrombosis. We systematically reviewed the literature to: (1) describe heparin administration practices and (2) explore the effects on transplant outcomes. We searched MEDLINE and EMBASE for studies reporting donation after circulatory death determination heparin practices including use, dosage, and timing (objective 1). To explore associations between antemortem heparin and transplant outcomes (objective 2), we (1) summarized within-study comparisons and (2) used meta-regression analyses to examine associations between proportions of donors that received heparin and transplant outcomes. We assessed risk of bias using the Newcastle Ottawa Scale and applied the GRADE methodology to determine certainty in the evidence. For objective 1, among 55 eligible studies, 48 reported heparin administration to at least some donors (range: 15.8%-100%) at variable doses (up to 1000 units/kg) and times relative to withdrawal of life-sustaining therapy. For objective 2, 7 studies that directly compared liver transplants with and without antemortem heparin reported lower rates of primary nonfunction, hepatic artery thrombosis, graft failure at 5 y, or recipient mortality (low certainty of evidence). In contrast, meta-regression analysis of 32 liver transplant studies detected no associations between the proportion of donors that received heparin and rates of early allograft dysfunction, primary nonfunction, hepatic artery thrombosis, biliary ischemia, graft failure, retransplantation, or patient survival (very low certainty of evidence). In conclusion, antemortem heparin practices vary substantially with an uncertain effect on transplant outcomes. Given the controversies surrounding antemortem heparin, clinical trials may be warranted.

Outcomes after simultaneous pancreas-kidney transplantation from donation after circulatory death donors: A UK registry analysis

There are concerns that simultaneous pancreas-kidney (SPK) transplants from donation after circulatory death (DCD) donors have a higher risk of graft failure than those from donation after brain death (DBD) donors. A UK registry analysis of SPK transplants between 2005 and 2018 was performed. Pancreas survivals of those receiving organs from DCD or DBD donors were compared. Multivariable analyses were used to adjust for baseline differences between the two groups and to identify factors associated with pancreas graft loss. A total of 2228 SPK transplants were implanted; 403 (18.1%) were from DCD donors. DCD donors were generally younger, slimmer, less likely to have stroke as a cause of death, with lower terminal creatinines and shorter pancreas cold ischemic times than DBD donors. Median (IQR) follow-up was 4.2 (1.6-8.1) years. On univariable analysis, there were no statistically significant differences in 5-year death-censored pancreas graft survival between the two donor types (79.5% versus 80.4%; p = .86). Multivariable analysis showed no statistically significant differences in 5-year pancreas graft loss between transplants from DCD (n = 343) and DBD (n = 1492) donors (hazard ratio 1.26, 95% CI 0.76-1.23; p = .12). The findings from this study support the increased use of SPK transplants from DCD donors.

Clinical use of donation after circulatory death pancreas for islet transplantation

Due to a shortage of donation after brain death (DBD) organs, donation after circulatory death (DCD) is increasingly performed. In the field of islet transplantation, there is uncertainty regarding the suitability of DCD pancreas in terms of islet yield and function after islet isolation. The aim of this study was to investigate the potential use of DCD pancreas for islet transplantation. Islet isolation procedures from 126 category 3 DCD and 258 DBD pancreas were performed in a 9-year period. Islet yield after isolation was significantly lower for DCD compared to DBD pancreas (395 515 islet equivalents [IEQ] and 480 017 IEQ, respectively; p = .003). The decrease in IEQ during 2 days of culture was not different between the two groups. Warm ischemia time was not related to DCD islet yield. In vitro insulin secretion after a glucose challenge was similar between DCD and DBD islets. After islet transplantation, DCD islet graft recipients had similar graft function (AUC C-peptide) during mixed meal tolerance tests and Igls score compared to DBD graft recipients. In conclusion, DCD islets can be considered for clinical islet transplantation.

Kidney transplant outcome of expanded criteria donors after circulatory death

The increase in the number of patients on the kidney transplant waiting list has led to an attempt to increase the number of potential donors by incorporating candidates that previously would not have been considered optimal, including donors after cardiac death (DCD) and those with "expanded" criteria (ECD). Recipients of controlled DCD (cDCD) grafts suffer more delayed graft function (DGF), but have a long-term evolution comparable to those of brain-dead donors, which has allowed an increase in the number of cDCD transplants in different countries in recent years. In parallel, the use of cDCD with expanded criteria (cDCD/ECD) has increased in recent years in different countries, allowing the waiting list for kidney transplantation to be shortened. The use of these grafts, although associated with a higher frequency of DGF, offers similar or only slightly lower long-term graft survival than those of brain death donors with expanded criteria. Different studies have observed that cDCD/ECD graft recipients have worse kidney function than cDCD/standard and brain death/ECD. Mortality associated with cDCD/ECD graft transplantation mostly relates to the recipient age. Patients who receive a cDCD/≥60 graft have better survival than those who continue on the waiting list, although this fact has not been demonstrated in recipients of cDCD/>65 years. The use of this type of organ should be accompanied by the optimization of surgical times and the shortest possible cold ischemia.

Donor Warm Ischemia Time in DCD Liver Transplantation-Working Group Report From the ILTS DCD, Liver Preservation, and Machine Perfusion Consensus Conference

Donation after circulatory death (DCD) grafts are commonly used in liver transplantation. Attributable to the additional ischemic event during the donor warm ischemia time (DWIT), DCD grafts carry an increased risk for severe ischemia/reperfusion injury and postoperative complications, such as ischemic cholangiopathy. The actual ischemia during DWIT depends on the course of vital parameters after withdrawal of life support and varies widely between donors. The ischemic period (functional DWIT) starts when either Spo2 or blood pressure drop below a certain point and lasts until the start of cold perfusion during organ retrieval. Over the years, multiple definitions and thresholds of functional DWIT duration have been used. The International Liver Transplantation Society organized a Consensus Conference on DCD, Liver Preservation, and Machine Perfusion on January 31, 2020 in Venice, Italy. The aim of this conference was to reach consensus about various aspects of DCD liver transplantation in context of currently available evidence. Here we present the recommendations with regards to the definitions used for DWIT and functional DWIT, the importance of vital parameters after withdrawal of life support, and acceptable thresholds of duration of functional DWIT to proceed with liver transplantation.

Hypoperfusion warm ischaemia time in renal transplants from donors after circulatory death

Background

The donor hypoperfusion phase before asystole in renal transplants from donors after circulatory death (DCD) has been considered responsible for worse outcomes than those from donors after brain death (DBD).

Methods

We included 10 309 adult renal transplants (7128 DBD and 3181 DCD; 1 January 2010–31 December 2016) from the UK Transplant Registry. We divided DCD renal transplants into groups according to hypoperfusion warm ischaemia time (HWIT). We compared delayed graft function (DGF) rates, primary non-function (PNF) rates and graft survival among them using DBD renal transplants as a reference.

Results

The DGF rate was 21.7% for DBD cases, but ∼40% for DCD cases with HWIT ≤30 min (0–10 min: 42.1%, 11–20 min: 43%, 21–30 min: 38.4%) and 60% for DCD cases with HWIT &gt;30 min (P &lt; 0.001). All DCD groups showed higher DGF risk than DBD renal transplants in multivariable analysis {0–10 min: odds ratio [OR] 2.686 [95% confidence interval (CI) 2.352–3.068]; 11–20 min: OR 2.531 [95% CI 2.003–3.198]; 21–30 min: OR 1.764 [95% CI 1.017–3.059]; &gt;30 min: OR 5.814 [95% CI 2.798–12.081]}. The highest risk for DGF in DCD renal transplants with HWIT &gt;30 min was confirmed by multivariable analysis [versus DBD: OR 5.814 (95% CI 2.798–12.081) versus DCD: 0–10 min: OR 2.165 (95% CI 1.038–4.505); 11–20 min: OR 2.299 (95% CI 1.075–4.902); 21–30 min: OR 3.3 (95% CI 1.33–8.197)]. No significant differences were detected regarding PNF rates (P = 0.713) or graft survival (P = 0.757), which was confirmed by multivariable analysis.

Conclusions

HWIT &gt;30 min increases the risk for DGF greatly, but without affecting PNF or graft survival.

Impact of warm ischemia time on outcomes for kidneys donated after cardiac death Post-KAS

Prolonged warm (WIT) and cold (CIT) ischemia times are often important considerations in the discard of DCD kidneys, but their impact on post-transplant outcomes in the post-KAS era is unclear. We examined the association of ischemia time on delayed graft function (DGF) and death-censored graft failure for DCD kidneys. The 2018 SRTR SAF was utilized to identify post-KAS DCD kidney transplants occurring from 2015 to 2018. Relative risk and Cox regression were used to calculate risk of delayed graft function and hazard of death-censored graft failure, respectively. We identified 4,680 kidneys from DCD donors transplanted from 2015 to 2018 with recorded WIT and CIT times. Median WIT was 21.0 minutes (IQR 14.0-28.0), and CIT was 18.5 hours (IQR 13.9-23.5). The overall incidence of DGF was 42.7%. In a univariable relative risk regression model, extended CIT (24-30 hours:RR 1.37, 95% CI 1.15-1.77; >30 hours:RR 1.47, 95% CI 1.22-1.77) and WIT (20-40 minutes:RR 1.10, 95% CI 1.03-1.17) were associated with increased risk of DGF. When included in a multivariable model, neither prolonged CIT nor WIT were significantly associated with death-censored graft failure. Prolonged WIT and CIT are associated with increased DGF but not death-censored graft failure in recipients of DCD kidney transplants in the post-KAS era. Extended ischemia alone should not be used as a basis for discard or non-utilization of these organs.

Contemporary patterns in kidney graft survival from donors after circulatory death in the United States

BACKGROUND

Kidney transplants from donors after circulatory death (DCD) make up an increasing proportion of all deceased donor kidney transplants in the United States (US). However, DCD grafts are considered to be of lower quality than kidneys from donors after brain death (DBD). It is unclear whether graft survival is different for these two types of donor kidneys.

MATERIALS AND METHODS

We conducted a retrospective cohort study of US deceased donor kidney recipients using data from the United Network of Organ Sharing from 12/4/2014 to 6/30/2018. We employed a Cox proportional hazard model with mixed effects to compare all-cause graft loss and death-censored graft loss for DCD versus DBD deceased donor kidney transplant recipients. We used transplant center as the random effects term to account for cluster-specific random effects. In the multivariable analysis, we adjusted for recipient characteristics, donor factors, and transplant logistics.

RESULTS

Our cohort included 27,494 DBD and 7,770 DCD graft recipients transplanted from 2014 to 2018 who were followed over a median of 1.92 years (IQR 1.08-2.83). For DCD compared with DBD recipients, we did not find a significant difference in all-cause graft loss (hazard ratio [HR] 0.96, 95% confidence interval [CI] 0.87-1.05 in univariable and HR 1.03 [95% CI 0.95-1.13] in multivariable analysis) or for death-censored graft loss (HR 0.97 (95% CI 0.91-1.06) in univariable and 1.05 (95% CI 0.99-1.11) in multivariable analysis).

CONCLUSIONS

For a contemporary cohort of deceased donor kidney transplant recipients, we did not find a difference in the likelihood of graft loss for DCD compared with DBD grafts. These findings signal a need for additional investigation into whether DCD status independently contributes to other important outcomes for current kidney transplant recipients and indices of graft quality.

Donation after circulatory determination of death in western Canada: a multicentre study of donor characteristics and critical care practices

PURPOSE

Donation after circulatory determination of death (DCD) has been performed in Canada since 2006. Numerous aspects of donor management remain controversial.

METHODS

We performed a multicentre cohort study involving potential DCD donors in western Canada (2008-2017), as well as recipients of their organs, to describe donor characteristics and critical care practices, and their relation to one-year recipient and graft survival.

RESULTS

There were 257 patients in four provinces that underwent withdrawal of life-sustaining therapies (WLST) in anticipation of possible DCD. The proportion of patients that died within two hours of WLST ranged from 67% to 88% across provinces (P = 0.06), and was predicted by deeper coma (P = 0.01), loss of pupillary light or corneal reflexes (P = 0.02), and vasopressor use (P = 0.01). There were significant differences between provinces in time intervals from onset of hypotension to death (9-11 min; P = 0.02) and death to vascular cannulation (7-10 min; P < 0.001). There was inconsistency in pre-mortem heparin administration (82-96%; P = 0.03), including timing (before vs after WLST; P < 0.001) and dose (≥ 300 vs < 300 units·kg-1; P < 0.001). Donation after circulatory death provided organs for 321 kidney, 81 liver, and 50 lung transplants. One-year recipient and graft survival did not differ among provinces (range 85-90%, P = 0.45). Predictors of death or graft failure included older recipient age (odds ratio [OR] per year, 1.04; 95% confidence interval [CI],1.01 to 1.07) and male donor sex (OR, 3.35; 95% CI, 1.39 to 8.09), but not time intervals between WLST and cannulation or practices related to heparin use.

CONCLUSION

There is significant variability in critical care DCD practices in western Canada, but this has not resulted in significant differences in recipient or graft survival. Further research is required to guide optimal management of potential DCD donors.

An international comparison of deceased donor kidney utilization: What can the United States and the United Kingdom learn from each other?

In transplant, meaningful international comparisons in organ utilization are needed. This collaborative study between the United Kingdom (UK) and the United States (US) aimed to develop a kidney utilization metric allowing for legitimate intercountry comparisons. Data from the UK and US transplant registries, including all deceased donor kidneys recovered from 2006 to 2017, were analyzed. To identify a potentially comparable kidney utilization rate (UR), several denominators were assessed. We discovered that the proportion of transplanted kidneys from elderly donors in the UK (10.7%) was 18 times greater than that in the US (0.6%). Conversely, en bloc pediatric kidney transplant was more common in the US. Donation after circulatory death utilization has risen in both countries but is twice as prevalent in the UK (39% of transplants) vs the US (20%). In addition, US and UK URs are not directly comparable due to fundamental system differences. However, using a suite of URs revealed practice areas likely to yield the most benefit if improved, such as efforts to increase kidney offer acceptance in the US and to reduce postacceptance discard in the UK. Methods used in this study, including novel intracountry risk-adjusted UR trend logistic regression analyses, can be translated to other international transplant registries in pursuit of further global learning opportunities.

The impact of deceased donor maintenance on delayed kidney allograft function: A machine learning analysis

Background

This study evaluated the risk factors for delayed graft function (DGF) in a country where its incidence is high, detailing donor maintenance-related (DMR) variables and using machine learning (ML) methods beyond the traditional regression-based models.

Methods

A total of 443 brain dead deceased donor kidney transplants (KT) from two Brazilian centers were retrospectively analyzed and the following DMR were evaluated using predictive modeling: arterial blood gas pH, serum sodium, blood glucose, urine output, mean arterial pressure, vasopressors use, and reversed cardiac arrest.

Results

Most patients (95.7%) received kidneys from standard criteria donors. The incidence of DGF was 53%. In multivariable logistic regression analysis, DMR variables did not impact on DGF occurrence. In post-hoc analysis including only KT with cold ischemia time<21h (n = 220), urine output in 24h prior to recovery surgery (OR = 0.639, 95%CI 0.444–0.919) and serum sodium (OR = 1.030, 95%CI 1.052–1.379) were risk factors for DGF. Using elastic net regularized regression model and ML analysis (decision tree, neural network and support vector machine), urine output and other DMR variables emerged as DGF predictors: mean arterial pressure, ≥ 1 or high dose vasopressors and blood glucose.

Conclusions

Some DMR variables were associated with DGF, suggesting a potential impact of variables reflecting poor clinical and hemodynamic status on the incidence of DGF.

Major Adverse Cardiovascular Events Following Simultaneous Pancreas and Kidney Transplantation in the United Kingdom

OBJECTIVE

People with type 1 diabetes and kidney failure have an increased risk for major adverse cardiovascular events (MACE). Simultaneous pancreas and kidney transplantation (SPKT) improves survival, but the long-term risk for MACE is uncertain.

RESEARCH DESIGN AND METHODS

We assessed the frequency and risk factors for MACE (defined as fatal cardiovascular disease and nonfatal myocardial infarction or stroke) and related nonfatal MACE to allograft failure in SPKT recipients with type 1 diabetes who underwent transplantation between 2001 and 2015 in the U.K. In a subgroup, we related a pretransplant cardiovascular risk score to MACE.

RESULTS

During 5 years of follow-up, 133 of 1,699 SPKT recipients (7.8%) experienced a MACE. In covariate-adjusted models, age (hazard ratio 1.04 per year [95% CI 1.01-1.07]), prior myocardial infarction (2.6 [1.3-5.0]), stroke (2.3 [1.2-4.7]), amputation (2.0 [1.02-3.7]), donor history of hypertension (1.8 [1.05-3.2]), and waiting time (1.02 per month [1.0-1.04]) were significant predictors. Nonfatal MACE predicted subsequent allograft failure (renal 1.6 [1.06-2.6]; pancreas 1.7 [1.09-2.6]). In the subgroup, the pretransplant cardiovascular risk score predicted MACE (1.04 per 1% increment [1.02-1.06]).

CONCLUSIONS

We report a high rate of MACE in SPKT recipients. There are a number of variables that predict MACE, while nonfatal MACE increase the risk of subsequent allograft failure. It may be beneficial that organs from hypertensive donors are matched to recipients with lower cardiovascular risk. Pretransplant cardiovascular risk scoring may help to identify patients who would benefit from risk factor optimization or alternative transplant therapies and warrants validation nationally.

DCD donor hemodynamics as predictor of outcome after kidney transplantation

Insufficient hemodynamics during agonal phase-ie, the period between withdrawal of life-sustaining treatment and circulatory arrest-in Maastricht category III circulatory-death donors (DCD) potentially exacerbate ischemia/reperfusion injury. We included 409 Dutch adult recipients of DCD donor kidneys transplanted between 2006 and 2014. Peripheral oxygen saturation (SpO2-with pulse oximetry at the fingertip) and systolic blood pressure (SBP-with arterial catheter) were measured during agonal phase, and were dichotomized into minutes of SpO2 > 60% or SpO2 < 60%, and minutes of SBP > 80 mmHg or SBP < 80 mmHg. Outcome measures were and primary non-function (PNF), delayed graft function (DGF), and three-year graft survival. Primary non-function (PNF) rate was 6.6%, delayed graft function (DGF) rate was 67%, and graft survival at three years was 76%. Longer periods of agonal phase (median 16 min [IQR 11-23]) contributed significantly to an increased risk of DGF (P = .012), but not to PNF (P = .071) and graft failure (P = .528). Multiple logistic regression analysis showed that an increase from 7 to 20 minutes in period of SBP < 80 mmHg was associated with 2.19 times the odds (95% CI 1.08-4.46, P = .030) for DGF. In conclusion, duration of agonal phase is associated with early transplant outcome. SBP < 80 mmHg during agonal phase shows a better discrimination for transplant outcome than SpO2 < 60% does.

The Impact of CPR in High-Risk Donation after Circulatory Death Donors and Extended Criteria Donors for Kidney Transplantation

The demand for organs for kidney transplantation (KTX) compels the use of high-risk donation after circulatory death donors (DCDs) and extended criteria donors (ECDs). Many deceased donors receive prehospital CPR, but the literature does not address CPR as a benefit to graft survival. We hypothesized that donor prehospital CPR correlates with improved graft survival with high-risk DCD/ECD kidneys. We retrospectively analyzed KTX recipients and their donor data from 2008 to 2013. A total of 646 cadaveric donors (498 SCDs, 55 DCDs, and 93 ECDs) facilitated 910 KTX. There were 223 KTX performed from 148 high-risk DCDs/ECDs (31 with CPR and 117 without CPR). The mean age of high-risk DCDs/ECDs with CPR was 44.94 versus 53.45 years without CPR (P = 0.005). The recipients of high-risk DCDs/ECDs revealed no significant difference in body mass index, length of stay, discharge Cr, CIT, or DGF with and without CPR. Graft survival at three years was significant with 0/50 failures from high-risk DCDs/ECDs with CPR versus 16/173 without CPR (P = 0.026). Our findings are limited as a single-center retrospective study; however, the result of significant three-year graft survival in high-risk DCDs/ECDs with CPR suggests that prehospital donor CPR should be further investigated for its contribution to the relative quality of the donor.

CD47 blockade reduces ischemia/reperfusion injury in donation after cardiac death rat kidney transplantation

Modulation of nitric oxide activity through blockade of CD47 signaling has been shown to reduce ischemia-reperfusion injury (IRI) in various models of tissue ischemia. Here, we evaluate the potential effect of an antibody-mediated CD47 blockade in a syngeneic and an allogeneic DCD rat kidney transplant model. The donor organ was subjected to 1 hour of warm ischemia time after circulatory cessation, then flushed with a CD47 monoclonal antibody (CD47mAb) in the treatment group, or an isotype-matched immunoglobulin in the control group. We found that CD47mAb treatment improved survival rates in both models. Serum markers of renal injury were significantly decreased in the CD47mAb-treated group compared with the control group. Histologically the CD47mAb-treated group had significantly reduced scores of acute tubular injury and acute tubular necrosis. The expression of biomarkers related to mitochondrial stress and apoptosis also were significantly lower in the CD47mAb-treated groups. Overall, the protective effects of CD47 blockade were greater in the syngeneic model. Our data show that CD47mAb blockade decreased the IRI of DCD kidneys in rat transplant models. This therapy has the potential to improve DCD kidney transplant outcomes in the human setting.

Results of Controlled Donation After Circulatory Death in a Third-Level Hospital

OBJECTIVE

To investigate the characteristics and evolution of controlled donation after circulatory death (DCD) type III.

MATERIALS AND METHODS

Observational and retrospective study of controlled DCD type III of donors conducted from 2014 to 2016. Clinical data, intensive care unit (ICU) stay, cause of death, warm ischemia time, and total time were collected. Delayed graft function (DGF) and survival of renal transplant were also registered. Qualitative variables are described as frequencies and absolute values and quantitative variables as medians and interquartile ranges.

RESULTS

A total of 21 donors were collected; 71% (15) were males, median age was 55 years (interquartile range [IR] 48-72), and median ICU stay was 7 days (IR 4-12). The main cause of death was anoxic encephalopathy (57%, 12), followed by intracerebral hemorrhage (28%, 6). In 48%, withdrawal of life support occurred in the operating room, and 98% of donors were preserved by abdominal super-rapid cannulation technique. Average warm ischemia time was 20 minutes (IR 16-24), and total ischemia time was 26 minutes (IR 23-34). Of the donations, 57% were livers and 90% were kidneys. Out of 42 kidneys donated, 54% (23) of them were valid. Median renal transplant hospital stay was 18 days (IR 6-24), and 46% develop DGF. Survival at discharge was 100%.

CONCLUSION

DCD type III ensures a source of organs. The main cause of death was anoxic encephalopathy. Most donors were able to donate some solid organ.

Use and Outcomes of Kidneys from Donation after Circulatory Death Donors in the United States

Donation after circulatory death (DCD) donors are an important source of kidneys for transplantation, but DCD donor transplantation is less common in the United States than in other countries. In this study of national data obtained between 2008 and 2015, recovery of DCD kidneys varied substantially among the country's 58 donor service areas, and 25% of DCD kidneys were recovered in only four donor service areas. Overall, 20% of recovered DCD kidneys were discarded, varying from 3% to 33% among donor service areas. Compared with kidneys from neurologically brain dead (NBD) donors, DCD kidneys had a higher adjusted odds ratio of discard that varied from 1.25 (95% confidence interval [95% CI], 1.16 to 1.34) in kidneys with total donor warm ischemic time (WIT) of 10-26 minutes to 2.67 (95% CI, 2.34 to 3.04) in kidneys with total donor WIT >48 minutes. Among the 12,831 DCD kidneys transplanted, kidneys with WIT≤48 minutes had survival similar to that of NBD kidneys. DCD kidneys with WIT>48 minutes had a higher risk of allograft failure (hazard ratio, 1.23; 95% CI, 1.07 to 1.41), but this risk was limited to kidneys with cold ischemia time (CIT) >12 hours. We conclude that donor service area-level variation in the recovery and discard of DCD kidneys is large. Additional national data collection is needed to understand the potential to increase DCD donor transplantation in the United States. Strategies to minimize cold ischemic injury may safely allow increased use of DCD kidneys with WIT>48 minutes.

A Rodent Model of Cardiac Donation After Circulatory Death and Novel Biomarkers of Cardiac Viability During Ex Vivo Heart Perfusion

BACKGROUND

Organ donation after circulatory death (DCD) is increasingly being used as a means of addressing the organ supply/demand mismatch in solid organ transplantation. There is reluctance to use DCD hearts, due to an inability to precisely identify hearts that have suffered irreversible injury. We investigated novel biomarkers and clinically relevant endpoints across a spectrum of warm ischemic times, before and during ex vivo heart perfusion (EVHP), to identify features associated with a nonviable cardiac phenotype.

METHODS

Donor rats sustained a hypoxic cardiac arrest, followed by variable acirculatory standoff periods (DCD groups). Left ventricular function, histochemical injury, and differences in left ventricular gene expression were studied before, and during, EVHP.

RESULTS

As warm ischemic time exposure increased in DCD groups, fewer hearts were functional during EVHP, and ventricular function was increasingly impaired. Histochemical assessment identified severely injured hearts during EVHP. A novel gene expression signature identified severely injured hearts during EVHP (upregulation of c-Jun, 3.19 (2.84-3.60); P = 0.0014; HMOX-1, 3.87 (2.72-5.50); P = 0.0037; and Hsp90, 7.66 (6.32-9.27); P < 0.0001 in DCD20), and may be useful in identifying high-risk hearts at the point of harvest (Hsp90).

CONCLUSIONS

We demonstrate that our preclinical model recapitulates the cardio-respiratory decompensation observed in humans, and that EVHP appears necessary to unmask distinguishing features of severely injured DCD hearts. Furthermore, we outline a clinically relevant multimodal approach to assessing candidate DCD hearts. Novel mRNA signatures correlated with elevations in cardiac Troponin-I in severely injured hearts during EVHP, and may also detect injury at the point of harvest.

Randomized Trial of Machine Perfusion Versus Cold Storage in Recipients of Deceased Donor Kidney Transplants With High Incidence of Delayed Graft Function

BACKGROUND

This study compared the use of static cold storage versus continuous hypothermic machine perfusion in a cohort of kidney transplant recipients at high risk for delayed graft function (DGF).

METHODS

In this national, multicenter, and controlled trial, 80 pairs of kidneys recovered from brain-dead deceased donors were randomized to cold storage or machine perfusion, transplanted, and followed up for 12 months. The primary endpoint was the incidence of DGF. Secondary endpoints included the duration of DGF, hospital stay, primary nonfunction, estimated glomerular filtration rate, acute rejection, and allograft and patient survivals.

RESULTS

Mean cold ischemia time was high but not different between the 2 groups (25.6 ± 6.6 hours vs 25.05 ± 6.3 hours, 0.937). The incidence of DGF was lower in the machine perfusion compared with cold storage group (61% vs. 45%, P = 0.031). Machine perfusion was independently associated with a reduced risk of DGF (odds ratio, 0.49; 95% confidence interval, 0.26-0.95). Mean estimated glomerular filtration rate tended to be higher at day 28 (40.6 ± 19.9 mL/min per 1.73 m² vs 49.0 ± 26.9 mL/min per 1.73 m²; P = 0.262) and 1 year (48.3 ± 19.8 mL/min per 1.73 m² vs 54.4 ± 28.6 mL/min per 1.73 m²; P = 0.201) in the machine perfusion group. No differences in the incidence of acute rejection, primary nonfunction (0% vs 2.5%), graft loss (7.5% vs 10%), or death (8.8% vs 6.3%) were observed.

CONCLUSIONS

In this cohort of recipients of deceased donor kidneys with high mean cold ischemia time and high incidence of DGF, the use of continuous machine perfusion was associated with a reduced risk of DGF compared with the traditional cold storage preservation method.

Effect of Hypothermic Machine Perfusion on the Preservation of Kidneys Donated After Cardiac Death: A Single-Center, Randomized, Controlled Trial

To assess the application of a hypothermic machine perfusion device (LifePort) in kidney transplantation from donation after cardiac death (DCD) donors, 24 pairs of DCD kidneys were randomly divided into two groups: one of the paired kidneys from the same donor was perfused with the LifePort machine (hypothermic machine perfusion [HMP]), and the contralateral kidney was prepared using common static cold preservation (CCP). The two groups were compared with respect to the incidence of delayed graft function (DGF), level of graft function, and pathological changes in time-zero biopsy specimens. The incidence of DGF was 16.7 and 37.5% in the HMP and CCP groups, respectively; the difference between the two groups was statistically significant (P < 0.05). The incidence of acute rejection was 4.1 (1/24) and 8.3% (2/24) in the HMP and CCP groups, respectively; this difference was not statistically significant (P > 0.05). Forty-eight kidney patients were followed up for 6 months, and the two groups of recipients all survived, yielding a survival rate of 100%. The mean 6-month serum creatinine levels were 98.7 ± 23.6 µmol/L in the HMP group and 105.3 ± 35.1 µmol/L in the CCP group; there was no significant difference between the two groups. HMP can reduce the incidence of DGF in DCD kidneys, and this effect is greater for expanded criteria donors kidneys. HMP can also improve early renal function.

Does DCD Donor Time-to-Death Affect Recipient Outcomes? Implications of Time-to-Death at a High-Volume Center in the United States

For donation after circulatory death (DCD), many centers allow 1 h after treatment withdrawal to donor death for kidneys. Our center has consistently allowed 2 h. We hypothesized that waiting longer would be associated with worse outcome. A single-center, retrospective analysis of DCD kidneys transplanted between 2008 and 2013 as well as a nationwide survey of organ procurement organization DCD practices were conducted. We identified 296 DCD kidneys, of which 247 (83.4%) were transplanted and 49 (16.6%) were discarded. Of the 247 recipients, 225 (group 1; 91.1%) received kidneys with a time to death (TTD) of 0-1 h; 22 (group 2; 8.9%) received grafts with a TTD of 1-2 h. Five-year patient survival was 88.8% for group 1, and 83.9% for group 2 (p = 0.667); Graft survival was also similar, with 5-year survival of 74.1% for group 1, and 83.9% for group 2 (p = 0.507). The delayed graft function rate was the same in both groups (50.2% vs. 50.0%, p = 0.984). TTD was not predictive of graft failure. Nationally, the average maximum wait-time for DCD kidneys was 77.2 min. By waiting 2 h for DCD kidneys, we performed 9.8% more transplants without worse outcomes. Nationally, this practice would allow for hundreds of additional kidney transplants, annually.

Allopurinol preconditioning attenuates renal ischemia/reperfusion injury by inhibiting HMGB1 expression in a rat model

PURPOSE

To investigate the potential effects of pretreatment with allopurinol on renal ischemia/reperfusion injury (IRI) in a rat model.

METHODS

Twenty four rats were subjected to right kidney uninephrectomy were randomly distributed into the following three groups (n=8): Group A (sham-operated group); Group B (ischemic group) with 30 min of renal ischemia after surgery; and Group C (allopurinol + ischemia group) pretreated with allopurinol at 50 mg/kg for 14 days. At 72 h after renal reperfusion, the kidney was harvested to assess inflammation and apoptosis.

RESULTS

Pretreatment with allopurinol significantly improved renal functional and histological grade scores following I/R injury (p<0.05). Compared with Group B, the expression levels of caspase-3 and Bax were markedly reduced in Group C, meanwhile, whereas expression of bcl-2 was clearly increased (p<0.05). A newly described marker of inflammation, High Mobility Group Box 1(HMGB1), showed reduced expression in Group C (p<0.05).

CONCLUSION

Pretreatment with allopurinol had a protective effect on kidney ischemia/reperfusion injury, which might be related to the inhibition of HMGB1 expression.

Role of donor hemodynamic trajectory in determining graft survival in liver transplantation from donation after circulatory death donors

Donation after circulatory death (DCD) donors show heterogeneous hemodynamic trajectories following withdrawal of life support. Impact of hemodynamics in DCD liver transplant is unclear, and objective measures of graft viability would ease transplant surgeon decision making and inform safe expansion of the donor organ pool. This retrospective study tested whether hemodynamic trajectories were associated with transplant outcomes in DCD liver transplantation (n = 87). Using longitudinal clustering statistical techniques, we phenotyped DCD donors based on hemodynamic trajectory for both mean arterial pressure (MAP) and peripheral oxygen saturation (SpO₂ ) following withdrawal of life support. Donors were categorized into 3 clusters: those who gradually decline after withdrawal of life support (cluster 1), those who maintain stable hemodynamics followed by rapid decline (cluster 2), and those who decline rapidly (cluster 3). Clustering outputs were used to compare characteristics and transplant outcomes. Cox proportional hazards modeling revealed hepatocellular carcinoma (hazard ratio [HR] = 2.53; P = 0.047), cold ischemia time (HR = 1.50 per hour; P = 0.027), and MAP cluster 1 were associated with increased risk of graft loss (HR = 3.13; P = 0.021), but not SpO₂ cluster (P = 0.172) or donor warm ischemia time (DWIT; P = 0.154). Despite longer DWIT, MAP and SpO₂ clusters 2 showed similar graft survival to MAP and SpO₂ clusters 3, respectively. In conclusion, despite heterogeneity in hemodynamic trajectories, DCD donors can be categorized into 3 clinically meaningful subgroups that help predict graft prognosis. Further studies should confirm the utility of liver grafts from cluster 2. Liver Transplantation 22 1469-1481 2016 AASLD.