Prediction models of donor arrest and graft utilization in liver transplantation from maastricht-3 donors after circulatory death

Predicting time to asystole following withdrawal of life-sustaining treatment: a systematic review

The planned withdrawal of life-sustaining treatment is a common practice in the intensive care unit for patients where ongoing organ support is recognised to be futile. Predicting the time to asystole following withdrawal of life-sustaining treatment is crucial for setting expectations, resource utilisation and identifying patients suitable for organ donation after circulatory death. This systematic review evaluates the literature for variables associated with, and predictive models for, time to asystole in patients managed on intensive care units. We conducted a comprehensive structured search of the MEDLINE and Embase databases. Studies evaluating patients managed on adult intensive care units undergoing withdrawal of life-sustaining treatment with recorded time to asystole were included. Data extraction and PROBAST quality assessment were performed and a narrative summary of the literature was provided. Twenty-three studies (7387 patients) met the inclusion criteria. Variables associated with imminent asystole (<60 min) included: deteriorating oxygenation; absence of corneal reflexes; absence of a cough reflex; blood pressure; use of vasopressors; and use of comfort medications. We identified a total of 20 unique predictive models using a wide range of variables and techniques. Many of these models also underwent secondary validation in further studies or were adapted to develop new models. This review identifies variables associated with time to asystole following withdrawal of life-sustaining treatment and summarises existing predictive models. Although several predictive models have been developed, their generalisability and performance varied. Further research and validation are needed to improve the accuracy and widespread adoption of predictive models for patients managed in intensive care units who may be eligible to donate organs following their diagnosis of death by circulatory criteria.

Liver machine perfusion technology: Expanding the donor pool to improve access to liver transplantation

The imbalance between organ supply and demand continues to limit the broader benefits of organ transplantation. Machine perfusion (MP) may increase the supply of donor livers by expanding the use of extended-criteria donors. Using the United Network for Organ Sharing/Organ Procurement and Transplantation Network and the Standard Transplant Analysis and Research dataset, we reviewed the effect of MP implementation on the behavior of transplant centers. We identified 15 high-utilizing MP centers that were matched to suitable controls based on volume and geographical proximity. We conducted a differences-in-differences analysis using linear regression to estimate the impact of MP adoption on the transplant centers' donor utilization. We found a significant increase in cold ischemia time and organs with donor warm ischemia time over 30 minutes (P < .05). After removing one outlier center, the analysis showed that these centers through MP accepted overall more donation after circulatory death donors, donation after circulatory death donors over 50 years old, donors with macrovesicular steatosis greater than 30% on liver biopsy, and donor warm ischemia time over 30 minutes (P < .05). MP has allowed centers to expand their use of extended-criteria donors beyond traditional cutoffs and to increase patient access to liver transplantation.

Prediction of survival time after terminal extubation: the balance between critical care unit utilization and hospice medicine in the COVID-19 pandemic era

BACKGROUND

We established 1-h and 1-day survival models after terminal extubation to optimize ventilator use and achieve a balance between critical care for COVID-19 and hospice medicine.

METHODS

Data were obtained from patients with end-of-life status at terminal extubation from 2015 to 2020. The associations between APACHE II scores and parameters with survival time were analyzed. Parameters with a p-value ≤ 0.2 in univariate analysis were included in multivariate models. Cox proportional hazards regression analysis was used for the multivariate analysis of survival time at 1 h and 1 day.

RESULTS

Of the 140 enrolled patients, 76 (54.3%) died within 1 h and 35 (25%) survived beyond 24 h. No spontaneous breathing trial (SBT) within the past 24 h, minute ventilation (MV) ≥ 12 L/min, and APACHE II score ≥ 25 were associated with shorter survival in the 1 h regression model. Lower MV, SpO2 ≥ 96% and SBT were related to longer survival in the 1-day model. Hospice medications did not influence survival time.

CONCLUSION

An APACHE II score of ≥ 25 at 1 h and SpO2 ≥ 96% at 1 day were strong predictors of disposition of patients to intensivists. These factors can help to objectively tailor pathways for post-extubation transition and rapidly allocate intensive care unit resources without sacrificing the quality of palliative care in the era of COVID-19. Trial registration They study was retrospectively registered. IRB No.: 202101929B0.

Predicting Time to Death After Withdrawal of Life-Sustaining Treatment in Children

Accurately predicting time to death after withdrawal of life-sustaining treatment is valuable for family counseling and for identifying candidates for organ donation after cardiac death. This topic has been well studied in adults, but literature is scant in pediatrics. The purpose of this report is to assess the performance and clinical utility of the available tools for predicting time to death after treatment withdrawal in children.

Prospective Multicenter Observational Cohort Study on Time to Death in Potential Controlled Donation after Circulatory Death Donors-Development and External Validation of Prediction Models: The DCD III Study

BACKGROUND

Acceptance of organs from controlled donation after circulatory death (cDCD) donors depends on the time to circulatory death. Here we aimed to develop and externally validate prediction models for circulatory death within 1 or 2 h after withdrawal of life-sustaining treatment.

METHODS

In a multicenter, observational, prospective cohort study, we enrolled 409 potential cDCD donors. For model development, we applied the least absolute shrinkage and selection operator (LASSO) regression and machine learning-artificial intelligence analyses. Our LASSO models were validated using a previously published cDCD cohort. Additionally, we validated 3 existing prediction models using our data set.

RESULTS

For death within 1 and 2 h, the area under the curves (AUCs) of the LASSO models were 0.77 and 0.79, respectively, whereas for the artificial intelligence models, these were 0.79 and 0.81, respectively. We were able to identify 4% to 16% of the patients who would not die within these time frames with 100% accuracy. External validation showed that the discrimination of our models was good (AUCs 0.80 and 0.82, respectively), but they were not able to identify a subgroup with certain death after 1 to 2 h. Using our cohort to validate 3 previously published models showed AUCs ranging between 0.63 and 0.74. Calibration demonstrated that the models over- and underestimated the predicted probability of death.

CONCLUSIONS

Our models showed a reasonable ability to predict circulatory death. External validation of our and 3 existing models illustrated that their predictive ability remained relatively stable. We accurately predicted a subset of patients who died after 1 to 2 h, preventing starting unnecessary donation preparations, which, however, need external validation in a prospective cohort.

Development of the Eurotransplant Discard Risk Index to Predict Acceptance of Livers for Transplantation: A Retrospective Database Analysis

OBJECTIVES

The utilization of liver allografts could be optimized if nonacceptance is predicted. This study aimed to evaluate the prognostic ability of an updated Discard Risk Index in Eurotransplant.

MATERIALS AND METHODS

Potential deceased donors from January 2010 to December 2015 who had been reported to Eurotransplant were included in our analyses. Liver utilization was defined by transplant status as the primary outcome to evaluate the performance of the Eurotransplant-developed Discard Risk Index.

RESULTS

Of 11670 potential livers, 9565 (81%) were actually transplanted. Donor sex, age, history of diabetes, drug abuse, use of vasopressors, body mass index category, serum sodium, cause of death, donor type, and levels of C-reactive protein, bilirubin, aspartate and alanine aminotransferases, international normalized ratio, and gamma-glutamyltranspeptidase were associated with discard and combined in the Eurotransplant-developed Discard Risk Index. Correlation between the two Discard Risk Indexes was high (r = 0.86), and both achieved high C statistics of 0.72 and 0.75 (P < .001), respectively. Despite strong calibration, discard rates of 0.8% for overall donors and 6% of donors after circulatory death could be predicted with 80% accuracy.

CONCLUSIONS

The Eurotransplant-developed Discard Risk Index showed a high prognostic ability to predict liver utilization in a European setting. The model could therefore be valuable for identifying livers at high risk of not being transplanted in an early stage. These organs might profit the most from modified allocation strategies or advanced preservation techniques.

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.

Improving the predictability of time to death in controlled donation after circulatory death lung donors

Although the use of donation after circulatory death (DCD) donors has increased lung transplant activity, 25-40% of intended DCD donors do not convert to actual donation because of no progression to asystole in the required time frame after withdrawal of cardiorespiratory support (WCRS). No studies have specifically focussed on DCD lung donor progression. This retrospective study reviewed intended DCD lung donors to make a prediction model of the likelihood of progression to death using logistic regression and classification and regression tree (CART). Between 2014 and 2018, 159 of 334 referred DCD donors were accepted, with 100 progressing to transplant, while 59 (37%) did not progress. In logistic regression, a length of ICU stay ≤ 5 days, severe infra-tentorial brain damage on imaging and use of vasopressin were related with the progression to actual donation. CART modelling of the likelihood of death within 90-minute post-WCRS provided prediction with a sensitivity of 1.00 and positive predictive value of 0.56 in the validation data set. In the nonprogressed DCD group, 26 died within 6 h post-WCRS. Referral received early after ICU admission, with nonspontaneous ventilatory mode, deep coma and severe infra-tentorial damage were relevant predictors. The CART model is useful to exclude DCD donor candidates with low probability of progression.

Machine Learning to Predict Cardiac Death Within 1 Hour After Terminal Extubation

OBJECTIVES

Accurate prediction of time to death after withdrawal of life-sustaining therapies may improve counseling for families and help identify candidates for organ donation after cardiac death. The study objectives were to: 1) train a long short-term memory model to predict cardiac death within 1 hour after terminal extubation, 2) calculate the positive predictive value of the model and the number needed to alert among potential organ donors, and 3) examine associations between time to cardiac death and the patient's characteristics and physiologic variables using Cox regression.

DESIGN

Retrospective cohort study.

SETTING

PICU and cardiothoracic ICU in a tertiary-care academic children's hospital.

PATIENTS

Patients 0-21 years old who died after terminal extubation from 2011 to 2018 (n = 237).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The median time to death for the cohort was 0.3 hours after terminal extubation (interquartile range, 0.16-1.6 hr); 70% of patients died within 1 hour. The long short-term memory model had an area under the receiver operating characteristic curve of 0.85 and a positive predictive value of 0.81 at a sensitivity of 94% when predicting death within 1 hour of terminal extubation. About 39% of patients who died within 1 hour met organ procurement and transplantation network criteria for liver and kidney donors. The long short-term memory identified 93% of potential organ donors with a number needed to alert of 1.08, meaning that 13 of 14 prepared operating rooms would have yielded a viable organ. A Cox proportional hazard model identified independent predictors of shorter time to death including low Glasgow Coma Score, high Pao2-to-Fio2 ratio, low-pulse oximetry, and low serum bicarbonate.

CONCLUSIONS

Our long short-term memory model accurately predicted whether a child will die within 1 hour of terminal extubation and may improve counseling for families. Our model can identify potential candidates for donation after cardiac death while minimizing unnecessarily prepared operating rooms.

Prediction Model for Timing of Death in Potential Donors After Circulatory Death (DCD III): Protocol for a Multicenter Prospective Observational Cohort Study

Background

Controlled donation after circulatory death (cDCD) is a major source of organs for transplantation. A potential cDCD donor poses considerable challenges in terms of identification of those dying within the predefined time frame of warm ischemia after withdrawal of life-sustaining treatment (WLST) to circulatory arrest. Several attempts have been made to develop models predicting the time between treatment withdrawal and circulatory arrest. This time window determines whether organ donation can occur and influences the quality of the donated organs. However, the selected patients used for these models were not always restricted to potential cDCD donors (eg, patients with cancer or severe infections were also included). This severely limits the generalizability of those data.

Objective

The objectives of this study are the following: (1) to develop a model predicting time to death within 60 minutes in potential cDCD patients; (2) to validate and update previous prediction models on time to death after WLST; (3) to determine timing and patient characteristics that are associated with prognostication and the decision-making process that leads to initiating end-of-life care; (4) to evaluate the impact of timing of family approach on organ donation approval; and (5) to assess the influence of variation in WLST processes on postmortem organ donor potential and actual postmortem organ donors.

Methods

In this multicenter observational prospective cohort study, all patients admitted to the intensive care unit of 3 university hospitals and 3 teaching hospitals who met the criteria of the cDCD protocol as defined by the Dutch Transplant Foundation were included. The target of enrolment was set to 400 patients. Previously developed models will be refitted in our data set. To further update previous prediction models, we will apply least absolute shrinkage and selection operator (LASSO) as a tool for efficient variable selection to develop the multivariable logistic regression model.

Results

This protocol was funded in August 2014 by the Dutch Transplant Foundation. We expect to have the results of this study in July 2020. Patient enrolment was completed in July 2018 and data collection was completed in April 2020.

Conclusions

This study will provide a robust multimodal prediction model, based on clinical and physiological parameters, that can predict time to circulatory arrest in cDCD donors. In addition, it will add valuable insight in the process of WLST in cDCD donors and will fill an important knowledge gap in this essential field of health care.

Trial Registration

ClinicalTrials.gov NCT04123275; https://clinicaltrials.gov/ct2/show/NCT04123275

International Registered Report Identifier (IRRID)

DERR1-10.2196/16733

Combined lung and liver procurement in controlled donation after circulatory death using normothermic abdominal perfusion. Initial experience in two Spanish centers

Combining simultaneously lung and liver procurement in controlled donation after circulatory death (cDCD) using normothermic abdominal perfusion (NRP) for abdominal grafts and cooling and rapid recovery technique (RR) for the lungs increases the complexity of the procurement procedure and might injure the grafts. A total of 19 cDCDs from two centers using this combined procedure were evaluated, and 16 liver and 21 lung transplantations were performed. As controls, 34 donors after brain death (DBDs) were included (29 liver and 41 lung transplantations were performed). Two cDCD liver recipients developed primary nonfunction (12.5%). No cases of ischemic cholangiopathy were observed among cDCD recipients. The 1-year and 2-year liver recipients survival was 87.5% and 87.5% for the cDCD group, and 96% and 84.5% for the DBD group, respectively (P = .496). The 1-year and 2-year lung recipients survival was 84% and 84% for the cDCD group and 90% and 90% for the DBD group, respectively (P = .577). This is the largest experience ever reported in cDCD with the use of NRP combined with RR of the lungs. This combined method offers an outstanding recovery rate and liver and lung recipients survival comparable with those transplanted with DBDs. Further studies are needed to confirm our findings.

Normothermic regional perfusion vs. super-rapid recovery in controlled donation after circulatory death liver transplantation

BACKGROUND & AIMS

Although there is increasing interest in its use, definitive evidence demonstrating a benefit for postmortem normothermic regional perfusion (NRP) in controlled donation after circulatory death (cDCD) liver transplantation is lacking. The aim of this study was to compare results of cDCD liver transplants performed with postmortem NRP vs. super-rapid recovery (SRR), the current standard for cDCD.

METHODS

This was an observational cohort study including all cDCD liver transplants performed in Spain between June 2012 and December 2016, with follow-up ending in December 2017. Each donor hospital determined whether organ recovery was performed using NRP or SRR. The propensity scores technique based on the inverse probability of treatment weighting (IPTW) was used to balance covariates across study groups; logistic and Cox regression models were used for binary and time-to-event outcomes.

RESULTS

During the study period, there were 95 cDCD liver transplants performed with postmortem NRP and 117 with SRR. The median donor age was 56 years (interquartile range 45-65 years). After IPTW analysis, baseline covariates were balanced, with all absolute standardised differences <0.15. IPTW-adjusted risks were significantly improved among NRP livers for overall biliary complications (odds ratio 0.14; 95% CI 0.06-0.35, p <0.001), ischaemic type biliary lesions (odds ratio 0.11; 95% CI 0.02-0.57; p = 0.008), and graft loss (hazard ratio 0.39; 95% CI 0.20-0.78; p = 0.008).

CONCLUSIONS

The use of postmortem NRP in cDCD liver transplantation appears to reduce postoperative biliary complications, ischaemic type biliary lesions and graft loss, and allows for the transplantation of livers even from cDCD donors of advanced age.

LAY SUMMARY

This is a propensity-matched nationwide observational cohort study performed using livers recovered from donors undergoing cardiac arrest provoked by the intentional withdrawal of life support (controlled donation after circulatory death, cDCD). Approximately half of the livers were recovered after a period of postmortem in situ normothermic regional perfusion, which restored warm oxygenated blood to the abdominal organs, whereas the remainder were recovered after rapid preservation with a cold solution. The study results suggest that the use of postmortem normothermic regional perfusion helps reduce rates of post-transplant biliary complications and graft loss and allows for the successful transplantation of livers from older cDCD donors.

Rescue of Discarded Grafts for Liver Transplantation by Ex Vivo Subnormothermic and Normothermic Oxygenated Machine Perfusion: First Experience in Spain

BACKGROUND

Ex vivo machine perfusion (MP) has been reported as a possibly method to rescue discarded organs. The main aim of this study was to report an initial experience in Spain using MP for the rescue of severely marginal discarded liver grafts, and to, secondarily, define markers of viability to test the potential applicability of these devices for the real increase in the organ donor pool.

METHODS

The study began in January 2016. Discarded grafts were included in a research protocol that consisted of standard retrieval followed by 10 hours of cold ischemia. Next, either normothermic (NMP) or controlled subnormothermic (subNMP) rewarming was chosen randomly. Continuous measurements of portal-arterial pressure and resistance were screened. Lactate, pH, and bicarbonate were measured every 30 minutes. The perfusion period was 6 hours, after which the graft was discarded and evaluated as potentially usable, but never implanted. Biopsies of the donor and at 2, 4, and 6 hours after ex vivo MP were obtained.

RESULTS

A total of 4 grafts were included in the protocol. The first 2 grafts were perfused by NMP and grafts 3 and 4 by subNMP. The second and third grafts showed a clear trend toward optimal recovery and may have been used. Lactate dropped to levels below 2.5 mmol/L with stable arterial and portal pressure and resistance. Clear biliary output started during MP. Biopsies showed an improvement of liver architecture with reduced inflammation at the end of the perfusion.

CONCLUSION

This preliminary experience has demonstrated the potential of MP devices for the rescue of severely marginal liver grafts. Lactate and biliary output were useful for viability testing of the grafts. The utility of NMP or subNMP protocols requires further research.

Heparin but not tissue plasminogen activator improves outcomes in donation after circulatory death liver transplantation in a porcine model

Ischemic-type biliary lesions (ITBLs) arise most frequently after donation after circulatory death (DCD) liver transplantation and result in high morbidity and graft loss. Many DCD grafts are discarded out of fear for this complication. In theory, microvascular thrombi deposited during donor warm ischemia might be implicated in ITBL pathogenesis. Herein, we aim to evaluate the effects of the administration of either heparin or the fibrinolytic drug tissue plasminogen activator (TPA) as means to improve DCD liver graft quality and potentially avoid ITBL. Donor pigs were subjected to 1 hour of cardiac arrest (CA) and divided among 3 groups: no pre-arrest heparinization nor TPA during postmortem regional perfusion; no pre-arrest heparinization but TPA given during regional perfusion; and pre-arrest heparinization but no TPA during regional perfusion. In liver tissue sampled 1 hour after CA, fibrin deposition was not detected, even when heparin was not given prior to arrest. Although it was not useful to prevent microvascular clot formation, pre-arrest heparin did offer cytoprotective effects during CA and beyond, reflected in improved flows during regional perfusion and better biochemical, functional, and histological parameters during posttransplantation follow-up. In conclusion, this study demonstrates the lack of impact of TPA use in porcine DCD liver transplantation and adds to the controversy over whether the use of TPA in human DCD liver transplantation really offers any protective effect. On the other hand, when it is administered prior to CA, heparin does offer anti-inflammatory and other cytoprotective effects that help improve DCD liver graft quality. Liver Transplantation 24 665-676 2018 AASLD.

External validation of prediction models for time to death in potential donors after circulatory death

Predicting time to death in controlled donation after circulatory death (cDCD) donors following withdrawal of life-sustaining treatment (WLST) is important but poses a major challenge. The aim of this study is to determine factors predicting time to circulatory death within 60 minutes after WSLT and validate previously developed prediction models. In a single-center retrospective study, we used the data of 92 potential cDCD donors. Multivariable regression analysis demonstrated that absent cough-, corneal reflex, lower morphine dosage, and midazolam use were significantly associated with death within 60 minutes (area under the curve [AUC] 0.89; 95% confidenence interval [CI] 0.87-0.91). External validation of the logistic regression models of de Groot et al (AUC 0.86; 95% CI 0.77-0.95), Wind et al (AUC 0.62; 95% CI 0.49-0.76), Davila et al (AUC 0.80; 95% CI 0.708-0.901) and the Cox regression model by Suntharalingam et al (Harrell's c-index 0.63), exhibited good discrimination and could fairly identify which patients died within 60 minutes. Previous prediction models did not incorporate the process of WLST. We believe that future studies should also include the process of WLST as an important predictor.

Development and Validation of a Nomogram for Predicting Incidence of Early Allograft Dysfunction Following Liver Transplantation

OBJECTIVE

Early allograft dysfunction (EAD) is frequent complication post-liver transplantation and is closely related to recipient's mortality and morbidity. We sought to develop a nomogram for predicting incidence of EAD.

METHODS

Based on multivariate analysis of donor, recipient, and operation data of 199 liver transplants from deceased donors between 2013 and 2015, we identified 5 significant risk factors for EAD to build a nomogram. The model was subjected to prospective validation with a cohort of 42 patients who was recruited between January and June 2016. The predictive accuracy and discriminative ability were measured by area under the receiver operating characteristic curve (AUC). The agreement between nomogram prediction and actual observation was showed by the calibration curve.

RESULTS

Incidence rate of EAD in the training set and validation cohort were 55.91% (104/199) and 54.76% (23/42), respectively. In the training set, according to the results of univariable and multivariable analysis, 5 independent risk factors including donor gender, donor serum gamma-glutamyl transpeptidase level, donor serum urea level, donor comorbidities (respiratory, cardiac, and renal dysfunction), and recipient Model for End-stage Liver Disease score were identified and assembled into the nomogram. The AUC of internal validation using bootstrap resampling and prospective validation using the external cohort of 42 patients was 0.74 and 0.60, respectively. The calibration curves for probability of EAD showed acceptable agreement between nomogram prediction and actual observation. According to the score table, the probability of EAD was under 30% when the total point tally was under 72. But when the total was up to 139, the risk of EAD increased to 60%.

CONCLUSION

We've established and validated a nomogram that can provide individual prediction of EAD for liver transplant recipients. The practical prognostic model may help clinicians to qualify the liver graft accurately, making a more reasonable allocation of organs.

A few realistic questions raised by organ retrieval in the intensive care unit

Organ transplantation saves the lives of many persons who would otherwise die from end-stage organ disease. The increasing demand for donated organs has led to a renewed interest in donation after circulatory determination of death (CDD). In many countries (including France), terminally ill patients who die of circulatory arrest after a planned withdrawal of life support may be considered as organ donors under certain conditions. While having equal responsibility towards the potential donor and the persons awaiting a transplant, caregivers may experience an ethical dilemma between the responsibility to deliver the best care to the dying, and the need to retrieve the organs. Once it has been established that the patient wishes to be a donor, we assume that end-of-life care and organ donation may have convergent goals when they contribute to transforming a comfortable death into a chance of life for others in need.

Prediction of potential for organ donation after circulatory death in neurocritical patients

BACKGROUND

The success or failure of donation after circulatory death depends largely on the functional warm ischemia time, which is closely related to the duration between withdrawal of life-sustaining treatment and circulatory arrest. However, a reliable predictive model for the duration is absent. We aimed to compare the performance of the Chinese Donation after Circulatory Death Nomogram (C-DCD-Nomogram) and 3 other tools in a cohort of potential donors.

METHODS

In this prospective, multicenter, observational study, data were obtained from 219 consecutive neurocritical patients in China. The patients were followed until circulatory death after withdrawal of life-sustaining treatment.

RESULTS

The C-DCD-Nomogram performed well in predicting patient death within 30, 60, 120 and 240 minutes after withdrawal of life-sustaining treatment with c-statistics of 0.87, 0.88, 0.86 and 0.95, respectively. The DCD-N score was a poor predictor of death within 30, 60 and 240 minutes, with c-statistics of 0.63, 0.69 and 0.59, respectively, although it was able to predict patient death within 120 minutes, with a c-statistic of 0.73. Neither the University of Wisconsin DCD evaluation tool (UWDCD) nor the United Network for Organ Sharing (UNOS) criteria was able to predict patient death within 30, 60, 120 and 240 minutes after withdrawal of life-sustaining treatment (UWDCD tool: 0.48, 0.45, 0.49 and 0.57; UNOS criteria: 0.50, 0.53, 0.51 and 0.63).

CONCLUSION

The C-DCD-Nomogram is superior to the other 3 tools for predicting death within a limited duration after withdrawal of life-sustaining treatment in Chinese neurocritical patients. Thus, it appears to be a reliable tool identifying potential donors after circulatory death.

Developing a donation after cardiac death risk index for adult and pediatric liver transplantation

AIM

To identify objective predictive factors for donor after cardiac death (DCD) graft loss and using those factors, develop a donor recipient stratification risk predictive model that could be used to calculate a DCD risk index (DCD-RI) to help in prospective decision making on organ use.

METHODS

The model included objective data from a single institute DCD database (2005-2013, n = 261). Univariate survival analysis was followed by adjusted Cox-regressional hazard model. Covariates selected via univariate regression were added to the model via forward selection, significance level P = 0.3. The warm ischemic threshold was clinically set at 30 min. Points were given to each predictor in proportion to their hazard ratio. Using this model, the DCD-RI was calculated. The cohort was stratified to predict graft loss risk and respective graft survival calculated.

RESULTS

DCD graft survival predictors were primary indication for transplant (P = 0.066), retransplantation (P = 0.176), MELD > 25 (P = 0.05), cold ischemia > 10 h (P = 0.292) and donor hepatectomy time > 60 min (P = 0.028). According to the calculated DCD-RI score three risk classes could be defined of low (DCD-RI < 1), standard (DCD-RI 2-4) and high risk (DCD-RI > 5) with a 5 years graft survival of 86%, 78% and 34%, respectively.

CONCLUSION

The DCD-RI score independently predicted graft loss (P < 0.001) and the DCD-RI class predicted graft survival (P < 0.001).

Can we prevent ischemic-type biliary lesions in donation after circulatory determination of death liver transplantation?

The pool of livers for transplantation consists of an increasingly greater proportion of marginal grafts, in particular those arising through donation after circulatory determination of death (DCD). However, a primary factor limiting the use of marginal livers, and, thereby, the applicability of liver transplantation in general, is concern over the subsequent development of ischemic-type biliary lesion (ITBL). ITBL is a devastating complication of liver transplantation; in its most severe forms, recipients suffer frequent infectious complications that require repeated invasive biliary procedures and ultimately result in either retransplantation or death. In the present review article, we discuss our current understanding of ITBL pathogenesis as it pertains to DCD, in particular. We discuss the most relevant theories regarding its development and provide a comprehensive overview of the most promising strategies we have available today to prevent the appearance of ITBL, strategies that may, furthermore, allow us to transplant a greater proportion of marginal livers in the future. Liver Transplantation 22 1025-1033 2016 AASLD.

Predicting time to death after withdrawal of life-sustaining therapy

PURPOSE

Predicting time to death following the withdrawal of life-sustaining therapy is difficult. Accurate predictions may better prepare families and improve the process of donation after circulatory death.

METHODS

We systematically reviewed any predictive factors for time to death after withdrawal of life support therapy.

RESULTS

Fifteen observational studies met our inclusion criteria. The primary outcome was time to death, which was evaluated to be within 60 min in the majority of studies (13/15). Additional time endpoints evaluated included time to death within 30, 120 min, and 10 h, respectively. While most studies evaluated risk factors associated with time to death, a few derived or validated prediction tools. Consistent predictors of time to death that were identified in five or more studies included the following risk factors: controlled ventilation, oxygenation, vasopressor use, Glasgow Coma Scale/Score, and brain stem reflexes. Seven unique prediction tools were derived, validated, or both across some of the studies. These tools, at best, had only moderate sensitivity to predicting the time to death. Simultaneous withdrawal of all support and physician opinion were only evaluated in more recent studies and demonstrated promising predictor capabilities.

CONCLUSIONS

While the risk factors controlled ventilation, oxygenation, vasopressors, level of consciousness, and brainstem reflexes have been most consistently found to be associated with time to death, the addition of novel predictors, such as physician opinion and simultaneous withdrawal of all support, warrant further investigation. The currently existing prediction tools are not highly sensitive. A more accurate and generalizable tool is needed to inform end-of-life care and enhance the predictions of donation after circulatory death eligibility.

Biomarkers to assess graft quality during conventional and machine preservation in liver transplantation

A global rising organ shortage necessitates the use of extended criteria donors (ECD) for liver transplantation (LT). However, poor preservation and extensive ischemic injury of ECD grafts have been recognized as important factors associated with primary non-function, early allograft dysfunction, and biliary complications after LT. In order to prevent for these ischemia-related complications, machine perfusion (MP) has gained interest as a technique to optimize preservation of grafts and to provide the opportunity to assess graft quality by screening for extensive ischemic injury. For this purpose, however, objective surrogate biomarkers are required which can be easily determined at time of graft preservation and the various techniques of MP. This review provides an overview and evaluation of biomarkers that have been investigated for the assessment of graft quality and viability testing during different types of MP. Moreover, studies regarding conventional graft preservation by static cold storage (SCS) were screened to identify biomarkers that correlated with either allograft dysfunction or biliary complications after LT and which could potentially be applied as predictive markers during MP. The pros and cons of the different biomaterials that are available for biomarker research during graft preservation are discussed, accompanied with suggestions for future research. Though many studies are currently still in the experimental setting or of low evidence level due to small cohort sizes, the biomarkers presented in this review provide a useful handle to monitor recovery of ECD grafts during clinical MP in the near future.

Improving outcomes in DCDD liver transplantation: there can only be strength in numbers

In the United States, liver transplantation using donation after circulatory determination of death (DCDD) donors is challenged by persistently inferior graft survival compared with donation after neurological death (DND), along with declining rates of liver transplantation relative to the total number of DCDD donors. Advances in adult-to-adult living donor liver transplantation graft survival temporally related to the Adult-to-Adult Living Donor Liver Transplantation Cohort Study consortium suggest that a similarly focused collaborative effort may serve to stimulate evolution within DCDD liver transplantation. Without a multi-center consortium to support innovative trials, the current state of DCDD liver transplantation is unlikely to progress.

Donation after circulatory death: current status

PURPOSE OF REVIEW

Donor shortage has forced transplant teams to explore new methods to increase the potential donor pool. Donation after circulatory death (DCD) has opened new perspectives and could be a valuable option to expand the brain-dead donors. The purpose of this review is to provide an overview of current practice and to identify remaining questions related to ethical and medical issues that should be further addressed in the future.

RECENT FINDINGS

Recent findings demonstrate acceptable outcomes after DCD kidney and lung transplantation but inferior graft survival for liver transplantation. The impact and importance of the agonal phase following withdrawal of treatment in controlled DCD is increasingly recognized. Premortem interventions are currently under debate related to preservation strategies or comfort therapy. New preservation strategies using in-situ/in-vivo extracorporeal membrane oxygenation or ex-vivo machine perfusion have large potential in the future. Finally, organizations and institutions are reporting more uniform guidelines related to declaration of death and DCD organ procurement.

SUMMARY

DCD donation has regained much attention during the last decade and is now part of standard clinical practice albeit this type of donation should not be regarded as an equally acceptable alternative for donation after brain death. It will be important to further explore the potential of DCD, to monitor the long-term outcomes and to further optimize the quality of these grafts. Development and implementation of uniform guidelines will be necessary to guarantee the clinical use of these donor pools.

Obstacles of non-heart-beating donor kidney transplantation in Japan to date and future perspectives

In Japan, multiple organ retrieval from brain-dead heart-beating donors has been gradually increasing since the law was adopted in 1997 and amended in 2009. However, almost more than 90% of total deceased donor kidney transplantation (DDKT) in Japan are still obtained from non-heart-beating donors (NHBD). The majority of NHBD are Maastricht categories IV and III. In category IV, we usually place a double balloon arterial and a venous drainage catheter via the femoral vessels after the diagnosis of clinical brain death and acquisition of informed consent from the family. After controlled cardiac arrest, the double balloons are inflated and in situ cold perfusion started as soon as possible to minimize warm ischemic time (WIT), seeking to achieve a zero to within a few minutes WIT in most cases. In category III, it is impossible to place the device prior to cardiac arrest. In these cases, after declaration of cardiac death, cardiopulmonary compression is accompanied by systemic heparinization, immediate laparotomy, and insertion of a cold perfusion catheter at the aortic and caval bifurcations to minimize WIT. NHBD kidney retrieval is critical; extirpation must be performed as rapidly as possible. The results of NHBD kidney transplantation in Japan are excellent, according to the advancement and utilization of in situ cannulation, organ perfusion, and sophisticated retrieval techniques. The patient and graft survival rates of DDKT at 1, 3, and 5 years in most recent 2001 to 2007 era were 95.4%, 92.2%, 89.1% (n = 945) and 89.2%, 83.7%, 77.8% (n = 919), respectively.

No-touch time in donors after cardiac death (nonheart-beating organ donation)

PURPOSE OF REVIEW

To evaluate arterial pulselessness and the no-touch time of 5 min in defining irreversible cessation of cardiorespiratory functions in nonheart-beating donation (NHBD).

RECENT FINDINGS

Experimental NHBD studies identified compensatory neurohumoral mechanisms elicited in controlled terminal shock after withdrawal of life support. The neurohumoral mechanisms can preserve the viability of the cardiovascular and central nervous systems by: 1) diverting systemic blood flow from nonvital to vital organs; and 2) maintaining the perfusion pressure (arterial to venous pressure gradient minus interstitial tissue pressure) and microcirculation in vital organs. These compensatory mechanisms cause an early onset of splanchnic hypoperfusion and antemortem ischaemia of transplantable organs and preclude irreversible cessation of cardiorespiratory functions after brief periods of circulatory arrest. Allograft ischaemia is associated with primary nonfunction or delayed function in transplant recipients similar in aetiology to organ dysfunction in the postresuscitation phase of shock.

SUMMARY

In-situ perfusion can reverse ceased cardiac and neurological functions after arterial pulselessness and a no-touch time of 5 min in experimental models. Perfusion pressures are superior to arterial pulselessness in determining reversibility of ceased cardiac and neurological functions in circulatory arrest. Utilizing physiologically relevant circulatory and neurological parameters in NHBD protocols is essential for ascertaining irreversible cessation of vital functions in donors.

Time to death after withdrawal of treatment in donation after circulatory death (DCD) donors

PURPOSE

Controlled donation after circulatory death (DCD) donors make an important contribution to organ transplantation but there is considerable scope for further increasing the conversion of potential to actual DCD organ donors. The period between withdrawal of life-supporting treatment and death (the withdrawal period) is a major determinant of whether organ donation proceeds and it is therefore timely to review recent relevant studies in this area.

RECENT FINDINGS

The duration and haemodynamic nature of the withdrawal period is extremely variable, and clinical guidelines for management of the potential donor during this period differ widely. Recent evidence suggests that kidneys from DCD donors with a prolonged withdrawal period can be used to increase the number of transplants performed and provide satisfactory graft function, suggesting that it is not the duration but the haemodynamic profile of the donor during this phase that are important. This suggestion questions the relevance of clinical indices predicting death within 1 h of treatment withdrawal.

SUMMARY

Future studies should aim to define clinical and physiological variables during the withdrawal period that can be used to maximize well tolerated use of organs from potential DCD donors; these thresholds are likely to differ according to organ type.