Characterization of the withdrawal phase in a porcine donation after the cardiac death model

Does Time to Asystole in Donors After Circulatory Death Impact Recipient Outcome in Liver Transplantation?

BACKGROUND

The agonal phase can vary following treatment withdrawal in donor after circulatory death (DCD). There is little evidence to support when procurement teams should stand down in relation to donor time to death (TTD). We assessed what impact TTD had on outcomes following DCD liver transplantation.

METHODS

Data were extracted from the UK Transplant Registry on DCD liver transplant recipients from 2006 to 2021. TTD was the time from withdrawal of life-sustaining treatment to asystole, and functional warm ischemia time was the time from donor systolic blood pressure and/or oxygen saturation falling below 50 mm Hg and 70%, respectively, to aortic perfusion. The primary endpoint was 1-y graft survival. Potential predictors were fitted into Cox proportional hazards models. Adjusted restricted cubic spline models were generated to further delineate the relationship between TTD and outcome.

RESULTS

One thousand five hundred fifty-eight recipients of a DCD liver graft were included. Median TTD in the entire cohort was 13 min (interquartile range, 9-17 min). Restricted cubic splines revealed that the risk of graft loss was significantly greater when TTD ≤14 min. After 14 min, there was no impact on graft loss. Prolonged hepatectomy time was significantly associated with graft loss (hazard ratio, 1.87; 95% confidence interval, 1.23-2.83; P = 0.003); however, functional warm ischemia time had no impact (hazard ratio, 1.00; 95% confidence interval, 0.44-2.27; P > 0.9).

CONCLUSIONS

A very short TTD was associated with increased risk of graft loss, possibly because of such donors being more unstable and/or experiencing brain stem death as well as circulatory death. Expanding the stand down times may increase the utilization of donor livers without significantly impairing graft outcome.

Biomarkers of Early Liver Graft Damage in Circulatory Death and Brain Death Donors: A Propensity Score Matching Analysis

BACKGROUND

Donation after circulatory death (DCD) is related to a warm ischemia time and more complications compared with traditional donors (donation after brain death [DBD]).

METHODS

This study included biopsy samples retrospectively collected from November 2014 to December 2018 to compare histologic and biological markers of DCD and DBD liver grafts. The analysis includes marker of early apoptosis (p21), senescence (telomerase reverse transcriptase [TERT]), cell damage (caspase-3 active), endothelial damage (vascular endothelial growth factor), stem cell (CD90), hypoxia (HIF1A), inflammatory activation (COX-2), and cross-organ allograft rejection (CD44). A propensity score matching (PSM) was used to match patients receiving DCD livers to those receiving DBD livers. We analyzed the immunohistochemical initial liver damage-related warm ischemia time.

RESULTS

Positive staining expression of liver damage biomarkers (COX-2, CD44, TERT, HIF1A, and CD90) was found, but no significant differences were found between DCD and DBD and with ischemic cholangiopathy. After PSM, there was a significant relationship between CD90 and male donors (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.07-0.91), TERT with donor sodium (OR, 1.11; 95% CI, 1.02-1.2), HIF1A with steatosis (OR, 0.33; 95% CI, 0.13-0.83), and CD44 with donor vasoactive drugs (OR, 0.36; 95% CI, 0.13-1) and glutamic oxaloacetic transaminase 1 week increase (OR, 1.01; 95% CI, 1-1.03).

CONCLUSIONS

DCD immunohistochemical initial liver damage was found to behave similarly to DBD. The increase in complications and cholangiopathy associated with warm ischemia could be related to a different later phenomenon.

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.

Evaluation of Liver Quality after Circulatory Death Versus Brain Death: A Comparative Preclinical Pig Model Study

The current organ shortage in hepatic transplantation leads to increased use of marginal livers. New organ sources are needed, and deceased after circulatory death (DCD) donors present an interesting possibility. However, many unknown remains on these donors and their pathophysiology regarding ischemia reperfusion injury (IRI). Our hypothesis was that DCD combined with abdominal normothermic regional recirculation (ANOR) is not inferior to deceased after brain death (DBD) donors. We performed a mechanistic comparison between livers from DBD and DCD donors in a highly reproducible pig model, closely mimicking donor conditions encountered in the clinic. DCD donors were conditioned by ANOR. We determined that from the start of storage, pro-lesion pathways such as oxidative stress and cell death were induced in both donor types, but to a higher extent in DBD organs. Furthermore, pro-survival pathways, such as resistance to hypoxia and regeneration showed activation levels closer to healthy livers in DCD-ANOR rather than in DBD organs. These data highlight critical differences between DBD and DCD-ANOR livers, with an apparent superiority of DCD in terms of quality. This confirms our hypothesis and further confirms previously demonstrated benefits of ANOR. This encourages the expended use of DCD organs, particularly with ANOR preconditioning.

The Impact of Hepatectomy Time of the Liver Graft on Post-transplant Outcome: A Eurotransplant Cohort Study

OBJECTIVE

Assessing the effect of donor hepatectomy time on outcome after transplantation.

SUMMARY OF BACKGROUND DATA

When blood supply in a deceased organ donor stops, ischemic injury starts. Livers are cooled to reduce cellular metabolism and minimize ischemic injury. This cooling is slow and livers are lukewarm during hepatectomy, potentially affecting outcome.

METHODS

We used the Eurotransplant Registry to investigate the relationship between donor hepatectomy time and post-transplant outcome in 12,974 recipients of deceased-donor livers (January 1, 2004, to December 31, 2013). Cox regression analyses for patient and graft survival (censored and uncensored for death with a functioning graft) were corrected for donor, preservation, and recipient variables. Donor hepatectomy time was defined as time between start of aortic cold flush and placement of the liver in the ice-bowl.

RESULTS

Median donor hepatectomy time was 41 minutes [interquartile range (IQR) 32 to 52]. Livers donated after circulatory death had longer hepatectomy times than those from brain-dead donors [50 minutes (35 to 68) vs 40 minutes (32 to 51), P < 0.001]. Donor hepatectomy time was independently associated with graft loss [adjusted hazard ratio (HR) 1.03 for every 10-minute increase, 95% confidence interval (95% CI) 1.02-1.05; P < 0.001]. The magnitude of this effect was comparable to the effect of each hour of additional cold ischemia time (adjusted HR 1.04, 95% CI 1.02-1.05; P < 0.001). Donor hepatectomy time had a similar effect on death-censored graft survival and patient survival. Livers donated after circulatory death and those with a higher donor risk index were more susceptible to the effect of donor hepatectomy time on death-censored graft survival.

CONCLUSION

Donor hepatectomy time impairs liver transplant outcome. Keeping this time short together with efficient cooling during hepatectomy might improve outcome.

Effect of donor nephrectomy time during circulatory-dead donor kidney retrieval on transplant graft failure

Background

When the blood supply ceases in a deceased organ donor, ischaemic injury starts. Kidneys are cooled to reduce cellular metabolism and minimize ischaemic injury. This cooling is slow and kidneys are lukewarm during nephrectomy. Smaller single-centre studies have shown that prolonged donor nephrectomy time decreases early kidney transplant function, but the effect on long-term outcome has never been investigated in large multicentre cohort studies.

Methods

The relationship between donor nephrectomy time and death-censored graft survival was evaluated in recipients of single adult-to-adult, first-time deceased-donor kidneys transplanted in the Eurotransplant region between 2004 and 2013.

Results

A total of 13 914 recipients were included. Median donor nephrectomy time was 51 (i.q.r. 39–65) min. Kidneys donated after circulatory death had longer nephrectomy times than those from brain-dead donors: median 57 (43–78) versus 50 (39–64) min respectively (P &lt; 0·001). Donor nephrectomy time was independently associated with graft loss when kidneys were donated after circulatory death: adjusted hazard ratio (HR) 1·05 (95 per cent c.i. 1·01 to 1·09) per 10-min increase (P = 0·026). The magnitude of this effect was comparable to the effect of each hour of additional cold ischaemia: HR 1·04 (1·01 to 1·07) per h (P = 0·004). For kidneys donated after brain death, there was no effect of nephrectomy time on graft survival: adjusted HR 1·01 (0·98 to 1·04) per 10 min (P = 0·464).

Conclusion

Prolonged donor nephrectomy time impairs graft outcome in kidneys donated after circulatory death. Keeping this short, together with efficient cooling during nephrectomy, might improve outcome.

Heterogeneity of Bile Duct Management in the Development of Ischemic Cholangiopathy After Liver Transplantation: Results of a European Liver and Intestine Transplant Association Survey

BACKGROUND

Surgical factors and direct cytotoxicity of bile salts on cholangiocytes may play a role in the development of ischemic cholangiopathy (IC) after liver transplantation (LTx). There is no validated consensus on how to protect the bile ducts during procurement, static preservation, and LTx. Meanwhile, IC remains the most troublesome complication after LTx.

AIM

To characterize bile duct management techniques during the LTx process among European transplant centers in cases of donation after brain death (DBD) and circulatory death (DCD).

METHOD

An European Liver and Intestine Transplant Association-European Liver Transplant Registry web survey designed to conceal respondents' personal information was sent to surgeons procuring and/or transplanting livers in Europe.

RESULTS

Sixty-five percent of responses came from large transplant centers (>50 procurements/y). In 8% of DBDs and 14% of DCDs the bile duct is not rinsed. In 46% of DBDs and 52% of DCDs surgeons prefer to remove the gallbladder after graft reperfusion. Protocols concerning preservation solutions (nature, pressure, volume) are extremely heterogeneous. In 54% of DBDs and 61% of DCDs an arterial back table pressure perfusion is performed. Steroids (20%-10%), heparin (72%-60%), prostacyclin (3%-7%), and fibrinolytics (4%-11%) are used as donor-protective interventions in DBD and DCD cases, respectively. In 2% of DBD and 6% of DCD cases a hepatic artery reperfusion is performed first. In 4% of DBD and 6% of DCD cases, fibrinolytics are administered through the hepatic artery during the bench and/or implantation.

CONCLUSION

This European web survey shows for the first time the heterogeneity in the management of bile ducts during procurement, preservation, and transplantation in Europe. In the context of sharing more marginal liver grafts, an expert meeting must be organized to formulate guidelines to be applied to protect liver grafts against IC.

In situ normothermic perfusion of livers in controlled circulatory death donation may prevent ischemic cholangiopathy and improve graft survival

Livers from controlled donation after circulatory death (DCD) donors suffer a higher incidence of nonfunction, poor function, and ischemic cholangiopathy. In situ normothermic regional perfusion (NRP) restores a blood supply to the abdominal organs after death using an extracorporeal circulation for a limited period before organ recovery. We undertook a retrospective analysis to evaluate whether NRP was associated with improved outcomes of livers from DCD donors. NRP was performed on 70 DCD donors from whom 43 livers were transplanted. These were compared with 187 non-NRP DCD donor livers transplanted at the same two UK centers in the same period. The use of NRP was associated with a reduction in early allograft dysfunction (12% for NRP vs. 32% for non-NRP livers, P = .0076), 30-day graft loss (2% NRP livers vs. 12% non-NRP livers, P = .0559), freedom from ischemic cholangiopathy (0% vs. 27% for non-NRP livers, P < .0001), and fewer anastomotic strictures (7% vs. 27% non-NRP, P = .0041). After adjusting for other factors in a multivariable analysis, NRP remained significantly associated with freedom from ischemic cholangiopathy (P < .0001). These data suggest that NRP during organ recovery from DCD donors leads to superior liver outcomes compared to conventional organ recovery.

Comprehensive Evaluation of a Donated After Circulatory Death (DCD) Donor Liver Model in Minipigs

Background

Graft livers from donors after death from circulatory disease (DCD) often suffer injury from severe ischemia or hypoxia before resection. Thus, earlier evaluation of these livers is critical for the survival of recipients.

Material/Methods

In our study, 18 minipigs, as DCD donor liver models, were evenly divided into a warm ischemia time (WIT) group and a hypoxia plus ischemia group. Another 18 minipigs served as recipients and were implanted with the donor livers of the DCD models. miR-122 levels and hepatic function were examined before and after liver transplantation.

Results

Results indicated that increased miR-122 levels appeared in the early stages of ischemia and hypoxia. Increases in ALT and GGT levels occurred earlier than changes in TBil.

Conclusions

The expression levels of miR-122 in donor liver might play a role in the evaluation of organ injury. Changes in donor liver functions were more sensitive to ischemia than hypoxia in this established porcine DCD model.

The Impact of Implantation Time During Liver Transplantation on Outcome: A Eurotransplant Cohort Study

Supplemental digital content is available in the text.

Background

The liver graft quickly rewarms during transplantation when the vascular anastomoses are being performed, potentially impacting on outcomes.

Methods

We investigated the relationship between implantation time and outcome in 5223 recipients of deceased-donor livers transplanted in Eurotransplant (2004-2013). Cox regression analyses were corrected for donor, preservation, and recipient variables. Transplant loss represents all-cause graft failure.

Results

Median implantation time was 41 minutes (interquartile range, 34-51). Implantation time independently associated with transplant loss (adjusted hazard ratio, 1.04 for every 10-minute increase; 95% confidence interval, 1.01-1.07; P = 0.007). The magnitude of the implantation time effect was comparable to the effect of each additional hour of cold ischemia (adjusted hazard ratio, 1.03; 95% confidence interval, 1.02-1.05; P < 0.001). The effect was most pronounced early posttransplant with no evidence of a significant effect beyond 3 months. A similar detrimental effect of implantation time was seen for graft and patient survivals. The increased risk for transplant loss in livers donated after circulatory determination of death could be attributed to donor warm ischemia time.

Conclusions

Implantation time associates with inferior liver transplant outcome in a continuous way. These findings need confirmation and further study of confounding factors is needed so steps toward improving outcomes can be made.

From "Gut Feeling" to Objectivity: Machine Preservation of the Liver as a Tool to Assess Organ Viability

Purpose of Review

The purpose of this review was to summarise how machine perfusion could contribute to viability assessment of donor livers.

Recent Findings

In both hypothermic and normothermic machine perfusion, perfusate transaminase measurement has allowed pretransplant assessment of hepatocellular damage. Hypothermic perfusion permits transplantation of marginal grafts but as yet has not permitted formal viability assessment. Livers undergoing normothermic perfusion have been investigated using parameters similar to those used to evaluate the liver in vivo. Lactate clearance, glucose evolution and pH regulation during normothermic perfusion seem promising measures of viability. In addition, bile chemistry might inform on cholangiocyte viability and the likelihood of post-transplant cholangiopathy.

Summary

While the use of machine perfusion technology has the potential to reduce and even remove uncertainty regarding liver graft viability, analysis of large datasets, such as those derived from large multicenter trials of machine perfusion, are needed to provide sufficient information to enable viability parameters to be defined and validated .

The influence of functional warm ischemia time on DCD liver transplant recipients' outcomes

BACKGROUND

Duration of functional warm ischemia (f-WIT) is thought to have a causal effect on outcomes in controlled donation after circulatory death (DCD) liver transplantation (LT).

METHODS

A retrospective cohort study was conducted at five centers. Data were extracted on donor and recipient characteristics, with attention to parameters recorded during withdrawal of life support to in situ cold perfusion. F-WIT was the time elapsed from any of the hemodynamic and oxygenation parameters to the start of in situ cold perfusion. Parameters were as follows: MAP ≤ 50 mm Hg; SBP ≤ 50 mm Hg; and SPO2 ≤ 60%. The primary endpoint was a composite of disseminated ischemic cholangiopathy (IC), primary non-function (PNF), and early graft failure.

RESULTS

35 patients (14%) developed one or more of the primary outcomes. On univariate analysis, older donors and longer WITs were associated with greater likelihood of complications. Of the f-WIT variations analyzed, only f-WIT with SpO2 ≤ 60% was longer among patients with complications. On multivariate analysis, only donor age was a significant predictor of complications.

CONCLUSION

This study demonstrates that, of the f-WITs, f-WIT with SpO2 ≤ 60% is most predictive of post-DCD complications. However, results suggest that there may be an alternate etiology for poor outcomes, and that donor age plays a key role.

Pathophysiological Trends During Withdrawal of Life Support: Implications for Organ Donation After Circulatory Death

BACKGROUND

Donation after circulatory death (DCD) provides an alternative pathway to deceased organ transplantation. Although clinical DCD lung, liver, and kidney transplantation are well established, transplantation of hearts retrieved from DCD donors has reached clinical translation only recently. Progress has been limited by concern regarding the viability of DCD hearts. The aim of this study was to document the pathophysiological changes that occur in the heart and circulation during withdrawal of life (WLS) support.

METHODS

In a porcine asphyxia model, we characterized the hemodynamic, volumetric, metabolic, biochemical, and endocrine changes after WLS for up to 40 minutes. Times to circulatory arrest and electrical asystole were recorded.

RESULTS

After WLS, there was rapid onset of profound hypoxemia resulting in acute pulmonary hypertension and right ventricular distension. Concurrently, progressive systemic hypotension occurred with a fall in left atrial pressure and little change in left ventricular volume. Mean times to circulatory arrest and electrical asystole were 8 ± 1 and 16 ± 2 minutes, respectively. Hemodynamic changes were accompanied by a rapid fall in pH, and rise in blood lactate, troponin-T, and potassium. Plasma noradrenaline and adrenaline levels rose rapidly with dramatic increases in coronary sinus levels indicative of myocardial release.

CONCLUSIONS

These findings provide insight into the nature and tempo of the damaging events that occur in the heart and in particular the right ventricle during WLS, and give an indication of the limited timeframe for the implementation of potential postmortem interventions that could be applied to improve organ viability.

TAK-242 treatment ameliorates liver ischemia/reperfusion injury by inhibiting TLR4 signaling pathway in a swine model of Maastricht-category-III cardiac death

OBJECTIVES

This study aims to test the effects of TAK-242 on liver transplant viability in a model of swine Maastricht-category-III cardiac death.

METHODS

A swine DCD Maastricht-III model of cardiac death was established, and TAK-242 was administered prior to the induction of cardiac death. The protein and mRNA level of TLR4 signaling pathway molecules and cytokines that are important in mediating immune and inflammatory responses were assessed at different time points following the induction of cardiac death.

RESULTS

After induction of cardiac death, both the mRNA and protein levels of key molecules (TLR4, TRAF6, NF-ϰB, ICAM-1, MCP-1 and MPO), TNF-α and IL-6 increased significantly. Infusion of TAK-242 1h before induction of cardiac death blocked the increase of immune and inflammatory response molecules. However, the increase of TLR4 level was not affected by infusion of TAK-242. Histology study showed that infusion of TAK-242 protect liver tissue from damage during cardiac death.

CONCLUSIONS

These results indicates that TLR4 signaling pathway may contribute to ischemia/reperfusion injury in the liver grafts, and blocking TLR4 pathway with TAk-242 may reduce TLR4-mediated tissue damage.

Physiologic Changes in the Heart Following Cessation of Mechanical Ventilation in a Porcine Model of Donation After Circulatory Death: Implications for Cardiac Transplantation

Hearts donated following circulatory death (DCD) may represent an additional source of organs for transplantation; however, the impact of donor extubation on the DCD heart has not been well characterized. We sought to describe the physiologic changes that occur following withdrawal of life-sustaining therapy (WLST) in a porcine model of DCD. Physiologic changes were monitored continuously for 20 min following WLST. Ventricular pressure, volume, and function were recorded using a conductance catheter placed into the right (N = 8) and left (N = 8) ventricles, and using magnetic resonance imaging (MRI, N = 3). Hypoxic pulmonary vasoconstriction occurred following WLST, and was associated with distension of the right ventricle (RV) and reduced cardiac output. A 120-fold increase in epinephrine was subsequently observed that produced a transient hyperdynamic phase; however, progressive RV distension developed during this time. Circulatory arrest occurred 7.6±0.3 min following WLST, at which time MRI demonstrated an 18±7% increase in RV volume and a 12±9% decrease in left ventricular volume compared to baseline. We conclude that hypoxic pulmonary vasoconstriction and a profound catecholamine surge occur following WLST that result in distension of the RV. These changes have important implications on the resuscitation, preservation, and evaluation of DCD hearts prior to transplantation.

Radiologic Characterization of Ischemic Cholangiopathy in Donation-After-Cardiac-Death Liver Transplants and Correlation With Clinical Outcomes

OBJECTIVE

The purpose of this study was to define the cholangiographic patterns of ischemic cholangiopathy and clinically silent nonanastomotic biliary strictures in donation-after-cardiac-death (DCD) liver grafts in a large single-institution series. We also examined the correlation of the radiologic findings with laboratory data and clinical outcomes.

MATERIALS AND METHODS

Data were collected for all DCD liver transplants at one institution from December 1998 to December 2011. Posttransplant cholangiograms were obtained during postoperative weeks 1 and 3 and when clinically indicated. Intrahepatic biliary strictures were classified by anatomic distribution and chronologic development. Radiologic findings were correlated with laboratory data and with 1-, 3-, and 5-year graft and patient survival rates.

RESULTS

A total of 231 patients received DCD grafts. Cholangiograms were available for 184 of these patients. Postoperative cholangiographic findings were correlated with clinical data and divided into the following three groups: A, normal cholangiographic findings with normal laboratory values; B, radiologic abnormalities and cholangiopathy according to laboratory values; and C, radiologic abnormalities without laboratory abnormalities. Group B had four distinct abnormal cholangiographic patterns that were predictive of graft survival. Group C had mild nonprogressive multifocal stenoses and decreased graft and patient survival rates, although cholangiopathy was not detected in these patients according to laboratory data.

CONCLUSION

Patterns and severity of nonanastomotic biliary abnormalities in DCD liver transplants can be defined radiologically and correlate with clinical outcomes. Postoperative cholangiography can depict the mild biliary abnormalities that occur in a subclinical manner yet cause a marked decrease in graft and patient survival rates in DCD liver transplants.

Donation after cardiac death liver transplantation: Graft quality evaluation based on pretransplant liver biopsy

Donation after cardiac death (DCD) liver grafts are associated with inferior clinical outcomes and high discard rates because of poor graft quality. We investigated the predictive value of DCD liver biopsy for the pretransplant graft quality evaluation. DCD liver transplants that took place between October 2010 and April 2014 were included (n = 127). Histological features of graft biopsy samples were analyzed to assess risk factors for graft survival. Macrovesicular steatosis ≥ 20% [hazard ratio (HR) = 2.973; P = 0.045] and sinusoidal neutrophilic infiltrate (HR = 6.969; P = 0.005) were confirmed as independent risk factors for graft survival; hepatocellular swelling, vacuolation, and necrosis failed to show prognostic value. Additionally, a donor serum total bilirubin level ≥ 34.2 μmol/L was also associated with a lower probability of graft survival. Our analysis indicates that macrovesicular steatosis ≥ 20% and sinusoidal neutrophilic infiltrate are novel and useful histological markers for DCD liver grafts with unacceptable quality. This finding can be used by transplant surgeons to improve DCD liver acceptance protocols.

Comparison of energy metabolism in liver grafts from donors after circulatory death and donors after brain death during cold storage and reperfusion

Background

Donation after circulatory death (DCD) liver grafts have supplemented the donor organ pool, but certain adverse outcomes have prevented exploration of the full potential of such organs. The aim of this study was to determine key differences in basic energy metabolism between DCD and donation after brainstem death (DBD) grafts.

Methods

Microdialysis samples from DCD and DBD allograft parenchyma from cold storage to 48 h after reperfusion were analysed by colorimetric methods. Interstitial lactate, pyruvate and glycerol levels were measured and the lactate/pyruvate ratio was calculated to estimate energy depletion of the grafts. Histological features of ischaemia and reperfusion injury were assessed.

Results

Donor age, extent of steatosis and cold ischaemia time were comparable between ten DCD and 20 DBD organs. DCD grafts had higher levels of interstitial lactate (median 11·6 versus 1·2 mmol/l; P = 0·015) and increased lactate/pyruvate ratio (792 versus 38; P = 0·001) during cold storage. There was no significant difference in glycerol levels between DCD and DBD grafts (225·1 versus 127·5 µmol/l respectively; P = 0·700). Rapid restoration of energy levels with lactate clearance, increased pyruvate levels and reduced lactate/pyruvate ratio was seen following reperfusion of functioning DCD grafts, parallel with levels in DBD grafts. Histology revealed more pronounced glycogen depletion in DCD grafts. Three allografts that failed owing to primary non-function showed energy exhaustion with severe glycogen depletion.

Conclusion

Liver grafts from DCD donors exhibited depletion of intracellular energy reserves during cold storage. Failed allografts showed severe energy depletion. Modified organ preservation techniques to minimize organ injury related to altered energy metabolism may enable better utilization of donor organs after circulatory death.

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.

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.

The super-rapid technique in Maastricht category III donors: has it developed enough for marginal liver grafts from donors after cardiac death?

PURPOSE OF REVIEW

Follow-up data from donors following cardiac death (DCD) liver transplants suggest an increased risk of graft failure and morbid complications, and the risk increased with grafts from marginal donors. Donor warm ischaemia (dWIT) stands out as the common aetiological factor. Aim of this review is to examine if super-rapid technique had developed sufficiently enough to improve the effects of dWIT that had been started since treatment withdrawal in category III DCD marginal donors.

RECENT FINDINGS

The recent findings suggest limited evolvement, but these have not been contributed to reduce dWIT significantly. Evidence suggests hypoperfusion and circulatory stop occurring well before electrophysical inactivity; hence, dWIT is probably underestimated. Time spent since cardiac death to aortic cross clamp is directly linked to ischaemic complications; limited modifications to surgical technique alone have failed to make an impact on these complications. Marginal grafts generally perform worse, increasing the overall financial cost of patient management.

SUMMARY

Irrespective of the speed at which aortic perfusion is instituted, the technical developments have not been able to improve outcomes/utility of marginal DCD grafts. The future of the DCD programmes should explore the means of reviving organ damage incurred during dWIT that are incorporated to the super-rapid technique of organ harvest.

Deceased donor risk factors influencing liver transplant outcome

As the pressure for providing liver transplantation to more and more candidates increases, transplant programs have begun to consider deceased donor characteristics that were previously considered unacceptable. With this trend, attention has focused on better defining those donor factors that can impact the outcome of liver transplantation. This review examines deceased donor factors that have been associated with patient or graft survival as well as delayed graft function and other liver transplant results.

Establishing a brain-death donor model in pigs

INTRODUCTION

An animal model that imitates human conditions might be useful not only to monitor pathomechanisms of brain death and biochemical cascades but also to investigate novel strategies to ameliorate organ quality and functionality after multiorgan donation.

METHODS

Brain death was induced in 15 pigs by inserting a catheter into the intracranial space after trephination of the skull and augmenting intracranial pressure until brain stem herniation. Intracranial pressure was monitored continuously; after 60 minutes, brain death diagnostics were performed by a neurologist including electroencephalogram (EEG) and clinical examinations. Clinical examinations included testing of brain stem reflexes as well as apnoe testing; then intensive donor care was performed according to standard guidelines until 24 hours after confirmation of brain death. Intensive donor care was performed according to standard guidelines for 24 hours after brain death.

RESULTS

Sixty minutes after brain-death induction, neurological examination and EEG examination confirmed brain death. Intracranial pressure increased continuously, remaining stable after the occurrence of brain death. All 15 animals showed typical signs of brain death such as diabetes insipidus, hypertensive and hypotensive periods, as well as tachycardia. All symptoms were treated with standard medications. After 24 hours of brain death we performed successful multiorgan retrieval.

DISCUSSION

Brain death can be induced in a pig model by inserting a catheter after trephination of the skull. According to standard guidelines the brain-death diagnosis was established by a flat-line EEG, which occurred in all animals at 60 minutes after induction.

Categories of donation after cardiocirculatory death

The interest in donation after cardiocirculatory death (DCD) was renewed in the early 1990s, as a means to partially overcome the shortage of donations after brain death. In some European countries and in the United States, DCD has become an increasingly frequent procedure over the last decade. To improve the results of DCD transplantation, it is important to compare practices, experiences, and results of various teams involved in this field. It is therefore crucial to accurately define the different types of DCD. However, in the literature, various DCD terminologies and classifications have been used, rendering it difficult to compare reported experiences. The authors have presented herein an overview of the various DCD descriptions in the literature, and have proposed an adapted DCD classification to better define the DCD processes, seeking to provide a better tool to compare the results of published reports and to improve current practices. This modified classification may be modified in the future according to ongoing experiences in this field.

Asystole to cross-clamp period predicts development of biliary complications in liver transplantation using donation after cardiac death donors

This study sought to determine the procurement factors that lead to development of intrahepatic bile duct strictures (ITBS) and overall biliary complications in recipients of donation after cardiac death (DCD) liver grafts. Detailed information for different time points during procurement (withdrawal of support; SBP < 50 mmHg; oxygen saturation <30%; mandatory wait period; asystole; incision; aortic cross clamp) and their association with the development of ITBS and overall biliary complications were examined using logistic regression. Two hundred and fifteen liver transplants using DCD donors were performed between 1998 and 2010 at Mayo Clinic Florida. Of all the time periods during procurement, only asystole-cross clamp period was significantly different between patients with ITBS versus no ITBS (P = 0.048) and between the patients who had overall biliary complications versus no biliary complications (P = 0.047). On multivariate analysis, only asystole-cross clamp period was significant predictor for development of ITBS (P = 0.015) and development of overall biliary complications (P = 0.029). Hemodynamic changes in the agonal period did not emerge as risk factors. The results of the study raise the possibility of utilizing asystole-cross-clamp period in place of or in conjunction with donor warm ischemia time in determining viability or quality of liver grafts.

A 10min "no-touch" time - is it enough in DCD? A DCD animal study

Donation after cardiac death (DCD) is under investigation because of the lack of human donor organs. Required times of cardiac arrest vary between 75s and 27min until the declaration of the patients' death worldwide. The aim of this study was to investigate brain death in pigs after different times of cardiac arrest with subsequent cardiopulmonary resuscitation (CPR) as a DCD paradigm. DCD was simulated in 20 pigs after direct electrical induction of ventricular fibrillation. The "no-touch" time varied from 2min up to 10min; then 30min of CPR were performed. Brain death was determined by established clinical and electrophysiological criteria. In all animals with cardiac arrest of at least 6min, a persistent loss of brainstem reflexes and no reappearance of bioelectric brain activity occurred. Reappearance of EEG activity was found until 4.5min of cardiac arrest and subsequent CPR. Brainstem reflexes were detectable until 5min of cardiac arrest and subsequent CPR. According to our experiments, the suggestion of 10min of cardiac arrest being equivalent to brain death exceeds the minimum time after which clinical and electrophysiological criteria of brain death are fulfilled. Therefore shorter "no-touch" times might be ethically acceptable to reduce warm ischemia time.

Improving the function of liver grafts exposed to warm ischemia by the Leuven drug protocol: exploring the molecular basis by microarray

Livers exposed to warm ischemia (WI) before transplantation are at risk for primary nonfunction (PNF), graft dysfunction, and ischemic biliary strictures, all associated with ischemia/reperfusion injury (IRI). Our multifactorial approach, Leuven drug protocol (LDP), has been shown to reduce these effects and increase recipient survival in WI/IRI-damaged porcine liver transplantation. The aim was the identification of the molecular mechanisms responsible for the hepatoprotective effects of the LDP. Porcine livers were exposed to 45 minutes of WI, cold-stored for 4 hours, transplanted, and either modulated (LDP group; n = 3) or not modulated (control group; n = 4). In the LDP group, the donor livers were flushed with streptokinase and epoprostenol before cold perfusion; the recipients received intravenous glycine, a-1-acid-glycoprotein, FR167653 (a mitogen-activated protein kinase inhibitor), a-tocopherol, glutathione, and apotransferrin. Liver samples were taken before WI and 1 hour after reperfusion. Gene expression was determined with microarrays and molecular pathways and key regulatory genes were identified. The number of genes changed between baseline and 1 hour after reperfusion was 686 in the LDP group and 325 in the control group. The extra genes in the LDP group belonged predominantly to pathways related to cytokine activity, apoptosis, and cell proliferation. We identified 7 genes that were suppressed in the LDP group. These genes could be linked in part to the administered drugs. New potential drug targets were identified on the basis of genes induced in the control group but unaffected in the LDP group and interactions predicted by the literature. In conclusion, the LDP primarily resulted in the suppression of inflammation-regulating genes in IRI. Furthermore, the microarray technique helped us to identify additional gene targets.

The impact of variation in donation after cardiac death policies among donor hospitals: a regional analysis

The Joint Commission requires all hospitals have a policy regarding donation after cardiac death. To this date however, a quantitative analysis of adult hospital donation after cardiac death (DCD) policies and its impact on transplantation outcomes has not been reported. Specific characteristics for DCD polices were identified from 90 of the 164 (54.9%) hospitals within the New England Organ Bank's donor service area. Forty-five policies (50.0%) allow family members to be present during withdrawal of life-sustaining therapy (WLST) whereas eight (8.9%) prohibit this. Seventeen policies (18.9%) require WLST to occur in the operating room (OR); 20 (22.2%) specify a location outside of the OR. Fifty-six (62.2%) policies fail to state the method of determining death; however, some require arterial line (15 policies, 16.6%) and/or EKG (10 policies, 11.1%). These variables were not associated with organ recovery, utilization or donor ischemia time. Our regional analysis highlights the high degree of variability of hospital DCD policies, which may contribute to misunderstanding and confusion among providers and patients that may influence acceptance of this mode of donation.