DCD kidney transplantation: results and measures to improve outcome.

Item does not contain fulltextPURPOSE OF REVIEW: The purpose of the present review is to describe the current kidney preservation techniques for donors after cardiac death and to give insight in new developments that may reduce warm ischemia times and therefore improve graft function after transplantation. RECENT FINDINGS: There is still a general reluctance to use donors after cardiac death for kidney donation and transplantation, because of a relatively high incidence of delayed graft function and primary nonfunction compared to conventional donors after brain death. New clinically applicable methods, such as automated chest compression devices and extracorporeal membrane oxygenation, may reduce warm ischemia time. SUMMARY: Kidneys from donors after cardiac death sustain an increased incidence of delayed graft function and primary nonfunction. However, transplanted kidneys that do not experience these complications survive as long as conventional kidneys from donors after brain death. Maintaining adequate organ perfusion after cardiac death by using automated chest compression devices and extracorporeal membrane oxygenation reduces warm ischemia time. Optimal organ preservation and careful selection of kidneys from donors after cardiac death may reduce the risk of delayed graft function and primary nonfunction. Major efforts should continue to be made to improve the quality of kidneys from donors after cardiac death and thereby expand the utilization of this large pool of donor kidneys to its full potential.1 april 201

Preservation techniques for donors after cardiac death kidneys

PURPOSE OF REVIEW: The purpose of the present review is to describe the techniques currently used to preserve kidneys from donors after cardiac death. RECENT FINDINGS: Automated chest compression devices may be used to improve organ perfusion between cardiac death and preservation measures. Normothermic extracorporeal membrane oxygenation reduces warm ischemic injury and has the ability to improve organ viability in donors after cardiac death. SUMMARY: Kidneys from donors after cardiac death expand the donor pool but are inevitably subjected to a period of warm ischemia. Reduction of warm ischemic injury to the organs improves transplant outcome. To reduce this injury in organs from donors after cardiac death, different preservation techniques are used. Automated chest compression devices improve organ perfusion between cardiac death and the start of organ preservation. In-situ preservation with double-balloon triple-lumen catheter is an easy technique to preserve organs in uncontrolled donors and is used in many centers to cool and flush the organs. In controlled donors, organs can also be flushed after laparotomy and direct cannulation of the aorta. Extracorporeal membrane oxygenation reduces warm ischemic injury and the use of normothermic perfusion seems promising. Optimal preservation is essential to improve the viability of kidneys from donors after cardiac death, to fully utilize this large donor pool

Machine perfusion viability testing

PURPOSE OF REVIEW: Pretransplant assessment of kidney graft viability may help clinicians to decide whether to accept or discard a kidney for transplantation. With the increasing demand for donor kidneys and the increased use of marginal kidneys, the need of viability markers has increased to pursue superior transplant outcomes. Hypothermic machine perfusion (HMP) provides the theoretical opportunity to assess the viability of donor kidneys. We discuss the novel developments in viability testing during HMP and address the future prospects. RECENT FINDINGS: HMP viability testing has focused on the analysis of machine perfusion parameters and perfusate biomarkers. Renal resistance and the biomarkers lactate dehydrogenase, aspartate transaminase, glutathione-S-transferase, N-acetyl-beta-D-glucosaminidase, heart-type fatty acid binding protein, lipid peroxidation products, redox-active iron and IL-18 are correlated with transplant outcome in terms of development of delayed graft function or graft survival. However, they all lack adequate predictive value for transplant outcome. New techniques including contrast-enhanced ultrasound, three-dimensional ultrasound and magnetic resonance spectrometry are promising methods to test kidney viability during HMP, but their value has to be established. The introduction of normothermic machine perfusion offers other promising opportunities for viability testing. SUMMARY: Machine perfusion characteristics and perfusate biomarkers have been extensively studied. They often correlate with the transplant outcome, but the present viability tests are not reliable predictors of transplant outcome. New developments in kidney graft viability assessment are necessary to have a chance of being clinically useful in the future

Kidneys from uncontrolled donors after cardiac death: which kidneys do worse?

Kidneys from uncontrolled donors after cardiac death (DCD) expand the donor pool, but are associated with more primary nonfunction (PNF) and delayed graft function (DGF) compared with more conventional donor kidneys. It remains unclear, which factors influence outcome of uncontrolled donation. Therefore, we studied which donor, graft, and recipient characteristics are associated with PNF in a large cohort study. The association between different characteristics and short-term graft function was analyzed for kidneys procured in the Maastricht region from 1 January 1981 to 1 July 2009. Patients were followed until 7 January 2010. A total of 135 uncontrolled donor kidneys were included in this study. The incidence of PNF and DGF was 22% and 61%, respectively. Increasing donor age is an independent risk factor for graft failure in a univariate analysis (OR 1.035, 95% CI 1.004-1.068, P = 0.028). Donor age remains strongly associated with PNF in a multivariate analysis (OR 1.064, 95% CI 1.013-1.118, P = 0.014). However, the predictive value of donor age alone is poor (AURC 0.640, 95% CI 0.553-0.721). Increasing donor age of uncontrolled DCD donors is a major risk factor for PNF. Other clinically relevant variables were not associated with PNF. Donor age is strongly associated with PNF and remains an important parameter in donor selection

Renovascular resistance of machine-perfused DCD kidneys is associated with primary nonfunction.

Item does not contain fulltextDonation after cardiac death (DCD) has shown to be a valuable extension of the donor pool despite a higher percentage of primary nonfunction (PNF). Limiting the incidence of PNF is of vital importance. Renovascular resistance is believed to predict graft outcome; however the literature is inconsistent. Therefore, we studied whether renovascular resistance is associated with PNF and whether this parameter should be used to discard donor kidneys. All transplanted DCD kidneys preserved by machine perfusion at our center between 1993 and 2007 were analyzed (n = 440). The effects of renovascular resistance on PNF, delayed graft function (DGF), and graft and patient survival were examined using multivariable analyses; predictive quality by calculating the area under the curve (AUC). We showed that renovascular resistance at the start of machine perfusion was significantly and independently associated with PNF (OR 2.040, 95% CI 1.362-3.056; p = 0.001), and DGF (OR 2.345, 95% CI 1.110-4.955; p = 0.025). Predictive quality was moderate (0.609, 95% CI 0.538-0.681). Graft and patient survival were not associated with renovascular resistance. We conclude that renovascular resistance in DCD kidneys is an independent risk factor for PNF; however, the predictive value is relatively low.1 december 201

Improvements in kidney transplantation from donors after cardiac death

To reduce the growing waiting list for kidney transplantation, we explored the limits of kidney transplantation from donors after cardiac death by liberally accepting marginal donor kidneys for transplantation. As the percentage of primary non-function (PNF) increased, we evaluated our transplantation program and implemented changes to reduce the high percentage of PNF in 2005, followed by a second evaluation over the period 2006-2009. Recipients of a kidney from a donor after cardiac death between 1998 and 2005 were analyzed, with PNF as outcome measure. During the period 2002-2005, the percentage of PNF increased and crossed the upper control limits of 12% which was considered as unacceptably high. After implementation of changes, this percentage was reduced to 5%, without changing the number of kidney transplantations from donors after cardiac death. Continuous monitoring of the quality of care is essential as the boundaries of organ donation and transplantation are sought. Meticulous donor, preservation, and recipient management make extension of the donor potential possible, with good results for the individual recipient. Liberal use of kidneys from donors after cardiac death may contribute to a reduction in the waiting list for kidney transplantation and dialysis associated mortality

Isotherm model for high-temperature, high-pressure adsorption of CO2 and H2O on K-promoted hydrotalcite

Sorption-enhancedwater-gas shift (SEWGS) combines thewater–gas shift reactionwith in situ adsorption of CO2 on potassium-promoted hydrotalcite (K-HTC) and thereby allows production of hot, high pressure H2 fromsyngas in a single process. SEWGS is a cyclic process, that comprises high pressure adsorption and rinse, pressure equalisation, and lowpressure purge. In order to design theSEWGS process, the equilibria and kinetics of adsorptionmust beknownfor the entire pressure range.Here, amulticomponent adsorptionisothermis presented for CO2 and H2O on K-HTC at 400 C and 0.5–24 bar partial pressure, that has been derived from integrated experimentally determined breakthrough curves with special attention being given to the high pressure interaction. The experimental results can be well described by assuming that the isothermconsists of a lowpartial pressure surface adsorption part and a high partial pressure nanopore adsorption part. Surface adsorption occurs at specific and different sites for CO2 or H2O. In contrast, the nanopore adsorption mechanism is competitive and explains the interaction observed in the capacity data at partial pressures over 5 bar. Based on the characteristics of the sorbent particles, a linear driving force relation has been derived for sorption kinetics. Adsorption isotherm and linear driving force kinetics have been included in a reactor model. Model predictions are in agreement with breakthrough as well as regeneration experiment

Measurement of renovascular circulating volume during hypothermic organ perfusion

BACKGROUND: Kidney donation after cardiac death leads to vascular damage as a result of warm ischemia, affecting renovascular circulating volume. Novel ultrasound dilution techniques may be used to measure renovascular circulating volumes during hypothermic machine perfusion of donor kidneys. METHODS: Renovascular circulating volumes of machine-perfused porcine kidneys were repeatedly measured by ultrasound dilution at different perfusion pressures (30, 40, 50, and 60 mm Hg), durations of perfusion (1 and 24 hr), and warm ischemia times (15 and 45 min). Validity of ultrasound dilution was assessed by comparing volume changes after clamping of renal artery branches. RESULTS: Repeatability of ultrasound dilution measurements of renovascular circulating volumes was good (mean coefficient of variation, 7.6%). Renovascular circulating volumes significantly increased with higher perfusion pressures, remained constant over time, and significantly decreased with longer warm ischemia times. Changes in ultrasound dilution measurements after renal artery branch clamping did not correlate with changes in actual perfused volumes. CONCLUSIONS: Ultrasound dilution is a reproducible method to assess renovascular circulating volumes in machine-perfused kidneys, which is susceptible to changes in warm ischemia times. Future studies should evaluate the value of renovascular volume in pretransplantation kidney viability testing