Dual hypothermic oxygenated machine perfusion in liver transplants donated after circulatory death.

BACKGROUND: Experimental studies have suggested that end-ischaemic dual hypothermic oxygenated machine perfusion (DHOPE) may restore hepatocellular energy status and reduce reperfusion injury in donation after circulatory death (DCD) liver grafts. The aim of this prospective case-control study was to assess the safety and feasibility of DHOPE in DCD liver transplantation. METHODS: In consecutive DCD liver transplantations, liver grafts were treated with end-ischaemic DHOPE. Outcome was compared with that in a control group of DCD liver transplantations without DHOPE, matched for donor age, donor warm ischaemia time, and recipient Model for End-stage Liver Disease (MELD) score. All patients were followed for 1 year. RESULTS: Ten transplantations involving liver grafts treated with DHOPE were compared with 20 control procedures. There were no technical problems. All 6-month and 1-year graft and patient survival rates were 100 per cent in the DHOPE group. Six-month graft survival and 1-year graft and patient survival rates in the control group were 80, 67 and 85 per cent respectively. During DHOPE, median (i.q.r.) hepatic adenosine 5'-triphosphate (ATP) content increased 11-fold, from 6 (3-10) to 66 (42-87) µmol per g protein (P = 0·005). All DHOPE-preserved livers showed excellent early function. At 1 week after transplantation peak serum alanine aminotransferase (ALT) and bilirubin levels were twofold lower in the DHOPE group than in the control group (ALT: median 966 versus 1858 units/l respectively, P = 0·006; bilirubin: median 1·0 (i.q.r. 0·7-1·4) versus 2·6 (0·9-5·1) mg/dl, P = 0·044). None of the ten DHOPE-preserved livers required retransplantation for non-anastomotic biliary stricture, compared with five of 20 in the control group (P = 0·140). CONCLUSION: This clinical study of end-ischaemic DHOPE in DCD liver transplantation suggests that the technique restores hepatic ATP, reduces reperfusion injury, and is safe and feasible. RCTs with larger numbers of patients are warranted to assess the efficacy in reducing post-transplant biliary complications.

Machine Perfusion of Donor Livers for Transplantation: A Proposal for Standardized Nomenclature and Reporting Guidelines.

With increasing demand for donor organs for transplantation, machine perfusion (MP) promises to be a beneficial alternative preservation method for donor livers, particularly those considered to be of suboptimal quality, also known as extended criteria donor livers. Over the last decade, numerous studies researching MP of donor livers have been published and incredible advances have been made in both experimental and clinical research in this area. With numerous research groups working on MP, various techniques are being explored, often applying different nomenclature. The objective of this review is to catalog the differences observed in the nomenclature used in the current literature to denote various MP techniques and the manner in which methodology is reported. From this analysis, we propose a standardization of nomenclature on liver MP to maximize consistency and to enable reliable comparison and meta-analyses of studies. In addition, we propose a standardized set of guidelines for reporting the methodology of future studies on liver MP that will facilitate comparison as well as clinical implementation of liver MP procedures.

Balance between von Willebrand factor and ADAMTS13 following major partial hepatectomy.

BACKGROUND: Conventional coagulation tests are frequently prolonged after liver surgery, suggesting a postoperative bleeding tendency. At the same time, thrombotic complications following partial hepatectomy (PH) are not uncommon. Little is known about changes in the platelet adhesive protein von Willebrand factor (VWF) and its cleaving protease a disintegrin and metalloprotease with a thrombospondin type 1 motif, member 13 (ADAMTS13) following a PH. METHODS: Plasma samples were collected before and after PH and pylorus-preserving pancreaticoduodenectomy (PPPD), and from 24 healthy individuals. Plasma levels of VWF and ADAMTS13, VWF activity and VWF-dependent platelet adhesion were measured, and compared between the groups. RESULTS: Median (i.q.r.) VWF levels increased more after PH (17 patients) than following PPPD (10), reaching the highest level on postoperative day (POD) 3 (570 (473-656) versus 354 (305-476) per cent respectively; P = 0·009). VWF levels remained raised on POD 30. A decrease in median (i.q.r.) ADAMTS13 activity was observed for both patient groups, reaching the lowest level on POD 7 (24 (16-32) versus 38 (23-66) per cent for PH and PPPD respectively; P = 0·049), and levels remained significantly reduced at POD 30. VWF activity was significantly higher on day 7 following PH compared with PPPD (median (i.q.r.) 517 (440-742) versus 385 (322-484) per cent respectively; P = 0·009), and remained increased at POD 30. VWF-dependent platelet adhesion under conditions of flow was increased until POD 30 in patients after PH and PPPD, but was more pronounced in the PH group. CONCLUSION: There are changes in the balance between VWF and ADAMTS13 levels and activity in patients after both PH and PPPD. Changes in the VWF-ADAMTS13 axis were more pronounced and of longer duration after PH than following PPPD.

Development of a Hyperactive Primary Hemostatic System During Off-Pump Lung Transplantation Resulting From an Unbalance Between von Willebrand Factor and Its Cleaving Protease ADAMTS13.

An unbalance between the platelet-adhesive protein von Willebrand factor (VWF) and its cleaving protease ADAMTS13 is a risk factor for thrombosis. Here, we assessed levels and functionality of VWF and ADAMTS13 in patients undergoing off-pump lung transplantation. We analyzed plasma of 10 patients and distinguished lung transplantation-specific effects from those generally accompanying open-chest surgeries by comparing results with 11 patients undergoing off-pump coronary bypass graft (CABG) surgery. Forty healthy volunteers were included for reference values. VWF antigen levels as well as the VWF ristocetin cofactor activity/VWF antigen ratio increased during lung transplantation and after CABG surgery. An increase in VWF propeptide levels was paralleled by a decrease in ADAMTS13 activity. This was more pronounced during lung transplantation. Similarly, the capacity of plasma to support platelet aggregation under shear flow conditions in vitro was more increased during lung transplantation. The proportion of high molecular weight VWF multimers was elevated in both groups without evidence for ultra-large VWF. VWF's collagen binding activity remained unchanged. In conclusion, a hyperactive primary hemostatic system develops during lung transplantation resulting both from a pronounced (functional) increase of the VWF molecule and decrease of ADAMTS13. This may increase the risk of platelet thrombosis within the allograft.

Subnormothermic machine perfusion for ex vivo preservation and recovery of the human liver for transplantation.

To reduce widespread shortages, attempts are made to use more marginal livers for transplantation. Many of these grafts are discarded for fear of inferior survival rates or biliary complications. Recent advances in organ preservation have shown that ex vivo subnormothermic machine perfusion has the potential to improve preservation and recover marginal livers pretransplantation. To determine the feasibility in human livers, we assessed the effect of 3 h of oxygenated subnormothermic machine perfusion (21°C) on seven livers discarded for transplantation. Biochemical and microscopic assessment revealed minimal injury sustained during perfusion. Improved oxygen uptake (1.30 [1.11-1.94] to 6.74 [4.15-8.16] mL O2 /min kg liver), lactate levels (4.04 [3.70-5.99] to 2.29 [1.20-3.43] mmol/L) and adenosine triphosphate content (45.0 [70.6-87.5] pmol/mg preperfusion to 167.5 [151.5-237.2] pmol/mg after perfusion) were observed. Liver function, reflected by urea, albumin and bile production, was seen during perfusion. Bile production increased and the composition of bile (bile salts/phospholipid ratio, pH and bicarbonate concentration) became more favorable. In conclusion, ex vivo subnormothermic machine perfusion effectively maintains liver function with minimal injury and sustains or improves various hepatobiliary parameters postischemia.

Ex vivo normothermic machine perfusion and viability testing of discarded human donor livers.

In contrast to traditional static cold preservation of donor livers, normothermic machine perfusion may reduce preservation injury, improve graft viability and potentially allows ex vivo assessment of graft viability before transplantation. We have studied the feasibility of normothermic machine perfusion in four discarded human donor livers. Normothermic machine perfusion consisted of pressure and temperature controlled pulsatile perfusion of the hepatic artery and continuous portal perfusion for 6 h. Two hollow fiber membrane oxygenators provided oxygenation of the perfusion fluid. Biochemical markers in the perfusion fluid reflected minimal hepatic injury and improving function. Lactate levels decreased to normal values, reflecting active metabolism by the liver (mean lactate 10.0 ± 2.3 mmol/L at 30 min to 2.3 ± 1.2 mmol/L at 6 h). Bile production was observed throughout the 6 h perfusion period (mean rate 8.16 ± 0.65 g/h after the first hour). Histological examination before and after 6 h of perfusion showed well-preserved liver morphology without signs of additional hepatocellular ischemia, biliary injury or sinusoidal damage. In conclusion, this study shows that normothermic machine perfusion of human donor livers is technically feasible. It allows assessment of graft viability before transplantation, which opens new avenues for organ selection, therapeutic interventions and preconditioning.

In vitro effects of proteases in human pancreatic juice on stability of liquid and carrier-bound fibrin sealants.

BACKGROUND: Fibrin sealants are used in pancreatic surgery to prevent leakage of pancreatic fluid and reduce associated complications. The efficacy of this approach is unclear. METHODS: Fibrin clots were generated in vitro from two commercially available liquid fibrin sealants (Tissucol Duo® and Evicel®) and the carrier-bound fibrin sealant Tachosil®, and exposed to normal saline or human pancreatic fluid. Stability of the sealants was assessed by release of the fibrin and collagen degradation products, D-dimer and hydroxyproline. The effect of protease inhibitors on sealant breakdown was assessed. RESULTS: Clots generated from liquid fibrin sealants degraded rapidly in pancreatic fluid, but not in normal saline. D-dimer release from fibrin clots by pancreatic fluid was approximately 1700 µg/ml after 24 h and less than 20 µg/ml by saline. Pancreatic fluid, but not normal saline, degraded both the fibrin and collagen component of Tachosil®. After 6 h, mean(s.e.m.) D-dimer levels in pancreatic fluid exposed to Tachosil® were 850(183) ng/ml, compared with 60(6) ng/ml in normal saline. The mean(s.e.m.) hydroxyproline concentration in pancreatic fluid was 497(17) µg/ml after a 24-h exposure to Tachosil®, compared with 26(12) µg/ml in normal saline. Protease inhibitors significantly inhibited breakdown of liquid sealants (D-dimer levels less than 50 µg/ml after 24 h) and Tachosil® (D-dimer release 179(12) ng/ml at 6 h; hydroxyproline release 181(29) µg/ml at 24 h). CONCLUSION: Proteases in pancreatic juice effectively degrade both liquid and carrier-bound fibrin sealants in vitro. The use of these products in pancreatic surgery with the aim of preventing leakage of pancreatic fluid is not supported by this experimental study.

The Eurotransplant donor risk index in liver transplantation: ET-DRI.

Recently we validated the donor risk index (DRI) as conducted by Feng et al. for the Eurotransplant region. Although this scoring system is a valid tool for scoring donor liver quality, for allocation purposes a scoring system tailored for the Eurotransplant region may be more appropriate. Objective of our study was to investigate various donor and transplant risk factors and design a risk model for the Eurotransplant region. This study is a database analysis of all 5939 liver transplantations from deceased donors into adult recipients from the 1st of January 2003 until the 31st of December 2007 in Eurotransplant. Data were analyzed with Kaplan-Meier and Cox regression models. From 5723 patients follow-up data were available with a mean of 2.5 years. After multivariate analysis the DRI (p < 0.0001), latest lab GGT (p = 0.005) and rescue allocation (p = 0.007) remained significant. These factors were used to create the Eurotransplant Donor Risk Index (ET-DRI). Concordance-index calculation shows this ET-DRI to have high predictive value for outcome after liver transplantation. Therefore, we advise the use of this ET-DRI for risk indication and possibly for allocation purposes within the Eurotrans-plant region.

Early hepatic regeneration index and completeness of regeneration at 6 months after partial hepatectomy.

BACKGROUND: The liver is known to regenerate following partial hepatectomy (PH), but little is known about the timing and completeness of regeneration relative to the resected volume. This study examined whether liver volume regeneration following PH and its completeness 6 months after surgery is related to the resected volume. METHODS: A consecutive series of patients undergoing PH were included. All patients underwent preoperative computed tomography (CT) before and 7 days after surgery. Additional scans were performed 6 months after operation. Preoperative total liver volume (TLV), resected volume, future liver remnant (FLR) and liver remnant (LR) volumes were measured on CT images by freehand drawing of regions of interest in the portal venous phase on 2-mm thick slices. Regeneration indices were calculated at 7 days (RI(early)) and 6 months (RI(total)) using the formula 100 × (LR volume-FLR volume)/FLR volume. Patients were classified into five groups based on resected volume as a percentage of TLV: 0-19, 20-39, 40-59, 60-69 and at least 70 per cent in groups 1-5 respectively. RESULTS: Ninety-one patients were enrolled. RI(early) varied from 11 to 66 per cent in groups 1-5 (P < 0·001). RI(early) did not increase linearly with increasing resection volume and a plateau was seen from group 3 and above. In contrast, RI(total) was related linearly to resected volume; values ranged from 21 to 233 per cent in groups 1-5 (P < 0·001). At 7 days, LR volume represented 97, 87, 70, 58 and 41 per cent of TLV in groups 1-5. At 6 months, respective values were 102, 99, 87, 82 and 91 per cent. CONCLUSION: Early postoperative liver volume regeneration was not related linearly to resected volume. At 6 months after surgery, RI was related linearly to resected volume, but LRs had not yet regenerated to preoperative TLV.

Risk factors for central bile duct injury complicating partial liver resection.

BACKGROUND: Bile duct injury is a serious complication following liver resection. Few studies have differentiated between leakage from small peripheral bile ducts and central bile duct injury (CBDI), defined as an injury leading to leakage or stenosis of the common bile duct, common hepatic duct, right or left hepatic duct. This study analysed the incidence, risk factors and consequences of CBDI in liver resection. METHODS: Patients undergoing liver resection between 1990 and 2007 were included in this study. Those having resection for bile duct-related pathology or trauma, or after liver transplantation were excluded. Characteristics and outcome variables were collected prospectively and analysed retrospectively. RESULTS: There were 19 instances of CBDI in 462 liver resections (4·1 per cent). One-third of patients with CBDI required surgical reintervention and construction of a hepaticojejunostomy. Resection type (P < 0·001), previous liver resection (P = 0·039) and intraoperative blood loss (P = 0·002) were associated with an increased risk of CBDI. Of all resection types, extended left hemihepatectomy was associated with the highest incidence of CBDI (2 of 9 procedures). CONCLUSION: Patients undergoing extended left hemihepatectomy or repeat hepatectomy were at increased risk of CBDI.

Impact of nationwide centralization of pancreaticoduodenectomy on hospital mortality.

BACKGROUND: The impact of nationwide centralization of pancreaticoduodenectomy (PD) on mortality is largely unknown. The aim of this study was to analyse changes in hospital volumes and in-hospital mortality after PD in the Netherlands between 2004 and 2009. METHODS: Nationwide data on International Classification of Diseases, ninth revision (ICD-9) code 5-526 (PD, including Whipple), patient age, sex and mortality were retrieved from the independent nationwide KiwaPrismant registry. Based on established cut-off points of annually performed PDs, hospitals were categorized as very low (fewer than 5), low (5-10), medium (11-19) or high (at least 20) volume. A subgroup analysis based on a cut-off age of 70 years was also performed. RESULTS: Some 2155 PDs were included. The number of hospitals performing PD decreased from 48 in 2004 to 30 in 2009 (P = 0·011). In these specific years, the proportion of patients undergoing PD in a medium- or high-volume centre increased from 52·9 to 91·2 per cent (P < 0·001). Nationwide mortality rates after PD decreased from 9·8 to 5·1 per cent (P = 0·044). The mortality rate during the 6-year period was 14·7, 9·8, 6·3 and 3·3 per cent in very low-, low-, medium- and high-volume hospitals respectively (P < 0·001). The difference in mortality between medium- and high-volume centres was statistically significant (P = 0·004). The volume-outcome relationship was not influenced by age (P = 0·467). The mortality rate after PD in patients aged at least 70 years was 10·4 per cent compared with 4·4 per cent in younger patients (P < 0·001). CONCLUSION: With nationwide centralization of PD, the in-hospital mortality rate after this procedure decreased. Further centralization of PD is likely to decrease mortality further, especially in the elderly.

Accuracy of non-invasive measurement of haemoglobin concentration by pulse co-oximetry during steady-state and dynamic conditions in liver surgery.

BACKGROUND: The Masimo Radical 7 (Masimo Corp., Irvine, CA, USA) pulse co-oximeter(®) calculates haemoglobin concentration (SpHb) non-invasively using transcutaneous spectrophotometry. We compared SpHb with invasive satellite-lab haemoglobin monitoring (Hb(satlab)) during major hepatic resections both under steady-state conditions and in a dynamic phase with fluid administration of crystalloid and colloid solutions. METHODS: Thirty patients undergoing major hepatic resection were included and randomized to receive a fluid bolus of 15 ml kg(-1) colloid (n=15) or crystalloid (n=15) solution over 30 min. SpHb was continuously measured on the index finger, and venous blood samples were analysed in both the steady-state phase (from induction until completion of parenchymal transection) and the dynamic phase (during fluid bolus). RESULTS: Correlation was significant between SpHb and Hb(satlab) (R(2)=0.50, n=543). The modified Bland-Altman analysis for repeated measurements showed a bias (precision) of -0.27 (1.06) and -0.02 (1.07) g dl(-1) for the steady-state and dynamic phases, respectively. SpHb accuracy increased when Hb(satlab) was <10 g dl(-1), with a bias (precision) of 0.41 (0.47) vs -0.26 (1.12) g dl(-1) for values >10 g dl(-1), but accuracy decreased after colloid administration (R(2)=0.25). CONCLUSIONS: SpHb correlated moderately with Hb(satlab) with a slight underestimation in both phases in patients undergoing major hepatic resection. Accuracy increased for lower Hb(satlab) values but decreased in the presence of colloid solution. Further improvements are necessary to improve device accuracy under these conditions, so that SpHb might become a sensitive screening device for clinically significant anaemia.

The International Normalized Ratio (INR) in the MELD score: problems and solutions.

The Model for End-Stage Liver Disease (MELD) score is widely used to prioritize patients for liver transplantation. One of the pitfalls of the MELD score is the interlaboratory variability in all three components of the score (INR, bilirubin, creatinine). The interlaboratory variability in the INR has the largest impact on the MELD score, with a mean difference of around 5 MELD points in most studies. During the 3rd conference on Coagulopathy and Liver disease, a multidisciplinary group of scientists and physicians discussed possible solutions for the INR problem in the MELD score with the intention to provide a constructive contribution to the international debate on this issue. Here we will discuss possible solutions and highlight advantages and disadvantages.

Similar liver transplantation survival with selected cardiac death donors and brain death donors.

BACKGROUND: The outcome of orthotopic liver transplantation (OLT) with controlled graft donation after cardiac death (DCD) is usually inferior to that with graft donation after brain death (DBD). This study compared outcomes from OLT with DBD versus controlled DCD donors with predefined restrictive acceptance criteria. METHODS: All adult recipients in the Netherlands in 2001-2006 with full-size OLT from DCD (n = 55) and DBD (n = 471) donors were included. Kaplan-Meier, log rank and Cox regression analyses were used. RESULTS: One- and 3-year patient survival rates were similar for DCD (85 and 80 per cent) and DBD (86.3 and 80.8 per cent) transplants (P = 0.763), as were graft survival rates (74 and 68 per cent versus 80.4 and 74.5 per cent; P = 0.212). The 3-year cumulative percentage of surviving grafts developing non-anastomotic biliary strictures was 31 per cent after DCD and 9.7 per cent after DBD transplantation (P < 0.001). The retransplantation rate was similar overall (P = 0.081), but that for biliary stricture was higher in the DCD group (P < 0.001). Risk factors for 1-year graft loss after DBD OLT were transplant centre, recipient warm ischaemia time and donor with severe head trauma. After DCD OLT they were transplant centre, donor warm ischaemia time and cold ischaemia time. DCD graft was a risk factor for non-anastomotic biliary stricture. CONCLUSION: OLT using controlled DCD grafts and restrictive criteria can result in patient and graft survival rates similar to those of DBD OLT, despite a higher risk of biliary stricture.

Hypothermic machine perfusion in liver transplantation.

Dynamic preservation strategies are a promising option to improve graft quality before transplantation, and to extend preservation time for either logistic or treatment reasons. In contrast to normothermic oxygenated perfusion, which intends to mimic physiological conditions in the human body, with subsequent clinical application for up to 24 hrs, hypothermic perfusion is mainly used for a relatively short period with protection of mitochondria and subsequent reduction of oxidative injury upon implantation. The results from two randomized controlled trials, where recruitment has finished are expected this year. Both ex situ perfusion techniques are increasingly applied in clinical transplantation including recent reports on viability assessment, which could open the door for an increased liver utilization in the future.

Development of a severe von Willebrand factor/ADAMTS13 dysbalance during orthotopic liver transplantation.

Patients with liver disease show profound changes in their hemostatic system, which may further change during liver transplantation. We previously demonstrated that highly elevated levels of the platelet adhesive protein von Willebrand factor (VWF) in patients with cirrhosis lead to an increased VWF-dependent platelet deposition under flow as compared to healthy controls. In this study we examined VWF parameters during the course of liver transplantation. We collected serial plasma samples from 20 patients undergoing liver transplantation in which we determined plasma levels of VWF and the VWF-cleaving protease ADAMTS13. Furthermore, we performed functional tests of VWF-dependent platelet adhesion. We found persistently elevated levels of VWF during and after liver transplantation. The capacity of VWF to interact with platelets normalized during the course of transplantation, and flow-mediated VWF-dependent platelet adhesion remained at levels far exceeding those observed in healthy individuals during and after transplantation. Plasma levels of ADAMTS13 dropped during transplantation, and in four patients levels below 10% of normal were observed after reperfusion. We observed the development of a hyperreactive primary hemostatic system, as evidenced by high levels of fully functional VWF and a temporary ADAMTS13 deficiency, during liver transplantation, and speculate that these changes contribute to postoperative thrombotic complications.

Increasing cycles of intermittent ischemia can effectively maintain liver function during the acute phase of ischemia reperfusion injury by promotion of bile flow and reduction in bile salt toxicity.

BACKGROUND/AIMS: Intermittent ischemia (INT) can improve liver function following inflow occlusion. The aim was to test whether the number of cycles of INT can be increased without impairing liver function. METHODS: Liver function in the acute phase of ischemia reperfusion injury was assessed by measuring bile flow in rat livers. Phospholipid and bile salts in bile, liver marker enzymes in blood, and liver histology were measured. Aged livers were compared with young livers. RESULTS: Clamping for 45 min reduced postperfusion bile flow to 13% of the initial value compared with 88 +/- 5% for control livers (means +/- SEM, n = 5-8), and substantially reduced the phospholipid:bile salt ratio in bile. Application of 3, 4, 5 and 6 cycles of INT (15 min) restored bile flow to 70 +/- 11, 61 +/- 4, 48 +/- 2 and 35 +/- 3% (p < 0.01) of the initial value, respectively, and restored the phospholipid:bile salt ratio. Multiple cycles of INT were less effective in aged rats. CONCLUSION: Several cycles of INT, through promotion of bile flow recovery and reduction in the cytotoxic actions of bile salts, may provide an effective clinical strategy for increasing clamping time in liver resections.