Portal Flush Research Articles

Post-Reperfusion Syndrome in Liver Transplantation: Does a Caval Blood Flush Vent Help?

BackgroundPost-reperfusion syndrome (PRS) during liver transplantation can range from a benign event to a profound hemodynamic excursion from baseline with significant morbidity. Multiple variables can be responsible for the diverse presentations. Over time, our group noticed that a blood flush of the liver graft via a caval vent (in addition to a standard chilled flush via the portal vein) appeared to result in a milder reperfusion effect. Attenuation of PRS via caval vent seemed to minimize hemodynamic instability and reduce metabolic derangements associated with reperfusion.Material/MethodsThis was a prospective observational pilot study of standard practice with the addition of lab values and hemodynamic evaluations. We methodically observed normal clinical flow in 20 adult orthotopic liver transplant recipients. We analyzed blood and fluid samples at set time intervals during the peri-reperfusion phase.ResultsSixteen out of 20 patients received a blood flush via caval venting. Mean arterial pressure (MAP) and heart rate were better preserved in the patient population that received a caval blood flush vent. Elevations in central venous pressure (CVP) were similar between the 2 groups. Lab values (blood gas, electrolyte, and hemoglobin) of the patients’ blood were similar, with no notable differences. Analysis of the initial blood flushed through the liver graft proved to be hypothermic, acidotic, and hyperkalemic.ConclusionsPre-reperfusion caval venting in liver transplantation (in addition to a portal vent and a chilled LR/albumin portal flush solution) appears to have favorable hemodynamic effects. The literature on this technique is sparse and larger studies are needed.

Procurement for visceral organ transplantation

Despite significant improvements in visceral organ transplantation over the last few decades, some technical aspects of organ harvesting remain controversial. The purpose of this article is to review and summarize the latest literature on how to perfuse in multiorgan procurement. Few prospective studies have analyzed and compared technical aspects of harvesting such as cannulation (aortic-only versus dual aortic and portal flush), flush rates and volumes as well as flush pressures (high pressure vs. gravity). However, these and most data available from additional retrospective and experimental studies do not clearly support one harvesting technique over another. Currently, because of lack of superiority data, no clear guidelines exist on what cannulation techniques to apply during organ procurements in visceral organ transplantation. Additional prospective trials are needed to clarify these questions.

Retrograde arterial flush of the liver graft in living donor liver transplantation may ameliorate post-transplantational cholestasis - a prospective randomized study

Retrograde arterial flush (RGAF) of liver grafts, which prevents arterial intima injuries in living donor liver transplantation (LDLT), seemed to reduce post-transplantational cholestasis by our preliminary study. The aim of this study was to further confirm this effect of RGAF of grafts in LDLT by a prospective randomized study. The enrolled cases were randomly divided into two groups, RGAF (portal flush plus RGAF) and non-RGAF (portal flush only). The outcome measures included intra-operative hemodynamic changes, one-month post-transplantational liver function tests and acute cellular rejection, vascular and biliary complications, the length of postoperative hospital stay, and graft and patient survivals. The significant findings of results were lower postoperative serum bilirubin in the RGAF group until three wk after transplantation (days 1, 3, 7, 14, and 21 serum total bilirubin, mg/dL: 5.82±5.46, 3.95±4.28, 4.87±5.01, 3.62±5.32, and 3.63±6.91 vs. 8.41±5.49, 7.47±5.61, 10.0±10.1, 9.06±11.6, and 6.02±9.84, respectively, in RGAF and non-RGAF, p=0.017, 0.002, 0.014, 0.011, 0.109) and shorter postoperative hospital stay in the RGAF group (31.1±17.6 vs. 44.8±32.3 d, respectively, in RGAF and non-RGAF, p=0.035). In conclusion, the RGAF of liver grafts on a back table may ameliorate postoperative functional cholestasis in LDLT, which possibly reduces postoperative hospital stay.

Retrograde Arterial Flush of the Liver Graft in Living Donor Liver Transplantation

ABSTRACT Formal hepatic arterial flush to preserve the liver graft in living donor liver transplantation (LDLT) is not recommended by most transplant centers because direct cannulation may injure the intima of the hepatic artery. The authors describe a method of retrograde arterial flush of the liver graft without arterial cannulation by hepatic venous outflow occlusion (HVOO) in LDLT. First, we proved no backflow of the hepatic artery without HVOO by portal flush to pig livers. Then we used HVOO on 15 LDLT cases (Group HVOO). The results were compared with those of 24 counterpart LDLT cases (Group non-HVOO) without hepatic artery flush. The two-week posttransplantational liver functions were not different between two groups except that the day-three and day-seven serum bilirubin levels were lower in Group HVOO (day-three total bilirubin: 4.99 ± 4.04 mg/dl versus 7.65 ± 4.33 mg/dl, p =.016; day-seven total bilirubin: 5.06 ± 5.02 mg/dl versus 9.57 ± 6.09, p =.005). The rates of vascular complications, six-month graft survival, and biliary anastomotic stricture in Group HVOO were 0, 93.3, and 13.3% respectively, which were not different from those of Group non-HVOO. In summary, to avoid intima injury, the retrograde arterial flush of liver graft by HVOO is safe in LDLT. The short-term results showed the effect of decreasing early functional cholestasis but the long-term benefits need further evaluation, especially with regards to biliary anastomotic complications.

A prospective randomized trial of N-acetyl cysteine administration during cold preservation of the donor liver for transplantation: Original Article

Aims: N-acetyl cysteine (NAC), an anti oxidant and a glutathione precursor, is effective in ameliorating liver injury of Tylenol overdose. There is experimental evidence that it also reduces ischemia reperfusion (I/R) injury. This clinical study was undertaken to study the effect of NAC administered in the donor operation.Methods: 22 patients were randomized to receive NAC (IV & Portal flush) or no NAC (Control Group) during donor operation. Peak AST levels and 1-hour postreperfusion biopsies were used to assess I/R injury. Episodes of acute rejection were recorded together with immunosuppressive drug levels.Results: There were 4 exclusions (re-exploration for post-operative hemorrhage x3, OLT for acute liver failure x1). The two groups (n = 9 each) were matched for recipient and donor ages and sex. Viral hepatitis accounted for cirrhosis in 3 patients in NAC Group and 6 patients in Control Group. Statistically, Cold and warm ischemia times were not significantly different as was the use of blood and blood products in both groups. Serum peak AST levels were similar and postreperfusion biopsy showed moderate to severe reperfusion injury in 3 recipients in the NAC Group and 4 in the Control Group. Excluding ones associated with low Tacrolimus levels (n = 4), there were 6 episodes of acute rejection (2-mild, 4-moderate) in the NAC Group and 5 in the Control Group (3-mild,1-moderate, 1-severe).Conclusion: In this pilot study, NAC administered during donor operation did not show a protective effect on I/R injury or on acute cellular rejection.

Energy Metabolism Following Prolonged Hepatic Cold Preservation: Benefits of Interrupted Hypoxia on the Adenine Nucleotide Pool in Rat Liver

The ability of brief hypothermic reperfusion (HtR) to restore hepatic energy metabolism following periods of cold hypoxic preservation was studied in isolated rat livers after storage times of 5, 10, and 24 h. In addition, investigations were performed on the effects of HtR used to restore liver oxidative metabolism in the middle of a prolonged (24 h) hypoxic preservation period. A histidine–lactobionate–raffinose solution was used for the initial cold portal flush in all groups. Results showed that cold hypoxia for either 5 or 10 h yielded livers capable of similar recoveries of ATP, energy charge, and total adenine nucleotides, but that HtR after 24 h cold preservation resulted in reduced regeneration of ATP, a lower energy charge, and a fall in tissue adenine nucleotides. When livers were stored for 24 h but subjected to brief HtR after either 5 or 10 h before return to hypoxic storage, improved recoveries of the energy metabolites were seen over those recorded after 24 h hypoxia alone. The fact that these improvements were not due to an improved supply of adenine nucleotide precursors was demonstrated by studying groups which were given HtR with perfusate containing precursors of adenine nucleotides (adenosine, adenine, and inosine) after 24 h cold hypoxia. These data are consistent with the hypothesis that poor metabolic recovery after long-term hepatic cold preservation results more from decreased mitochondrial oxidative phosphorylation than from a lack of precursors for adenine nucleotide resynthesis. In addition, restoring oxidative metabolism at hypothermia for brief periods can to some extent protect final metabolic status after prolonged storage.