Efficacy of liver graft washout as a function of the perfusate, pressure, and temperature

Abstract

Donor graft washout can be impaired by colloids in organ preservation solutions that increase the viscosity and agglutinative propensity of red blood cells (RBCs) and potentially decrease organ function. The colloid-induced agglutinative effects on RBCs and RBC retention after liver washout with Ringer's lactate (RL), histidine tryptophan ketoglutarate solution, University of Wisconsin solution, and Polysol were determined as a function of the washout pressure (15 or 100 mm Hg) and temperature (4 or 37 C) in a rat liver washout model with 99m Tc-pertechnetate-labeled RBCs. Colloids (polyethylene glycol in Polysol and hydroxyethyl starch in University of Wisconsin) induced RBC agglutination, regardless of the solution's composition. RL was associated with the lowest degree of 99m Tc-pertechnetate-labeled RBC retention after simultaneous arterial and portal washout at 37 C and 100 mm Hg. RL washout was also associated with the shortest washout time. A single portal washout with any of the solutions did not result in differences in the degree of RBC retention, regardless of the temperature or pressure. In conclusion, no differences were found in portal washout efficacy between colloidal solutions, histidine tryptophan ketoglutarate, and RL. Simultaneous arterial and portal washout with RL at 37 C and 100 mm Hg resulted in the least RBC retention and the shortest washout time.

Improving Research Practice in Rat Orthotopic and Partial Orthotopic Liver Transplantation: A Review, Recommendation, and Publication Guide

“…the removal of blood components from the microvasculature during liver retrieval, may affect subsequent graft injury and function [76,77]. Numerous parameters related to graft washout in transplantation settings might influence its efficacy in removing blood cells: (1) type of solution (colloid content, viscosity) [78]; (2) temperature (hypothermic or normothermic washout) [79]; (3) high or low washout pressure/speed (shear stress) [76,80,81]; (4) washout time [77]; (5) heparinization [82,83], and (6) way of washout (portal venous, arterial, or simultaneous) [77]. …”

The effect of blood cells retained in rat livers during static cold storage on viability outcomes during normothermic machine perfusion

“…[41][42][43] Prior studies in human livers have also shown that initial warm LR ush results in the least RBC retention, challenging the long-held belief of cold washout as the rst step in liver procurement. [19] However, a limitation of this work is that the rate of cooling effect in rat livers with an in-situ ush is much faster compared to other animal models with larger livers. Using cold ush solutions for the purpose of metabolic depression leverages the fact that tissue deterioration slows down at decreasing temperatures.…”

“…Post et al showed that ushing with warm lactated ringers (LR) resulted in less RBC retention and shorter washout times compared to cold UW and histidine tryptophan ketoglutarate (HTK) ushes. [19] Additional studies demonstrated that the high potassium concentration in UW solution combined with cold temperature resulted in vasoconstriction, [20] and the high viscosity of UW lead to poor initial reperfusion of the liver graft due to RBC aggregation. [21] Prior literature has shown that the interacting factors of cold temperature, solution composition, and viscosity of ushing solutions interact to in uence donor blood cell retention/aggregation as well as allograft physiology.…”

The use of third-party packed red blood cells during ex situ normothermic machine perfusion of organs for transplantation: Underappreciated complexities?

“…In the UK, the “fate” of a unit of pRBCs transfused into a deceased donor just prior to organ procurement is electronically linked to the deceased donor, rather than the recipient of those organs, even though a very small volume of the third‐party blood donor's pRBCs is likely to be transferred to the organ recipient(s) 10 . In contrast, a unit of pRBCs used on ex situ NMP can either be “fated” to the organ itself, or to the organ recipient.…”

“…After undergoing ex situ NMP, organs are flushed with cold preservation solution before being implanted. Although cold flushing will remove the vast majority of red blood cells within the organ, small numbers remain 10 . These residual red blood cells may cause biologically significant effects 11 .…”