Cold flush after dynamic liver preservation protects against ischemic changes upon reperfusion - an experimental study

Abstract

Summary Ex vivo machine perfusion of the liver after cold storage has found to be most effective if combined with controlled oxygenated rewarming up to (sub)‐normothermia. On disconnection of the warm graft from the machine, most surgeons usually perform a cold flush of the organ as protection against the second warm ischemia incurred upon implantation. Experimental evidence, however, is lacking and protective effect of deep hypothermia has been challenged for limited periods of liver ischemia in other models. A first systematic test was carried out on porcine livers, excised 30 min after cardiac arrest, subjected to 18 h of cold storage in UW and then machine perfused for 90 min with Aqix‐RSI solution. During machine perfusion, livers were gradually rewarmed up to 20 °C. One group (n = 6) was then reflushed with 4 °C cold Belzer UW solution whereas the second group (n = 6) remained without cold flush. All livers were exposed to 45 min warm ischemia at room temperature to simulate the surgical implantation period. Organ function was evaluated in an established reperfusion model using diluted autologous blood. Cold reflush after disconnection from the machine resulted in a significant increase in bile production upon blood reperfusion, along with a significant reduction in transaminases release alanine aminotransferase and of the intramitochondrial enzyme glutamate dehydrogenase. Interestingly, free radical‐mediated lipid peroxidation was also found significantly lower after cold reflush. No differences between the groups could be evidenced concerning histological injury and recovery of hepatic energy metabolism (tissue content of adenosine triphosphate). Post‐machine preservation cold reflush seems to be beneficial in this particular setting, even if the organs are warmed up only to 20 °C, without notion of adverse effects, and should therefore be implemented in the protocol.

Extended hypothermic oxygenated machine perfusion enables ex situ preservation of porcine livers for up to 24 hours

“…We did not confirm our findings in a transplantation model, but an ex-situ whole blood reperfusion model was used to test liver viability, as done previously by others. 15,[38][39][40] In addition, it was recently shown that 2.5 h of normothermic reperfusion is sufficient to assess hepatobiliary viability. 21 It is generally accepted that the pig liver is a very rigorous model of organ preservation, with maximum successful SCS preservation times that are substantially shorter than those regularly achieved in clinical practice.…”

Comparison of thermal variations in post‐retrieval graft conditioning on rat livers

“…17,18 The preservation time of 18 h can be considered as a standard period that has served very well in studies using this model. 10,11 Although shorter preservation times would certainly be preferred under clinical circumstances, the logistically well implementable set up using 18 h of total CIT seems very well suited for the detection of the therapeutic potential of treatment options over a deliberately rather marginal control group. However, this primary in vitro study is subject to certain limitations which are inherent to the in vitro model used.…”

“…Treated organs were temporarily resuscitated using 1 h of oxygenated, recirculating machine perfusion at different temperatures with 150 ml of Aqix RS I, a serum like, well buffered solution that is appropriate for normothermic as well as hypothermic perfusion of grafts 8–10 …”

“…For technical details see text buffered solution that is appropriate for normothermic as well as hypothermic perfusion of grafts. [8][9][10] Immediately after retrieval, livers were flushed with Aqix RS I at the appropriate initiation temperature and put on a recirculating perfusion set up, perfused via the portal vein. Machine perfusion has been performed in a pressurecontrolled manner.…”

Phenothiazines Enhance the Hypothermic Preservation of Liver Grafts: A Pilot in Vitro Study

“…Liver preservation consists of the methods employed to minimize in vitro damage to tissue in advance of engraftation. For decades, this was achieved through the maintenance of low environmental temperatures (0–4°C) that function to decrease the metabolism and decelerate the degeneration of liver function 1 . More recently, organ preservation solutions such as the University of Wisconsin (UW) cold storage solution have emerged to augment static cold storage (SCS) 2 ; UW accomplishes this by reducing oxidative injury and metabolic disorder 3 .…”