Normothermic Perfusion of Livers From Donors After Cardiac Death

NEW YORK (Reuters Health) – Compared to traditional static cold storage (SCS), normothermic regional perfusion of livers procured from donors after cardiac death (DCD) improves outcomes in the recipients of those livers, new data show.

Recipients of DCD livers that underwent in situ normothermic regional perfusion had improved one- and three-year actuarial survival compared to recipients of livers preserved with SCS (93% vs 90% and 86% vs 84% respectively; p=.034), according to researchers at Cambridge University.

Dr. Rohit Gaurav and colleagues compared 97 SCS livers with 69 grafts managed with in situ normothermic regional perfusions (NRP) and 67 managed with ex situ normothermic machine perfusion.

Overall, 17 grafts (7.3%) failed in the first 6 months. The most common cause was primary nonfunction (PNF), followed by hepatic artery thrombosis. Five livers (5%) were lost to PNF in the SCS group compared to one after NMP (1.5%) and none after NRP group. There was no difference among the groups in rates of hepatic artery thrombosis.

While the 6-month death-censored graft survival rate was similar between groups, in a Cox proportional hazard regression analysis adjusted for risk factors, NRP livers had a lower risk of 6 month transplant failure compared to SCS livers. (HR 0.3, p=0.06). NRP livers also had better actuarial survival at one and three years compared to SCS livers, an advantage not seen in the NMP group.

The NRP group also had a significantly lower rate of retransplant (SCs 18%, NMP 12%,and NRP 4% p=0.04).

SCS livers showed more evidence of reperfusion injury with higher peak ALT levels than both the NRP and NMP livers (710 U/L vs 491 u/l vs 360u/l, p<.001). The Model for Early Allograft Function (MEAF) score was significantly higher for SCS livers compared to both NRP and NMP livers (5.3 vs 4.1.vs 3.7, p<0.001).

SCS recipients also had a higher rate of acute kidney injury (SCS 55%, NRP 30%, and NMP 40%) although the difference did not reach significance (p=0.08). Rates of chronic kidney disease were similar in the three groups at 6 months.

Investigations for biliary complications were performed in 35% of NRP patients compared to 57% and 52% of SCS and NMP patients respectively (p=0.21). There was a significant decrease in non-anastomotic strictures in the NRP group, with an 6% incidence, vs 25% in the SCS group and 19% in the NMP group (p=0.009) and no patient in the NRP group had clinically significant non anastomotic strictures (vs 14% and 11% in the SCS and NMP groups respectively, p=0.009).

NRP was predominantly used in local donors, while NMP was more often employed at remote hospitals where donors may have been less ideal, which may have led to selection bias, the authors acknowledge.. However, they point out, the “superior outcomes of NRP livers were maintained after adjusting for cold ischemia time and other risk factors.”

They conclude that although SCS “remains the benchmark for organ preservation worldwide and is both relatively simple and inexpensive, with the increase in the risk profiles of both donor livers and recipients, it is necessary to investigate dynamic preservation techniques both normothermic and hypothermic.”

SOURCE: Annals of Surgery, online March 3, 2022.

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