FORT LAUDERDALE, Fla.—Renal resistance after three hours of machine perfusion may be a more sensitive marker than renal histology for predicting allograft survival, researchers reported.

Investigators retrospectively analyzed 226 deceased donor kidneys recovered by the New York Organ Donor Network in New York. Before the kidneys were transplanted, they were placed on machine perfusion using the Lifeport Kidney Transporter.

Pre-transplant needle biopsies for histologic assessment were performed on 188 of them (83%). Twenty-six allografts (11%) failed within 12 months of transplantation. Among these 26 graft failures, five failed during the first week post-transplant and were excluded from the analysis.

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Allograft survival at one year was negatively correlated with machine perfusion resistance at three hours. Histologic markers of chronic disease, such as glomerulosclerosis, tubular atrophy, and arteriolar intimal narrowing in this select group did not correlate with renal resistance or graft survival.

“What we have noticed, and what many programs have noticed, is that the resistance tapers down after three hours and usually stabilizes after that,” said lead investigator Josue Alvarez Casas, MD, an organ preservation researcher at the New York Organ Donor Network (NYODN).

“We used that three-hour machine perfusion renal resistance value and noticed that it had greater statistical significance than the donor type and the pathology. So, basically it is bringing machine perfusion into a different realm, not only as a preservation function but also an evaluation function.”

Dr. Alvarez Casas, who presented study findings here at the American Society of Transplant Surgeons 10th Annual State of the Art Winter Symposium, acknowledged that the study was relatively small and more research is needed, but he said the findings suggest that the lower the resistance on machine perfusion, the better the outcomes. 

After three hours, if the renal resistance was below 0.2, the graft failure rate was less than 9%. If the resistance rate was between 0.2 and 0.3, the graft failure rate was less than 10%. However, if the rate exceeded 0.3, failure rate was 19%.

“I believe this is one of the first large volume studies showing that renal resistance actually may have impact on survival,” said co-investigator Michael Goldstein, MD, Medical Director of the NYODN. “Up until this point, we knew that organs that did not pump well or have high resistance may not function at the outset.”

Using machine perfusion renal resistance values may enable clinicians to ascertain the quality of an organ more accurately, which could lead to a decreased likelihood of delayed graft function, Dr. Goldstein said.

“Everyone is looking for ways to improve early outcomes and maximize the number of organs we are able to utilize,” Dr. Goldstein said.

“With a dramatic shortage for kidney donors and increasing death on the waiting list, the goals of the transplant societies are to increase the number of organs that can be utilized for transplantation. So now we think that characteristics of the kidney itself—the resistance in the organ—can help one predict which kidneys are going be right for which recipients.”

In addition to Dr. Alvaras Casas and Dr. Goldstein, Yuriy Yushkov, PhD, MBA, and Steven Dikman, MD, collaborated in this investigation.