Ex vivo normothermic perfusion for quality assessment of marginal donor kidney transplants

BackgroundA significant proportion of kidneys procured for transplantation are discarded because of concerns about their suitability. In this study ex vivo normothermic perfusion (EVNP) was used as a quality assessment device before renal transplantation. MethodsSeventy-four human kidneys deemed unsuitable for transplantation following retrieval underwent 60min of EVNP with an oxygenated red cell-based solution at 36 degrees C. Receiver operating characteristic (ROC) curves were used to identify thresholds of renal blood flow and urine output. These thresholds and a grading of macroscopic appearance were incorporated into an EVNP assessment score (highest quality, 1; lowest, 5). This was applied to a series of 36 kidneys transplanted after EVNP. ResultsIn the discarded kidney series, 60 (81 per cent) scored 1-4 and 14 (19 per cent) scored 5. Although none of these kidneys was transplanted, those with a score from 1 to 4 were considered suitable for transplantation. In the 36 transplanted kidneys, the score ranged between 1 and 3 (score 1, 17; score 2, 11; score 3, 8). All of these kidneys were transplanted without any complications or primary non-function. The delayed graft function rate was 6 per cent (1 of 17) in kidneys scoring 1, 0 per cent (0 of 11) in those scoring 2 and 38 per cent (3 of 8) in those scoring 3 (P = 0024). The mean(s.d.) estimated glomerular filtration rate at 12months was 51(16), 63(15) and 38(21) ml in kidneys scoring 1, 2 and 3 respectively (P = 0015). ConclusionEVNP combined with a simple scoring system is an innovative technology for pretransplant assessment of kidney quality and acceptability for transplantation. This study suggests that a high percentage of retrieved kidneys are being discarded unnecessarily. Maximizes kidney use