less than 60 mmHg however
the Eurotransplant trial the perfusion pressure was set at 30 mmHg for the
kidneys that had MP 8.
Machine perfusion flow
Several studies have demonstrated that the higher the
flow rate was (at a given perfusion pressure) the better the results were with
regards to immediate function, DGF, duration of dysfunction, post-operative
creatinine and length for urine output to exceed 2Lt / day 54. There was
further confirmation of the correlation between the flow rate and the
proportion of kidneys immediately functioning and those with primary non-function.
54, 55. Moreover, another team reported a case of immediate non-function in a
MP graft with optimal perfusion pressures and biomarkers levels but with low
flow rate in order to support the importance of it 56. Newcastle viability
criteria suggested flow rate of > 25 ml/min/100 g of tissue 8.
It has been shown that
rising resistance to flow in MP is related to a not desirable outcome. 57 It
was also confirmed in trials with human renal grafts when they studied the
resistive index and its correlation with instant function rate versus delayed
graft function 58. There is a number of studies with empirical use of
different values for renal resistance as a predictor of graft response /
outcome. An interesting analysis of the Eurotransplant RCT showed that renal
resistance is a predicting factor of graft outcome and especially DGF and graft
survival which also may have prognostic power 59.
perfusate biomarkers 8
main focus of this field of research is to identify special biomarkers of the
perfusate and their correlation with urine output that could be used for
assessment of kidney’s viability while being preserved with MP. The majority is
based on experimental models using animals and so far, evidence is
controversial. In general, high such
enzyme levels within the perfusate indicate an increased extent of cellular
damage which may mean higher risk of PNF 60. In an extension of the
Eurotrasplant RCT where they analysed in depth the levels of certain biomarkers
of the perfusate they showed that there was a relationship between increased
levels of those enzymes and greater flow resistance and eventually kidneys that
had delayed graft function. However, they failed to find any correlation of the
above with the primary non-function 61. It is expected these biomarkers to be
embedded in clinical viability scores compared to isolated use. The current
research is concentrated on alanine aminopeptidase, lactate dehydrogenase
(LDH), glutathione S-transferase (GST), N-acetyl-?-DGlycosaminidase, aspartate
aminotransferase (AST) and heart-type fatty acid binding protein 8.
has been affirmed that a-glutathione
is one of the most
reliable pre-transplant renal perfusate markers in predicting the transplant outcome via anticipating the
primary non-function versus function or even immediate versus DGF 62.
According to the Newcastle criteria
for viability testing GST:
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