Assessment of hemodynamic and blood parameters that may reflect macroscopic quality of porcine kidneys during normothermic machine perfusion using whole blood.

PURPOSE: Using ex vivo normothermic machine perfusion (NMP) with whole blood we assessed marginal porcine kidneys under reperfusion. The aim was to link measureable machine and clinical blood parameters with the currently used visual assessment. This could serve as a baseline for a standardized evaluation score to identify potentially transplantable kidneys in the future. METHODS: Kidneys and autologous whole blood were procured from slaughterhouse pigs (n = 33) and were perfused for 4 h using NMP. The hemodynamic parameters arterial pressure (AP), renal blood flow (RBF) and intrarenal resistance (IRR) were measured. Activity of aspartate transaminase (AST), gamma-glutamyltransferase (GGT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and lactate were assessed in blood at 0/1/2/4 h. Kidneys were grouped into "potentially transplantable" (PT) or "not transplantable" (NT) based on their overall macroscopic appearance after NMP by an experienced physician. RESULTS: PT-kidneys (n = 20) had a significantly lower IRR and higher RBF than NT-kidneys (n = 13). GGT, ALP and LDH did not differ significantly, but at 4 h, AST was significantly higher in PT-kidneys compared to NT-kidneys. Lactate levels kept increasing during NMP in NT-kidneys and were significantly higher at 1/2/4 h than in PT-kidneys. CONCLUSION: The immediately assessed macroscopic aspects of examined kidneys correlated with hemodynamic parameters, increased lactate and lower AST in this study. In the future, NMP with whole blood could be a useful tool to extend the donor pool by allowing the assessment of otherwise unknown characteristics of marginal kidneys before transplantation.

Inulin Clearance During Ex vivo Normothermic Machine Perfusion as a Marker of Renal Function.

Normothermic machine perfusion (NMP) offers a unique opportunity to objectively assess donor organ quality. This study describes the evaluation of inulin clearance as a potential marker for the ex vivo function of porcine kidneys during NMP. The function assessment was performed in both kidneys from slaughterhouse pigs (n = 20) and kidneys from pigs in a laboratory setting (n = 28). The kidneys were exposed to different warm ischemia times (WIT). After a period of static cold storage, the kidneys underwent a 4-hour NMP with autologous whole blood. Inulin clearance, hemodynamic parameters, and urine output were measured. Based on the inulin excretion behavior laboratory pig kidneys were assigned to three classes (functional, limited functional, and nonfunctional), slaughterhouse pig kidneys to two classes (limited functional and nonfunctional), respectively. Contrary to the marginal kidneys of the slaughterhouse pigs, the functional variation of kidneys of the laboratory pigs was associated with the WIT. A correlation between functional kidneys and a WIT less than 25 min was shown. Because none of the slaughterhouse pig kidneys could be assigned to the functional class, only the laboratory pig kidneys were used for examinations with functional markers. Renal blood flow and urine output during NMP correlated significantly ( p < 0.01) with ex vivo kidney function. This study demonstrated that inulin is a marker of high quality for the evaluation of suggested kidney function after NMP with whole blood. Furthermore, surrogate markers measured during NMP can be used to describe and predict the physiologic behavior of kidneys before transplantation.