Renal haemofiltration prevents metabolic acidosis and reduces inflammation during normothermic machine perfusion of the vascularised composite allograft - a preclinical study.

Introduction Recent experimental evidence suggests normothermic machine perfusion of the vascularised composite allograft (VCA) results in improved preservation compared to static cold storage, with less reperfusion injury in the immediate post-operative period. However, metabolic acidosis is a common feature of VCA perfusion, primarily due to the inability to process metabolic by-products. We evaluated the impact of combined limb-kidney perfusion on markers of metabolic acidosis and inflammation in a porcine model. Methods Ten paired pig forelimbs were used for this study, grouped as either limb-only (LO, n=5) perfusion, or limb-kidney (LK n=5) perfusion. Infrared thermal imaging was used to determine homogeneity of perfusion. Lactate, bicarbonate, base, pH, and electrolytes, along with an inflammatory profile generated via the quantification of cytokines and cell-free DNA in the perfusate were recorded. Results The addition of a kidney to a limb perfusion circuit resulted in the rapid stabilisation of lactate, bicarbonate, base and pH. Conversely, the LO circuit became progressively acidotic, correlating in a significant increase in pro-inflammatory cytokines. Global perfusion across the limb was more homogenous with LK compared to LO. Conclusion The addition of a kidney during limb perfusion results in significant improvements in perfusate biochemistry, with no evidence of metabolic acidosis.