Background Attempts to improve limb preservation for transplantation using ex vivo perfusion have yielded promising results. However, metabolic acidosis, aberrant perfusate biochemistry and significant perfusion-induced oedema are reported universally. Optimizing perfusion protocols is therefore essential for maintaining tissue health. Methods A randomized, two-stage open preclinical trial design was used to determine the optimal temperature and mean arterial pressure for machine perfusion. Conditions compared were: normothermic machine perfusion at 70 mmHg (NMP-70); subnormothermic perfusion (28°C) at 70 mmHg; subnormothermic (28°C) perfusion at 50 mmHg; and hypothermic perfusion (10°C) at 30 mmHg. Following this, a head-to-head experiment was undertaken comparing the optimal machine perfusion with static cold storage. Paired bilateral limbs (10 in total) were randomized to either 8 h of static cold storage, or 2 h of static cold storage and 6 h of optimal machine perfusion. Both groups of limbs were then reperfused on a circuit primed with matched blood from unrelated donors for 4 h without immunosuppression. Results NMP-70 resulted in less tissue injury and stable perfusion biochemistry. Assessing reperfusion outcomes, static cold storage resulted in acidosis with increased lactate and a worsening electrolyte profile, necessitating bolus infusions of bicarbonate to prevent graft loss. Conversely, NMP-70 was associated with haemodynamic and biochemical stability. Histologically, on reperfusion with allogeneic whole blood, limbs subjected to static cold storage exhibited multifocal ischaemic injury and increased inflammation, which was absent with NMP-70. Static cold storage also resulted in significant oedema compared with NMP-70. Conclusion Normothermic perfusion resulted in superior graft preservation and less reperfusion injury compared with the current static cold storage protocol.

No abstract

No abstract

Introduction:Recent experimental evidence suggests normothermic machine perfusion of the vascularized composite allograft 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 vascularized composite allograft 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 stabilization of lactate, bicarbonate, base, and pH. Conversely, the LO This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.