*Purpose: There are no established criteria for discontinuing EVNLP before irreversible muscle and endothelial cell damage occur. This study aimed to evaluate weight gain as a real-time clinical indicator of injury during EVNLP

*Methods: Sixteen forelimbs were procured from Yorkshire pigs and preserved using EVNLP (37°C) (n=8) or static cold storage (SCS 4°C) (n=8). An oxygenated perfusate containing oxygen carrier HBOC-201 was used. EVNLP continued for 24 hours or until systolic perfusate pressure was ≥115 mmHg, fullness of compartments or a reduction of tissue oxygen saturation by 20% were observed. Limb weight, contractility, hemodynamic parameters, perfusate electrolytes, metabolites and gases were recorded and analysed. Biopsies of biceps muscles were collected 6 hourly, and muscle injury scores (MIS) calculated. Outcomes were compared at 2%, 5%, 10%, and 20% limb weight gain. Pearson’s correlation between parameters, t-test or ANOVA followed by Tukey post hoc pairwise comparisons were performed.

*Results: EVNLP lasted 20±3 hours. Weight gain was observed after 13±5 h (2%), 15±6 h (5%), 16±6 h (10%), and 19±4 h (20%). Weight gain correlated positively with MIS (r=0.92, p<0.01), perfusate potassium (r=0.81, p<0.01) and mean perfusate pressure (r=0.63, p<0.01). Weight correlated negatively with contractility (r=-0.71, p<0.01). At 5% weight gain, significantly higher MIS (p<0.01), perfusate potassium (p=0.03), and lactate (p=0.02) were recorded compared to the baseline. Mean MIS at 5% weight gain was not significantly different from SCS limbs at 6 hours (p=0.07). Arterial resistance increased over time (r=0.55, p<0.05) and at 20% weight gain was significantly higher (p=0.02) than at 5% weight gain, the latter being not significantly different from baseline (p=0.28). No significant difference was observed between glucose consumption (p=0.48), oxygen uptake rate (p=0.94) or creatine kinase (p=0.30) at the different weight levels. Median muscle contractility was 4 (1-5) at 5% weight gain, which decreased to 3 (0-4) and 2 (0-2) at 10% (p=0.32) and 20% (p=0.24), respectively.

*Conclusions: Weight gain precedes increasing arterial resistance. Muscle injury in limbs at 5% weight gain is similar to that of limbs preserved at 4°C for 6 h (standard cold ischemia time) and therefore 5% weight increase may serve as a criterion for discontinuation of EVNLP.

« Back to 2021 American Transplant Congress