PC33. Comparison of Ex Vivo Normothermic Preservation of Vascularized Composite Allografts in A Porcine Model: 12 vs 24 Hour Perfusion

PURPOSE: Ex vivo normothermic perfusion (EVNP) extends the ischemia time for soft tissue flaps. We hypothesized that extended EVNP of flaps for 24-hour was feasible and outcomes were equivalent to 12-hour preservation. METHODS: Eighteen superior epigastric artery flaps were procured from Yorkshire pigs. Flaps were preserved by EVNP for 12 (PFP12; n=5) and 24 hours (PFP24; n=4). Contralateral flaps were preserved at 4°C as static cold storage controls (SCS;(n=9). Outcome measures, including perfusate dynamics, flap temperature, gases, metabolites, electrolytes, and flap weight, were monitored and evaluated using Mann-Whitney U test. Indocyanine Green (ICG) angiography was utilized to analyze skin perfusion before division of the pedicle and at perfusion endpoint. RESULTS: Warm ischemia time for PFP12 and PFP24 was 15.7±5.2min and 13.50±7.05min (p=0.42), respectively. Flap temperatures were 29.0±1.9°C (PFP12) and 28.15± 2.06 (PFP24)(p= 0.84). Average arterial pressures were 45±12 mmHg (PFP12) and 35.75±4.11 mmHg (PFP24)(p=0.19). Arterial PaO2 was 453±77mmHg(PFP12) and 580±35.52(PFP24)(p=0.56). Perfusate pH was not significantly different between groups (7.30±0.04 and 7.39±0.06;p=0.41). Lactate was 5.1±0.8 mmol/L(PFP12) and 7.37±0.52(PFP24)(p=0.99). Creatine kinase increased (TP0.5 864±468 U/L vs. TP12 6340±1764 U/L (PFP12)(p=0.001); TP0.5 1593±5.41 U/L vs. TP24 5467±2966 U/L (PFP24)(p=0.001). Potassium and sodium were not significantly different (PFP12)3.9±0.22mEq/L; (PFP24)3.75±0.31(p=0.13) and (PFP12)159±3mEq/L;(PFP24)155±0.82(p=0.71) between groups. Flap weight did not change between groups (TP0 0.222±0.041kg vs. TP12 0.223±0.044kg(p=0.48);[PFP24]TP0.5 0.18±0.06 vs. TP24 0.18±0.06; p=0.99). ICG angiography fluorescence scores were significantly higher in the PFP24 ([PFP12]21.23±13.26 vs. (PFP24)34.95±2.90; p=0.03). CONCLUSION: EVNP can preserve soft tissue flaps for 24 hours. Outcome at 24 hours were not significantly different from 12 hours.