Extended ex vivo normothermic perfusion for preservation of vascularized composite allografts

Abstract

Ischemia and reperfusion injury remains a significant limiting factor for the successful revascularization of amputated extremities. Ex vivo normothermic perfusion is a novel approach to prolong the viability of the amputated limbs by maintaining physiologic cellular metabolism. This study aimed to evaluate the outcomes of extended ex vivo normothermic limb perfusion (EVNLP) in preserving the viability of amputated limbs for over 24 hours. A total of 10 porcine forelimbs underwent EVNLP. Limbs were perfused using an oxygenated colloid solution at 38°C containing washed RBCs. Five forelimbs (Group A) were perfused for 12 hours and the following 5 (Group B) until the vascular resistance increased. Contralateral forelimbs in each group were preserved at 4°C as a cold storage control group. Limb viability was compared between the 2 groups through assessment of muscle contractility, compartment pressure, tissue oxygen saturation, indocyanine green (ICG) angiography and thermography. EVNLP was performed for 12 hours in group A and up to 44 hours (24-44 hours) in group B. The final weight increase (−1.28 ± 8.59% vs. 7.28 ± 15.05%, P = .548) and compartment pressure (16.50 ± 8.60 vs. 24.00 ± 9.10) (P = .151) were not significantly different between the two groups. Final myoglobin and CK mean values in group A and B were: 875.0 ± 325.8 ng/mL (A) versus 1133.8 ± 537.7 ng/mL (B) (P = .056) and 53 344.0 ± 16 603.0 U/L versus 64 333.3 ± 32 481.8 U/L (P = .286). Tissue oxygen saturation was stable until the end in both groups. Infra-red thermography and ICG-angiography detected variations of peripheral limb perfusion. Our results suggest that extended normothermic preservation of amputated limbs is feasible and that the outcomes of prolonged EVNLP (>24 hours) are not significantly different from short EVNLP (12 hours).

Large Animal Models of Vascularized Composite Allotransplantation: A Review of Immune Strategies to Improve Allograft Outcomes

“…The same group then extended their perfusion time to 24 hours, instead of 12, with similar results ( 73 ). These results demonstrate that normothermic ex vivo machine perfusion of VCA grafts up to 24 hours is possible without major metabolic derangements and leads to superior functional outcomes compared to static cold storage ( 73 , 74 ).…”

Ex vivo normothermic preservation of amputated limbs with a hemoglobin-based oxygen carrier perfusate

“…We subsequently confirmed that perfused porcine forelimbs retain physiological variables for a median of 25 hours with an average weight increase of 7.28 ± 15.05% and a compartment pressure of 24 ± 9 mm Hg. Infrared thermography and ICG angiography showed minimal variations in surface and peripheral limb perfusion over time 48 . Eventually, in a preclinical model, using human upper extremities donated for research, 10 arms underwent EVNLP with a perfusate containing pRBCs and plasma for an average of 41.6 ± 9.4 hours with a final weight change of 0.4 ± 12.2%, average compartment pressure of 20 ± 14 mm Hg, and tissue oxygen saturation of 87.4 ± 11.4%.…”

“…Infrared thermography and ICG angiography showed minimal variations in surface and peripheral limb perfusion over time. 48 Eventually, in a preclinical model, using human upper extremities donated for research, 10 arms underwent EVNLP with a perfusate containing pRBCs and plasma for an average of 41.6 ± 9.4 hours with a final weight change of 0.4 ± 12.2%, average compartment pressure of 20 ± 14 mm Hg, and tissue oxygen saturation of 87.4 ± 11.4%. Infrared thermography and ICG angiography depicted uniform peripheral perfusion throughout the experiments.…”

Renal hemofiltration prevents metabolic acidosis and reduces inflammation during normothermic machine perfusion of the vascularized composite allograft: A preclinical study

“…A common, and somewhat speculative limitation to successful VCA perfusion relates to the perpetually increasing metabolic by-products and toxins, when compared with solid organ perfusion. [15][16][17][18] Increasing lactate levels beyond physiological range are observed in all published cases (where data is presented). We hypothesize that regulating key metabolites will improve perfusion biochemistry by preventing imbalances associated with hypo-perfusion in the in vivo setting.…”