Ex Vivo Normothermic Preservation of Amputated Limbs with a Hemoglobin-Based Oxygen Carrier (HBOC-201) Perfusate.

Background Ex vivo normothermic limb perfusion (EVNLP) preserves amputated limbs under near-physiologic conditions. Perfusates containing red blood cells (RBCs) have shown to improve outcomes during ex vivo normothermic organ perfusion, when compared to acellular perfusates. To avoid limitations associated with use of blood-based products, we evaluated the feasibility of EVNLP utilizing a polymerized Hemoglobin-Based Oxygen Carrier-201 (HBOC-201). Methods Twenty-four porcine forelimbs were procured from Yorkshire pigs. Six forelimbs underwent EVNLP with an HBOC-201-based perfusate, six with an RBC-based perfusate, and twelve served as static cold storage controls (SCS). EVNLP was terminated in presence of systolic arterial pressure ≥ 115 mmHg, fullness of compartments, or drop of tissue oxygen saturation by 20%. Limb contractility, weight change, compartment pressure, tissue oxygen saturation, oxygen uptake rates (OUR) were assessed. Perfusate fluid-dynamics, gases, electrolytes, metabolites, methemoglobin (MetHb), creatine kinase (CK) and myoglobin concentration were measured. Uniformity of skin perfusion was assessed with indocyanine green (ICG) angiography and infrared thermography (IRT). Results Warm ischemia time before EVNLP was 35.50 ± 8.62 min (HBOC-201), 30.17 ± 8.03 min (RBC) and 37.82 ± 10.45 (SCS) (p = 0.09). EVNLP duration was 22.5 ± 1.7 (HBOC-201) and 28.2 ± 7.3 (RBC) hours (p = 0.04). Vascular flow (325 ± 25 vs. 444.7 ± 50.6 ml/min; p = 0.39), OUR (2.0 ± 1.45 vs. 1.3 ± 0.92 mlO2/min*g of tissue; p = 0.80), lactate (14.66 ± 4.26 vs. 13.11 ± 6.68 mmol/L; p = 0.32), perfusate pH (7.53 ± 0.25 HBOC-201; 7.50 ± 0.23 RBC; p = 0.82), flexor (28.3 ± 22.0 vs. 27.5 ± 10.6; p = 0.99) and extensor (31.5 ± 22.9 vs. 28.8 ± 14.5; p = 0.82) compartment pressures, and weight changes (23.1 ± 3.0% vs. 13.2 ± 22.7; p = 0.07) were not significantly different between HBOC-201 and RBC groups, respectively. In HBOC-201 perfused limbs, MetHb levels increased, reaching 47.8 ± 12.1% at endpoint. Methemoglobin saturation did not affect OUR (ρ = -0.15, r2 = 0.022; p = 0.45). A significantly greater number of necrotic myocytes was found in the SCS group at endpoint (SCS: 127 ± 17 cells; HBOC-201: 72 ± 30 cells; RBC-based: 56 ± 40 cells; vs. p = 0.003). Conclusion HBOC-201- and RBC-based perfusates similarly support isolated limb physiology, metabolism, and function. Level of evidence N/A.