OMX: A NOVEL OXYGEN DELIVERY BIOTHERAPEUTIC IMPROVES OUTCOMES IN AN OVINE MODEL OF CONTROLLED HEMORRHAGIC SHOCK

Hemorrhagic shock is a major source of morbidity and mortality worldwide. While whole blood or blood product transfusion is a first-line treatment, maintaining robust supplies presents significant logistical challenges, particularly in austere environments. OMX is a novel nonhemoglobin (Hb)-based oxygen carrier derived from the H-NOX (heme-nitric oxide/oxygen binding) protein family. Because of their engineered oxygen (O 2 ) affinities, OMX proteins only deliver O 2 to severely hypoxic tissues. Additionally, unlike Hb-based oxygen carriers, OMX proteins do not scavenge nitric oxide in the vasculature. To determine the safety and efficacy of OMX in supporting tissue oxygen delivery and cardiovascular function in a large animal model of controlled hemorrhage, 2-3-week-old lambs were anesthetized, intubated, and mechanically ventilated. Hypovolemic shock was induced by acute hemorrhage to obtain a 50% reduction over 30 min. Vehicle (n = 16) or 400 mg/kg OMX (n = 13) treatment was administered over 15 min. Hemodynamics, arterial blood gases, and laboratory values were monitored throughout the 6-h study. Comparisons between groups were made using t tests, Wilcoxon rank sum test, and Fisher's exact test. Survival was assessed using Kaplan-Meier curves and the log-rank test. We found that OMX was well-tolerated and significantly improved lactate and base deficit trends, and hemodynamic indices ( P < 0.05). Median survival time was greater in the OMX-treated group (4.7 vs. 6.0 h, P < 0.003), and overall survival was significantly increased in the OMX-treated group (25% vs. 85%, P = 0.004). We conclude that OMX is well-tolerated and improves metabolic, hemodynamic, and survival outcomes in an ovine model of controlled hemorrhagic shock.