Anticoagulate the Circuit, Not the Patient: Nitric Oxide Reduces Thrombus Formation During Extracorporeal Carbon Dioxide Removal

Solutions to reduce the need for systemic anticoagulation during extracorporeal life support would improve safety and utility. The study objective was to evaluate the safety and efficacy of a nitric oxide-generating extracorporeal carbon dioxide removal (ECCO 2 R) system without systemic anticoagulation in a translational swine model. We hypothesized that nitric oxide reduces circuit thrombosis, without untoward systemic effects. Anesthetized, mechanically ventilated swine (50-60 kg) received bicaval jugular cannulation for 72 hour venovenous ECCO 2 R. Control (n = 6) received a standard ECCO 2 R device with systemic heparinization. Treatment (n = 6) received the same device, but with nitric oxide-generating circuitry and 80 ppm nitric oxide added to sweep gas, without systemic heparinization. No between-group differences in vitals, ventilator settings, blood gases, extracorporeal gas exchange, or fluid balance occurred. In both groups, ECCO 2 R enabled reduction in tidal volume. Oxygenator thrombus area, quantified following dissection and imaging, was reduced in treatment (10.2 ± 1.2%) versus control (15.2 ± 1.6%) ( p = 0.03). One control oxygenator occluded. No nitric oxide-related adverse effects were observed, including methemoglobinemia. Nitric oxide-enhanced ECCO 2 R enabled 72 hours of support without systemic anticoagulation, and without altering oxygenator performance or causing untoward systemic effects. Future studies are needed to investigate efficacy in subjects with underlying coagulopathy and/or contraindications for systemic anticoagulation.