Alkaline Liquid Ventilation of the Membrane Lung for Extracorporeal Carbon Dioxide Removal (ECCO(2)R): In Vitro Study

Extracorporeal carbon dioxide removal (ECCO(2)R) is a promising strategy to manage acute respiratory failure. We hypothesized that ECCO(2)R could be enhanced by ventilating the membrane lung with a sodium hydroxide (NaOH) solution with high CO(2) absorbing capacity. A computed mathematical model was implemented to assess NaOH–CO(2) interactions. Subsequently, we compared NaOH infusion, named “alkaline liquid ventilation”, to conventional oxygen sweeping flows. We built an extracorporeal circuit with two polypropylene membrane lungs, one to remove CO(2) and the other to maintain a constant PCO(2) (60 ± 2 mmHg). The circuit was primed with swine blood. Blood flow was 500 mL × min(−1). After testing the safety and feasibility of increasing concentrations of aqueous NaOH (up to 100 mmol × L(−1)), the CO(2) removal capacity of sweeping oxygen was compared to that of 100 mmol × L(−1) NaOH. We performed six experiments to randomly test four sweep flows (100, 250, 500, 1000 mL × min(−1)) for each fluid plus 10 L × min(−1) oxygen. Alkaline liquid ventilation proved to be feasible and safe. No damages or hemolysis were detected. NaOH showed higher CO(2) removal capacity compared to oxygen for flows up to 1 L × min(−1). However, the highest CO(2) extraction power exerted by NaOH was comparable to that of 10 L × min(−1) oxygen. Further studies with dedicated devices are required to exploit potential clinical applications of alkaline liquid ventilation.