can improved design and permissive hypercapnia achieve adequate respiratory support during severe respiratory failure?
The intravenacaval oxygenator and carbon dioxide removal device (IVOX) conceived by Mortensen at CardioPulmonics is a diffusion-limited device capable of removing 30% of CO2 production of an adult at normocapnia with minimal reduction in ventilator requirements. Through mathematical modeling, an ex vivo venovenous bypass circuit to model the vena cava and animal models of severe smoke inhalation injury, the practice of permissive hypercapnia has been established to enhance CO2 removal by IVOX. By allowing the blood PCO2 to rise gradually, the CO2 excretion by IVOX can be linearly increased in a 1:1 relationship. Experimental and clinical studies have shown that CO2 removal by IVOX increased from 30-40 ml/min at normal blood PCO2 to 80-90 ml/min at PCO2 of 90 mm Hg. In addition, IVOX with permissive hypercapnia allowed a significant reduction in minute ventilation and peak airway pressure. Design changes could also improve the performance of IVOX. Increased surface area and mixing with
