Oxygen delivery, carbon dioxide removal, energy transfer to lungs and pulmonary hypertension behavior during venous-venous extracorporeal membrane oxygenation support: a mathematical modeling approach

OBJECTIVE: To describe (1) the energy transfer from the ventilator to the lungs, (2) the match between venous-venous extracorporeal membrane oxygenation (ECMO) oxygen transfer and patient oxygen consumption (VO(2)), (3) carbon dioxide removal with ECMO, and (4) the potential effect of systemic venous oxygenation on pulmonary artery pressure. METHODS: Mathematical modeling approach with hypothetical scenarios using computer simulation. RESULTS: The transition from protective ventilation to ultraprotective ventilation in a patient with severe acute respiratory distress syndrome and a static respiratory compliance of 20mL/cm H(2)O reduced the energy transfer from the ventilator to the lungs from 35.3 to 2.6 joules/minute. A hypothetical patient, hyperdynamic and slightly anemic with VO(2) = 200mL/minute, can reach an arterial oxygen saturation of 80%, while maintaining the match between the oxygen transfer by ECMO and the VO(2) of the patient. Carbon dioxide is easily removed, and normal PaCO(2) is easily reached. Venous blood oxygenation through the ECMO circuit may drive the PO(2) stimulus of pulmonary hypoxic vasoconstriction to normal values. CONCLUSION: Ultraprotective ventilation largely reduces the energy transfer from the ventilator to the lungs. Severe hypoxemia on venous-venous-ECMO support may occur despite the matching between the oxygen transfer by ECMO and the VO(2) of the patient. The normal range of PaCO(2) is easy to reach. Venous-venous-ECMO support potentially relieves hypoxic pulmonary vasoconstriction.