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

ABSTRACT

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 (VO₂), (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 H₂O 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 VO₂ = 200mL/minute, can reach an arterial oxygen saturation of 80%, while maintaining the match between the oxygen transfer by ECMO and the VO₂ of the patient. Carbon dioxide is easily removed, and normal PaCO₂ is easily reached. Venous blood oxygenation through the ECMO circuit may drive the PO₂ 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 VO₂ of the patient. The normal range of PaCO₂ is easy to reach. Venous-venous-ECMO support potentially relieves hypoxic pulmonary vasoconstriction.

Keywords:
Respiratory failure; Acute Respiratory Distress Syndrome; Mechanical ventilation; Extracorporeal membrane oxygenation; Intensive care unit; Mathematical model