The principle of a membrane oxygenator relies primarily on which of the following processes?

The principle of a membrane oxygenator is fundamentally based on the process of diffusion. In a membrane oxygenator, oxygen and carbon dioxide are exchanged through a semi-permeable membrane. This membrane allows gases to move from areas of higher concentration to areas of lower concentration, which is the essence of diffusion.

During cardiopulmonary bypass using a membrane oxygenator, oxygen from the blood is transferred across the membrane into a gas phase where it is continuously replenished with pure oxygen. Simultaneously, carbon dioxide diffuses in the opposite direction—from the blood through the membrane to the gas phase—where it can be removed. This exchange occurs without direct contact between the blood and the gas, minimizing the risk of activation of the immune system and reducing the potential for hemolysis and other complications associated with direct contact oxygenation methods.

This diffusion-driven mechanism is critical for maintaining appropriate gas levels in the blood during surgical procedures requiring cardiopulmonary bypass, ensuring that tissues receive adequate oxygenation and that carbon dioxide is effectively removed from circulation.