The role of the hollow fiber in an oxygenator is to:

The primary function of the hollow fiber in an oxygenator is to increase the surface area available for gas exchange. This design takes advantage of the vast surface area created by the numerous small, hollow fibers that allow for maximal contact between the blood and the gas (usually oxygen) being delivered.

In essence, the hollow fibers facilitate an efficient exchange of gases by maximizing the interface between oxygen and blood, thus enhancing oxygen uptake and carbon dioxide removal. This is critical in clinical situations where a patient is reliant on mechanical support for respiration, such as during cardiopulmonary bypass or extracorporeal membrane oxygenation (ECMO). The increased surface area provided by these fibers significantly improves the efficiency of gas transfer, which is essential for maintaining adequate oxygenation of the body during surgical procedures or in cases of respiratory failure.

The other roles mentioned—improving gas solubility, reducing blood pressure, and filtering impurities—do not accurately describe the function of hollow fibers; these aspects are influenced by other components or mechanisms within the oxygenator system.