A blood gas analysis method (100) is provided for determining the partial pressure of oxygen of arterial blood exiting an oxygenator, wherein the oxygenator generates arterial blood by exposing venous blood to an oxygenation gas and releases excess oxygenation gas as exhaust gas. The method (100) comprises a step (140) of determining an estimate of the partial pressure of oxygen in the exhaust gas, a step (150) of determining the blood oxygen uptake in the oxygenator, and a step (160) of determining the partial pressure of oxygen in the arterial blood by adjusting the estimate using the blood oxygen uptake value. Used in a clinical setting, the method (100) allows a more accurate output of the partial pressure of oxygen in the arterial blood to be provided, which facilitates oxygenator operation.
