What is the value of "s3" in the modified Fick equation?

In the modified Fick equation, "s3" represents the patient arterial saturation. This is a crucial component of the equation as it reflects the amount of oxygen bound to hemoglobin in the arterial blood, which is vital for assessing oxygen delivery to tissues. The equation itself is used to calculate oxygen consumption (VO2) based on the difference in oxygen content between arterial and venous blood, and arterial saturation is a key variable in determining the oxygen content of arterial blood.

Correctly identifying "s3" as patient arterial saturation highlights the significance of understanding how much oxygen is available for tissue perfusion and is pivotal in evaluating the effectiveness of therapies such as ECMO, where monitoring oxygen delivery is critical. This saturation influences the overall oxygen content and is essential for calculating oxygen transport and assessing the adequacy of the patient's respiratory function, especially when extracorporeal support is implemented.