What is hypoxemia?

Hypoxemia refers specifically to a decrease in the level of oxygen in the arterial blood. This condition is critical to understand as it directly affects the body's ability to deliver adequate oxygen to tissues, impacting cellular function and overall organ performance. The arterial blood's oxygen level is often measured through arterial blood gas analysis, which helps in diagnosing and monitoring various respiratory and cardiovascular conditions.

Recognizing that hypoxemia is about arterial oxygen levels distinguishes it from other concepts related to oxygen such as general tissue oxygenation, which may be influenced by factors like hemoglobin levels or circulatory status. For example, even if tissues are not receiving enough oxygen, the arterial blood may still be relatively normal initially in certain conditions.

Other options, while related to issues of oxygen, do not accurately define hypoxemia. For instance, a decrease in oxygen available to tissues encompasses a broader range of conditions and does not focus solely on the blood levels. In contrast, increased oxygen saturation refers to conditions where oxygen levels in the blood are normal or elevated and does not pertain to hypoxemia. Lastly, metabolic alkalosis is a completely different physiological concept related to acid-base balance rather than oxygen levels.