Which range of SaO2 corresponds to severe hypoxemia?

• A. 90-94%
• B. 75-89%
• C. 50-74%
• D. Less than 75%

Answer: (D)

Severe hypoxemia is a critical condition characterized by significantly low levels of oxygen in the blood, which can lead to serious physiological consequences. The saturation of oxygen in arterial blood, denoted as SaO2, reflects the percentage of hemoglobin binding sites in the bloodstream occupied by oxygen.

When SaO2 falls below 75%, it indicates a severe deficiency in the oxygen available to tissues, which can cause impairment of cellular metabolism and function. In such cases, the body struggles to maintain adequate oxygenation, leading to symptoms such as confusion, restlessness, and in severe cases, loss of consciousness or respiratory failure. This range is recognized in clinical settings as a threshold that necessitates immediate medical intervention to restore adequate oxygen levels and prevent further complications.

The ranges above 75% can still suggest varying degrees of hypoxemia, but they do not reach the severity where immediate clinical action is required, making them less critical in terms of patient management compared to levels that are less than 75%. Therefore, recognizing that severe hypoxemia is associated with SaO2 levels below this threshold is crucial for understanding the urgency and potential treatment needs of affected patients.