Which of the following symptoms indicates hypoxemia?

Decreased oxygen saturation is a classic indicator of hypoxemia, which refers to an abnormally low level of oxygen in the blood. Oxygen saturation is measured as a percentage of hemoglobin molecules in the blood that are saturated with oxygen. When this level falls below normal, it directly signifies that the body's tissues may be receiving inadequate oxygen, prompting a series of physiological responses to compensate for this deficiency.

Hypoxemia can result from various conditions such as respiratory disorders, issues with oxygen delivery, or environmental factors that limit oxygen availability. Monitoring the oxygen saturation level is crucial in clinical settings to assess respiratory function and the effectiveness of ventilation. It allows for prompt intervention when oxygen levels are dangerously low, ensuring that the patient's oxygenation status is adequately managed.

The other symptoms listed, such as increased heart rate, elevated blood pressure, and shortness of breath, can occur in response to hypoxemia, but they are not definitive indicators of low oxygen saturation. They may be broader signs of the body reacting to various stressors or pathologies and do not specifically pinpoint hypoxemia itself.