What does a pulse oximeter measure?

A pulse oximeter measures the ratio of saturated to unsaturated hemoglobin in the blood. This is indicated by its primary function of checking oxygen saturation levels, which tells you the percentage of hemoglobin molecules in the bloodstream that are bound with oxygen compared to those that are not. The main component being measured is oxygen saturation (SpO2), which is crucial for determining how well oxygen is being transported to the body's tissues.

Understanding oxygen levels in the blood is vital, especially in clinical settings where patients may have respiratory issues or are at risk of hypoxia. The pulse oximeter provides a non-invasive method for continuous monitoring of this ratio, making it an essential tool in both emergency care and routine checks in various medical environments.

The other options listed relate to different physiological measurements, such as carbon dioxide concentration, heart rate variability, and blood pressure, which are not the function of a pulse oximeter. Each of these measurements is captured using different devices or methods, showcasing the specificity of what a pulse oximeter is designed to assess.