Which vital sign is used to measure the oxygen saturation level in the blood?

The measurement of oxygen saturation levels in the blood is specifically achieved through pulse oximetry. This process involves using a device that typically clips onto a fingertip or earlobe, where it utilizes light wavelengths to assess how much hemoglobin in the blood is saturated with oxygen. This is essential for determining how effectively oxygen is being transported to tissues throughout the body, which is critical for evaluating a patient's respiratory function and overall health.

In contrast, blood pressure measures the force of blood against the walls of arteries and provides information about cardiovascular health. Heart rate refers to the number of heartbeats per minute, indicating how fast the heart is working. Temperature reflects the body's thermal state, which can indicate the presence of infection or illness. While these vital signs provide important information regarding a person's health status, none of them specifically quantify oxygen saturation levels as accurately and non-invasively as pulse oximetry does.