What does a pulse oximeter measure?

A pulse oximeter is a non-invasive device specifically designed to measure the oxygen saturation level in the blood. It works by passing a light through a relatively thin part of the body, usually a fingertip or earlobe, and measuring the absorption of light by oxygenated and deoxygenated hemoglobin. This allows healthcare providers to gauge how effectively oxygen is being transported throughout the body, which is crucial for assessing a patient's respiratory function and overall oxygenation status.

While heart rate, blood pressure, and respiratory rate are critical vital signs, they are measured through different techniques and devices. For instance, heart rate is typically assessed using a stethoscope or heart rate monitors, blood pressure is measured with a sphygmomanometer, and respiratory rate is counted by observing the number of breaths taken in a minute. Thus, the pulse oximeter's specific and primary function is to measure oxygen saturation, making option B the correct answer.