What is the primary function of a pulse oximeter?

A pulse oximeter primarily functions to measure the percentage of hemoglobin in the blood that is saturated with oxygen. This is crucial in assessing a patient's oxygenation status, providing a non-invasive way to monitor how well oxygen is being transported throughout the body.

The device works by passing light through the skin, typically on a fingertip, and analyzing the light absorption which varies based on the levels of oxygen in the blood. This information helps healthcare providers determine if a patient is hypoxemic, or lacking adequate oxygen, which can be critical for patient management in various clinical situations.

While the other options involve important aspects of patient assessment, they do not pertain specifically to the primary role of a pulse oximeter. Blood pressure measurement is conducted by sphygmomanometers or automated devices, heart rate detection typically involves an electrocardiogram or pulse monitors, and lung compliance assessment usually requires more invasive or specific tests like spirometry or mechanical ventilation monitoring.