Blood Gases
If the lungs are not functioning properly, the amount of oxygen and carbon dioxide in the blood (blood gases) may be affected. Blood gases can be measured by taking a sample of blood from an artery.
Alternatively, pulse oximetry provides a noninvasive way to measure hemoglobin oxygen saturation (the level of oxygen in the blood). In pulse oximetry, a sensor that directs a beam of light through the tissue is placed on the fingertip or earlobe. The sensor monitors oxygen saturation by measuring the amount of light absorbed by oxygenated hemoglobin (the oxygen-carrying pigment in red blood cells).
Sleep Studies
Sleep studies (polysomnography) can be used to monitor certain body functions during sleep. Polysomnography involves electrocardiography to monitor heart rate and rhythm; electroencephalography to monitor brain waves; electromyography to monitor muscle activity; pulse oximetry to measure oxygen saturation; and measures of airflow and movements of the chest and abdomen.