Screening Sleep Apnea through Pulse Oximetry

The major function of a pulse oximeter is to read the concentration of oxygen present in the blood continuously or periodically. One particular area of interest in pulse oximetry is its use as a screening tool for sleep apnea.

Sleep apnea is a sleeping disorder in which a person pauses in breathing for 10 seconds or more that occur repeatedly during sleep. The problem with such condition is its capacity to cause sleep and oxygen deprivation that may result to certain complications. At present, the main diagnostic tool for sleep apnea is through a polysomnogram or otherwise called a “sleep study”.

Polysomnography is a test performed at a sleep center where the person with suspected sleep apnea will stay overnight. The device uses several electrodes that monitors and records any biophysiologic changes that occur during sleep such as a person’s brain activity, heart rate, breathing, body movements, and a few others. During the test, changes in oxygen saturation are also measured; hence, a pulse oximeter plays an integral part in screening for sleep apnea. Ideally, polysomnography is the only accepted method of diagnosis. However, its lack of general availability and high cost makes it arduous for patients to get diagnosed and be rendered with immediate treatment.

The use of home overnight pulse oximeter as a screening tool for obstructive sleep apnea has been suggested hoping that such device alone will eventually replace the need for sleep clinics. Pulse oximeters have been shown to be very specific, but on the contrary studies revealed that pulse oximeters are not sensitive enough to detect mild sleep apnea as it does with the more severe forms of the disorder. It may have a high sensitivity and specificity in people with 25 or more fluctuations in oxygen saturation (desaturation) per hour, but their sensitivity drops between 60 to 80% in people with less than 15 desaturations per hour. Hence, experts conclude that pulse oximeters alone are not a reliable means of screening for sleep apnea. They shall be used in conjunction with a polysomnogram test and clinical data for a more accurate result and diagnosis.