Overnight Pulse Oximetry

Overnight pulse oximetry is a test used to monitor the level of oxygen in your blood as you sleep during the night. The basic information it provides about the fluctuation of oxygen in your blood allows your pulmonologist to evaluate whether you have a common sleep disorder called sleep apnea, or need further sleep study testing to determine how to treat your sleep disorder.


What is Sleep Apnea

Sleep apnea is a common sleep disorder in which one stops breathing during the night for ten seconds or longer, because one's upper airway is obstructed. This may occur hundreds of times every night. During apnea events, there is a drop in blood oxygen level that can be detected and diagnosed by the overnight pulse oximetry test.

How Does an Overnight Pulse Oximetry Test Work?

This test can be performed in the comfort of your own home.  Your pulmonologist will give you supplies to perform the test, which include:

- an oximeter: the machine that records your blood oxygen level; it will either be shaped like a wristwatch, or function as a separate unit.  It will record your heart rate and oxygen level throughout the night.

- an oxygen sensor that clips painlessly to the end of your finger.  It contains a red light that shines through your finger, as well as a sensor that detects your heart rate and the color of your blood.  Oxygen level can be determined by blood color: highly oxygenated blood is red, while poorly oxygenated is blue.

Desaturations, or abnormal drops in blood oxygen level, as well as increases in heart rate, may suggest that you have sleep apnea.



How Do I Preparefor the Test?

Your pulmonologist will want you to follow your normal daily routine.  If you use oxygen, your doctor will tell you whether he or she wants you to use it during the test.

Overnight pulse oximetry is a safe and painless test.  The only problems that can occur are equipment damage, or the chance of inadequate results.

Remember not to turn off the oximeter during the night, or remove its batteries, because that will result in incomplete data.


More Information on Overnight Pulse Oximetry

Simple overview of how pulse oximetry works to diagnose sleep apnea and show the need to test for other sleep disorders.

Fact sheet for patients on overnight pulse oximetry, including what to expect, how to prepare, and why the test is useful.

We wish you good luck with your test! If you have any other questions, feel free to call our office at 203.759.3666