Pulse Oximetry

What is Overnight Pulse Oximetry?

Overnight Pulse Oximetry is a simple test using a small device with a finger probe that uses an infra-red light to measure the saturation levels.  You will simply wear the probe on your finger during the night while you sleep and return the device in the morning.  The results will be uploaded from the device to a computer and your doctor will discuss the results with you.

The test allows your doctor to have a picture of your breathing and pulse rate while you are asleep.  The oxygen levels help determine whether or not you are dropping below the normal level of 90% SpO2 or if you have periodic drops in oxygen levels throughout the night.  If the oxygen is dropping below the normal level of 90% SpO2, then it might be that your doctor will prescribe supplemental oxygen therapy.  Based on the periodic drops in oxygen levels could be indicative of an underlying sleep disorder.  Typically the next step is to have an additional sleep study to get a more detail picture with additional recordings of breathing patterns at night.

An overnight pulse oximetry can also be used to ensure if your doctor has prescribed the proper liter flow of supplemental oxygen at night by using the pulse oximetry at night while also using the supplemental oxygen.  If the levels saturation levels are remaining below the 90% SpO2, then the liter flow may need to be increased.

Another use is to use the pulse oximetry with CPAP/BiPAP therapy.  This gives a snapshot of to see if the therapy is eliminating the periodic drops in saturation levels.  If the periodic drops are present, then your doctor may prescribe an auto titrating CPAP/BiPAP to reevaluate the pressure settings needed to overcome the apnea or hypopnea that’s still occurring.


The overnight oximeter measures and records the oxygen levels in your blood during sleep.  The doctor will then review the information to determine if further testing or treatment is needed.

1)    The detector should be taped to your finger with the glowing red surface against your fingernail.  Remove all nail polish from this finger to obtain the best signal.

2)    Turn on the machine when you enter bed and turn it off in the morning.

3)    The test is being done on you under the following conditions:

The machine MUST be returned before noon on the next business day before the batteries lose power or your data may be lost.