Overnight oximetry

Overnight oximetry

An oximetry test measures the amount of oxygen in the blood and can be used in the assessment of your child's breathing during sleep. 

Copyright: KidsHealth

Girl having overnight oximetry test

Key points to remember

  • an oximetry test measures the amount of oxygen in the blood
  • it is safe, simple and painless
  • an overnight oximetry test can be used in the assessment of your child's breathing during sleep (for example, due to narrowing or obstruction of the airway)
  • even if your child’s overnight oximetry is normal, they may still have problems breathing during sleep
  • the doctor who arranged the overnight oximetry test is responsible for letting you know the results and arranging any follow-up treatment or tests

What is an oximetry?

An oximetry test measures the amount of oxygen in the blood. It's a simple and painless test.

An oximetry is a test done by a machine called a pulse oximeter. A sensor is placed onto your child's finger, toe or ear lobe. The sensor uses light to measure the amount of oxygen in your child's blood, as well as their heart rate.  It does not hurt and is very simple to put on and use.

When is an oximetry test used?

Oximetry can be used to measure the amount of oxygen in your child's blood in either of these ways:

  • as a quick and easy test done in a few minutes (spot oximetry), or
  • over a longer period of time, either at home or in hospital

Spot oximetry

Spot oximetry can be used to check for low oxygen levels (hypoxia) in newborn babies to help identify those who may have been born with heart problems. It only takes a few minutes. The neonatal doctor (a doctor who looks after newborn babies) will give you more information.  

Continuous pulse oximetry

Continuous pulse oximetry over a period of hours or days can be used in hospital when a child is sick. It can help guide decisions about whether your child needs oxygen therapy. Sometimes when a child needs to use respiratory equipment at night for their breathing, continuous oximetry is used to make sure the treatment is working properly.

Overnight pulse oximetry 

Overnight pulse oximetry can be done in hospital or at home to measure oxygen levels when a child is asleep. It can be used in the following ways.

  • to measure lung function (for example, in a baby who was premature and may need oxygen)
  • to find out if there is disordered breathing during sleep

Disordered breathing during sleep can be due to:

  • narrowing or obstruction of the airway (called 'sleep disordered breathing' – see snoring or noisy breathing)
  • pauses in breathing (apnoea)
  • shallow breathing (hypoventilation) 

How do I get an overnight oximetry for my child?

Your doctor arranges an overnight oximetry test through your local hospital. Usually a technologist or nurse will set up the oximeter in the hospital so that the settings and alarms are right for your child. They will give you instructions for using the machine, including how to place and fix the sensor for best results. You usually borrow the machine overnight and return it to the hospital the next day.

Is there anything else I need to do for an overnight oximetry?

Before the oximetry test, you can help prepare your child by explaining what is going to happen and reassuring them. If your child is having oximetry to find out if they have sleep disordered breathing, there may be a short sleep questionnaire to complete. It will really help your doctor to have a summary of your child's symptoms (for example, snoring, noisy breathing, pauses in breathing, daytime sleepiness and behaviour problems).

During the overnight oximetry it can also be really helpful if you keep a note of any important events that take place while the oximeter is recording and what time they happened. Examples are being awake, crying, being asleep, feeding, noisy breathing or snoring, problems with equipment, alarms. It's also a good idea to record whether you felt your child's sleep was typical of a normal night's sleep for them.  The doctors need to have as much of your child's overnight sleep recorded as possible on the oximeter, or at least 6 hours of recording. 

Are there any risks?

There is little risk involved. Very occasionally a child's skin may react to the tapes or sensors resulting in a short-term rash. Oximetry itself is painless but may be distracting or annoying for some children because of the red light from the sensor. Staff will tell you how to hide the sensor, if on a foot, by putting a sock over the top.

How do I get the results of an overnight oximetry?

When you return the oximeter to the hospital, the doctor will analyse the data or information from the machine and send a report to the doctor who arranged the oximetry test. If the recording time is less than 6 hours, your child may need to do another oximetry test.

When oximetry testing is used to help find out if there is snoring or noisy breathing, it's important to remember that having a normal oxygen level does not mean that your child does not have sleep disordered breathing, or that no further tests or treatments are needed. The doctor who arranged the overnight oximetry is responsible for letting you know the results of the study and working with you and your child if any further follow-up tests or treatments are necessary.

Paediatric Sleep Medicine Clinical Network. Paediatric Society New Zealand. 2014. Revised 2015. Guidelines for the assessment of sleep-disordered breathing in children. https://www.starship.org.nz/for-health-professionals/new-zealand-child-and-youth-clinical-networks/paediatric-sleep-medicine-clinical-network/guidelines-for-the-assessment-of-sleep-disordered-breathing-in-children/  [Accessed 21/03/2017]

Starship Clinical Guidelines. 2009. Oximetry. https://www.starship.org.nz/for-health-professionals/starship-clinical-guidelines/o/oximetry/ [Accessed 21/03/2017]

The content on this page has been developed and approved by the Paediatric Sleep Medicine Clinical Network, Paediatric Society New Zealand. 

This page last reviewed 23 March 2017.
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