Hypoxic challenge test

A hypoxic challenge test is used to aid clinicians when assessing if your child will require supplemental (extra) oxygen while on an aircraft. This page from Great Ormond Street Hospital (GOSH) describes what a hypoxic challenge test involves, what will happen when your child has the test and the reasons why the test may have been requested.

Aircraft cabins are pressurised to between 5,000 to 8,000 feet, which means that the partial pressure of oxygen inside the aircraft is lower than what we breathe at sea level.

As a result of the lower oxygen levels in the aircraft cabin, most passengers will experience a small decrease in oxygen saturation – the amount of oxygen circulating in the body.

This is normally tolerated well in healthy individuals. People with cardiac and respiratory problems, however, may require additional oxygen for the flight.

The hypoxic challenge test will help evaluate how well your child will tolerate the reduced oxygen levels in the aircraft cabin.

What does the test involve?

The hypoxic challenge test takes place in a large cabin that simulates being in an aircraft. The child sits inside the cabin for a set amount of time usually 20 minutes but in some patients who require additional monitoring this will be longer, during which a pulse oximetry probe will be attached to a finger or toe. The probe is a painless wrap which uses light to measure oxygen saturation levels

Your child can take toys and personal devices for use whilst inside to keep them amused throughout the test (the department has patient iPads available for use if required). Parents can sit inside with younger children but will need to wear a pulse oximetry probe too.

Whilst inside the cabin babies can be bottle fed or breastfed as required.

Nasal prongs will be secured at the beginning of the test. If required, oxygen will be provided via the nasal prongs during the test.

The results of the test will be uploaded onto your child’s electronic patient record system for the doctor to view. If you are seeing the doctor in clinic or later that day, they will go through the results of this test. If you are not seeing the doctor on the same day they will still be able to view the results ready for your child’s next appointment.

How long will it take?

The appointment takes approximately 45 minutes but some tests may be slightly longer if additional monitoring is required so we would advise you to allow at least one hour.

What should we bring to the test?

Any medical equipment that your child may require e.g. suction equipment. You may wish to bring along a favourite toy, book or electronic game which can help as a distraction during the test.

It can get hot inside the cabin, so if you need to sit inside the cabin with your child, you may wish to wear light clothing.

Please note, the person bringing your child for the test should have ‘Parental Responsibility’ for them. Parental Responsibility refers to the individual who has legal rights, responsibilities, duties, power and authority to make decisions for a child. If the person bringing your child does not have Parental Responsibility, we may have to cancel the test.

Compiled by:
Lung Function Unit in collaboration with the Child and Family Information Group
Last review date:
November 2022