Hypoxic challenge test

A hypoxic challenge test is used to assess 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 has 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 in room air (at sea level).

As a result of the lower oxygen levels at altitude, most passengers will experience a 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 experience complications.

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 20 minutes during which a pulse oximetry probe will be attached to a finger or toe to assess oxygen saturation levels.

Your child can take toys and a portable DVD player inside to keep them amused throughout the test. Parents can sit inside with younger children.

Nasal prongs will be secured at the beginning of the test. If required, oxygen will be provided via the nasal prongs while remaining in the cabin.

The results will be sent back to your consultant.

How long will it take?

The test takes approximately 45 minutes, however we would advise you to allow one hour for unexpected delays.

What should we bring to the test?

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.

Compiled by:
the Arsenal Lung Function Unit in collaboration with the Child and Family Information Group
Last review date:
November 2020