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 aeroplane.
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. To monitor oxygen saturations a pulse oximeter will be attached to your child's finger or toe. The oximeter probe is painless wrap which uses light to measure oxygen saturation levels.
Your child can take toys or a personal device for use whilst inside the cabin 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.
Some patients who already have medical devices for example non-invasive ventilators (BPAP machine) may have a modified hypoxic challenge test. During the modified test the patient will also be monitored whilst wearing their medical device. For these tests parents/guardians will be notified to bring the device with them to the appointment.
The results of the test will be uploaded onto your child’s electronic patient record system for the doctor to view. If you is seeing the doctor in clinic that day, they will go through the results of this test. If do not have an appointment on the same day the doctor can view the results ready for your child’s next appointment.
How long will it take?
The appointment takes approximately 60 minutes but some tests may be longer if additional monitoring is required.
What should we bring to the test?
Any medical equipment that your child requires e.g. suction equipment. Please 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.