Hypoxic Challenge Test

What is a Hypoxic Challenge Test (HCT)?

This test is performed when patients with known lung conditions want to travel on an aeroplane to determine if they will require oxygen while flying. The test will take approximately 60 minutes.

Preparing for your test

• Avoid wearing perfume or cologne as some of our patients’ symptoms are triggered by strong smells.
• Withhold from smoking on the day of your test.
• Avoid vigorous exercise for 1 hour prior to your test.

The Test

First, you will be asked to do some routine lung function tests. For these tests, you will wear a soft nose clip and breathe on a mouthpiece. Each of these tests will be repeated several times. These tests are done so the doctor knows what your lung function is at the time of the hypoxic challenge test.

Hypoxic challenge test

You will then be asked to sit in a chair and a device that clips on to your finger, ear or forehead will be used to measure your oxygen levels.

A soft nose-clip will be put on your nose, and you will be asked to breathe through a mouthpiece that is connected to a bag that contains 15% oxygen (like the air on an aeroplane) for a maximum of 25 minutes. Your oxygen levels will be continuously monitored throughout this time.

Towards the end of the test, you may be asked to perform light exercise such as sitting and standing for one minute. These exercises are designed to mimic what you may do on a plane.

At the end of the test, you will come off the mouthpiece and the scientist will monitor you to ensure your oxygen levels return to normal before you leave.

If your oxygen level falls during the test, your doctor may recommend the use of oxygen during the flight. Airlines differ in the way that this is organised.  If you fall into this category, please discuss with your doctor your intention to travel before booking any flights.