Exercise Oximetry

What is oxygen desaturation evaluation or exercise pulse oximetry test?

When a healthy person exercises, the blood oxygen pressure (PaO2) and oxygen saturation (O2 sat) stays the same or increases. In a person with lung disease, during exercise the oxygen pressure and O2 saturation may drop. This is called an oxygen desaturation. If the O2 drops to a level that is too low, that can put a stress on your lungs and body. Extra oxygen may be needed during activity to keep the O2 saturation in a healthy range.

In our office, we may advise you to undergo an exercise test to check your oxygen levels during activity. Oxygen saturation is measured using a pulse oximeter. A drop in O2 saturation of 4% from the O2 saturation at rest or an O2 saturation of less than or equal to 88% is considered significant.

Checking for oxygen desaturation during exercise may also be done as part of a cardiopulmonary exercise test. O2 sat levels are checked during a Six minute walk test which also looks at how far a person can walk in a set amount of time. The test may also be done if you are planning to go to an area that is at high altitude and has lower oxygen pressure of the air.

How is this test performed ?

The person wears a pulse oximeter and a staff person is assisting and watching the numbers. You will wear a pulse oximeter probe on your finger or earlobe throughout the test. Follow directions from the staff person on how to hold it still to get a good reading while exercising. Holding the hand with the finger probe relaxed and up against the chest at heart level is best for getting good readings while walking. The staff during the test may talk to you to encourage you to keep exercising or have you slow down at times. You may have to stop during the test if you are on oxygen so the flow rate can be adjusted. Testing can also be done while a person is wearing oxygen to see whether the oxygen flow rate is high enough during activity to keep O2 sat at a good level. The goal is to see what the lowest level of oxygen is needed at rest and with exercise to keep O2 sat up, usually 90% or higher. If you are not feeling well and want to stop, tell the staff person. If you have any of the following symptoms during testing, let the staff person know right away: Chest pain, chest tightness, or palpitations (heart racing) Wheezing, Shortness of breath, Dizziness or feeling faint a Feeling like you cannot walk or go any longer The staff person may also ask you to stop if your heart rate is too high or your O2 sat drops too low. You will rest after the test and the staff will check how your O2 sat changes or recovers as well.

Are there any reasons I should not, or might not be able to perform the test?

An exercise desaturation test should not be done if you have had: a unstable chest pains (such as angina or other heart problems) a Poorly controlled high blood pressure (hypertension) a Recent blood clots (in your lungs or elsewhere in your body) If your O2 sat is low at rest off of oxygen (less than or equal 85%), you may not be tested without use of extra oxygen. There may be other reasons the test is not done and we can help you decide if you are stable to do the test.

How should I prepare for the test?

Each lab may have slightly different instructions. You will receive specific instructions for the lab. Commonly, people are advised to: a wear comfortable clothes and shoes you can walk in to do the test. a not smoke or vape or inhale smoke the day of testing. a avoid eating a large meal in the hour before testing. A light meal is okay. You can take your usual medications before the test unless directed not to by our team.