The official blog of the Lung Institute.
What Does the Test Look Like?
You start to notice that you tire more easily. When you clean the house, you need to take frequent breaks. You feel out of breath after a short walk to the mailbox. You go to a pulmonologist and he shares the following news: you have a lung disease. It might be chronic obstructive pulmonary disease (COPD) or pulmonary fibrosis, so a number of breathing tests are ordered to pinpoint your diagnosis. One of the ordered tests is a nitrogen washout test, and you can’t help but think about what it’s going to entail.
The Basics of a Nitrogen Washout
The nitrogen washout test, in name alone, is a test that often scares patients. In practice however, it is quite simple. To accurately measure the effects a lung disease will have on lung functioning, there are many basic characteristics of your lungs that must be known. Namely, these include:
- Lung Volume – the overall amount of air that could theoretically fill your lungs.
- Lung Capacity – the actual amount of air your lungs use during regular breathing.
- Functional Residual Capacity – the amount of air that normally sits in your lungs not being used.
- Diffusing Capacity – the ability of small air sacs in your lungs to absorb oxygen into the blood stream.
- Airflow – your physical ability to pull in and expel air.
The nitrogen washout test gauges the functional residual capacity of your lungs and airflow. Specifically, a pulmonologist is looking for the dead space in the small air sacs of the lungs, where air sits and is not taking part in the exchange of gases. This is usually caused by a nonfunctioning capillary that is attached to the air sacs, which are not absorbing oxygen or expelling carbon dioxide. A large amount of dead space in the lungs will add to lowered efficiency and poor lung function.
The Testing Process and Results
The test can be performed in two ways, as one deep breath or a series of breaths over a few minutes. First, you will be asked to breathe through a machine that supplies you with nothing but pure oxygen. No other gases will be present in the air. Then, you will exhale as long as possible through the machine that will then read the amount of nitrogen in your breath. Since nitrogen is not exchanged in the lungs, it sits there until you exhale. But if your breath is too shallow due to respiratory inflammation, it does not escape easily.
The air you normally breathe is roughly 78 percent nitrogen due to the nitrogen in the earth’s atmosphere. Therefore, if you breathe in just oxygen, you should exhale the residual nitrogen that has been sitting in your lungs. The amount of nitrogen over 78 percent, which is the assumed normal amount, will indicate how much residual gas sits in the lungs.
You may also be asked to breathe normally for a few minutes during which time you will continue to inhale pure oxygen. Typically, this measures how long it takes you to expel the nitrogen in your lungs. In a healthy person, this would take around 7 minutes, but a person suffering from a lung disease may need much longer.
The nitrogen washout test is just one of the many tests that are needed to judge the functioning of your lungs. When you or a loved one has been diagnosed with a lung disease, these tests may be used to help form a treatment plan. If you are interested in learning about cellular therapy as a treatment for lung disease, please contact one of our patient care coordinators today at 888-745-6697 to schedule a free consultation.