Home lung function test

Testing your peak expiratory flow (PEF) or your forced expiratory volume at 1 second (FEV1) at home may help:

• Measure how well your lungs are working if you have a long-term (chronic) lung disease, such as asthma.
• Guide the treatment and monitor the effectiveness of treatment for asthma. Peak expiratory flow monitoring provides information to help people with asthma make better treatment decisions.
• Monitor your lung function if you are regularly exposed to substances at work that can damage your lungs (occupational asthma).
• Monitor for early signs of rejection if you have had a lung transplant.

Before you begin to test your peak expiratory flow (PEF), remove any gum or food you may have in your mouth. Follow these steps to use your peak flow meter:

• Set the pointer on the gauge of the peak flow meter to 0 (zero).
• Attach the mouthpiece to the peak flow meter.
• Sit up or stand up as straight as possible to allow yourself to take a deep breath. Make sure you use the same position each time you test your PEF.
• Take a deep breath in. Place the peak flow meter mouthpiece in your mouth and close your lips tightly around the outside of the mouthpiece. Do not put your tongue inside the mouthpiece.
• Breathe out as hard and as fast as you can using a huff. You do not need to breathe out for more than a second.
• Note the value on the gauge.
• Move the pointer on the gauge back to 0 (zero) before you blow again.
• Blow into the peak flow meter 2 more times. Record your values each time you blow. If you cough or make a mistake during the testing, do the test over.
• After you have blown into your peak flow meter 3 times, record the highest value on your daily record sheet.

Results from a peak flow meter or home spirometer can be compared to monitor the progression of disease or help measure your response to medical treatment for a long-term (chronic) lung disease, such as asthma.

Peak expiratory flow, or peak flow, is how much air you breathe out when you try your hardest. You can help manage asthma by checking your peak flow and comparing it with your personal best measurement. If you find abnormal results on any of the tests, check your asthma action plan or discuss your results with your doctor.

• Normally, peak flows vary slightly throughout the day. They are usually lower in the morning and higher in the afternoon.
• A person with poorly controlled asthma may have peak flows that vary more widely throughout the day.