A peak flow meter is a small handheld medical device that measures the fastest speed that air leaves your lungs during a forceful exhalation. This exercise is helpful to asthmatics as the results can help predict if your asthma is under control, or if an attack is eminent.
Using the peak flow meter is simple to do and only takes a few minutes. It serves as an important indicator of how well your airways are open and if your breathing is under control—or if you are headed for problems. The peak flow meter can indicate that your airways are closing long before you begin to feel any tightness or shortness of breath, enabling to can take your medications and prevent an attack from happening.
The peak flow meter has a mouthpiece that you place your teeth on and seal your lips tightly around so that no air escapes. The meter has a scaled set of numbers that begin low at the mouthpiece end and increase. Within the scale is a flow indicator and a spring-loaded push aperture.
Taking as deep a breath as you can, forcefully exhale from your mouth as fast as possible—imagine blowing out birthday candles from 3 feet away. The spring aperture will push the flow indicator to the highest speed that your exhaled air reached and the spring aperture will return to it resting place and the flow indicator will remain at that high flow so that you can read the results. After looking at your results, manually slide the flow indicator back to the baseline.
You should perform this baseline test on a day when your asthma is well under control and you are not in any distress. To get a good idea of what your target number is, you should perform this maneuver at least 3 times, taking your best result.
Once you know your target number, you need to establish 3 zones. The first zone is the green zone. The green zone represents 80% or higher of your target number. When you perform a peak flow test and your results are between 80 and 100%, your asthma is well under control.
The yellow zone is in the range of 50% to 79% of your target number. Anytime your best results fall in this range, you should take your rescue medication, wait 20-30 minutes and repeat your peak flow maneuver. If your results are not in the green zone, call your doctor.
The red zone is anything below 50% of your target number. If you find yourself in the red zone, take your breathing treatment or rescue inhaler immediately. If you do not feel any improvements following your treatment, and call your doctor or 911.
Using the peak flow meter can be an effective tool for managing your asthma, but there are additional steps you can take.
Develop an asthma plan, and learn to manage your asthma medications and when to take them. Document when you do take them and note any triggers or conditions that are present in the environment that is making you short of breath.
See your doctor on regular basis even when you are not short of breath. Your conditions may change over time and your medications may also need to be changed as well.
Lastly, avoid any known triggers that set off an attack. Regular exercise, a healthy weight, and abstaining from smoking will all contribute to better managing your asthma and improving your quality of life.