A peak flow meter is a portable, inexpensive, hand-held device that measures your ability to push air out of your lungs. Air flow is measured by the amount of air that you can blow out in one "fast blast." Show
Peak flow meters come in two ranges to measure the air pushed out of your lungs. A low range peak flow meter is for small children, and a standard range peak flow meter is for older children, teenagers, and adults. An adult has much larger airways than a child and needs the larger range. There are several types of peak flow meters available. Talk to your healthcare provider or pharmacist about which type to use. Determining a "Normal" Peak Flow RatePeak flow rates are commonly split into three zones. The colors of a traffic light – green, yellow, red – are used to represent the three zones. In general, a normal peak flow rate can vary as much as 20 percent. Be aware of the following general guidelines. Keep in mind that recognizing changes from "normal" is important. Your healthcare provider may suggest other zones to follow.
Some healthcare providers may suggest zones with a smaller range, such as 90 to 100 percent. Always follow your healthcare provider's suggestions about your peak flow rate. Asthma Action Plan Based on Peak Flow ReadingsIt is important to know your peak flow reading, but it is even more important to know what you will do based upon that reading. Work with your healthcare provider to develop an asthma action plan that follows your green, yellow, and red zone. Record the peak flow readings that your healthcare provider recommends for your green zone, yellow zone, and red zone. Then work out with your healthcare provider what you plan to do when your peak flow falls in each of those zones.
Page last updated: September 7, 2022 Peak flow measurement is a quick test to measure air flowing out of the lungs. The measurement is also called the peak expiratory flow rate (PEFR) or the peak expiratory flow
(PEF). Peak flow measurement is mostly done by people who have asthma. Peak flow measurement can show the amount and rate of air that can be forcefully breathed out of the lungs. The measurement should be started after a full lung inhalation. During the test, you blow forcefully into the mouthpiece of a device. A peak flow meter (PFM) is used most often. This is a small handheld device made of plastic. A PFM is small and light enough to be used almost anywhere. It’s important to
use the same PFM on a regular basis. The readings can vary between brands and types of meters. In some cases, the test is done in a healthcare provider's office or a hospital with a spirometer. This device has a handheld mouth piece that’s attached by cord to a larger electronic machine. An important part of peak flow measurement is noting peak flow zones. Peak flow zones are areas of measurement on a peak flow meter. The goal of the peak flow zones is to show early symptoms of
uncontrolled asthma. Peak flow zones are set differently for each person. Your healthcare provider will help determine your peak flow zones. The 3 peak flow zones are noted by color and include: Green . This means “go.” The green zone is 80% to 100% of your highest peak flow reading, or personal best. This is the zone you should be in every day. When your measurements are in this zone, air is moving well through the large airways in your lungs. It means that you
can do your usual activities and go to sleep without trouble. Yellow. This means “caution” or “slow down.” The yellow zone is 50% to 80% of your personal best. Measurements in this zone are a sign that your large airways are starting to narrow. You may start to have mild symptoms, such as coughing, feeling tired, feeling short of breath, or feeling like your chest is tightening. These symptoms may keep you from your usual activities or from sleeping well. Red. This means “stop.” The red zone is less than 50% of your personal best. Readings in this zone mean you have severe narrowing of your large airways. This is a medical emergency. You should get help right away. You may be coughing, very short of breath, wheezing while breathing in and out, or having retractions (the muscles between the ribs are working hard to help you breathe). You may also have trouble walking and talking. Peak flow measurement using a peak flow meter is useful for people with asthma. During an asthma flare-up, the large airways in the lungs slowly begin to narrow. This slows the speed of air moving through the lungs. A peak flow meter can help show the narrowing of the airways well before an asthma attack happens. A peak flow meter can help you determine: When to get emergency medical care How well an asthma treatment plan is
working When to stop or add medicine as directed by your healthcare provider What triggers an asthma attack, such as exercise A peak flow meter can help you manage asthma. It can give you and your healthcare provider information about how open the airways are in your lungs. The PFM can detect small changes in the large airways before you start to wheeze. Using a PFM every day will let you know when your peak flows are starting to drop. This
allows you to make early changes in your medicine or routine to help keep asthma symptoms from getting worse. The PFM can also identify the reading at which you need to call your healthcare provider or go to the emergency room. Your healthcare provider may not advise you use a PFM unless your asthma is moderate or severe and you are managing it with medicine. PFM can also be used to assess other lung problems, such as:
What are the risks of peak flow measurement?All procedures have some risks. The risks of this procedure may include:
Certain factors may interfere with the accuracy of peak flow measurement, such as:
How do I get ready for peak flow measurement?Your healthcare provider will explain the procedure to you. Ask him or her any questions you have. You may be asked to sign a consent form that gives permission to do the procedure. Read the form carefully. Ask questions if anything is not clear. Tell your healthcare provider if you take any medicines. This includes prescriptions, over-the-counter medicines, vitamins, and herbal supplements. Make sure to:
Before starting daily peak flow meter measuring, your healthcare provider may have you follow a detailed schedule over 2 to 3 weeks. This is done to find your “personal best” peak flow measurement. This value will be used as a baseline for your daily measurements. What happens during peak flow measurement?Peak flow measurement is done 1 or more times daily at the same time of day, or whenever you are having early signs of an asthma attack. Or you should use it when directed by your healthcare provider. Use the peak flow meter (PFM) before taking asthma medicine. Your healthcare provider may advise other times when using a PFM is useful. In most cases, peak flow measurement follows this process:
What happens after peak flow measurement?Note which peak flow zone your measurement falls into. Follow the instructions below:
Your healthcare provider may give you more instructions about what to do for each peak flow zone. How do you use a peak flow meter for asthma?How Do I Use a Peak Flow Meter?. Place the indicator at the base of the numbered scale.. Stand up.. Take a deep breath.. Place the meter in your mouth between your teeth and close your lips around the mouthpiece. ... . Blow out as hard and fast as you can in a single blow.. Write down the number you get.. What are the steps behind carrying out a peak flow test?hold the peak flow meter so it's horizontal and make sure that your fingers are not obstructing the measurement scale. breathe in as deeply as you can and place your lips tightly around the mouthpiece. breathe out as quickly and as hard as you can. when you've finished breathing out, make a note of your reading.
How do you instruct a client to use a peak flow meter?Place the peak flow meter in the mouth, with the tongue under the mouthpiece. Close the lips tightly around the mouthpiece. Blow out as hard and fast as possible; do not throw the head forward while blowing out. Breathe a few normal breaths and then repeat the process two more times.
What happens to peak flow in asthma?Peak flow measurement using a peak flow meter is useful for people with asthma. During an asthma flare-up, the large airways in the lungs slowly begin to narrow. This slows the speed of air moving through the lungs. A peak flow meter can help show the narrowing of the airways well before an asthma attack happens.
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