A peak flow meter is a small device that helps you check how well your asthma is controlled. Peak flow meters are most helpful if you have moderate to severe persistent asthma. Show
Measuring your peak flow can tell you and your health care provider how well you blow air out of your lungs. If your airways are narrowed and blocked due to asthma, your peak flow values drop. You can check your peak flow at home. Here are the basic steps:
Many children under age 5 cannot use a peak flow meter very well. But some are able to. Start using peak flow meters before age 5 to get your child used to them. To find your personal best peak flow number, take your peak flow each day for 2 to 3 weeks. Your asthma should be under control during this time. To find your personal best, take your peak flow as close to the following times of day as you can:
These times for taking your peak flow are only for finding your personal best. Write down the number you get for each peak flow reading. The highest peak flow number you had during the 2 to 3 weeks is your personal best. Ask your provider to help you fill out an asthma action plan. This plan should tell you when to call the provider for help and when to use medicines if your peak flow drops to a certain level. Your personal best can change over time. Ask your provider when you should check for a new personal best. Once you know your personal best, make taking your peak flow a habit. Take your peak flow:
Check to see which zone your peak flow number is in. Do what your provider told you to do when you are in that zone. This information should be in your action plan. If you use more than one peak flow meter (such as one at home and another one at school or work), be sure that all of them are the same brand. Peak flow meter - how to use; Asthma - peak flow meter; Reactive airway disease - peak flow meter; Bronchial asthma - peak flow meter Boulet LP, Godbout K. Diagnosis of asthma in adults. In: Burks AW, Holgate ST, O'Hehir RE, et al, eds. Middleton's Allergy: Principles and Practice. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 51. Chassay CM. Pulmonary function testing. In: Fowler GC, ed. Pfenninger and Fowler's Procedures for Primary Care. 4th ed. Philadelphia, PA: Elsevier; 2020:chap 81. National Asthma Education and Prevention Program website. How to use a peak flow meter. How to use a metered-dose inhaler. www.nhlbi.nih.gov/health/public/lung/asthma/asthma_tipsheets.pdf. Updated March 2013. Accessed April 22, 2022. National Heart, Lung and Blood Institute. Asthma Management Guidelines: Focused Updates 2020. www.nhlbi.nih.gov/health-topics/asthma-management-guidelines-2020-updates. Updated February 4, 2021. Accessed January 8, 2022. Viswanathan RK, Busse WW. Management of asthma in adolescents and adults. In: Burks AW, Holgate ST, O'Hehir RE, et al, eds. Middleton's Allergy: Principles and Practice. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 52. Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. 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. Why might I need peak flow measurement?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:
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 many readings should you take when you are measuring a patient's peak expiratory flow rate?The 3 readings should be close together. If not, adjust your technique. If you cough during a measurement, repeat the measurement. Record only the highest of the 3 readings on a graph or in a notebook.
How many readings should you take when you are measuring a patient's peak expiratory flow rate quizlet?How do you calculate the peak expiratory flow rate from the three readings? Use the highest reading as the peak expiratory flow rate.
How often should you measure peak flow?Measure your peak flow at least once a day, usually in the morning before you take your asthma medicines. You might have to check it more often if you are having more episodes than usual, or if your reading is below 80 percent of your personal best.
What should my reading be on a peak flow meter?Peak expiratory flow (PEF) is measured in litres per minute. Normal adult peak flow scores range between around 400 and 700 litres per minute, although scores in older women can be lower and still be normal.
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