A peak flow meter for asthma is like a thermometer for a fever. It is a simple, portable device, which helps you monitor what's going on inside your lungs by measuring airflow Asthma patients blow into them quickly and forcefully, and the resulting peak flow reading indicates how open your airways are. If used appropriately, a peak flow meter can be a valuable tool by evaluating how well your asthma is being controlled. The peak flow meter can be used to find out if there is narrowing in the airways hours or even days, before you have symptoms of worsening asthma. By taking action early, you may be able to stop the episode quickly and avoid a serious episode of asthma.

This guide will help you learn how to take your peak flow measurement, how to find your personal best peak flow number, how to use this best peak flow number to set your peak flow zones, and when to take your peak flow.

Follow these general steps when using a peak flow meter:

  • Make sure the device reads zero or is at base level.
  • Stand up (unless you have a physical disability).
  • Take as deep of a breath as possible.
  • Place the meter in your mouth and close your lips around the mouthpiece.
  • Blow out as hard and as fast as possible for one to two seconds.
  • Do not cough or let your tongue block the mouthpiece.
  • Write down the value obtained.
  • Repeat the process two additional times, and record the highest of the three numbers.

It also helps to record peak flow readings before and after using your inhaled medications. Use different symbols, such as "X" and "O," to document these readings each morning and night. Your health care provider can learn a great deal about the course of your asthma by reviewing these readings. This also will help you to gain a better understanding of your lung function.

Keep a chart of your peak flow readings, with each day recorded in a column, to show how your asthma symptoms are progressing. Graphs for plotting peak flow readings often come with the devices and can be photocopied for regular use.

Remember, your peak flow meter needs some care, so make sure to follow the cleaning instructions enclosed with each unit. This will help to ensure its accuracy.

It is important that you establish a baseline peak flow number when you are at your best. This Personal Best Peak Flow Number will be compared to peak flow numbers in the future to evaluate the degree of airway obstruction at that time. To find your personal best peak flow number your asthma should be under good control and your medication therapy stable. Take your peak flow between noon and 2:00 pm each day for two to three weeks and after each time you take your quick-relief medicine to relieve symptoms. Your health care provider may suggest different times. Write down the number you get for each peak flow reading. The highest peak flow number you measured during the 2-3 weeks is your personal best. Your personal best can change over time. Ask your health care provider when to check for a new personal best.

Your Peak Flow Zones

To help you evaluate your daily peak flow measurements, the results will fall within three zones based on your personal best peak flow number. The zones will help you check your asthma and take the right actions to keep it under control. The colors used with each zone come from the traffic light.

  • The Green Zone is 80-100% of your personal best and signals good control. You are relatively symptom-free and can continue your normal asthma therapy.
  • The Yellow Zone is 50-79% of your personal best and signals caution: your asthma is getting worse. You may need to change your asthma medicines as directed by your health care provider and you need to be concerned about further deterioration in your asthma.
  • The Red Zone is below 50% of your personal best and signals medical alert! If your peak flow readings do not return to at least the yellow zone, you need to contact your health care provider immediately!

Things to Remember

  • A peak flow meter is easy to use at home and can help you manage your asthma
  • It is important that you establish a Personal Best Peak Flow Number to understand the importance of your daily measurements
  • Remember to write down your daily peak flow numbers on a chart and bring them to your appointments with your health care provider
  • Understand the importance of your peak flow zones, mark the zones on your peak flow meter with colored tape or a marker, and develop a plan with your health care provider for each zone.

The contents of wired.MD are for informational purposes only. Nothing contained in wired.MD is intended to substitute for medical advice, diagnosis or treatment. If you have health care related concerns or questions, please seek the advice of your physican or other qualified healthcare providers. You should never disregard professional medical advice or delay in seeking it because of something you have read or seen on wired.MD.

Special Thanks to Medtronic for their help in the making of this production.

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