Like HowStuffWorks on Facebook!

Peak Flow Meter

        Health | Asthma

Using Your Peak Flow Meter

Use your peak flow readings to monitor how you are doing compared with your personal best on a day-to-day basis. Your personal best is the highest peak flow number that you have achieved when you are symptom free.

Find your personal best by measuring your peak flow every day for 2 to 3 weeks while your asthma is well-controlled. During this 2- to 3-week period, write down the peak flow reading taken between noon and 2:00 PM every day and after you use quick-relief medicine. The highest peak flow number that you have during the 2- to 3-week time period is your personal best. Remember that this process is only for finding your personal best. To monitor your asthma daily, continue to measure your peak flow each morning, or more often, if your doctor says to.

Compare your daily reading with your personal best. Keep an ongoing record for your personal use and to review with your healthcare team. Make sure to ask your doctor when you should check again for a new personal best.

How To Use Your Peak Flow Meter:

  • It is best to stand up when using your peak flow meter.
  • Move the indicator to the bottom of the numbered scale (to zero).
  • Take a deep breath in.
  • Place it in your mouth and seal your lips around the mouthpiece.
  • Blow out as hard and fast as possible.
  • The first time that you use your meter, look where the indicator stops and write down that number.
  • Reset the indicator to zero.
  • Blow again, then write down that number and reset to zero.
  • Blow a third time and write down that number.

The highest number of the three is called your "peak flow rate." Compare this number with your "personal best," the highest reading you have had when you are free of symptoms. Share your peak flow results with your doctor.

Cleaning Your Peak Flow Meter

To keep your peak flow meter working as it should and to ensure accurate results, clean it at least once a week according to the manufacturer's instructions as indicated on the packaging. Never boil, heat, or clean your peak flow meter in the dishwasher unless the packaging indicates that it is a dishwasher-safe model.

Written by Karen Serrano, MD

Emergency Medicine resident at the University of Wisconsin-Madison.

Reviewed by Lisa V. Suffian, MD

Instructor of Clinical Pediatrics in the Division of Allergy and Pulmonary Medicine at Saint Louis Children's Hospital, Washington University School of Medicine

Assistant Clinical Professor in the Department of Pediatrics at Cardinal Glennon Children's Hospital, Saint Louis University

Board certified in Allergy and Immunology

Last updated June 2008