I'm a respiratory therapist and have found that many times when a peak flow meter is prescribed, the correct use is either not given or reviewed at a pace where it's hard to absorb all the info. The following is the correct method and the info is taken from Krames On Demand which is a computer program found in a lot of the hospitals. This is meant for educational purposes only & not as medical advice. Using the correct method will help you control your asthma more effectively.
A peak flow meter measures how fast you can push air out of your lungs. This tells you how well you are controlling your asthma. Measure your peak flow as many times a day as your health care provider tells you to.
Step 1: Move the marker to 0, or to the lowest number on the scale. Stand. (If you can't stand, be sure to sit up straight). Make sure you're in the same position each time you test.
Step 2: Take as deep a breath as you can. Put the mouthpiece of the meter in your mouth, between your teeth. Close your lips tightly around it. Be sure your tongue does not block the opening. Blow into the mouthpiece once, as hard and as fast as you can (only one breath).
Step 3: Take the meter out of your mouth. Look at the marker; it will have moved along the numbered scale. Write this number down.
Step 4: Repeat the test 2 more times. Write the highest of the 3 numbers on your chart or in your diary. THIS IS YOUR PEAK FLOW NUMBER.
Hope this info helps all who use peak flow meters!