A peak flow monitor is a small plastic device that you can use to identify changes in your breathing capacity, often before any of your symptoms even occur, so you can adjust your treatment as needed

An Easy-to-Use Early Warning System

You may not be aware of your very earliest asthma symptoms, but one of the first signs is often a slow narrowing of your airways. Over time this may progress into a range of symptoms, including coughing, tightness in your chest and a deep tiredness. But by the time you notice these effects, you may already be in distress.
That’s where a peak flow monitor can help. Peak flow meters are available over the counter in most drug stores and they look like a ruler with a tube attached. When you blow into the tube, the breath you expel propels the marker up the ruler. The better your breathing is, the higher the marker will move.

Peak Flow Monitor Zones

Your doctor will have you take record your peak flow readings over a course of a few weeks so you will know your “personal best” or Green Zone, which is when everything is going well. He or she will have you continue to take--and record—daily readings so you will notice changes right away. Typically, when your peak flow reading drops to 50 to 80 percent of your best, this is the “warning sign” or the Yellow Zone and means you need to adjust your medication accordingly. If your reading goes below 50 percent of your personal best, this is your danger area, or Red Zone and alerts you to use your emergency plan.

Tips for Success

A peak flow monitor is very easy to use if you know what to do. Here are some tips to get the most accurate results:

  • Reset the market to zero.

  • Stand to use.

  • Blow out as hard as you can into the mouthpiece

  • Read where the marker has landed.

  • Repeat twice.

  • Record the highest reading.

If you experience asthma symptoms or lower readings and need to use your rescue inhaler, you will want to take a reading before the medication and again 20 minutes or so after, just to be sure it is taking effect.