Why it's done

A peak flow meter allows you to measure day-to-day changes in your breathing. Using a peak flow meter can help you:

• Track the control of your asthma over time
• Show how well your treatment is working
• Recognize signs of a flare-up before symptoms appear
• Know what steps to take when you have signs of an asthma flare-up
• Decide when to call your doctor or get emergency care