Checking your "peak flow" is one of the best ways to empower yourself and gain control over your asthma. It can help you make sure your asthma is not getting worse and can bring you peace of mind.

Asthma is a condition that builds slowly -- it usually does NOT suddenly attack without warning. One way you know an attack is coming is that symptoms appear and grow worse. However, a second way is to check your peak flow -- this can help you to "see an attack coming" and take the appropriate action, sometimes before you even feel any symptoms. If you are not monitoring your asthma, an attack can take you by surprise.

What is "peak flow"?

Peak flow is a measurement of how well you can blow air out of your lungs. If your airways become narrow and blocked due to asthma, you can't blow air out as well, and your peak flow values drop.

Peak flow is measured at home with a small, inexpensive plastic meter. Several companies make these meters, and they vary in look and feel. Some peak flow meters have tabs on the side that you can adjust to match your action plan zones (green, yellow, red). If your meter does not have these, you can mark them with colored tape or a marker.

To view an interactive guide on using a peak flow meter, click here.

Record charts

You'll need some form of record chart (also called a "log" or "diary") to write down your peak flow scores. These charts are included with peak flow meters -- it is a good idea to photocopy the chart and keep the sheets to show your doctor, who can glance through your whole history of peak flow values to see how they have changed over time.

A good record chart also will contain a place to note:

1. Any signs or symptoms you felt each day,
2. Steps you took if you had symptoms or your peak flow dropped,
3. Changes the doctor made in your medication, and
4. Any asthma triggers you were exposed to.

This information will help make a complete picture of all factors that are impacting your asthma.

Who should use a peak flow meter?

According to guidelines from the National Institutes of Health, the following people might benefit from peak flow monitoring:

• Anyone with moderate-to-severe persistent asthma. These people should consider using a peak flow meter every day or two, even when they are feeling well.
• People who are just starting to work with their doctor to develop a new treatment plan. A peak flow meter can help determine how well the medications are working and help the doctor figure out how to fine tune the treatment plan.
• Anyone who has ever had a severe asthma episode (attack).
• Anyone who wants to fully master their asthma management and gain the peace of mind that comes with it.

Many children under age 5 can't use a peak flow meter well enough to make the numbers useful, so their asthma must be managed by an adult who needs to watch carefully for the asthma signs. The age 5 "cutoff" is somewhat arbitrary, however, and can be adjusted based on the abilities of the individual child. It's a good idea to start using peak flow meters before age 5 to get the child used to them, but not to actually rely on them too much for monitoring the child's condition.