| Where It's Done | Who Does It | How Long It Takes | Discomfort/Pain |
| At home, in a hospital, or virtually anywhere. | Patient. | Less than 1 minute. | None. |
| Results Ready When | Special Equipment | Risks/complications | Average Cost |
| Immediately. | Peak flow meter. | May make you feel temporarily out of breath, but no real risk. | $ (only cost of meter). |
To monitor the condition of the airways in order to monitor asthma, help predict an asthma attack, and determine when medication or emergency care is needed. Because it is a self-test, it can be done at virtually any time.
How it worksThe flow of air you are able to generate forcefully into a closed cylinder is an indication of whether or not your airways are constricted.
PreparationAvoid eating a heavy meal for about three hours before taking the test.
Test procedure- Insert the mouthpiece of the peak flow meter between your teeth, and make sure your lips form a tight seal.
- Exhale strongly, with the greatest possible force.
- Repeat the maneuver at least twice, until results vary by no more than 10%.
- Record the maximum flow rate shown on the meter.
If results are within 20% of your normal capacity, no special care is necessary (see Interpretation below).
Factors affecting results- Insufficient effort on your part during the test.
- Lack of a tight seal over the mouthpiece.
- Improper handling of the peak flow meter (most devices must be held horizontally to achieve accurate measurements).
Compare the measurements with your usual results. If they drop 20% below your average, follow your doctor's orders for taking medication or getting medical help.
Advantages- You and your physician may be able to use peak flows to help you monitor your asthma.
- It's quick, inexpensive, and noninvasive.
- It provides valuable information for asthmatics.
It's reliable only if performed properly.
The next stepYou take your medication if it is indicated.
Peak flow measurement is a simple test that asthmatics can do to monitor themselves, thus enabling them to take preventive medication and perhaps avoid the need for emergency medical care. It is recommended for all asthmatics, and in particular for the following persons:
- People who experience severe asthma attacks with little warning.
- Those who require daily, high-dose, or low-dose inhaled corticosteriods.
- Those with wide variations (20% or more) in the peak flow rate.
- Home peak flow meters are easy enough to use that they can be used for children with asthma. Many models are small, lightweight (less than 3 ounces) cylinders that can be carried in a purse or briefcase.
