Peak Flow Meter

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KEY POINTS

• Asthma is a chronic lung disease that can cause shortness of breath, coughing, wheezing, and sometimes chest tightness.
• A peak flow meter is a small hand-held device that measures how well air moves out of your child’s lungs. It does this by measuring how fast your child can blow air out of his or her lungs.
• Peak flow readings tell if your child’s asthma is under good control, if your child needs to take medicine, or if your child needs to get help right away.
• Each brand of peak flow meter works a little differently. Make sure you and your child know how to use the peak flow meter correctly. To have accurate peak flow readings, your child needs to give his or her best effort each time.

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What is asthma?

Asthma is a long-lasting (chronic) lung disease. It can cause shortness of breath, coughing, wheezing, and sometimes chest tightness.

Asthma symptoms are caused by two different problems in the airways:

• One problem is that the tiny muscles around the airways tighten up, which causes shortness of breath, coughing, wheezing, and sometimes chest tightness.
• The other problem is redness, swelling, irritation, and too much mucus in the airways.

If your child has asthma, symptoms often start after your child is exposed to a trigger. Asthma triggers can include:

• Exercise and other physical activity
• Allergies such as dust, pollen, mold, or animal dander
• Something that irritates the lungs such as cold air, smoke, or strong smells such as paint, soap, candles, or perfume
• Nonsteroidal anti-inflammatory medicines (NSAIDs) such as aspirin, ibuprofen, and naproxen
• An infection such as a cold, the flu, or a sinus infection
• Strong emotions or stress
• Indigestion or heartburn, also called gastroesophageal reflux disease, or GERD. If your child often has problems with indigestion you may have more asthma symptoms, especially while lying down.

Try to limit your child’s contact with these triggers, especially in places where your child spends a lot of time such as at home and school or work. Your child should keep a rescue inhaler with him or her at all times in case your child has an asthma attack.

What is a peak flow meter?

A peak flow meter is a small hand-held device that measures how well air moves out of your child’s lungs. It does this by measuring how fast your child can blow air out of his or her lungs. Peak flow readings tell you if your child's asthma is in good control, if your child needs to take medicine, or if you need to get help right away.

Measuring the peak flow regularly can help detect asthma symptoms before you notice them. Also, using the colored zone system (green, yellow, red) with the peak flow meter will help you know when your child needs help and how to better manage your child's asthma.

There are several different types of peak flow meters, so for accurate readings, it is important to understand how to use the peak flow meter and to follow instructions carefully. It is also important to use the same peak flow meter for all readings. There are two main kinds of peak flow meters:

• One type has a sliding marker that moves as your child blows air forcefully into the device.
• The other type is a digital peak flow meter that records each reading in the device.

Peak flow meters usually show a numbered scale that measures the amount of air your child breathed out. The numbered scale usually ranges from 0 to 750. Some units also display "traffic light" colored peak flow zones based on the child's personal best peak flow reading.

When should my child use a peak flow meter?

First you need to figure out your child's personal best peak flow reading. This is done by taking peak flow readings twice a day for a couple of weeks when your child is breathing well and asthma is under good control. At the end of the 2 or 3 weeks, look at the results and pick out the highest readings. These readings determine your child’s personal best peak flow meter reading. Record all of your child's readings on a chart and take the chart to your healthcare provider. The personal best reading will give you and your provider something to judge all of your child's future peak flow readings against.

Your healthcare provider may suggest that your child measure peak flow every day or that your child take readings 2 or 3 times a week.

• Daily use: If your child needs to record a peak flow every day, the first reading should be a morning reading before taking any medicine. If your child’s peak flow readings in the morning are low, check the peak flow again in the early afternoon. If your child takes medicine in the evening, your provider may recommend that you take another reading in the evening before your child takes his or her medicine.
• Weekly use: If your child needs to take peak flow readings just 2 or 3 times a week, take a reading in the morning and again in the evening each day that you take a measurement. Measure the peak flow before taking inhaled medicine. If a rescue inhaler is used, repeat the peak flow reading 15 minutes after taking the medicine and record any change. If the morning and evening readings are different by more than 20%, talk to your healthcare provider about how to manage the asthma better.

Use a chart to record your child's peak flow readings along with the date and time of day the readings are taken. Also record if your child used a rescue inhaler.

You should also measure your child's peak flow reading when your child has an asthma attack. Measure your child’s peak flow both before and after using the rescue inhaler to check how well the medicine is working.

You should recheck your child’s personal best reading every year or whenever you get a new meter.

What is the zone system?

The zone system is an easy way to check if your child's asthma is under good control, if your child needs to take medicine, or if you need to get help right away. The peak flow meter can be marked with three colored zones (green, yellow, and red). This makes it easy to read. The zones are different for each person and are based on your child's personal best peak flow reading. Your healthcare provider will help you figure out the right number range for each zone. Many peak flow meters come with a sticker to mark the zones.

An asthma action plan is a written plan developed by your healthcare provider to help you manage asthma and prevent your child’s asthma attacks. It is based on your child’s peak flow zone.

What do the zones mean?

The colored zones on the peak flow meter are modeled after the traffic light.

Green means good control (80 to 100% of personal best reading). When the reading is in the green zone, it means your child's asthma is under good control.

If your child has stayed in the green zone for at least 3 months, talk to your healthcare provider about possibly reducing your child's medicines.

Yellow means caution (50% to 80% of personal best reading). If the reading is in the yellow zone, it means your child is probably having asthma symptoms or may soon be having symptoms (asthma attack). Your child may be having trouble with normal activities or having symptoms at night.

If your child’s peak flow is often in the yellow zone, or stays in the yellow zone after treatment, it means your child’s asthma is not under good control. Talk to your healthcare provider about adjusting your child's medicine.

Red means danger (less than 50% of personal best reading). If the peak flow reading is in the red zone, it means your child's asthma is dangerously out of control. Your child is probably having serious asthma symptoms such as shortness of breath (even at rest), chest tightness, wheezing, and trouble talking and sleeping. Follow your child’s healthcare provider’s instructions, and call for emergency help right away.

If your child’s peak flow is low, but your child feels fine, take the peak flow test again, making sure your child is blowing hard into the meter.

To have accurate peak flow readings, your child needs to give his or her best effort each time.

How is the peak flow meter used?

Each brand of peak flow meter works a little differently. Carefully read and follow the instructions included with your child’s meter. Make sure you and your child know how to use the peak flow meter correctly. Ask your healthcare provider to watch your child use it.

When and how should the peak flow meter be cleaned?

The mouthpiece of the meter should be cleaned weekly with warm soapy water. Rinse well. Allow to air dry.