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Asthma In Children

Asthma in Children: The Peak Flow Meter

Friday, March 16, 2012 - 17:30

Contributing Author: Guy Slowik FRCS

The peak flow meter is an important device that can give you valuable information about your child's air passages - whether air is passing through freely, or whether they are partially blocked.

The meter measures how fast the child is able to breathe into it. This measurement is known as the "peak flow."

Most children over the age of five can learn to use the meter, though with young children it's important to make sure they are doing it correctly.

Monitoring Your Child's Peak Flow

You should learn to use the peak flow meter as a tool for managing your child's asthma and for predicting attacks.

This involves taking regular peak flow measurements and comparing them against your child's best peak flow rates. This is the highest peak flow number a child can produce in the doctors office, when perfectly well, after inhaling medication to open the airways.

Together with your doctor you will decide on a plan of action if the peak flow reading falls significantly.

Why Peak Flow Numbers Are So Useful

By regularly measuring your child's peak flow you can:

  • Predict when an attack may occur, by detecting a drop in peak flow hours or even a day or two before obvious symptoms appear.
  • Know how well your child is responding to medication.
  • Know whether your child's asthma is under control.

When To Use The Peak Flow Meter

The doctor will tell you how often the child should use the meter, and will show you and the child how to use it.

  • If the asthma is quite severe, the doctor may want the child to use the meter daily, at the time of day when the asthma is usually worst.
  • If the asthma is quite mild, the doctor may suggest using the meter only when the child is wheezing, or feels an attack may be coming on.

It is also useful to measure peak flow when the child is starting on a new medicine, because it will show clearly how well the medication is working.

How To Information

How To Use A Peak Flow Meter

Your child should:

  • Have an empty mouth - no gum or food.
  • Stand up.
  • Set the meter at "zero."
  • Hold the meter correctly, so fingers don't get in the way.
  • Take a really deep breath, with the chest puffed up as far as it can go.
  • Close lips around the mouthpiece, with the tongue out of the way.
  • Blow as hard and fast as possible - as if blowing out candles on a cake. The arrow will move until it points to a number on the scale. This is the peak flow number.
  • Blow into the meter three times, and write down the best number.

Parents should:

  • Watch. The child's chest should puff out - the cheeks should not.
  • Listen. There should not be a whistling noise from the meter.
  • Check the numbers on the scale and keep a record. This is best recorded on a calendar.
  • Keep your child's peak flow meter clean. Wash the plastic body in warm water at least once a week.

Children can get readings that are too low by not taking a deep enough breath or by not blowing hard enough when blowing out. They can also get readings that are artificially high, by spitting into the meter or putting their hand in the wrong place on the meter. Parents may need to watch closely to make sure the child is doing it right.

Interpreting Peak Flow Numbers

Here's how you and your child can use a peak flow reading to help decide the severity of his or her immediate condition.

The peak flow reading will fall into one of three zone based on accepted medical standards:

  • The Safety or Green Zone - This includes readings higher than 80% of the child's best peak flow rate. This indicates there is no problem and suggests that current treatment is working.
  • The Caution or Yellow Zone - The child is only able to achieve 50% to 80% of his or her personal best peak flow rate. A reading in the caution zone means that the asthma is worse, even if your child feels fine and looks well.

Now you need to act on the plan worked out with your doctor - give or increase a particular medication or prepare for an attack. Your plan should make clear when the doctor is to be contacted. In many cases, this is not necessary unless readings repeatedly enter the Caution Zone, or stay there even after the treatment prescribed in your plan has been given.

  • The Danger or Red Zone - The child is able to achieve only half, or less than half, of his or her personal best peak flow rate. This usually means an attack has begun.

Your plan should make clear what you need to do. This will include specific medication to be taken immediately. You should get in touch with your doctor if the medicine doesn't stop the attack, or go immediately to the emergency room.

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