|A peak flow meter is an important tool to help manage asthma and which can help us to determine how your child is doing. Most children are able to use a peak flow meter once they are five to six years old. You can discuss with your pediatrician if your child should be monitoring peak flows at home.
Your child's peak flows represent how much air he can get out of his lungs. By monitoring his peak flows on a daily basis, you will know what to do when he has an asthma attack and may even be able to predict and prevent them. You Pediatrician will also probably check your child's peak flows during office visits.
It is best to check your child's peak flows two or three times a day and keep a diary of them on your peak flow calendar, especially until his asthma is under good control. Regularly monitoring peak flows will allow you to track changes in his peak flows over time. For many kids, their peak flows will begin to drop just before they are going to have an acute attack, even before they begin to have symptoms, so if you are checking peak flows every day you may catch an asthma attack early or even predict when an attack is about to start. Starting his treatments early according to his asthma action plan may help to prevent a severe asthma attack.
Regular peak flow monitoring can also help to determine if your Pediatrician needs to change your child's daily medications, and they can be used to help determine when to stop or decrease a medication or when to begin or increase a medication.
Monitoring peak flows on a regular basis may also help you to identify triggers that make your child's asthma worse. If you notice that his peak flows drop every time that he is around cats, then you will know that cats are a trigger for his asthma and you will know to avoid them in the future.
Once your determine your child's personal best peak flow (see below), we can use this number to help determine his peak flow zones. These zones are grouped into a green zone, which is 80-100% of his personal best, yellow zone, which is 50-80% of his personal best, and red zone, which is below 50% of his personal best. If your child's peak flows vary greatly from day to day, especially if they often dip down into his yellow or red zone, then this may be a sign that his asthma isn't under very good control and you should see your Pediatrician to talk about it.
The green zone is where your child should be everyday. This means his asthma is under good control and he is not having any symptoms. You should continue to use your daily medications according to your asthma treatment plan, but he shouldn't need to use a short acting bronchodilator medicine (unless it is for preventing exercise induced asthma).
When your child begins to have symptoms with his asthma, then he may move into his yellow zone (50-80% of his personal best peak flow). He may begin coughing, wheezing, have a tight chest, shortness of breath, have difficulty performing his normal activities, and he may wake up at night coughing. This is a cautionary zone that your child should not be in every day. You should begin using your bronchodilator medicine according to your asthma action plan. Your doctor may also have you increased the amount of inhaled steroid that you are on when you are in your yellow zone.
If your child's peak flows are less than 50% of his personal best, then he is in the red zone, which is a danger zone that indicates that your child's asthma is worsening. You should use your bronchodilator medicine right away and call your physician. When in the red zone, your child may be breathing hard and fast, have constant coughing, have difficulty talking or walking, and his ribs may be showing when he breathes.
An alternative method of calculating peak flow zones used by some physicians is a green zone between 90-100% of a personal best peak flow, high yellow zone between 70-90% of a personal best, low yellow zone between 50-70% of a personal best, and a red zone below 50% of a personal best.