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Once your child has been diagnosed asthmatic, you and your doctor should write
up an Asthma Management Plan. These plans vary according to the child and
the severity of their asthma.
The plan should cover:
how to recognise the signs of an attack, and what steps to take
when and how to step up medication if necessary
what action to take in an emergency situation
when to call a doctor or take your child to the hospital
A peak flow meter may be used to help monitor symptoms. However, there is little objective evidence to show improved asthma care or a reduction in mortality and morbidity from asthma. A report published in the British Medical Journal,1 studied 12 boys aged 11 to 17
over a three month period, comparing their peak flow readings to a computerised machine. In some of the boys, none of the readings were accurate, while in other youths the self-monitoring machines worked most of the time. Not one device proved 100% accurate. As a result some peak flow meters overestimated the need for drugs, while others failed to diagnose an asthma attack. As a result, it is urged that parents monitor asthmatic children by symptoms as well as peak flow readings.
The limitations for peakflows in children include:
Age
The age at which a child becomes able to use a peak flow meter effectively is variable, but is approximately 4 years. It is important to note that a child who can use a peak flow meter with adequate technique when well, may be unable to do so when experiencing airflow obstruction.2
Effort Dependence
Peakflow is effort dependent, and so accuracy depends upon the motivation of the child. It may be difficult to encourage children to consistently give a maximum blow.2
Compliance
The majority of patients prove able to comply with regular peak flowing over short periods of time. However, many are unable to comply with long-term regular measurement.2
Technique
There are a number of ways in which the measurements can be falsified. Very high measurements can be produced by the technique of `spitting', especially in meters with a small mouthpiece. This manoeuvre, an explosive decompression of the gas in the upper airway using the tongue to cover the mouthpiece, is more common in boys than girls, and can produce values up to 100% higher than the true value. Conversely, peak flow `faking', a technique more common in teenage girls, can lead to very low readings.2
References
1. Sly PD, Cahill P, Willet K, Burton P. Accuracy of mini peak flow meters in indicating changes in lung function in children with asthma. BMJ 1994;308:572 -4.
2. Clough JB. Recommendations for peak flow monitoring in children. Respiratory Medicine Sept;1996:Vol 90:No 8: 459 - 461
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