Peak Flow Recording

Although some have suggested that routine self monitoring of peak flow in patients with asthma does not improve morbidity or mortality,¹ some studies have indicated that, when used in association with a self management plan, routine measurement of peak expiratory flow can be effective in reducing symptoms of asthma and improving lung function.²
Peak expiratory flow rate may also have a role in detecting patients with chronic obstructive pulmonary disease.³

Peak expiratory flow measurement is recommended for⁴:

• Diagnosis:
  • Diurnal variability of peak expiratory flow rate greater than 20% for at least three days in a week for two weeks is typical of asthma.
  • Or ≥improvement in peak expiratory flow:
    • 10 minutes after high dose bronchodilator through a spacer
    • After a six week course of inhaled steroids
    • After 14 days of 30mg prednisolone
  • Assessment of the response to treatment
• Monitoring:
  • The use of peak flow recording in monitoring asthma must be part of an individual management plan for the patient.
  • Quality of life indicators may be as good as peak flow for predicting exacerbations.
    • Have you had any asthma symptoms during the day?
    • Any difficulty sleeping because of symptoms?
    • Has the asthma interfered with usualy activities e.g. work, school?
  • The patient must have a clear understanding of the use and interpretation of peak flow results, and understand how to use the results to adjust treatment and seek medical advice when necessary.
• Adults should have their peak flow reassessed every 5 years, to monitor the decrease in lung function with age.

• The patient should be sitting down.
• Ensure that the marker on the scale is set to zero.
• After a full breath in, the patient should then breathe out with a rapid forced maximal expiratory puff through the mouth and in to the meter.
• Repeat to give a total of three readings and take the best reading as the result.

Written personalised action plans as part of self-management education have been shown to improve health outcomes for people with asthma.⁴They are very important for all patients with asthma, but especially those with moderate to severe disease.
Self-management plans improve outcomes such as self-efficacy, knowledge and confidence.
The National Asthma Campaign provides resource materials useful for providing patients with a self management plan.⁵ These resource materials can be downloaded.

The European Commission adopted a standard (EN 13826) for peak flow meters in 2004.
The Wright scale has been previously noted to over-represent changes in airflow in the mid-range, and under represent changes in the low and high ranges.⁶
Peak expiratory flow readings obtained on the EU scale meter are more accurate than those from a Wright scale meter, because readings change uniformly for the whole range of the meter.
Until the new EN 13826 Standard meters are used for all measurements, it is important to note which scale has been used.