Factors influencing peak expiratory flow in teenage boys.

BACKGROUND

Peak expiratory flow (PEF) is a useful measure of pulmonary health status and is frequently utilised in asthma management. Reduction in PEF is usually indicative of onset of asthma symptoms. However, use can be made of PEF values only if normal values are known. The definition of normal range is always difficult and may vary between regions and be affected by a variety of factors.

OBJECTIVE

To establish PEF values for teenage boys in a Cape Town suburb and examine factors that possibly influence this measurement.

SETTING

A high school for boys in the southern suburbs of Cape Town.

METHODS

Measurements of PEF were taken for 124 boys. Subjects were approximately 16 years old and apparently healthy at the time of survey. Further details were provided by means of a questionnaire.

RESULTS

PEF ranged from 350 to 760 l/min, with a mean (+/- standard deviation (SD)) of 539 +/- 68 l/min. Factors expected to influence PEF included height and mass, whereas unexpected factors included sport intensity and academic grade. A trend to reduced peak flow was already evident in boys who smoked and boys from homes where a parent smoked. Regression analysis suggested peak flow differences in our population compared with the standard reference.

CONCLUSION

Interpretation of results obtained from peak-flow instruments should take into account additional knowledge concerning the individual. Further surveys of the South African population and of different groups should be done to establish local standards and factors influencing PEF.