Assessment of a peak flow whistle in nonasthmatic children

Abstract

We tested the agreement of peak expiratory flow (PEF) measurements between an electronic spirometer and a peak flow whistle (Whistle Watch®, HarMed, Capetown, South Africa). One hundred and three healthy children between ages 6-13 years and with no previous experience in lung function tests participated in the study, Sequential PEF-readings were obtained from the spirometer and the peak flow whistle; all children had an equal number of attempts using both devices. In the case of the spirometer, the highest PEF reading of three acceptable and reproducible efforts was noted as the best PEF (PEF(SPIRO)). Whistle Watch® readings were taken as the highest value when the child could activate the whistle. Despite a strong correlation (r = 0.91; R2 = 83%) between the readings of the spirometer and Whistle Watch®, there was a lack of agreement between the two devices. For any individual subject, the 95% probability interval ranged between +30.4 to -47 L.min-1; 64% of the children obtained higher PEF-values on Whistle Watch®, compared to the spirometer. These findings suggest that the whistle sound of the peak flow whistle was a significant incentive, which resulted in greater maximal expiratory efforts.