Abstract
OBJECTIVE: Peak flowmeters have been widely used to monitor the course of asthma. The objective of this study was to develop a simple, convenient and effective method to evaluate these devices routinely.METHODS: A rubber band-driven 3 L syringe was used to generate airflows, and a pneumotachometer was connected in series with the peak flowmeter as a standard. Waveforms were recorded and compared with maximal expiratory curves. The accuracy of peak flowmeters was analyzed by linear regression and by calculating the percentage of the difference measured by the flowmeter (F) and the pneumotachometer (P), expressed as (F--P)/P (%).RESULTS: This set-up generated waveforms similar to the initial phase of maximal expiratory curves, with linear increment of peak flow rates up to 790 L/min (R=0.999, PÃ0.001). Both waveforms and peak flow rates were highly reproducible with coefficients of variation less than 5% throughout the full range tested. Fourteen peak flowmeters from seven different models were evaluated. Most of these devices revealed a satisfactory linear relationship with the pneumotachometer. The interdevice variation of different models and variations of each device at different flow rates were clearly demonstrated by (F--P)/P (%).CONCLUSION: The system developed in the present study can be easily set up and used to evaluate the performance of peak flowmeters.