An assessment of three portable peak flow meters

Peak flow has become widely used as in independent measure of lung function, particularly in asthma, because it can be quickly and easily determined by simple portable instrumentation. Three relatively inexpensive devices, the Armstrong mini-Wright peak flow meter, Vitalograph pulmonary monitor, and HealthScan peak flow meter, were tested for accuracy and reproducibility. Five units of each type were individually connected in series to a pneumotachograph, and 20 measurements (five in each of four flow ranges) were made on each unit at pulsatile flows ranging from 120 to 480 Lpm. The mean percentage of discrepancy (D%) for each instrument of a particular model was calculated at each flow range, and these subsequently averaged to give an inter-instrument percentage of discrepancy at each flow for each model. Intra-instrument variability was also assessed as the mean percentage of discrepancy for all flow rates for each individual instrument. While only the Armstrong mini-wright peak flow meter meets flow range criteria established by the American Thoracic Society and American College of Chest Physicians for flow devices, only the HealthScan-Organon peak flow meter meets the established criteria for accuracy and reproducibility.