Comparison of five portable peak flow meters

Abstract

Objective: To compare the measurements of spirometric peak expiratory flow (PEF) from five different PEF meters and to determine if their values are in agreement. Inaccurate equipment may result in incorrect diagnoses of asthma and inappropriate treatments.

Methods: Sixty-eight healthy, sedentary and insufficiently active subjects, aged from 19 to 40 years, performed PEF measurements using Air Zone, Assess, Galemed, Personal Best and Vitalograph peak flow meters. The highest value recorded for each subject for each device was compared to the corresponding spirometric values using Friedman's test with Dunn's post-hoc (p<0.05), Spearman's correlation test and Bland-Altman's agreement test.

Results: The median and interquartile ranges for the spirometric values and the Air Zone, Assess, Galemed, Personal Best and Vitalograph meters were 428 (263-688 L/min), 450 (350-800 L/min), 420 (310-720 L/min), 380 (300-735 L/min), 400 (310-685 L/min) and 415 (335-610 L/min), respectively. Significant differences were found when the spirometric values were compared to those recorded by the Air Zone(R) (p<0.001) and Galemed (p<0.01) meters. There was no agreement between the spirometric values and the five PEF meters.

Conclusions: The results suggest that the values recorded from Galemed meters may underestimate the actual value, which could lead to unnecessary interventions, and that Air Zone meters overestimate spirometric values, which could obfuscate the need for intervention. These findings must be taken into account when interpreting both devices' results in younger people. These differences should also be considered when directly comparing values from different types of PEF meters.

Keywords: Airway obstruction; Asthma; Meters; Monitoring; Peak expiratory flow rate.

Figure 1

Peak expiratory flow median values and interquartile ranges referring to the spirometry and the five meters. Friedman’s Test, Dunn’s post-hoc, **p<0.01; ***p<0.001.

Figure 2

Agreement rate between PEF spirometric values and those of the Air Zone® meter (A); the Assess® meter (B); the Galemed® meter (C); the Personal Best® meter (D); and the Vitalograph® meter (E) according to a Bland-Altman analysis. PEF = peak expiratory flow; Bias = mean of the differences among the averages; SD = standard deviation; n = number of subjects; ±1.96SD= 95% of confidence interval (CI). Orange line = regression line of differences versus averages; blue line= 95% CI of limits of agreement; brown dashed line= 95% CI mean of differences.