Impact of breathing frequency on respiratory oscillometry measurements: a randomised cross-over and observational study of asthma patients

INTRODUCTION: The impact of breathing frequency on respiratory oscillometry measurements is unknown. We aimed to investigate the impact of different breathing frequencies in patients with asthma. METHOD: We recruited patients from the severe asthma clinic at Cambridge University Hospitals. Using a randomised-crossover design, participants performed the forced oscillation technique at three different breathing frequencies (15, 30, 40 bpm) in a randomised order for each participant. A metronome was used to ensure the correct breathing frequency. Analysis of variance (ANOVA) and Friedman tests were utilised to assess the significance of any differences across the breathing frequencies. We then leveraged cross-sectional data from asthma patients who performed respiratory oscillometry and investigated the determinants of self-selected breathing frequency using multivariable linear regression. RESULTS: )/FVC z-score -2.56 (-3.26 to -1.96). As breathing frequency increased from 15 bpm to 40 bpm, there was a significant reduction (-8.6%, p