Technical validity and usability of a novel smartphone-connected spirometry device for pediatric patients with asthma and cystic fibrosis

Abstract

Background: Diagnosis and follow-up of respiratory diseases traditionally rely on pulmonary function tests (PFTs), which are currently performed in hospitals and require trained personnel. Smartphone-connected spirometers, like the Air Next spirometer, have been developed to aid in the home monitoring of patients with pulmonary disease. The aim of this study was to investigate the technical validity and usability of the Air Next spirometer in pediatric patients.

Methods: Device variability was tested with a calibrated syringe. About 90 subjects, aged 6 to 16, were included in a prospective cohort study. Fifty-eight subjects performed conventional spirometry and subsequent Air Next spirometry. The bias and the limits of agreement between the measurements were calculated. Furthermore, subjects used the device for 28 days at home and completed a subject-satisfaction questionnaire at the end of the study period.

Results: Interdevice variability was 2.8% and intradevice variability was 0.9%. The average difference between the Air Next and conventional spirometry was 40 mL for forced expiratory volume in 1 second (FEV1) and 3 mL for forced vital capacity (FVC). The limits of agreement were -270 mL and +352 mL for FEV1 and -403 mL and +397 mL for FVC. About 45% of FEV1 measurements and 41% of FVC measurements at home were acceptable and reproducible according to American Thoracic Society/European Respiratory Society criteria. Parents scored difficulty, usefulness, and reliability of the device 1.9, 3.5, and 3.8 out of 5, respectively.

Conclusion: The Air Next device shows validity for the measurement of FEV1 and FVC in a pediatric patient population.

Keywords: Air Next; home; pulmonary function test; smartphone; spirometry.

Conflict of interest statement

The authors declare that there are no conflict of interests.

© 2020 The Authors. Pediatric Pulmonology published by Wiley Periodicals LLC.

Figures

Figure 1

Concordance between Air Next and conventional spirometry. A, C, E, and G, Bland‐Altman plots displaying the differences between conventional spirometry and Air Next spirometry against the averages of the two techniques for FEV1, FVC, FEV1/FVC ratio, and PEF, respectively. Dotted lines reflect the average bias (middle line) and the 95% limits of agreement (outer lines). B, D, F, and H, Pearson correlation between the two measurements. FEV1, forced expiratory volume in 1 second, FVC, forced vital capacity; PEF, peak expiratory flow

Figure 2

ERS/ATS grades for measurements performed at home. All spirometry sessions were graded according to ATS/ERS guidelines for FEV1 and FVC separately. Grade A‐E represent sessions with acceptable maneuvers but with varying repeatability. Grade U includes session with usable but not with acceptable maneuvers and grade F is reserved for session without acceptable or usable maneuvers. A, Proportion of spirometry sessions that were awarded each grade for FEV1. B, Proportion of spirometry sessions that were awarded each grade for FVC. C, Boxplot of average FEV1 grade per study group. Dots represent individual averages. There was a statistically significant difference between the CF and uncontrolled asthma group (P = .02). D, Boxplot of average FVC grade per study group. Dots represent individual averages. There was a statistically significant difference between the CF and uncontrolled asthma group (P = .03). ATS, American Thoracic Society; CF, cystic fibrosis; ERS, European Respiratory Society; FEV1, forced expiratory volume in 1 second, FVC, forced vital capacity [Color figure can be viewed at wileyonlinelibrary.com]