Validation of the portable Bluetooth® Air Next spirometer in patients with different respiratory diseases

Abstract

Background: Chronic respiratory diseases constitute a considerable part in the practice of pulmonologists and primary care physicians; spirometry is integral for the diagnosis and monitoring of these diseases, yet remains underutilized. The Air Next spirometer (NuvoAir, Sweden) is a novel ultra-portable device that performs spirometric measurements connected to a smartphone or tablet via Bluetooth®.

Methods: The objective of this study was to assess the accuracy and validity of these measurements by comparing them with the ones obtained with a conventional desktop spirometer. Two hundred subjects were enrolled in the study with various spirometric patterns (50 patients with asthma, 50 with chronic obstructive pulmonary disease and 50 with interstitial lung disease) as well as 50 healthy individuals.

Results: For the key spirometric parameters in the interpretation of spirometry, i.e. FEV₁, FVC, FEV₁/FVC and FEF_25-75%, Pearson correlation and Interclass Correlation Coefficient were greater than 0.94, exhibiting perfect concordance between the two spirometers. Similar results were observed in an exploratory analysis of the subgroups of patients. Using Bland-Altman plots we have shown good reproducibility in the measurements between the two devices, with small mean differences for the evaluated spirometric parameters and the majority of measurements being well within the limits of agreement.

Conclusions: Our results support the use of Air Next as a reliable spirometer for the screening and diagnosis of various spirometric patterns in clinical practice.

Fig. 1

The Air Next spirometer and the reported spirometric parameters

Fig. 2

Correlation plots between the values obtained from the two spirometers, for the spirometric parameters considered in this work: (A) FEV₁, (B) FVC, (C) FEV₁/FVC, (D) FEF_25–75%, (E) PEF, (F) MEF_25%, (G) MEF_50%, (H) MEF_75%

Fig. 3

Bland-Altman plots for the evaluated spirometric parameters: (A) FEV₁, (B) FVC, (C) FEV₁/FVC, (D) FEF_25–75%, (E) PEF, (F) MEF_25%, (G) MEF_50%, (H) MEF_75%. Dashed lines represent the mean difference between measurements and dotted lines the 95% limits of agreement