Comparison of Pneumotachometer and Portable Digital Turbine Spirometry for Field-Based Assessment: An Air Quality, Environment, and Respiratory Outcomes in Bronchopulmonary Dysplasia Study.

Introduction: Data on the use of remote spirometry are limited in the pediatric population. We sought to assess the feasibility and accuracy of a digital turbine spirometer, Medical International Research (MIR) Spirobank Smart (MIR, New Berlin, WI, USA), compared with a pneumotachography spirometer, Pneumotrac (Vitalograph Inc., Lenexa, KS, USA), in field-based clinical research. Methods: This is a cross-sectional study of a subgroup of school-aged participants enrolled in the Air quality, Environment, and Respiratory Outcomes in Bronchopulmonary Dysplasia (BPD) study, who performed same-day paired coached baseline spirometry measurements from the Pneumotrac and MIR devices. Proportion of successful tests was estimated for each device and compared using McNemar's test. Correlation between devices forced expiratory volume in 1 second (FEV₁) and forced vital capacity (FVC) was analyzed by Lin's concordance correlation, and Bland-Altman plots were generated. Results: Twenty-one participants with history of BPD completed home spirometry maneuvers on both devices. The mean age of participants was 8.7 years. The mean FEV₁ and FVC measurement was 81% predicted and 90.4% predicted, respectively. The proportion of acceptable tests appeared higher using Pneumotrac (81%) than when using MIR (67%), although without evidence of discordance (P = 0.317). Among subjects with successful tests on both devices, Lin's concordance correlation demonstrated moderate agreement (FEV₁ r = 0.955, 95% confidence interval [CI]: 0.87-0.98; FVC r = 0.971, CI: 0.91-0.99). The mean difference in FEV₁ between Pneumotrac and MIR was 0.079 L (95% limits of agreement were -0.141 to 0.298 L) and FVC was 0.075 L (95% limits of agreement were -0.171 to 0.322 L). These were relatively small and without evidence of systematic or volume-dependent bias. Conclusions: Utilizing turbine spirometers may be a promising and feasible way to perform pulmonary function testing for field research in children.