Assessment of the AirWatch lung function monitoring system

Abstract

Accuracy is defined by the median relative bias (MRB), with the initial acceptable range of ± 15% and repeat testing within ± 5% of the initial value.7 Precision is defined by the interquartile range (IQR), with the initial acceptable range less than 10% and repeat testing less than 5% greater than the initial value.7 Different peak expiratory flow (PEF) rates were created by 12 compressions of a Jones calibrating syringe connected in series to a pneumotachograph (standard) and 12 separate AW devices (Fig 1). This allowed for simultaneous recorded measurements of PEF and calculation of accuracy and precision. For FEV1 accuracy and precision, each of the 20 AW devices was placed in an airtight chamber in series between a spirometer and 3 different sources of flow generation: the Jones syringe, a 4-L syringe, and a wave form generator. AW durability was assessed by determining the MRB and IQR for 5 different flow rates at each of 6 clinic visits over a 10-week Abbreviations used ACRN: Asthma Clinical Research Network AW: AirWatch IQR: Interquartile range MRB: Median relative bias PEF: Peak expiratory flow