Incentive spirometry and smart phones: Performance validation and user impressions [HLN 750 Dissertation]
Clarence Anthony Baxter · QUT ePrints (Queensland University of Technology) · 2018
Incentive spirometry (ISy) is a longstanding respiratory therapy technique which encourages gradual maximal inhalation. Purposeful inflation of the lungs over and above normal inhalation is postulated to promote mucus clearance, reducing respiratory complications during post-surgical recovery, and in some chronic conditions. Contemporary ISy devices have clear plastic cases encasing spheres or a piston. As one inhales via a connected tube, the spheres or piston levitate, motivating effort and persistence with multiple iterations of inhalation for clinical efficacy. This study concerns a novel ‘virtual’ incentive spirometer app for smart phones called ‘QUT Inspire’. This new app employs the built-in smart phone microphone to detect breath sounds, displaying inhalation effort graphically on screen in several alternative layouts. Calibrated mechanical air flows were applied to reference devices and a selection of physical ISy devices to benchmark performance. Sampled audio recordings of these flows were applied to the built-in microphones in a range of modern smart phones at varying distances, flow rates and flow aperture sizes to evaluate the app. The latter aperture size modelled different mouth shapes and diameters while using the app. Performance of the new app was also compared between common contemporary smart phones. Further, user impressions were sought from a cohort of disease-free subjects (n=19) as to optimal screen graphics to incentivise effort, in a participatory action research component to this study. The QUT Inspire app performed comparably with flow-based physical incentive spirometers, demonstrating precision and reliability in detecting simulated air flows, particularly at distances of 5 cm or less from the phone microphone. The equivalent of pursed lips generated higher airflows, optimising the detection of inhalation by the phone microphone. Differences in app performance on different phone types were observed. Users preferred multiple sphere and bar-style animated displays in deference to sparser display animation alternatives. This study offers insight into techniques for evaluating mobile health (mHealth) app performance and display preferences for a virtualised respiratory therapy technique.