Visualizing respiratory therapy effects: An EIT-based assessment of lung physiology

Background: The incentive spirometer (IS) promotes lung expansion, but its physiological effects remain unclear. We hypothesized that the low-cost Asepto syringe could be a viable alternative. This study compared the different number of IS balls and Asepto syringe in healthy volunteers, evaluating their impacts on tidal volume (Vt), end-expiratory lung volume (EELV), regional ventilation distribution, lung homogeneity, and dynamic lung strain. Methods: In this prospective crossover pilot trial, healthy volunteers were randomly assigned to start with either the Asepto syringe or incentive spirometer. All participants used both devices, and lung function was assessed using Electrical Impedance Tomography (EIT). Results: The study included 24 participants (63%female). Vital signs remained stable post-intervention. Three-ball IS produced the highest Vt in mL: 1868 [1313-2392], followed by the Asepto syringe 1264 [770-1728], 2-ball IS 1231 [942-1629] and 1-ball IS 920 [624-1591] compared to Vt at baseline (p < 0.0001). The 1- and 2-ball IS improved EELV in mL (439 [251-908] and 496 [117-767], respectively, p < 0.001) with a higher number of breaths achieving target per minute. All devices increased dorsal ventilation compared to baseline (p = 0.048). Although dynamic lung strain from IS and Asepto syringe was higher than baseline (p < 0.0001), all values were below threshold of potential lung injury. Conclusion: For promoting lung expansion in healthy volunteers, the Asepto syringe might be an alternative to employing an incentive spirometer. One-or two-ball IS improved EELV and adherence. Effects in patients with lung disease warrant further study.