Effect of Inspiratory Muscle Training on Aerosol Deposition and Pulmonary Perfusion in Post-COVID-19 Syndrome: A Gamma Scintigraphy Study

Background: Pulmonary dysfunction in individuals with post-coronavirus disease-2019 (COVID-19) syndrome may impair aerosol deposition and pulmonary perfusion, compromising respiratory efficiency. Inspiratory muscle training (IMT) has been proposed as a strategy to improve respiratory mechanics and lung function. Objective: To compare aerosol deposition and pulmonary perfusion in individuals with post-COVID-19 syndrome before and after 8 weeks of IMT. Methods: This was a randomized controlled clinical trial involving 19 participants, divided into an IMT group ( n = 10) and a control group ( n = 9). The IMT group performed training with a load adjusted to 50% of maximal inspiratory pressure, while the control group used a device without resistance. Aerosol deposition and pulmonary perfusion were evaluated by gamma scintigraphy using the radioisotopes technetium-labeled diethylene-triamine-pentaacetic acid and technetium99-labeled macroaggregated human serum albumin, respectively. Total radiopharmaceutical activity in both lungs, as well as in the right and left lungs separately, was quantified pre- and post-intervention. Results: After 8 weeks, the IMT group showed a significant increase in total lung activity for both aerosol deposition ( p = 0.028) and perfusion ( p = 0.013). In the right lung, activity increased significantly for aerosol deposition ( p = 0.005) and perfusion ( p = 0.005). In the left lung, significant increases were also observed for perfusion ( p = 0.007). No significant increases were observed in the control group. In the between-group analysis, the IMT group showed higher activity in both lungs combined and separately, compared with controls, for aerosol deposition (all p < 0.05) and in the right lung for perfusion ( p = 0.010). Conclusion: IMT improved total aerosol deposition and perfusion in individuals with post-COVID-19 syndrome. These findings support the use of IMT as a rehabilitation strategy to enhance pulmonary deposition of inhaled agents and increase pulmonary perfusion in this population.