Incentive Spirometer in COVID-19: A Systematic Review

Background/Objectives: COVID-19 and its sequelae have affected millions worldwide, with many individuals experiencing persistent symptoms such as dyspnea, fatigue and reduced quality of life. Respiratory physiotherapy is commonly used to support patients with pulmonary conditions. This systematic review aimed to evaluate the effects of the incentive spirometer on cardiopulmonary, functional and patient-reported outcomes in adults during the acute and post-COVID-19 phases. Methods: A systematic literature search was conducted in PubMed, CINAHL, Scopus, Clinical Trials.gov and Google Scholar to identify studies published between January 2020 and April 2025. Owing to substantial heterogeneity in study design, populations, interventions and outcome measures, quantitative synthesis was not feasible and findings were synthesized narratively. Results: Twelve studies involving 573 participants were included. Within-group analyses showed improvements in pulmonary outcomes (including FEV₁, FVC, and oxygen saturation), reductions in dyspnea, and improvements in quality of life following incentive spirometer. Improvements in pulmonary function were reported primarily in post-COVID-19 populations, whereas reductions in anxiety and improvements in quality of life were reported mainly in acute COVID-19 settings. Between-group comparisons demonstrated statistically significant differences in favor of the incentive spirometer for selected pulmonary and functional outcomes (including FVC, DLCO, oxygen saturation, six-minute walk test, and 30 s sit-to-stand test), while no significant differences were observed for other outcomes such as peak expiratory flow, respiratory rate, or heart rate variability. Randomized controlled trials were judged to have a moderate risk of bias, non-randomized studies a moderate-to-serious risk, and certainty of evidence ranged from very low to moderate. Conclusions: Incentive spirometer may support respiratory, functional, and psychological recovery in adults during the acute and post-COVID-19 phases. However, effects vary across outcomes and comparator interventions, and the overall certainty of evidence is low to moderate. Further high-quality research is required to confirm effectiveness and guide optimal clinical use.