Respiratory Disorders in Parkinson's Disease

Background: Parkinson's disease (PD) non motor symptoms may present early in the disease course and worsen with advancing disease. Respiratory changes can affect individuals to remain physically active, contributing to a reduction of functionality and quality of life. Objective: The aim of this systematic review is to synthesize evidence of respiratory disorders in patients with PD. Methods: An electronic search was performed up to November 2020 on PubMed-MEDLINE, Embase, Web of Science, Lilacs, Cinahl, and Cochrane using the following keyword combination: {[}({''}Parkinson disease{''}) AND ({''}respiratory function tests{''} OR ``evaluation{''}) AND ({''}respiratory system{''} OR ``respiration disorders{''} OR ``respiratory muscles{''})]. Results: The electronic search resulted in 601 references in English or Portuguese. The selection process and data extraction were made by two independent reviewers. We selected 19 studies including cross-sectional studies that investigated the respiratory disorders in patients with PD through pulmonary function, respiratory muscle strength, or physical capacity evaluation. We excluded studies that considered patients with other diseases. Eighteen studies evaluated the pulmonary function in patients with PD, eleven studies verified the influence of PD on respiratory muscle strength, and three studies assessed the physical capacity through functional tests. Conclusion: The evidence showed that PD patients have higher chances to present a pulmonary dysfunction, either obstructive or restrictive, when compared to healthy subjects. In addition, these patients present lower respiratory muscle strength and a consequent decrease in physical capacity in endurance exercises. The respiratory impairment in PD seems to be directly related to the progression of the disease. (AU)