Association Between Subglottic Pressure and Pulmonary Function in Individuals With Parkinson's Disease

Introduction: In individuals with Parkinson's disease (PD), pulmonary complication such as weakness and rigidity of respiratory muscles and reduced cough airflow may be associated with reduced voice production due to limited pulmonary capacity and reduced airflow needed to vibrate the vocal folds. It is not clear, however, which pulmonary function parameter is determinant in the association with peak subglottic pressure (SGP). Therefore, the purpose of this study was to determine the association between peak SGP and pulmonary function parameters in individuals with PD. Methods: Forty-two individuals with diagnosis of idiopathic PD of both genders were recruited in the study. Mean and peak SGP, spirometric indices, maximum inspiratory pressure, maximum expiratory pressure (MEP), and peak cough flow (PCF) during reflex and voluntary cough were measured on all participants. Results: The analysis revealed that peak SGP had a moderate but significant linear association with MEP (r = 0.38; P = 0.013), voluntary (r = 0.31; P = 0.051), and reflex PCF (r = 0.40; P = 0.012), but not with maximum inspiratory pressure (r = 0.23; P = 0.145). Higher values in peak SGP were associated with higher values in MEP, voluntary PCF, and reflex PCF. No linear association was detected between peak SGP and spirometric indices. Conclusions: Peak SGP has a direct association with voluntary and reflex PCF, and expiratory muscle strength, but not with inspiratory muscle strength. The association with peak SGP is higher for reflex PCF than for voluntary PCF.