Background Parkinson's disease (PD) causes a series of movement disorders, many of them starting in the early stage. Objective To analyze the pulmonary function of mild-stage subjects with PD and to investigate the effects of levodopa on it. Methods We included 21 patients with idiopathic PD and 20 healthy control subjects. The participants were submitted to spirometry and impulse oscillometry assessments. The PD patients were evaluated during the “off” and “on” phases of their anti-PD medication, which was was converted to levodopa in an equivalent daily dose. A statistical analysis was performed with cross-sectional (PD patients “off” medication versus controls) and paired (PD patients “off” medication versus PD patients “on” medication) tests. The effect of levodopa was calculated with partial Eta-squared (η2 ρ). Significance was set at 5%. Results The PD patients presented normal values in the impulse oscillometry. Regarding spirometry, the results indicated an incipient obstructive ventilatory disorder in the PD group – confirmed by patients' flow-volume curves. The PD patients received a daily dose of 354.7 ± 148.2 mg of levodopa. The paired analyses showed a small effect of anti-PD medication on pulmonary parameters (η2 ρ = 0.197 for spirometry and η2 ρ= 0.043 for impulse oscillometry). Conclusion Patients with PD in the mild stage of the disease present pulmonary compliance and resistance compatible with normal parameters. The differences regarding the spirometric results indicate an incipient obstructive ventilatory disorder in patients with PD. Levodopa had small effect on pulmonary function in the mild stage of the disease.

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