Assessment of Pulmonary Functions in Parkinson's Disease and Unveiling the Role of Levodopa Therapy: A Cross-Sectional Study.

Introduction: This investigation aimed to thoroughly characterize the range of pulmonary function abnormalities present in individuals with Parkinson's disease (PD) and to evaluate the effects of levodopa therapy on these respiratory dysfunctions.

Methods:  Ninety-five PD patients diagnosed via the UK Parkinson's Disease Society Brain Bank Diagnostic Criteria were recruited, excluding those with a smoking history or unable to perform pulmonary function tests (PFTs). Severity was assessed using the Hoehn and Yahr Scale. Spirometry-measured PFT parameters (forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and peak expiratory flow rate (PEFR)) were compared against matched predicted values. The changes in PFT parameters post-levodopa challenge were assessed.

Results: Most of the PD patients were aged between 51-60 years, with a mean age of 55.89 ± 8.37 years. Of these, 65.3% were male. A significant proportion of the cohort exhibited restrictive pulmonary patterns (73.7%), while a smaller fraction displayed obstructive (7.4%) or normal (18.9%) pulmonary function patterns. Notably, levodopa treatment correlated with marked improvements in all measured PFT parameters, especially evident in the enhancements from the "off" medication stage to the "on" stage for FVC and FEV1 (P=0.0001). A weak positive correlation between the severity of respiratory restriction and the duration of PD (r = 0.139, P = 0.021) was found, suggesting that PD's progression exerts an increasingly adverse effect on respiratory function over time.

Conclusion:  The findings of this study illustrate that restrictive pulmonary abnormalities are more prevalent than obstructive patterns in PD patients and that these patients respond favorably to levodopa therapy.