Modification of respiratory function parameters in patients with severe Parkinson's disease.

Respiratory dysfunction remains one of the most common causes of death in patients with complicated Parkinson's disease (PD). The aim of this study was to investigate pulmonary function in fluctuating PD patients during "on" and "off" states of the disease. We studied 12 fluctuating, non-smoking PD patients (H&Y stages 3-5) without a history of lung or cardiovascular disease; all patients underwent Hoehn and Yahr scale (H&Y) and Unified Parkinson Disease Rating Scale (UPDRS items 18-31) to evaluate extrapyramidal impairment, as well as pulmonary function tests (PFT) and arterial blood gas analyses to assess respiratory function. All evaluations were performed during a stable on state of disease and in an off state produced by 12 hours of therapy withdrawal. A restrictive pattern of flow-volume loop was observed both in on and off states of disease. In the off state, we found a significant worsening in both FEV1 and FVC; the FEV1/FVC ratio was unmodified. These results suggest a restrictive pattern of flow-volume loop in these patients.