Airway dysfunction in patients with Parkinson's disease

Abstract

To investigate pulmonary function abnormalities in Parkinson's disease (PD), we obtained maximal inspiratory and expiratory flow-volume curves in 63 patients (59 under treatment) with different stages of the disease, not filtered for respiratory symptoms. PD severity was evaluated by the Unified PD Rating Scale, the Webster's scale, and Hoehn and Yahr staging. Patients with more severe PD had lower percentage forced vital capacity (FVC%), and peak inspiratory and expiratory flows. Those with fluctuations and/or dyskinesias had lower FVC% and percentage forced expiratory flow volume in 1 sec (FEV1%). There were a number of weak but significant correlations between PD scales and spirographic parameters. Thirty one patients (49.2%) had pathological flow-volume curves. The clinical profile and the duration of the disease did not influence the pattern of the curve. Physiologic evidence of upper airway obstruction was observed in 3 cases. A spirometric restrictive ventilatory defect (FEV1/FVC higher than or equal to 80%) was observed in 54 patients (85%), while generalized airway obstruction was present only in one nonsmoker. We conclude that abnormal flow-volume loop contour is a frequent finding in PD. This probably reflects involvement of the upper airway musculature, that in some patients can produce upper airway obstruction. Generalized airflow limitation is not an important characteristic of PD. By contrast, a restrictive spirometric defect, probably due to incoordinated expiratory effort or abnormally low chest wall compliance, is the main spirometric finding in these patients.

Prospective evaluation of pulmonary function in Parkinson's disease patients with motor fluctuations

“…Prior studies in smaller groups of PD patients had reported a 29% to 67% incidence of "sawtooth" morphology [6][7][8][9]. We found only a 3% incidence, undoubtedly related at least in part to differing methods of patient selection.…”

“…"Sawtooth" curves demonstrated a sawtooth shape during exhalation, typically after the PEFR ( Figure 1B). This pattern has been attributed to upper-airway obstruction [6][7][8][9]. "Low PEFR, reproducible" curves had a rounded peak but were consistently reproducible ( Figure 1C), as is typically seen in patients with neuromuscular weakness [6][7][8][9].…”

“…When present, the most common patterns have been characterized as restrictive pulmonary dysfunction, obstructive airflow disease, and upper airway obstruction [1,[7][8][9][21][22][23][24]. Abnormal ventilatory control has also been described, even though respiratory flows and volumes were normal in most of the patients [25].…”

“…This pattern has been attributed to upper-airway obstruction [6][7][8][9]. "Low PEFR, reproducible" curves had a rounded peak but were consistently reproducible ( Figure 1C), as is typically seen in patients with neuromuscular weakness [6][7][8][9]. "Low PEFR, not reproducible" was applied to curves with a slow rise to peak flow, a rounded peak, and inconsistent reproducibility, suggesting poor effort, difficulty with the test maneuver, or detriments such as pain ( Figure 1D).…”

“…PD may also affect a patient's ability to perform the respiratory maneuvers required for pulmonary function tests (PFTs) such as spirometry [5]. In PD patients, PFT patterns suggesting restrictive pulmonary dysfunction and central-or upper-airway obstruction have been described [1,[6][7][8][9]. However, the pathophysiologic basis for differing patterns and the precise relation of each such pattern to PD motor dysfunction remain unclear [1].…”