BACKGROUND: Spirometry patterns suggesting restrictive and obstructive pulmonary 
dysfunction have been reported in Parkinson's disease (PD). However, the 
patterns' precise relation to PD pathophysiology remains unclear. Purpose/Aim. 
To assess ON- versus OFF-state pulmonary function, the quality of its 
spirometric evaluation, and the quality of longitudinal spirometric findings in 
a large sample of PD patients with motor fluctuations.
METHODS: During a placebo-controlled trial of an inhaled levodopa formulation, 
CVT-301, in PD patients with ≥2 h/d of OFF time, spirometry was performed by 
American Thoracic Society (ATS) guidelines at screening and throughout the 
4-week treatment period.
RESULTS: Among 86 patients, mean motor impairment during an OFF state at 
screening was moderately severe. However, mean spirometry results at screening 
were within normal ranges, and in a mixed model for repeated measures (MMRM), 
the results at screening were not dependent on motor state (ON vs. OFF). In the 
placebo group (n = 43), 76% of ON-state and 81% of OFF-state examinations 
throughout the study met ATS quality metrics, and in an MMRM analysis, mean 
findings at these patients' arrivals for treatment-period visits showed no 
significant 4-week change. Across all 86 patients, flow-volume curves prior to 
any study-drug administration showed only a 3% incidence of "sawtooth" 
morphology.
CONCLUSIONS: In PD patients with motor fluctuations, longitudinal spirometry of 
acceptable quality was generally obtained. Although mean findings were normal, 
about a quarter of spirograms did not meet ATS quality criteria. Spirogram 
morphology may be less indicative of various forms of respiratory dysfunction 
than has previously been reported in PD.