title: Diurnal variations in the parameters of pulmonary function and respiratory muscle strength in patients with COPD.
abstract: OBJECTIVE
  To evaluate the magnitude of diurnal changes in the parameters of pulmonary function and respiratory muscle strength/endurance in a sample of patients with COPD.
  
  
  METHODS
  A group of 7 patients underwent spirometry, together with determination of MIP and MEP, at two distinct times (between 8:00 and 8:30 a.m. and between 4:30 and 5:00 p.m.) on a single day. Between assessments, the patients remained at rest in the laboratory.
  
  
  RESULTS
  In accordance with the Global Initiative for Chronic Obstructive Pulmonary Disease staging system, COPD was classified as moderate, severe, and very severe in 1, 3, and 3 of the patients, respectively. From the first to the second assessment, there were significant decreases in FVC, FEV1, and MEP (of 13%, 15%, and 10%, respectively), as well as (less than significant) decreases in PEF, MIP, and maximal voluntary ventilation (of 9%, 3%, and 11%, respectively).
  
  
  CONCLUSIONS
  In this sample of COPD patients, there were diurnal variations in the parameters of pulmonary function and respiratory muscle strength. The values of FEV1, FVC, and MEP were significantly lower in the afternoon than in the morning.
authors.affiliation: Laboratory of Respiratory Physical Therapy, Department of Physical Therapy, Regional University Hospital of Northern Paraná, State University at Londrina, Londrina, Brazil. fregonezi@ufrnet.br
authors.forename: Guilherme
authors.initials: G
authors.lastname: Fregonezi
authors.forename: Vanessa Regiane
authors.initials: VR
authors.lastname: Resqueti
authors.forename: Juliana Loprete
authors.initials: JL
authors.lastname: Cury
authors.forename: Elaine
authors.initials: E
authors.lastname: Paulin
authors.forename: Antonio Fernando
authors.initials: AF
authors.lastname: Brunetto
mesh_terms: D000368:Aged; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000503:physiopathology*; D012720:Severity of Illness Index; D013147:Spirometry