title: Correlation of levels of obstruction in COPD with lactate and six-minute walk test.
abstract: Chronic obstructive pulmonary disease (COPD) is a leading cause of morbid-mortality world wide, leading not only to pulmonary damage but also to multisystemic impairment, with repercussions on skeletal muscles and the ability to undertake effort, as measured in the six-minute walk test (6-MWT).
  
  
  OBJECTIVE
  To correlate the level of obstruction in COPD with lactate concentration and heart rate (HR) at rest, and distance walked. To correlate distance walked with blood gas analysis and correlate desaturation in 6-MWT with post 6-MWT lactate concentration and heart rate.
  
  
  METHODS
  COPD patients underwent spirometry, blood gas analysis and 6-MWT to evaluate distance walked, heart rate, capillary lactate (CL) concentration pre- and post 6-MWT, and desaturation with 6-MWT.
  
  
  RESULTS
  91 patients with all levels of obstruction were evaluated. HR and CL increased significantly post 6-MWT. The decrease in peripheral saturation of haemoglobin to oxygen observed with 6-MWT was also significant. The distance walked was shorter the greater the obstruction. The correlation analysis was significantly positive between FEV1 and distance walked, negative between FEV(1) and HR at rest and negative between distance walked and PaCO(2), and not significant for the other variables.
  
  
  CONCLUSIONS
  Increased obstruction in COPD and higher PaCO(2) values contribute to a reduction in distance walked in 6-MWT. The level of obstruction in COPD leads to a haemodynamic impairment with increased HR at rest of these patients.
authors.affiliation: Hospital Universitário de Brasília da Universidade de Brasília (HUB/UnB). dante@unb.br
authors.forename: Dante
authors.initials: D
authors.lastname: Brasil Santos
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: de Assis Viegas
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D005080:Exercise Test; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008875:Middle Aged; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000503:physiopathology*; D012720:Severity of Illness Index; D013997:Time Factors; D016138:Walking
chemical_list: D019344:Lactic Acid