title: Physiologic correlates of distal lung inflammation in asthma.
abstract: BACKGROUND
  The distal lung is an important site of inflammation in asthma. Maximal midexpiratory flows and the ratio of maximal:partial flows are purported to reflect distal lung function.
  
  
  OBJECTIVE
  We obtained contemporaneous transbronchial biopsy, spirometry, and plethysmography to describe more accurately the relationship between physiology and distal lung inflammation in asthma.
  
  
  METHODS
  Ten patients with severe, persistent asthma with mean +/- SE FEV(1) of 2.8 +/- 0.2 L and overnight fall in FEV(1) of 22.8% +/- 3.8% underwent transbronchial biopsy, spirometry, maximal midexpiratory flows, maximal:partial ratio, and lung volumes, all at 4 am. Morphometric analysis was performed after immunohistochemistry for eosinophils, lymphocytes, macrophages, mast cells, and neutrophils.
  
  
  RESULTS
  Maximal midexpiratory flows, maximal:partial ratio, FEV(1), and forced vital capacity were not significantly correlated with alveolar tissue inflammation. However, the degree of eosinophilic alveolar inflammation was significantly and positively correlated with both total lung capacity (Spearman rho=0.70; P=.03) and thoracic gas volume (rho=0.62; P=.05). Correlation between eosinophils and other lung volumes was not observed. Other inflammatory cell types did not correlate with lung volumes.
  
  
  CONCLUSIONS
  Purported physiologic measures of distal lung function are poorly correlated with histopathologic evidence of distal lung inflammation. Measurement of lung volumes more accurately reflects eosinophilic distal lung inflammation.
authors.affiliation: Department of Medicine, National Jewish Medical and Research Center, 1400 Jackson Street, J-217, Denver, CO 80206, USA. sutherlande@njc.org
authors.forename: E Rand
authors.initials: ER
authors.lastname: Sutherland
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Martin
authors.forename: Russell P
authors.initials: RP
authors.lastname: Bowler
authors.forename: Yujun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Michael D
authors.initials: MD
authors.lastname: Rex
authors.forename: Monica
authors.initials: M
authors.lastname: Kraft
mesh_terms: D000328:Adult; D001249:Asthma / Q000473:pathology* / Q000503:physiopathology*; D004802:Eosinophilia / Q000473:pathology; D005260:Female; D006801:Humans; D007249:Inflammation / Q000473:pathology*; D008168:Lung / Q000473:pathology* / Q000503:physiopathology; D008176:Lung Volume Measurements; D008297:Male; D008450:Maximal Midexpiratory Flow Rate