title: Exhaled carbon monoxide as a noninvasive marker of airway neutrophilia after lung transplantation.
abstract: BACKGROUND
  Neutrophilic airway inflammation and associated oxidative stress contribute to airway injury and the development of bronchiolitis obliterans syndrome after lung transplantation (LTx). Exhaled carbon monoxide (eCO) reflects heme oxygenase-1 activity in response to oxidative stress. We investigated whether airway neutrophilia and eCO levels are associated in stable LTx recipients.
  
  
  METHODS
  In this cross-sectional pilot study, 45 stable LTx recipients were included. During routine follow-up at the outpatient clinic, pulmonary function testings together with eCO measurements before broncho-alveolar lavage (BAL) were performed. BAL cell differentials and interleukin (IL)-8 protein levels were assessed and correlated with eCO.
  
  
  RESULTS
  In the studied cohort, eCO levels were increased in patients with elevated (>3%) BAL neutrophilia compared with those with normal BAL neutrophilia (P=0.025). Furthermore, eCO levels significantly correlated with BAL neutrophilia and IL-8 levels in the cohort as a whole (r=0.50; P=0.0005 for total cells, r=0.43; P=0.003 for %cells and r=0.30; P=0.045 for IL-8). This was even more obvious in the LTx recipients with increased (>3%) BAL neutrophilia (r=0.70; P=0.0007 for total cells and r=0.80; P<0.0001 for %cells). For a cutoff of 4 ppm, sensitivity, specificity, positive and negative predictive value of eCO for detecting elevated BAL neutrophilia were 84.0%, 45.0%, 65.6%, and 69.2%, respectively (P=0.049).
  
  
  CONCLUSIONS
  Elevated eCO levels in stable LTx recipients may reflect an increased BAL neutrophilia and could, therefore, be used as a noninvasive marker for airway inflammation after LTx.
authors.affiliation: Laboratory of Pneumology, Katholieke Universiteit Leuven, University Hospital Gasthuisberg, Leuven, Belgium.
authors.forename: Robin
authors.initials: R
authors.lastname: Vos
authors.forename: Colin
authors.initials: C
authors.lastname: Cordemans
authors.forename: Bart M
authors.initials: BM
authors.lastname: Vanaudenaerde
authors.forename: Stéphanie I
authors.initials: SI
authors.lastname: De Vleeschauwer
authors.forename: Annemie
authors.initials: A
authors.lastname: Schoonis
authors.forename: Dirk E
authors.initials: DE
authors.lastname: Van Raemdonck
authors.forename: Lieven J
authors.initials: LJ
authors.lastname: Dupont
authors.forename: Geert M
authors.initials: GM
authors.lastname: Verleden
mesh_terms: D000328:Adult; D000402:Airway Obstruction / Q000175:diagnosis*; D001989:Bronchiolitis Obliterans / Q000175:diagnosis*; D001992:Bronchoalveolar Lavage Fluid; D002097:C-Reactive Protein / Q000378:metabolism; D002248:Carbon Monoxide / Q000032:analysis*; D003430:Cross-Sectional Studies; D045853:Exhalation; D005260:Female; D006801:Humans; D007249:Inflammation / Q000175:diagnosis*; D008171:Lung Diseases / Q000145:classification / Q000601:surgery; D016040:Lung Transplantation / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D011183:Postoperative Complications / Q000175:diagnosis*; D029424:Pulmonary Disease, Chronic Obstructive / Q000601:surgery; D012129:Respiratory Function Tests; D012907:Smoking / Q000453:epidemiology
chemical_list: D002248:Carbon Monoxide; D002097:C-Reactive Protein