Exhaled carbon monoxide as a noninvasive marker of airway neutrophilia after lung transplantation.
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.
Vos
Robin
R
Laboratory of Pneumology, Katholieke Universiteit Leuven, University Hospital Gasthuisberg, Leuven, Belgium.
Cordemans
Colin
C
Vanaudenaerde
Bart M
BM
De Vleeschauwer
Stéphanie I
SI
Schoonis
Annemie
A
Van Raemdonck
Dirk E
DE
Dupont
Lieven J
LJ
Verleden
Geert M
GM
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
D002248:Carbon Monoxide; D002097:C-Reactive Protein