Exhaled nitric oxide correlates with airway eosinophils in childhood asthma.
BACKGROUND
Exhaled nitric oxide has been proposed as a marker for airway inflammation in asthma. The aim of this study was to compare exhaled nitric oxide levels with inflammatory cells and mediators in bronchoalveolar lavage fluid from asthmatic and normal children.


METHODS
Children were recruited from elective surgical lists and a non-bronchoscopic bronchoalveolar lavage (BAL) was performed after induction of anaesthesia. Exhaled nitric oxide (parts per billion) was measured by two techniques: tidal breathing and restricted breath.


RESULTS
Median (interquartile range) exhaled nitric oxide measured by restricted breath was increased in asthmatics compared with normal children (24.3 (10.5-66.5) v 9.7 (6.5-16.5), difference between medians 14.6 (95% CI 5.1 to 29.9), p=0.001). In asthmatic children exhaled nitric oxide correlated significantly with percentage eosinophils (r=0.78, p<0.001 (tidal breathing) and r=0.78, p<0.001 (restricted breath)) and with eosinophilic cationic protein (r=0.53, p<0.01 (restricted breath)), but not with other inflammatory cells in the BAL fluid. The area under the receiver operator characteristic curves for the prediction of the presence of eosinophilic airways inflammation by exhaled nitric oxide (tidal and restricted) was 0.80 and 0.87, respectively.


CONCLUSIONS
Exhaled nitric oxide correlates closely with percentage eosinophils in BAL fluid in asthmatic children and is therefore likely to be a useful non-invasive marker of airway inflammation.
Warke
T J
TJ
Department of Child Health, Institute of Clinical Science, Queen's University of Belfast, Belfast BT12 6BJ, N. Ireland, UK.
Fitch
P S
PS
Brown
V
V
Taylor
R
R
Lyons
J D M
JD
Ennis
M
M
Shields
M D
MD
D001249:Asthma / Q000378:metabolism / Q000473:pathology*; D015415:Biomarkers; D001944:Breath Tests; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002648:Child; D004804:Eosinophils / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D012372:ROC Curve; D012680:Sensitivity and Specificity
D015415:Biomarkers; D009569:Nitric Oxide