Exhaled nitric oxide correlates with airway eosinophils in childhood asthma
- 1Department of Child Health, Queen's University of Belfast, Belfast, UK
- 2Department of Clinical Biochemistry, Queen's University of Belfast
- 3Royal Belfast Hospital for Sick Children, Belfast, UK
- Correspondence to:
Dr M D Shields, Department of Child Health, Queen's University of Belfast, Institute of Clinical Science, Belfast BT12 6BJ, UK;
m.shields{at}qub.ac.uk
- Accepted 12 November 2001
- Revised 16 October 2001
Abstract
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.
