Exhaled nitric oxide and sputum eosinophil markers of inflammation in asthmatic children

Exhaled nitric oxide and eosinophil sputum markers are considered noninvasi ve ways in which to evaluate airway inflammation in asthma. The aim of this study was to evaluate the relationships between these methods of evaluatio n in asthmatic children. In a cross-sectional study of 25 mild-moderate asthmatic children (aged 6-1 3 yrs, 10 patients on inhaled steroids) exhaled NO was measured along with induced sputum by inhalation of hypertonic saline solution. The sputum was processed for eosinophil count and eosinophil cationic protein (ECP) determ ination. Serum ECP and lung function (forced expiratory volume in one secon d (FEV1)) were also measured. A significant correlation was observed between exhaled NO and sputum eosino phils (r=0.438, p=0.032) as well as between sputum eosinophils and sputum E CP (r=0.532, p<0.01). No correlation was observed among exhaled NO and seru m ECP, sputum ECP, FEV1, respectively. Furthermore no correlation was obser ved between sputum eosinophil(%) and serum ECP and between sputum eosinophi ls and FEV1. There was no correlation among the investigated parameters in children treated with inhaled steroids. In conclusion, exhaled NO and sputum eosinophil counts are concordant in ev aluating the degree of airway inflammation in patients with mild-to-moderat e asthma. However, the association between these two noninvasive markers be comes less in steroid treated patients.