OBJECTIVETo study the roles of allergen testing in vitro and impulse oscillometry for lung function measurements in preschool children with cough variant asthma (CVA).

METHODSethodsForty-four preschool children with acute asthma, 41 with chronic asthma, 46 with CVA, and 35 healthy preschool children as control were recruited in the study. Inhaled allergen, food allergen, and mite-specific IgE were determined by Pharmacia UniCAP System. Serum eosinophil cationic protein (ECP) and total IgE levels were measured. Lung function was assessed by impulse oscillometry.

RESULTSThe positive rates of inhaled allergen and food allergen, and total IgE levels in the CVA, acute asthma and chronic asthma groups were higher than those in the control group (P<0.01). However, no significant differences were found among the three case groups. The serum ECP levels in the CVA group were lower than those in the acute asthma group (P<0.01), but did not show differences when compared with the chronic asthma group. The impulse oscillometry demonstrated that the respiratory total impedance (Zrs), airway resistance at 5 Hz (R5), airway resistance at 20 Hz (R20), subtracting R5 from R20 (R5-R20) and resonant frequency (Fres) in the CVA, acute asthma and chronic asthma groups were higher than those in the control group (P<0.01). Zrs, R5, R20, R5-R20, and Fres in the CVA and chronic asthma groups were lower than those in the acute asthma group (P<0.01). Serum ECP levels were positively correlated with Zrs, R5, R5-R20 and Fres (P<0.05) in the CVA and chronic asthma groups.

CONCLUSIONSThe measurements of allergens, serum ECP and impulse oscillometry for lung function are helpful for the evaluation of airway inflammation and airway obstruction in preschool children with CVA.