Oscillometric and spirometric bronchodilator response in preschool children with and without asthma.

BACKGROUND

Bronchodilator responses (BDR) are routinely used in the diagnosis and management of asthma; however, their acceptability and repeatability have not been evaluated using quality control criteria for preschool children.

OBJECTIVES

To compare conventional spirometry with an impulse oscillometry system (IOS) in healthy and asthmatic preschool children.

METHODS

Data from 30 asthmatic children and 29 controls (two to six years of age) who underwent IOS and spirometry before and after salbutamol administration were analyzed.

RESULTS

Stable asthmatic subjects significantly differed versus controls in their spirometry-assessed BDR (forced expiratory volume in 1 s [FEV1], forced vital capacity and forced expiratory flow at 25% to 75% of forced vital capacity) as well as their IOS-assessed BDR (respiratory resistance at 5 Hz [Rrs5], respiratory reactance at 5 Hz and area under the reactance curve). However, comparisons based on the area under the ROC curve for ΔFEV1 %initial versus ΔRrs5 % initial were 0.82 (95% CI 0.71 to 0.93) and 0.75 (95% CI 0.62 to 0.87), respectively. Moreover, the sensitivity and specificity for ΔFEV1 >=9% were 0.53 and 0.93, respectively. Importantly, sensitivity increased to 0.63 when either ΔFEV1 >=9% or ΔRrs5 >=29% was considered as an additional criterion for the diagnosis of asthma.

CONCLUSION

The accuracy of asthma diagnosis in preschool children may be increased by combining spirometry with IOS when measuring BDR.