Spirometry in 3-5-year-old children with asthma

Spirometry with incentive games was applied to 207 2–5‐year‐old preschool children (PSC) with asthma in order to refine the quality‐control criteria proposed by Aurora et al. (Am J Respir Crit Care Med 2004;169:1152–159). The data set in our study was much larger compared to that in Aurora et al. (Am J Respir Crit Care Med 2004;169:1152–159), where 42 children with cystic fibrosis and 37 healthy control were studied. At least two acceptable maneuvers were obtained in 178 (86%) children. Data were focused on 3–5‐year‐old children (n = 171). The proportion of children achieving a larger number of thresholds for each quality‐control criterion (backward‐extrapolated volume (Vbe), Vbe in percent of forced vital capacity (FVC, Vbe/FVC), time‐to‐peak expiratory flow (time‐to‐PEF), and difference (Δ) between the two FVCs (ΔFVC), forced expiratory volume in 1 sec (ΔFEV1), and forced expiratory volume in 0.5 sec (ΔFEV0.5) from the two “best” curves) was calculated, and cumulative plots were obtained. The optimal threshold was determined for all ages by derivative function of rate of success‐threshold curves, close to the inflexion point. The following thresholds were defined for acceptability: Vbe ≤75 ml and ≤10% of FVC, time‐to‐PEF