Reference values for forced inspiratory flows in children aged 7-15 years.

In order to construct reference equations, we attempted to measure forced inspiratory flows, i.e., peak inspiratory flow (PIF) and maximal inspiratory flow at 50% of FVC (MIF50%FVC) in 332 healthy schoolchildren aged 7-15 years during flow-volume loop measurements, using an electronic spirometer. In 255 children (122 boys and 133 girls), the results were satisfactory. Statistical analysis revealed that the only predictive variables were sex and height. The best fit of the data was obtained with the power model (Y = A * H(B)); the coefficients of correlation between flows and height ranged from 0.66-0.77, and were slightly greater for boys. Forced inspiratory flows in children increase with height, and the variability is higher than for forced expiratory flows. Reference values for forced inspiratory flows can be useful in assessing the ability of children to generate affective inspiratory flows for choosing an inhalation device, or in resolving diagnostic problems, e.g., extrathoracic obstruction.