Cough peak flows: standard values for children and adolescents

We describe the distribution of cough peak flows (CPFs) in a random population of healthy children and adolescents. Spirometric and peak expiratory flows including CPF data were collected on 649 (341 females, 308 males) healthy children ages 4-18 yrs, using a portable spirometer and a peak flow meter. CPFs were related to anthropometric characteristics, age, and gender by linear multiple regression analysis. Reference values for CPF were estimated through regression models and calculation of empirical percentiles of data distribution. Other than peak expiratory flow rate, which was normally distributed, all other variables required logarithmic transformation to attain normal distribution. Significant relationships were found between CPF and gender, height, and body mass surface (P < 0.001) in both males and females. Age, even if correlated with CPF, does not add predictive value to the model. Fiftieth percentiles were from 147 to 488 liters/min and from 162 to 728 liters/min in females and males, respectively, through an age range of 4-18 yrs, with levels in males being generally higher than those in females at any particular age. CPF values also significantly correlated with other respiratory variables. The availability of reference levels for CPF in the pediatric population, as provided by this study, could be useful for establishing the risk of acute respiratory complications for young patients with weak coughs, particularly those with neuromuscular disease and restrictive pulmonary syndromes.