Preschool children have recently been shown to perform reliable forced spirometry. Due to their different physiology and shorter expiratory times, several measurements have been proposed for the evaluation of lower airway obstruction. As Area under the maximum expiratory flow-volume curve (Aex ) appears to be a sensitive, and convenient parameter in detecting bronchoconstriction and bronchodilation, our aim was to establish normative data for an extensive number of parameters including Aex in healthy 3 to 5 year old children in our population.
The study population consisted of healthy Caucasian children aged between 3 and 5 years in 11 different daycare centers in the Eastern Townships of Quebec . Measurements were obtained as recommended by ATS guidelines using the Ms Pneumo spirometer (Jaeger) . As children have been shown to exhale in less than one second, expiratory manoeuvres lasting less than one second were included. Aex was calculated from the curve showing the highest sum of FEVx (where x can be one second or less) + FVC and analysed in relation to sex, age, height and weight.
One hundred forty three children were tested of which 69 were males (48%). Twenty-three were 3 years old, 56 were 4 years old and 64 were 5 years old. One hundred and twenty-eight (90%)were able to perform at least two technically acceptable expiratory manoeuvres. Log Aex = -16.989 + 3.749 Log height (r=0.574, p less than 0.001) and Log Aex = -16.019 + 3.528 Log height (r=0.651, p less than 0.001) were the best equations for boys and girls respectively.
Aex can be easily and successfully performed in 3 to 5 year old children and can be predicted from height using power equations in both the males and females of our population.
Aex is a promising measure of lung function which can potentially be used in the the diagnosis and follow up of obstructive airways disease in very young children.
Caroline Pesant, Grant monies (from sources other than industry) Quebec Foundation for Research; Grant monies (from industry related sources) Merck Frosst Canada.