SPIROMETRIC MEASUREMENTS OF LUNG FUNCTION IN HEALTHY CHILDREN

Abstract

A group of 50 normal children between the ages of 5¾ and 14 years has been studied by means of gross spirometry in an attempt to derive base line results for comparison with patients suffering from pulmonary disease. The results of these studies are summarized below: 1. The normal range of vital capacity for a given height is estimated on the basis of these observations to be given by the equation y = -2.41 + 0.0341 x ± 2(0.199), where y = vital capacity in liters, and x = standing height in cm. The subdivisions of vital capacity are expressed in terms of per cent of vital capacity. For this group the average inspiratory reserve was 76.0% and the standard deviation of the distribution was 4.6%. Correspondingly, the average expiratory reserve was 24.0%, and the standard deviation was 4.6%. 2. The normal range of maximum voluntary ventilatory capacity is estimated as y = -39.001 + 0.7712 x ± 2(8.077), where y = maximum voluntary ventilatory capacity in 1./min. and x = standing height in cm. 3. The average breathing reserve in the group studied was 89.7%, and the standard deviation 3.4%. These studies compared favorably with those observed by other investigators. 4. The results of resting ventilation, average tidal air and oxygen consumption revealed more variation than similar studies in adults as illustrated by wider standard deviations. This variability would be expected in view of the apprehension and excitability of young children. The mean resting ventilation for the group studied was 5.94 l./min./m² with a standard deviation of 1.64. The mean oxygen consumption was 174.64 ml./min./m² and the standard deviation was 39.20. The group studied was a relatively small one and the results must thus be subject to review as more data on pulmonary function in children becomes available.