CHANGES IN THE NORMAL MAXIMAL EXPIRATORY FLOW-VOLUME CURVE WITH GROWTH AND AGING

Abstract

Based on their answers to a self-administered questionnaire, 697 nonsmoking healthy subjects were chosen from a randomly selected sample representative of the whole non-Mexican-American population of Tucson, Arizona [USA], enrolled in a longitudinal study of respiratory health. For each subject, the 1st satisfactory set of flow-volume data obtained during the first 3 consecutive surveys was selected for analysis. For forced vital capacity (FVC) and 1-s forced expiratory volume (FEV1), the single best value for each subject was selected. Oher flow-volume measurements were derived from the single test with the best sum of FEV1 plus FVC. These data were used to derive improved prediction equations for each sex by age group for 5 spirometric and flow-volume variables. The resulting predicted values demonstrate the effects of development, maturation and senescence on ventilatory function. Normal limits are proposed that take into consideration the between-subject variability and non-Gaussian distribution of the various measurements.