Maximal ventilation at rest and exercise in patients with chronic pulmonary disease.

74 subjects of different ages: normal children, 19 boys (A) and 7 girls (C) aged between 11 and 15 years; asthmatic boys (n = 7, group B) and girls (n = 7, group D), with similar ages; normal male adult subjects (n = 10, group E) and pulmonary patients with restrictive (n = 8, group G) or obstructive (n = 16, group F) ventilatory impairment, were submitted to measurements of vital capacity (VC), forced expiratory volume in 1 s, (FEV1), maximal voluntary ventilation (MVV), maximal peak expiratory (PEF) and inspiratory (PIF) flows at rest, and two maximal exercise stress tests in which the ventilation at maximal exercise (MEV) were retained. Indirect MVV was obtained by multiplying the FEV1 by 35 and 37.5. The correlation coefficients between MVV and VC, FEV1, PEF and PIF were always as high as r greater than 0.76. (p less than 0.001), with a discrepancy between the calculated and measured MVV. The average ratio MVV/FEV1 always exceeds 39 and is much higher in groups B, C and G. The mean percent values of the ratio MEV/MVV were 0.63 in normal men and 0.74 in normal boys. In patients, this ratio is higher than in adult normals: F = 0.81 and G = 0.88, and is not due to methodological errors, but seems to correspond to several physiological features playing only a role during exercise (MEV). This work shows the difficulty in predicting correctly the MVV at rest and in assessing the ventilatory reserve during maximal exercise in chronic pulmonary patients.