We can test the hypothesis of isometric growth of lungs and airways as follows.
- Ask children to perform a maximum expiratory flow-curve at regular intervals, say once every 6 months, and continue to do this over a number of years.
- Assess MEF each time in each child at a comparable lung volume, for example 70% of the TLC.
- Plot the logarithm of MEF as a function of the logarithm of lung volume.
- If the points are on a straight line the slope of which is between 0.67 and 1.37, then the hypothesis cannot be refuted, and is possibly correct.
Such a study was performed in hundreds of adolescent boys -and girls. They took part in a 7 year follow-up study, during which lung volumes and flow-volume curves were obtained at half year intervals. A similar study was also performed in a (smaller) group of children with asthma.
- Merkus PJFM, van Pelt W, van Houwelingen JC, van Essen-Zandvliet LEM, Duiverman EJ, Kerrebijn KF, Quanjer PH. Inhaled corticosteroids and growth of airway function in asthmatic children. Europ Respir J 2004; 23: 861-868.