SPIROMETRY STUDIES

Summary Static and dynamic spirometry have been performed in 27 patients with a varying degree of physical handicap and kyphoscoliosis. The following observations are made. 1. The total lung capacity is within the normal range in groups I and II, but moderately decreased in group III + IV. 2. The vital capacity is generally somewhat decreased, most markedly in group III + IV (to 72 per cent of the predicted value). The residual volume is significantly increased in all groups; it amounts to 141 per cent ot the predicted value in group 1 and 120 per cent in group III + IV. 3. The functional residual capacity is significantly increased in groups I and II. In group III + IV, the residual capacity is kept within the normal range by the decreased expiratory volume. 4. In all groups, the functional residual capacity and residual volume are characteristically elevated in relation to the total lung capacity (mean 144 and 121 percent, respectively, of the predicted values). 5. Increased residual volume and functional residual capacity, combined with normal total lung capacity, result in an elevated level of the tidal volume. This is most pronounced in groups I and II, in which there is a lesser degree of kyphoscoliosis. A disturbance in the respiratory mechanics is suggested to be responsible for this phenomenon. 6. The forced expiratory volume in one second is, as a rule, ordinary. However, the patients have great difficulty in carrying out repeated forced ventilation, in view of the incoordinated activity of the respiratory muscles. 7. In Friedreich's ataxia, the neurological disorder causes a disturbed regulation of ventilation, which may result in abnormal rhythmic activity. This is ascribed to interrupted transmission of afferent impulses from receptors in the intercostal muscles.