Changes in respiratory function in disorders of the thoracic cage. With special reference to the ventilatory mechanism and the regulation in scoliosis.

After describing the clinical and functional effects of pathological changes in the thoracic cage ("mechanical syndrome" and "neuromuscular syndrome"), the authors discuss the disorders of respiratory function observed in a group of patients with poliomyelitic scoliosis. The aim was to establish the type and nature of these changes with a view to clarifying certain pathogenetic aspects. Two factors suggest that the altered geometry of the thoracic cage in scoliosis is responsible for the mechanical inefficiency of the thoracopulmonary apparatus, namely: 1. changes in respiratory function, since there was a strict correlation between the severity of the scoliosis and the degree of change in certain indices of respiratory function (vital capacity, maximum expiratory volume per second, maximum ventilation per minute); 2. changes in the regulation of ventilation, indicated by: a) good correlation between the ventilatory response to CO2 and the severity of the anatomical lesion; b) a reduction in the occlusion pressure, which is regarded as the pressure available to produce ventilation.