Pulmonary function in childhood connective tissue diseases.

The term connective tissue diseases (CTD) defines a group of illnesses characterized by the presence of immune abnormalities and by widespread inflammation involving various organs and tissues including the lung. These diseases are not frequent in the paediatric age group. Very few data on pulmonary function are available in paediatric CTD. We investigated possible early lung function abnormalities and any likely relationship with clinical activity of the disease in a group of 81 paediatric CTD patients, without clinical or radiological evidence of pulmonary involvement. Measurement of lung volumes and diffusion lung capacity were performed. A sample of 65 subjects, defined as normal on the basis of history and clinical examination, and matched by age and height with the group of patients, was chosen as control group. CTD patients did not show significant deviations from the control distribution with respect to functional residual capacity (FRC) and maximal expiratory flow at 75\% of the forced vital capacity (MEF75) values. On the contrary, both vital capacity (VC) and diffusing capacity of the lungs for carbon monoxide (DLCO) were quite impaired in most CTD during the active phase of the disease. Our results show a functional lung impairment in most children with clinically active CTD, even in absence of abnormalities on chest X-ray pictures.