Value of spirometric investigations in amyotrophic lateral sclerosis.

The respiratory function has been studied in 37 patients with ALS. 15 of them (5 till death) were followed with serial spirometric tests. The data, as a whole, show a diminution of vital capacity, a diminution of forced expiratory volume per second, an increase of the residual volume and of the Motley index; blood gas analysis showed no significant alterations apart from slight hypoxemia. Patients with bulbar ALS presented marked abnormalities of the spirometric and blood gas analysis parameters. In the cases followed with serial spirometric tests VC, Motley index and FEV1 gradually deteriorated as the disease advanced. In the deceased patients a sudden and serious aggravation of these values occurred. This was especially true for FEV1 and Motley index during the 3 months preceding death. The variations in residual volume were less indicative. Finally, the influence of smoking and of pulmonary and bronchial pathology, present or past, was not significant.