Myasthenia gravis: lung-function studies without and with edrophonium chloride.

25 myasthenia gravis-afflicted patients (14 crisis-endangered and 11 not endangered) were investigated with respect to their respiratory function and reaction of the respiratory parameters to Tensilon (edrophonium chloride). Results show that the vital capacity and the value of respiratory function parameters, measured under forced conditions, were partly significantly lower than those given as predicted values for healthy individuals. Maximal inspiratory flows indicated the greatest decrease. After intravenously administered Tensilon, the pathologically reduced maximal inspiratory flows increased. This positive effect of Tensilon can mark the alteration of the respiratory muscles and also the undertreatment of the patients. The observation that Tensilon may increase -- with some permanency -- the respiratory flow resistance and may decrease the maximal expiratory flow values, draws attention to the side effect (causing obstruction of the bronchi) of the drug, limiting its therapeutic use for patients in myasthenic crisis, especially in those complicated by obstructive lung disease.