The signs of obstruction of the superior vena cava have aroused clinical interest since Stokes1 described the syndrome over a century ago. The recent reviews of Ehrlich and others,2 Ochsner and Dixon3 and Hinshaw and Rutledge4 discussed in detail the anatomic and clinical manifestations of this disorder. A number of authors5 have described the findings on angiocardiography. The abnormal physical findings consist of striking venous engorgement, cyanosis and often edema, which are limited to the head, neck, arms and chest. Common complaints are headache, dizziness, fulness in the head, mental clouding and respiratory manifestations such as dyspnea, orthopnea and periodic breathing; in addition, paroxysmal dyspnea has been described by several authors,6 and Ferris7 reported "brief but severe attacks of hyperpnea" in 1 patient. The occurrence of respiratory symptoms in patients with stasis and with high venous pressure limited to the superior vena cava and its tributaries and with