A case of Cushing's syndrome associated with chronic respiratory failure due to metabolic alkalosis.

A case of Cushing's syndrome associated with chronic respiratory failure is presented. Although arterial blood gas analysis showed severe metabolic alkalosis, hypoxemia and mild hypercapnia, the patient had no evidence of pulmonary disease or neuromuscular disorder. Voluntary hyperventilation and inhalation of 100% oxygen (O2) revealed normalized arterial oxygen tension (PaO2). Following the recovery from metabolic alkalosis by the treatment with potassium chloride, PaO2 was elevated and arterial carbon dioxide tension (PaCO2) was lowered. Therefore, it was strongly suggested that the main cause of chronic respiratory failure was compensatory alveolar hypoventilation as a response to metabolic alkalosis.