Idiopathic hypoventilation syndrome: importance of preventing nocturnal hypoxemia and hypercapnia.

This report describes a young woman with unexplained chronic hypoventilation that was greatly exacerbated during sleep. Treatment with nocturnal O2 during a 2-yr period was associated with stable cardiovascular function but severe morning headaches and lethargy, presumably related to nightly bouts of hypercapnia and acidosis during sleep. A subsequent 2-yr period in which ventilation was assisted during sleep by means of a rocking bed, but supplementary O2 was not used, was associated with disappearance of the headaches and improved psychosocial function, but with the insidious development of signs of pulmonary hypertension and right ventricular hypertrophy. This patient's clinical course demonstrates the separate adverse effects of intermittent hypoxemia and hypercapnia and emphasizes the importance of preventing both hypoxemia and hypercapnia during sleep.