Effects of tracheostomy in two cases of hypersomnia with periodic breathing.

Two non-obese patients suffering from hypersomnia with periodic breathing, who presented predominantly obstructive apnoea persisting throughout sleep, underwent tracheotomy with placement of a permanent tracheal cannula. Before tracheostomy there was a serious state of alveolar hypoventilation with a marked rise in pulmonary arterial pressure which appeared during sleep. After tracheostomy breathing during sleep became regular, pulmonary arterial pressure became normal, and daytime drowsiness disappeared. These observations suggest that the obstruction of the upper air tracts during sleep represents the most important factor in the pathogenesis of hypersomnia with periodic breathing.