Determinants of hypoventilation during wakefulness and sleep in diaphragmatic paralysis.

A 45-yr-old man with limb girdle muscular dystrophy, bilateral diaphragmatic paralysis, chronic carbon dioxide retention, and hypersomnolence was studied to determine the causes of hypoventilation during wakefulness and during sleep. Awake hypoventilation was associated with an insufficient inspiratory effort in the presence of inefficient respiratory muscles and a shortened inspiratory time. During sleep, severe hypoventilation and oxygen desaturation occurred only during REM-induced intercostal and accessory muscle inhibition.