Cystic fibrosis respiratory disease leads to chronic respiratory insufficiency, pulmonary hypertension and cor pulmonale. Clinical evaluation must be helped by diurnal artérial gasometry and nocturnal saturation measure, especially in acute phase and during the weeks after respiratory infections. Treatment of hypoxemia is based on oxygenotherapy, but also on nasal nocturnal ventilation for patients waiting for a pulmonary transplantation. Association of them is able to conserve or enhance respiratory and nutritional status.