Long-term oxygen therapy--state of the art.

Long-term oxygen therapy prolongs life in adults with chronic hypoxia caused by chronic bronchitis and emphysema who have cor pulmonale, pulmonary hypertension, and secondary polycythemia ('blue bloaters'). Good results require oxygen therapy for more than 15 hours and preferably 20-24 hours per day. The oxygen concentrator, delivering 1 to 3 l/min of oxygen by nasal prongs, is probably the most cost-effective method of providing this therapy. Dangers of the therapy include fires and burning of patients who smoke, and this is a contraindication to treatment. Excessive CO2 retention during sleep should not result from controlled low-dose oxygen therapy unless the patient also has an obstructive sleep apnea syndrome. Oxygen therapy during sleep may prevent hypoxemic episodes in blue bloaters, and it may thus reverse their pulmonary hypertension, which probably potentiates the risk of right-heart failure and cor pulmonale.