Code 6847 Sleep Apnea Syndromes (Obstructive, Central, Mixed): Chronic respiratory failure with carbon dioxide retention or cor pulmonale or; requires tracheostomy – 100% Requires use of breathing assistance device such as continuous airway pressure (CPAP) machine – 50% Persistent day-time hypersomnolence – 30% Asymptomatic but with documented sleep disorder breathing – 0%