copd chronic obstructive pulmonary disease

air airway apnea appliance awakenings breath breathing central chronic continuous copd cpap device disease disorder disturbance durable equipment exhale face flexible headgear health healthy heated hose humidifier hypopnea illustration inhale machine mask medical model mouth nasal nose obstruction obstructive oral plastic positive pressure pressurized pulmonary ramp respiratory rest sleep sleepiness snore strap therapy treatment tube vector