a device for the application of continuous positive airway pressure delivering 100 % oxygen during thoracic surgery utilizing one - lung anesthesia . the device comprises a hollow , cylindrical member serving as a conduit for oxygen . one end of the device is connected to a source of oxygen delivered at a constant flow rate . the opposite end attaches to one lumen of a double - lumen endotracheal tube . a removable cap is attached to the device . if the cap is removed , a breathing bag can be attached for allowing the periodic expansion of the lung connected to the apparatus . a venting device is provided to allow the egress of oxygen under pressure . by changing a venting orifice , varying degrees of pressure of oxygen will be delivered to the one lumen of the double - lumen tube .