The Continuous Positive Airway Pressure (CPAP) machine is a medical device used for treating sleep-disordered breathing. CPAP therapy does not inherently provide supplemental oxygen; its fundamental purpose is to deliver pressurized air. The machine takes in ambient air from the room, filters it, and increases its pressure before delivering it through a hose and mask. Therefore, a standard CPAP machine delivers pressurized room air, distinguishing it from oxygen therapy.
The Primary Function of CPAP Therapy
The primary function of CPAP therapy is to act as a pneumatic splint for the upper airway during sleep. This positive pressure is delivered continuously, preventing the collapse of the pharynx and larynx, which is the root cause of Obstructive Sleep Apnea (OSA). The pressure is measured in centimeters of water (cm H2O), reflecting the force required to keep the soft tissues from obstructing the breathing passage. The constant flow of pressurized air maintains the structural patency of the airway, ensuring an open path for air exchange. By keeping the airway open, CPAP prevents the repeated pauses in breathing and associated drops in blood oxygen levels, focusing on fixing the mechanical issue of obstruction.
The Source of Air in a CPAP Machine
A standard CPAP machine operates by drawing in the air present in the user’s environment. The machine’s blower motor pulls the surrounding air through a filter to remove particulates before pressurizing it. This ambient air naturally contains approximately 21% oxygen at sea level. The CPAP device simply pressurizes this existing air mixture without chemically altering its oxygen concentration, meaning the air delivered remains 21% oxygen.
Integrating Supplemental Oxygen
While the CPAP machine does not supply oxygen, it is possible to combine CPAP with supplemental oxygen therapy when medically necessary. This combination is indicated for patients with co-existing conditions, such as Chronic Obstructive Pulmonary Disease (COPD) or severe hypoxemia, causing consistently low blood oxygen levels. The oxygen is supplied by a separate device, such as a tank or concentrator, which requires a distinct medical prescription.
The supplemental oxygen is introduced into the CPAP circuit via specific connection points. Methods include using an oxygen bleed-in adapter placed between the CPAP machine and the breathing tube, or using CPAP masks manufactured with a dedicated oxygen port. This integrated approach ensures the patient receives positive airway pressure and enriched air to maintain adequate blood oxygen saturation.