Continuous Positive Airway Pressure (CPAP) therapy is the most effective treatment for obstructive sleep apnea, delivering pressurized air to keep the upper airway from collapsing during sleep. Many users, however, experience uncomfortable side effects, including gassiness, abdominal bloating, and stomach discomfort. This gastrointestinal distress is medically known as aerophagia, which simply means “swallowing air.” Understanding this phenomenon is the first step toward managing it and ensuring you continue to benefit from sleep therapy.
The Mechanism of Air Swallowing (Aerophagia)
Aerophagia occurs when positive pressure air intended for the lungs is inadvertently directed into the digestive tract, primarily the esophagus and stomach. The CPAP machine acts as a pneumatic splint, keeping the pharynx open, but the air follows the path of least resistance. This path sometimes leads past the pharynx and into the esophagus, rather than solely into the trachea and lungs.
The body uses muscular rings called sphincters to control the passage of substances, including the upper esophageal sphincter (UES) located at the top of the esophagus. During sleep, these muscles naturally relax, allowing pressurized air from the CPAP device to be pushed into the stomach. Once the air enters the stomach, it causes distension, which triggers symptoms like belching, flatulence, and uncomfortable fullness.
This gastric distension can also affect the lower esophageal sphincter (LES), which separates the esophagus from the stomach. Excessive air increases the rate of transient LES relaxations, the main mechanism behind gastroesophageal reflux (GER) events. Therefore, CPAP-induced air swallowing may not only cause gassiness but can also precipitate or worsen symptoms of acid reflux and heartburn.
Common Reasons CPAP Users Experience Aerophagia
The severity of aerophagia often relates to specific factors within the therapy setup, with pressure settings being a primary contributor. If the CPAP pressure is too high, excess air is more likely to be forced past the relaxed esophageal sphincter into the stomach. Conversely, if the pressure is too low, the user may instinctively gulp or swallow air to compensate for inadequate pressure, forcing air into the digestive system.
A poor mask fit or consistent air leaks also increase the likelihood of air swallowing. Leaks can cause the user to unconsciously alter their breathing pattern, leading to unintentional air intake. Users who breathe through their mouth while wearing a nasal mask are significantly more prone to aerophagia, as this creates an easier route for air to travel down the esophagus.
Sleeping position is another factor that influences aerophagia symptoms. Lying flat on the back can exacerbate the issue, making it easier for air to enter the digestive tract. Existing nasal congestion, such as from allergies or a cold, forces the user to breathe through their mouth, which heightens the risk of swallowing pressurized air.
Adjustments and Solutions for Reducing Gassiness
The most effective way to manage CPAP-related gassiness is to work with a sleep physician to fine-tune the therapy settings. Adjusting the pressure is the first step, as lowering a high-pressure setting reduces the force driving air toward the stomach. If a fixed pressure setting is difficult to tolerate, switching to an Auto-CPAP (APAP) or BiPAP machine may be helpful, as these devices automatically adjust pressure or use two distinct pressure levels.
Many modern CPAP machines offer comfort features like Expiratory Pressure Relief (EPR), which temporarily drops the pressure level during exhalation. Using this feature makes breathing out feel more natural, helping to prevent the user from gulping or struggling against the constant airflow. Ensuring the mask fits correctly is also important, as a proper seal prevents leaks that disrupt the pressure and trigger reactive air swallowing.
For individuals who breathe through their mouth, using a chin strap with a nasal mask or switching to a full-face mask that covers both the nose and mouth can be a simple solution. Positional therapy, such as sleeping on the side or elevating the head of the bed by about 30 degrees, can help reduce pressure on the diaphragm and esophagus. If these adjustments do not resolve the symptoms, it is important to discuss underlying digestive issues, such as GERD, with a physician, as these conditions can contribute to aerophagia.