CPAP therapy is the standard treatment for obstructive sleep apnea. While it delivers significant health benefits, a common side effect is “CPAP belly,” or aerophagia—the excessive swallowing of air that travels into the digestive system. This results in gas accumulation in the stomach and intestines, causing abdominal distension, bloating, and discomfort upon waking.
How Pressurized Air Causes Bloating
The air delivered by a CPAP machine is pressurized to keep the throat open, but this force can overcome the body’s natural defenses. The upper esophageal sphincter (UES) is a muscle ring at the top of the esophagus that acts as a barrier between the airway and the digestive tract. During sleep, this muscle relaxes, making it susceptible to the continuous positive pressure. If the pressure is too high, air can be forced down the esophagus and into the stomach.
Once air enters the stomach, the excess air stretches it, triggering a reflex relaxation of the lower esophageal sphincter (LES). This allows air to move further into the small and large intestines, causing bloating and flatulence. Factors like mouth breathing or weak esophageal sphincter function due to conditions like GERD can increase this likelihood.
Adjustments to Relieve CPAP Belly
Addressing CPAP-related bloating starts with optimizing pressure settings, as excessively high pressure frequently causes aerophagia. Patients should work closely with their sleep specialist to evaluate if the prescribed pressure can be safely lowered without compromising treatment effectiveness. Many modern CPAP devices offer Expiratory Pressure Relief (EPR), which temporarily reduces air pressure during exhalation. This makes breathing out easier and potentially reduces air forced into the esophagus.
Switching to an Auto-CPAP (APAP) machine can be beneficial, as these devices automatically adjust pressure in real-time based on the user’s needs. This dynamic adjustment often results in a lower average pressure than a fixed CPAP setting, decreasing the force against the UES. For patients requiring consistently high pressure, a BiPAP (Bilevel Positive Airway Pressure) machine is an effective alternative. BiPAP delivers two distinct pressures—a higher one for inhalation and a lower one for exhalation—making therapy more comfortable and reducing air swallowing.
Positional changes during sleep are another strategy to minimize air ingestion. Sleeping on the back (supine position) increases the risk of aerophagia and may promote gastric reflux. Shifting to side-sleeping or elevating the head of the bed by about 30 degrees helps reduce the pressure gradient favoring air entry. Furthermore, ensuring a proper mask fit is important, as air leaks cause the machine to compensate by increasing pressure, which exacerbates bloating.
Signs That Require Medical Consultation
While mild bloating and belching are common side effects, certain signs indicate professional medical evaluation is necessary. If abdominal pain becomes severe, persistent, or is accompanied by vomiting, consult a healthcare provider immediately. Similarly, if bloating prevents the passing of gas or bowel movements, it could suggest a more serious underlying issue.
A sleep specialist should be consulted if adjustments to pressure and sleeping position do not resolve the symptoms, or if discomfort causes the user to stop using the CPAP device. Abandoning CPAP therapy leads to the return of untreated sleep apnea, which carries significant health risks. The specialist can re-evaluate pressure settings, check for comorbidities like GERD, or recommend switching to a different type of positive airway pressure device.