Continuous Positive Airway Pressure (CPAP) therapy is the standard treatment for obstructive sleep apnea, using pressurized air to keep the upper airway open during sleep. While effective, some users experience aerophagia, the technical term for excessive air swallowing, which results in uncomfortable bloating, belching, and abdominal distension. This side effect can compromise compliance with the therapy. The discomfort arises when the delivered air bypasses the lungs and enters the esophagus, leading to gas buildup in the stomach and intestines.
Understanding the Cause of Air Swallowing
CPAP machines deliver air pressure high enough to act as a pneumatic splint, preventing the throat tissues from collapsing. Aerophagia occurs when this positive pressure air is inadvertently forced down the esophagus and into the gastrointestinal tract. This happens because the pressure required to keep the airway open may exceed the threshold needed to keep the upper esophageal sphincter (UES) closed during sleep. As muscles relax in deep sleep, the UES may relax, allowing pressurized air to enter the stomach. High pressure settings are the most frequent factor contributing to aerophagia, often called “CPAP belly.”
Technical Solutions: Adjusting CPAP Pressure Settings
The most direct way to mitigate air swallowing is by optimizing the machine’s pressure delivery, ideally in consultation with a sleep specialist. Utilizing the machine’s Ramp feature is an effective solution. Ramp starts the therapy at a low, comfortable pressure, which then gradually increases over a set period (often 15 to 45 minutes). This allows the user to fall asleep before reaching the full prescribed therapeutic pressure. This initial lower pressure reduces the likelihood of air being forced past the esophageal sphincters while the user is still awake or lightly sleeping.
Switching to an Auto-CPAP (APAP) device can also provide relief, as these machines automatically adjust the pressure on a breath-by-breath basis. The APAP device delivers only the minimum pressure required to prevent an apneic event, avoiding the constant, excessive high pressure of a fixed CPAP setting. By minimizing pressure spikes, the APAP reduces the overall force available to push air into the esophagus.
Another function to explore is Expiratory Pressure Relief (EPR), sometimes called C-Flex or A-Flex. This setting momentarily lowers the pressure by one to three centimeters of water (cm H2O) when the user exhales. The risk of air swallowing is heightened when breathing against a high constant pressure. Lowering the pressure during exhalation makes breathing feel more natural and reduces the resistance that promotes air ingestion. Users should always consult their physician when adjusting these advanced settings to ensure the changes do not compromise the treatment’s effectiveness against sleep apnea.
Optimizing Mask Fit and Equipment
A poor mask seal can exacerbate aerophagia by causing the CPAP machine to compensate with higher pressure. When a large leak is detected, the machine increases the air pressure to maintain the required therapeutic level, raising the risk of air being forced into the stomach. Therefore, regularly checking the mask seal and ensuring the cushion size is correct for the face prevents this excessive pressure compensation.
The choice of mask type also influences the tendency toward air swallowing. Full-face masks are necessary for consistent mouth-breathers, but they sometimes require higher pressure settings than nasal masks or nasal pillows. Nasal pillows deliver air directly into the nostrils, minimizing air dispersion. This may be a more comfortable option for some users and can indirectly reduce aerophagia by ensuring a consistent seal and machine pressure. For those who involuntarily breathe through their mouth, combining a nasal interface with a chin strap or switching to a full-face mask is necessary to prevent pressure loss, which would prompt the machine to increase pressure.
Behavioral and Positional Adjustments
Adjusting sleeping posture can offer relief from gas and bloating associated with aerophagia. Sleeping on the side, particularly the left side, can help reduce pressure on the abdomen and aid in the natural release of trapped gas. Elevating the head of the bed by about 30 degrees, often achieved with a foam wedge pillow, is also beneficial. This slight incline reduces the pressure required to keep the airway open and helps position the esophagus to minimize air entry.
Users should avoid talking or swallowing excessively while the machine is running, especially when awake during the initial moments of therapy. Dietary choices before bed can also compound the discomfort. Avoiding carbonated beverages, which introduce extra gas into the stomach, and limiting gas-producing foods before sleep can prevent severe bloating and abdominal pain.