Continuous Positive Airway Pressure (CPAP) is the primary treatment for obstructive sleep apnea, delivering pressurized air through a mask to keep the upper airway open. Gastroesophageal Reflux Disease (GERD) is a chronic digestive condition where stomach acid flows back into the esophagus, causing discomfort known as acid reflux. For many users, CPAP seems to trigger or worsen their acid reflux symptoms. While CPAP often helps reduce reflux, the mechanical nature of the pressurized air can sometimes provoke symptoms.
The Relationship Between Sleep Apnea and GERD
Acid reflux and obstructive sleep apnea frequently occur together, often regardless of CPAP use. Studies suggest that between 58% and 62% of people with sleep apnea also experience GERD. This high prevalence indicates they share a strong underlying physiological link and common risk factors, such as obesity.
The mechanical stress of untreated sleep apnea directly contributes to acid reflux events. When a person attempts to inhale against a blocked airway, it creates a powerful negative pressure inside the chest cavity. This suction effect pulls stomach contents, including acid, upward past the lower esophageal sphincter (LES) and into the esophagus. Treating sleep apnea with CPAP removes this vacuum effect, which is why CPAP therapy often significantly reduces nocturnal GERD symptoms.
How CPAP Therapy Can Trigger or Worsen Reflux
While CPAP often improves reflux, the delivery of pressurized air can introduce a new mechanism that exacerbates the problem. This mechanism is called aerophagia, which means “air swallowing.” Aerophagia occurs when the continuous stream of positive pressure air is inadvertently forced past the upper esophageal sphincter and into the stomach.
The presence of excess air in the stomach causes gastric distension, leading to bloating and increased intra-abdominal pressure. This increased pressure pushes against the lower esophageal sphincter (LES), the muscular valve meant to prevent acid backup. If the patient has a compromised LES, this abdominal pressure can overcome the sphincter, causing stomach contents to reflux.
The pressure setting of the CPAP device significantly influences aerophagia. If the prescribed pressure is too high, air is more likely to be redirected into the digestive tract rather than staying in the airway. Conversely, if the pressure is too low, obstructive events can cause the user to gasp, which also leads to air swallowing.
Mask fit also influences aerophagia and subsequent reflux symptoms. A leaky mask causes the CPAP machine to automatically increase its pressure to compensate for lost air. This unintended high pressure increases the risk of air being forced into the stomach, thereby increasing the potential for reflux.
Practical Strategies for Managing Symptoms While Using CPAP
Adjusting CPAP parameters and incorporating lifestyle changes can effectively manage reflux symptoms while maintaining sleep apnea therapy. The first step involves consulting a sleep specialist to review the CPAP pressure settings. If aerophagia is suspected, the specialist may lower the pressure or adjust the exhalation pressure relief settings to reduce the force of the air delivered.
Switching to a different type of positive airway pressure machine can also alleviate the problem. A BiPAP (Bilevel Positive Airway Pressure) machine delivers separate, customizable pressures for inhalation and exhalation, which may reduce air swallowing compared to standard CPAP. An Automatic CPAP (APAP) machine is also beneficial, as it automatically adjusts pressure throughout the night to the minimum level needed, preventing unnecessarily high pressures.
Beyond equipment adjustments, simple changes to sleeping habits can dramatically reduce nighttime reflux.
Lifestyle Adjustments
- Elevate the head of the bed by four to eight inches using a wedge pillow or bed risers. This uses gravity to keep stomach acid down and ensures the esophagus remains above the stomach.
- Avoid eating large meals within two to three hours of bedtime, allowing the stomach to empty before lying down.
- Sleep on the left side, which is recommended due to the anatomical positioning of the stomach.
- If symptoms persist, discuss anti-reflux medications, such as proton pump inhibitors, with a healthcare provider to manage underlying GERD.