Continuous positive airway pressure (CPAP) is a highly effective treatment for obstructive sleep apnea, but it is not without its side effects. One of the most common complaints with its use is CPAP-related gas, including increased burping and farting after use. What causes CPAP gas? Are there effective treatment options to avoid its occurrence? Explore some of the symptoms related to CPAP gas and what can be done about it.
Causes of CPAP Gas
CPAP works by providing a constant flow of air that keeps the airway open and prevents its collapse during sleep. When tolerated, it is highly effective for preventing sleep apnea, a condition characterized by repeated collapse of the upper airway that leads to oxygen level drops and awakenings. This airflow can be problematic, however, especially if the air goes where it is not wanted.
If you envision a tube running from the tip of your nose to your lungs, the pressurized airflow of CPAP keeps this tube open. It will push soft tissues aside, especially in the soft palate and upper throat. The lower part of the airway is supported by bony structures and includes the trachea, which leads to the bronchi and lungs. Right near the entry to the trachea is an opening that leads to the esophagus and stomach. Therefore, if air is misdirected down the esophagus, the stomach may fill with air and this could lead to increased gassiness. This is sometimes called aerophagia, which literally means "air swallowing".
Symptoms of Air Swallowing
When the pressurized air from CPAP improperly enters the stomach, it leads to a few common complaints. These include:
- Burping or belching
- Farting (flatus)
- Full or distended stomach (bloating)
- Vomiting of air (rarely)
- Stomach pain
These symptoms may be relatively minor and tolerable. Most people may notice relief in the first hour of the day by passing the gas. However, it can also be quite severe and distressing. The fortunate thing is that there is little risk of permanent damage to your body. Nevertheless, it can be desirable to seek out ways to make this less troublesome by decreasing both the frequency and degree.
Treatments of CPAP Gas Depend on Underlying Cause
As discussed above, CPAP gas is basically caused by the swallowing of air with the use of CPAP. There are ways to decrease this occurrence. One of the most common causes of CPAP gas is that the pressure setting of the machine is simply too high. If the pressure was not set as part of a titration study, or if you have lost at least 10 percent of your body weight, this is more likely. By turning down the pressure, or setting a range of pressures that includes a lower setting, the air swallowing may improve substantially.
Another important factor is your sleep position. If you sleep on your back, it can be helpful to sleep at an incline. This will prevent a "kink" in the esophagus that may lead it to more easily allow the passage of air into the stomach. Most people find it helpful to sleep at an angle of about 30 to 40 degrees. This can be accomplished by sleeping on a wedge pillow. You should be certain that a stack of pillows does not simply move your head forward. It is really about your head, neck, shoulders, and upper body being fully supported in a neutral position. Some people opt for an adjustable bed, but this can be expensive. Another option would be to raise the bed as a whole. With the use of books (such as old telephone books) or even cinder blocks, you can prop up the two feet at the head of your bed. Therefore, the entire bed will be kept at a slant. This is usually well tolerated by a bed partner, if you have one, and there is little risk of sliding out of bed at the proper angle.
It is fairly common for the cause of aerophagia and CPAP gas to be related to untreated gastro-esophageal reflux disease (GERD). Heartburn, especially when it occurs at night, can exacerbate the air swallowing. The lower part of the esophagus has a muscular ring called the lower esophageal sphincter. This ring closes the esophagus off from the stomach. This prevents the contents of the stomach, including stomach acid, from splashing up into the esophagus. However, in people with GERD or heartburn, the sphincter becomes weakened. It does not close off the esophagus as well as it should. This allows reflux of the stomach acid into the esophagus, but it also can allow air to get into the stomach with the use of CPAP. Some people will find the use of medications for GERD to be helpful in preventing CPAP gas, including Prilosec, Tagamet, Zantac, and others.
An additional treatment option can be the use of Gas-X (sold over-the-counter under the generic name of simethicone). This may provide some relief, but if the amount of air swallowed is significant, it may not be adequate. Though unpleasant, a greater relief may be to simply pass the gas out naturally through burping or farting.
Finally, people often ask if the type of CPAP mask has a role in worsening air swallowing. For example, if the mask is just over the nose as compared to covering the nose and mouth, does this make a difference? The short answer is no. Whether the pressurized air is being delivered through the nose or mouth, it ultimately comes to the same passage at the back of the throat. The problem lies farther down in the airway and not at the nose or mouth where a mask could be applied differently. Therefore, it won’t make a substantial difference which mask you choose to use.
If you find CPAP gas to be particularly bothersome, you should start by speaking with your sleep doctor about your pressure setting. It may be necessary to turn it down, or even try another therapy called bilevel. In addition, there are other changes you can make that may provide additional relief, including adjusting the angle of your sleep position and treating any underlying heartburn. The good news is that the inconveniences related to CPAP gas can usually be overcome and the effectiveness of the therapy can be enjoyed.
Kryger, MH et al. "Principles and Practice of Sleep Medicine." Elsevier, 5th edition.