Its because you sleep with your head in the wrong position as I use to but once I read up on the subject it all stopped. As Im not very good at explaining things so heres some information that will solve your problems like it did mine...
Over the last eight years we've heard plenty of complaints from CPAP users regarding various side-effects of CPAP therapy. All too often we hear people complaining of a bloated feeling, like their stomachs have filled with air. Generally these people are awakened during the night and they can't get restful sleep. The CPAP therapy may be working for them inasmuch as it's addressing the issue of obstructive sleep apnea, but it's creating a new, significant problem: aerophagia. While it's not clear how many CPAP users suffer from aerophagia, we can say for sure it's a problem we hear about quite frequently, and it's certainly an issue that needs to be addressed in order to achieve positive results from CPAP therapy.
First let's define aerophagia, and then we'll explore why it might occur and what can be done to mitigate it or to altogether prevent the phenomenon from occurring during CPAP therapy. Remember, I'm not a doctor, so this isn't medical advice. If you've got medical issues which need immediate attention, I'm not your guy. Call your doctor, make an appointment, and go in and have a nice conversation with him. If you suspect he might not know anything about aerophagia vis-a-vis CPAP therapy, you can print out this article and bring it in for a little show-and-tell.
Aerophagia is defined very simply as the condition in which a person swallows too much air into the stomach. Aerophagia can cause bloating and discomfort, and can result in excessive burping. Everyone has experienced aerophagia to a certain extent, and when it happens and enough air is swallowed it's often expelled through burping. Aerophagia can be caused by eating foods that produce gas in the stomach - like bran, vegetables, beer or soda - or by excessive salivation. Eating quickly, eating with your mouth open, and drinking while eating are also said to contribute to aerophagia. So, at the dinner table you can try to avoid aerophagia by having good manners! In bed, though, with a CPAP machine pumping air up your nose or into your mouth, good manners aren't enough.
To the casual observer it seems obvious enough. If air is pumped into your nose and mouth then you're going to swallow it. But wait. It's not so simple. Why would the air go down your esophagus and into your stomach, rather than going down your trachea and into your lungs? There are a couple of potential reasons.
First on the list is the position of the head, and how the position affects the trachea. If the trachea is not fully opened and is not able to accomodate the amount of pressure being delivered by the CPAP machine, then the overflow is going to get pushed into the esophagus. Did you ever take a CPR class? The key to blowing air into someone's lungs is to properly align the neck and head. If you don't do this - that is, if you don't fully open the airway - then you'll be blowing air into the esophagus and stomach. The same principle applies to other non-invasive ventilation techniques, including CPAP therapy.
Second on the list of reasons also has to do with basic fluid dynamics. The CPAP machine might be delivering too much air for your trachea and lungs to handle. This is very closely related to the head position, but it's a little different because the problem could potentially occur when the head and neck are properly aligned and when the trachea is wide open. Remember the last traffic jam you were in? Cars started to leave the jammed up street to take a different route. The same thing happens with gases like air. If the air doesn't fit in the trachea, it's going to go somewhere else. Too much air can cause you to swallow involuntarily (like an uncontrollable gag, really), opening the epiglottis. If you have a high pressure setting, this could be an issue.
Third on the list of reasons is air leaks. No matter your level of CPAP pressure, if air is going in through your nose and is leaking out of your mouth, you will undoubtedly swallow involuntarily. If the leaks are bad enough you'll probably end up ripping your mask off your face during the night without even knowing it. Leaks out the mouth when using a nasal mask are very uncomfortable and bascially intolerable, and can definitely contribute to aerophagia.
If you're experiencing the symptoms of aerophagia, you can try to address the issues accordingly:
•Adjust the position of your head so that it's not tilting forward while you sleep - keep the airway wide open
•Talk to your prescribing doctor about reducing the pressure setting on your CPAP machine
•Consider an automatic CPAP machine - they generally deliver much less than prescribed pressure
•Consider a machine with exhalation pressure relief - this will help prevent involuntary swallowing; in conjunction with an automatic machine your aerophagia days may be over rather quickly
The best choice for an automatic CPAP machine with exhalation pressure relief is the REMstar Auto M Series with A-Flex.
If you want to save a little money and get a better warranty I suggest the IntelliPAP AutoAdjust. It doesn't have exhalation pressure relief, but it's an excellent automatic CPAP machine.
I can't stress enough the importance of visiting your doctor if you continue to experience negative side-effects while using your CPAP machine. If you continue to experience aerophagia while using your CPAP machine even after trying some of the tips above, then you need to determine once and for all the cause of your problem. Perhaps the cause is unrelated to CPAP therapy. Get to the bottom of it.
Information taken from : [link removed - see my post below, DC. -SS]
. In the cpap articles section