What is CPAP Rainout and How to Prevent It

CPAP therapy

CPAP therapy is the most popular and effective solution for sleep apnea, and more precisely obstructive sleep apnea (OSA). Obstructive sleep apnea is the most common type of sleep apnea and, as Mayo Clinic explains it: …it occurs when the muscles in the back of your throat relax too much to allow normal breathing. These muscles support structures including the back of the roof of your mouth (soft palate), the triangular piece of tissue hanging from the soft palate (uvula), the tonsils, and the tongue. When the muscles relax, your airway narrows or closes as you breathe in, hampering your breathing for 10 seconds or longer. This can lower the level of oxygen in your blood and cause a buildup of carbon dioxide.

To prevent this, sleep apnea patients are recommended to use CPAP therapy. CPAP therapy is done using CPAP Breathing Machine. Three main parts of the CPAP machine are a motor/compressor (the machine itself), a hose, and a mask. Other parts are air filter(s), humidifier, mask straps, tube connectors and adapters, CPAP muffler, HME filter, heated hose… These “other parts” are not the key parts of the CPAP device, and you can even do without some of them, but they are mostly used as regular parts of the CPAP device (especially humidifiers). Some of the "other parts" might even be considered CPAP accessories, as they are not necessary, but when used are highly beneficial. One of the accessories we recommend for all new sleep apnea patients is CPAP Pillow (we can recommend PrimeClean® CPAP Pillow, as it is considered to be the Best pillow for sleep apnea).

Studies have shown that up to 70% of CPAP users experience dry nose and throat, nasal congestion, sore throat, even nose bleeds (epistaxis), or general discomfort from the cold and dry air from the CPAP machine. The most common solution for this is heated humidification of the airflow, which is done with a humidifier and heated hose. Of course, a heated hose is not necessary, a humidifier (or heated humidifier) will do the job (make the air humid, and that should be enough to avoid the above-mentioned discomforts) …but in some cases, it might be as important as a humidifier (especially in colder areas).

CPAP Rainout

What is CPAP rainout? How does it happen, and what causes rainout in CPAP?

To reply with questions to the first question: Have you ever woken up to see water in your mask? Have you noticed (a lot of) condensation in your tubing? Have you ever been woken up by the water in your mask? If your reply to this question is Yes, then you have experienced a rainout in your CPAP equipment. This experience can be so discomforting to the level of making some people give up on CPAP therapy. This most likely happens if you use heated humidification, with a heated humidifier (but not if you used a heated hose).

Rainout is unpleasant and discomforting, but it is a problem that is quite simple to resolve! But before we deal with that, let’s first see what causes rainout… 

Behind the CPAP rainout is essential primary school level physics! It is a simple condensation issue. Rainout happens when warm, humid air from your CPAP machine, cools inside the (colder) CPAP hose and forms condensation water droplets. This condensation builds up in the hose and then at some point it might start flowing from the hose into the mask. 

Rainout is a common problem with CPAP devices that have heated humidification, without a heated hose, especially if users live in colder areas so that the room and by that the hose is cold as well.

Is CPAP Rainout dangerous?

If we put the discomfort that it causes aside, there is no other negative effect of the rainout. We can safely say that CPAP rainout is not dangerous. The amount of water that is created is not that big to cause any serious problem with breathing even if it gets directly into your mouth (keep in mind that those are (only) condensation droplets). That being said, rainout can in a way be dangerous as it keeps your hose and masks moist and wet, and we mentioned many times before that hot and wet areas are an ideal breeding ground for all sorts of germs, bacteria, fungi, viruses… So, if you have CPAP rainout occurring often with your CPAP equipment, you must take special attention to it because of this reason, and you must make sure to clean and sterilize your equipment more often, on daily basis. But this doesn’t have to be a hustle for you! You can use some of the automatic cleaners/sanitizers (CPAP Cleaner Ozone Sterilizer Disinfector Sanitizer), we can recommend PrimeClean® CPAP Cleaner as one of the most efficient and proven CPAP sanitizers on the market; it will clean/sanitize your CPAP equipment within 30 minutes with just one click of the button. You can buy it now at a special discounted price of only $79.00!

How to prevent CPAP Rainout?

There are more solutions to the CPAP rainout problem. Most of them are simple. Some require investment, but some just need one or two things that you probably have in your home. Let’s see how to prevent CPAP rainout…

1. Use CPAP heated hose

This one is the simplest and most effective solution. Buying CPAP heated hose might be an investment, but it is a sure way to solve the problem! If the air inside the hose remains warm, it doesn’t condense into droplets. A heated hose usually has a copper wire wrapped around it (inside the hose wall) which is heated and thus helps reduce CPAP rainout by keeping the temperature of the hose and air in the hose consistent.

2. Wrap hose to keep it warm

CPAP accessories industry offers many solutions for a small amount of money. One of these solutions is a hose wrapper or hose jacket. This is a specially created hose wrap that helps to insulate the hose and keep it warm. This is especially effective and recommended in cold rooms. If you don’t have hose wrap, you can try wrapping it with whatever clothes you have, even put it under the blanket if possible.

3. Adjust your humidifier settings

Some heated humidifiers have a temperature setting option. Usually, humidifiers will try to heat the air to around 80°F, but you might try to increase or decrease this. However, this method should be done with consultation with your CPAP doctor. Setting humidification to be too hot can make the air lose some of its humidity and be less effective.

4. Automated Adjustment CPAP Machines

With the advancement of technology and the development of the CPAP industry, everything that can be automated is being automated. Leading CPAP industry companies are competing which one will make the best CPAP solution, reduce discomforts, and improve the CPAP experience. So, for example, the S9 and Air Solutions CPAP machines from ResMed feature automated adjustments designed to maintain humidity levels. This climate control feature monitors the temperature of the air in the mask and how it is affected by ambient temperature. If needed, the system will simultaneously adjust the humidifier and hose heating levels, to provide an optimal temperature and thus prevent CPAP rainout.

5. Adjust the room temperature

If this is an option, you can try to resolve the issue by simply adjusting the room temperature. If your room is cold and that is what's causing the rainout, you can try and set the room temperature to be warmer. This is a quick and simple fix, but it comes with the price of your sleeping comfort if you are used to sleeping in a colder room.

6. Move CPAP machine

Again, one simple and quick solution that doesn't require any investment or has any influence on your sleep comfort… By moving your CPAP machine to the lower level than your bed (your mask), you will apply simple physics and with the help of gravity, you will get rid of the rainout! Or at least you will get rid of the rainout in your mask. Any water droplets that form the condensation will flow back into the humidifier instead of flowing to your mask.

To sum it up

CPAP rainout is an inconvenience, a discomfort, that might occur in some situations where the room temperature and humidifier heat settings are not in line. Rainout is a simple condensation and it is an easily fixable problem that shouldn't be ignored. We have listed 6 simple and most common solutions for the CPAP rainout, but in general, you can improvise and be creative if none of the above is a possibility. If you understand the physics behind the condensation than you should be able to understand and find the way to resolve the CPAP rainout problem!