CPAP Humidifiers are Common Among CPAP Users
By Andrew Senske, President CPAP-Supply.com
Last Updated 12/7/2006 10:37:00 PM



I'm sitting in my living room typing this article - which is going to tell you what I know about CPAP humidification - and I'm looking down at my hands noticing how dry they are. They're so dry my skin is beginning to crack. So now I'm thinking about things like relative humidity, the heat index, my kids' hermit crabs (who need at least 50% relative humidity to survive, poor things), and of course, CPAP humidifiers.

A common question for new CPAP users is whether a CPAP humidifier is necessary. It's sort of difficult to answer the question because the answer depends on several variables, not the least of which is personal preference. Then there's environmental conditions which vary from one geographic location to the next, and from one house to the next. So instead of trying to answer the question I'll just focus on what humidifiers do and the impact a CPAP humidifier might have on your CPAP therapy.

There's a common misconception that a heated CPAP humdifier will deliver air that's warmer than room temperature to the patient. This isn't true. However, there's always the possibility that the air feels slightly warmer due to the phenomenon described by the heat index. Simply put, the heat index shows us that the temperature of the air will feel colder when the relative humidity is low. Conversely, the temperature of the air feels warmer when the relative humidity is high. If your CPAP humidifier is filled with water and working correctly then the relative humidity of the air being blown through your CPAP mask should be high, and therefore the air temperature may feel slightly warmer. You probably won't notice it, though.

As air travels across the water in a CPAP humidifier, the air picks up water vapor through the process of evaporation. There are a couple of methods of increasing the amount of water vapor the air stream can pick up. One method is to increase the surface area of the water over which the air is traveling to allow for more evaporation to occur. Stand-alone cool passover humidifiers are designed so that the pool of water within has a large surface area, and that's why these types of humidifiers are the shape that they are. Another method of adding water vapor to the air is to heat the pool of water over which the air is traveling. The evaporative process is enhanced due to the higher temperature of the water.

It's clear then that one of the benefits of a heated CPAP humidifier - and perhaps the primary benefit - is the size and shape of the unit. Since the heated water contributes to higher levels of evaporation the humidifier design doesn't have to be such that the surface area of the water needs to be considered. In a heated CPAP humidifier the water chamber can be much more compact.

At some point in your use of a CPAP humidifier you may experience rainout. Rainout occurs when the relative humidity reaches 100%. At that point the air can no longer hold water and it... rains. Literally. In your CPAP tube. We know that warmer air can hold more moisture, so if you experience rainout you've got a couple of options. First, you can ensure the air temperature of the room is higher than when the rainout occurred. Second, you can reduce the humidification setting on your heated humidifier. Finally, you can get a heated CPAP tube which reduces the chances of condensation.

In the winter the relative humidity often drops in homes. Even without CPAP therapy people may wake up with dry mouths and dry, sore throats. To alleviate this you could humidify your entire house, or just certain rooms in your house. An ideal relative humidity in a house is approximately 45%. The heat index shows us that at this relative humidity the temperature we feel is almost exactly equal to the air temperature. if you're feeling cold when the thermostat reads 68 or 70, get a hygrometer to find out the relative humidity in your home. If the relative humidity is low, then the temperature likely feels a few degrees colder than it actually is.

Whether it's winter or summer, CPAP therapy can be tough to tolerate without humidification. If you're like me and your hands are dry and cracked, then consider what your mouth and throat might feel like without proper humidification during CPAP therapy. If you do experience dryness and irritation during CPAP treatment without a humidifier then consider doing one of two things: purchase a heated humidifier for your CPAP machine, or purchase a humidifier for your room. Either way, the air you breathe will have more moisture in it.

Provided the hermit crabs are still alive, I'm going to go give them a spray.

Andrew Senske
President
www.cpap-supply.com

CPAP-Supply.com is a leading online retailer of CPAP equipment. Located in Spokane, WA CPAP-Supply.com has been serving thousands of customers around the world since 2001. Founded on a belief that patients are their own best primary care providers, CPAP-Supply.com understands the importance of educating patients and customers on both the effects of and treatment for obstructive sleep apnea. For more information visit CPAP-Supply.com or call toll free 1-888-955-2727.

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