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    CPAP Equipment: CPAP Humidification

    CPAP Humidifier

    CPAP Humidifiers

    The movement of CPAP air through the air passages can dry out the airway. Humidifiers add moisture to the airstream to help reduce irritation to the nasal passages. Not only are dry air passages uncomfortable, but the swelling can actually narrow the airway affecting therapy pressure requirements. Humidification is the comfort feature most commonly added to CPAP therapy. There are two kinds of humidifiers: cool passover and heated. A cool passover humidifier passes room temperature air over a chamber of room temperature water. A heated humidifier heats water to warm it and as the airstream passes over the heated water, it picks up the moisture and warms the air. The heated air is able to hold enough moisture to maintain a comfortable airway.

    CPAP Humidification FAQs

    What is humidification?
    Humidification adds moisture to the CPAP air, reducing irritation to the nasal passages caused by the increased airflow.

    CPAP air is an irritant - to one degree or another - to everyone. In some cases the irritation dries out the nasal passages and may cause bleeding. It may also cause swelling, excess mucous, congestion or sneezing. The irritation may create a very fertile ground for infections to begin. The irritation may be cumulative, building up over time. The only way to reduce the irritation is to add moisture.

    Humidification is therefore a critical part of CPAP Therapy.

    What are the benefits of using a humidifier?
    Many PAP users experience nasal congestion and dryness of the nose and throat during treatment. This can be especially problematic for new users who are adapting to treatment. Humidification adds moisture to the air helping to reduce the symptoms of dryness and congestion.

    Nasal congestion also leads to mouth breathing, which perpetuates the problem of dryness. If this is an issue for you, try a heated humidifier.
    What is a heated humidifier?
    A heated humidifier uses heat to warm the water to add moisture to the airstream. The heat is adjustable for more or less moisture. A heated humidifier water chamber is much smaller than a passover humidifier water chamber.

    In our experience, it is common for CPAP users to report that their therapy is greatly enhanced by the use of a heated humidifier.

    There are three types of heated humidifiers:
    • Stand Alone Humidifiers
    • Integrated Humidifiers
    • Built In Humidifiers
    What is a passover humidifier?
    A passover humidifier uses a chamber of room temperature water with the CPAP to add moisture to the airflow and reduce irritation to the nasal passages.

    Air flows from the CPAP through a short hose to the humidifier chamber where the air "passes over" the water to pick up whatever moisture it can. The air then flows into the six foot hose to the mask.

    Passover humidifiers may provide sufficient moisture with CPAPs set at lower-end pressures. However, if the moisture is not sufficient there is no way to increase the amount of moisture added. The water is room temperature. In cold climates, the water temperature will drop causing the CPAP air to become very cold, and causing the amount of moisture to be reduced.
    What is an integrated humidifier?
    An integrated humidifier is used with a specific CPAP and fits directly onto the machine. For most heated humidifiers, this design eliminates the need for a second hose as well as a second power cord.

    An advantage of an integrated humidifier is that it works very closely with the CPAP machine to deliver humidification. Also, an integrated humidifier is a compact unit that uses fewer parts to provide moisture to the user.

    A disadvantage of the integrated humidifier is the user will receive less moisture when it is used with a passover humidifier. The smaller surface area effects the amount of moisture produced. Also, a integrated humidifier will only function with the CPAP for which it was designed.

    You can see if your machine has an integrated humidifier option by reviewing our Compare Charts.

    An example of an integrated humidifier is the PR System One Heated Humidifier as seen below attached to a machine in the PR System One line. PR System One Heated Humidifier
    What is a built in humidifier?
    A "built in" humidifier is designed as a part of the CPAP machine and cannot be removed or separated from the CPAP machine. As with an integrated humidifier, the design eliminates the need for a second hose or power cord. The water chamber can be removed for cleaning or replacement purposes.

    The advantage of a "built-in" humidifier is its compact shape, which operates on fewer parts. This integrated design helps to ensure optimum moisturized comfort and effectiveness when CPAP therapy and humidification are used together. Also, it allows an option for the humidification to be turned off while the CPAP is blowing.

    A disadvantage is that a built in humidifier may produce less moisture if used as passover because the surface area is typically smaller. Also, since the humidifier is "built in" to the machine, detaching it is not an option. This can be an issue for frequent travelers. Lastly, if the machine or humidifier stops working, the entire unit must be sent in for repair or replacement, not just the component that failed.

    An example of a machine with a built in humidifier is the ICON Auto CPAP Machine with Built In Heated Humidifier and SensAwake as seen below. ICON Auto CPAP Machine with Built In Heated Humidifier and SensAwake
    What is a stand alone humidifier?
    A stand alone humidifier is a component that will work with any CPAP and does not attach directly to the machine. It has its own power cord and a short hose to connect it to the CPAP. Generally it will sit next to the CPAP machine and is slightly larger than an integrated humidifier.

    The advantage of a stand alone humidifier is the fact that it may be used with any CPAP machine.

    The main disadvantages are that the size is often larger than either a "built in" or integrated humidifier and that a short hose is needed to connect it to the CPAP machine.

    An example of a stand alone humidifier is the Fisher & Paykel HC150 Heated Humidifier as seen below. HC150 Heated Humidifier
    How do I care for my humidifier?
    To care for your humidifier simply empty and clean the water tank each morning. Only distilled water should be used in the humidifier to avoid mineral deposit build up. S9 Dishwasher Safe Humidifier Chamber
    Why do I need to use distilled water with in my humidifier chamber?
    Use distilled water to help keep the humidifier chamber clean and mineral deposit free. Tap water should not be used as it will leave hard white mineral deposits in the chamber as the water evaporates, or it may lead to mold growth. Cases of lung disease have been connected to using contaminated well water in a CPAP humidifier.* Source

    If distilled water is not available where you live, use bottled water. It will be important to clean the chamber each morning, do not leave standing water in the chamber between uses.
    What maintenance is required on machines?
    The only care a CPAP or BiPAP machine requires is to clean or change the filters at the air intake. This keeps the internal parts from accumulating dust. Fine paper filters should be changed out every 30 days, or when they appear soiled. Foam washable filters should be rinsed with clear running water once a week, allowed to air dry, and reinserted.

    Here are some other suggested actions to care for your machine:
    • Keep the area around your machine clean by removing any dust from the area to improve the air quality delivered to your machine and to you.
    • Keep the air intake of the machine unblocked. Curtains, bedding, and papers can easily block the air intake of your machine, reducing the airflow.
    • If a humidifier is used with your therapy, do not pick up the machine with the humidifier attached. With most machines it is easy to spill water from the humidifier chamber into the machine causing damage. Manufacturer warranties are voided by water damage to the machine. To avoid this, remove the chamber from the humidifier and then remove the humidifier from the machine rather than transporting them together.
    • If a humidifier is used, empty the water from the chamber every morning. Accidents happen. If a family pet or family member moves the machine and humidifier with water in the chamber it is more likely that water could be spilled into your machine. Water damage to a machine voids the manufacturer warranty.
    How can I get help from a CPAP expert?

    • By Live Chat: Click on the Chat now field in the lower right hand corner of the page. If after hours, click Leave a message to enter your question and we will get back in touch with you.
    • By Phone: 800.356.5221 (8 AM - 10 PM CST Mon-Fri; 8 AM - 6 PM CST Sat)
    • Email Us:
    • By Fax: 866.353.2727
    • Could not find what you were looking for? Please send us your question. Question Submission Form

    Can I use my Heated Humidifier with my machine if I am running on Battery Power?
    Using a heated humidifier on a 12volt battery power source will significantly reduce the length of time the machine will run. In most cases, usage is reduced to less than half the estimated operational time. CPAPs or BiPAPs requiring inverters reduce the power time even more.

    Please note that some heated humidifiers are not capable of being operated on 12volt battery power sources. The later M Series heated humidifiers with the 6'' 'pigtail' connectors are capable of running on 12volt DC power sources. Earlier model M Series heated humidifiers without the pigtail are not 12Volt capable.

    For optimum performance of your battery, plan to use your CPAP without the heated humidifier. You may also have the humidifier connected and filled with water, but without the power turned on. This changes a typical heated humidifier into a passive humidifier.

    We suggest testing the battery setup you are planning to use with your machine in advance. To determine the actual amount of power time you will receive and whether or not heated humidification is required for your comfort, test the battery at home before traveling.
    What is rainout?
    Rainout is the accumulation of water in a CPAP tube due to warm moist air cooling and condensing on its way from your CPAP machine to your CPAP mask.

    The image below from Fisher & Paykel explains how rainout is formed. Warm, moist air leaves the heated humidifier and travels through the CPAP tube. As air flows through the tube, the temperature of the room causes the tube to cool. As the tube cools, the air inside releases its moisture, and creates condensation in the hose.

    Solutions to rainout include:
    • Raise the temperature of your bedroom.
    • Keep your CPAP machine at the same level as your bed.
    • Insulate your tubing with a hose cover like Snugglehose.
    • Reduce the tempurature setting on your heated humidifier.
    • Purchase a CPAP machine with a rainout reduction comfort feature.
    • Some machine systems offer a compatible heated CPAP hose which maintains the temperature from the machine all the way to the mask, reducing the occurrence of rainout. The list of available heated hoses can be found here: Hoses With Heating Coils.
    • If your machines uses a standard hose, consider the ComfortLine Heated Tubing Kit.

    Conventional Humidification
    Why would I want to insulate my CPAP hose?
    Cool air holds less moisture than warm air. If warm air from a heated humidifier cools while moving through the CPAP hose, water will condense inside the hose rather than travel to the user. The condensation that accumulates inside the CPAP hose is referred to as "rainout."

    Insulating the CPAP hose will help maintain the moisture in the airflow all the way to the mask.
    What is a hose cover?
    A hose cover is placed over the hose in order to insulate the hose and to make the hose more comfortable. The simplest and most cost effective way to insulate a CPAP hose is to wrap it in an insulating fabric. This enables the hose to remain flexible and adds little weight.

    Companies such as Snugglehose provide a cost effective tubing insulation available in several colors and styles. Not only will the covers reduce or eliminate rainout, they also provide a more personal and less institutionalized appearance. An example of a Snugglehose is shown below.

    What is a heated CPAP hose?
    A heated CPAP hose contains copper coils embedded in, or wrapped around, the hose. These coils are gently heated to conduct a constant temperature throughout the length of the hose. This enhances the comfort of the therapy and reduces or eliminates rainout caused by the water condensing as it travels through the hose to the mask.

    Heated hoses are more expensive alternatives to cloth tubing insulation, but they prevent rainout in nearly all cases. The ComfortLine Heated Tubing Kit is a stand alone option that can be used with any machine to prevent rainout and increase delivered humidification.
    Hybernite Rainout Control System
    Some manufacturers have developed heated hoses to work specifically with select machines in their product lines. The ClimateLine Tubing is used with S9 and H5i Climate Control System machines.
    ClimateLine Tubing
    The following video shows how to install a ClimateLine hose on a S9 Series Machine with H5i Heated Humidifier:

    The PR System One Heated Tube is used with PR System One 60 Series CPAP Machines.
    PR System One Heated Tube
    The ThermoSmart Heated Hose is used with Fisher & Paykel 600 Series machines.
    ThermoSmart Heated Hose
    Do machines come with Rainout Reduction features?
    Yes. Manufacturers have been working on developing ways to reduce rainout to better deliver humidification.

    The Hybernite Rainout Control System can be used with any CPAP machine to reduce or eliminate rainout.

    ResMed has developed Climate Control technology. The Climate Control system is made up of the combination of the S9 machines, H5i heated humidifier, and the ClimateLine heated tubing. Air is delivered at the temperature requested while five sensors, including one close to the mask, monitor multiple conditions to provide optimal humidification to avoid condensation.

    Philips Respironics has developed System One 60 Series Heated Tube Humidity Control technology. System One Humidity Control technology tracks room temperature and adjusts the heat throughout the system to avoid condensation.

    Fisher & Paykel has developed Thermostart Technology and Ambient Tracking Technology. Thermostart technology is a unique heated hose which maintains the warm environment for the airflow to prevent condensation. Ambient Tracking Technology monitors the ambient temperature and adjusts heat to maintain the most effective humidification, given the ambient conditions.
    What is Climate Control Technology?
    Climate Control technology is a rainout reduction feature created by RedMed. The Climate Control system is made up of the combination of the S9 machines, H5i heated humidifier, and the ClimateLine heated tubing. Air is delivered at the temperature requested while five sensors, including one close to the mask, monitor multiple conditions to provide optimal humidification to avoid condensation.

    Climate Control Technology Fact Sheet
    What is System One Humidity Control?
    System One Humidity Control technology is a rainout reduction feature created by Philips Respironics. System One Humidity Control technology analyzes ambient room temperature, relative humidity, and air flow from the tube to the CPAP user. Then, it adjusts heat to deliver an optimal level of humidification that avoids rainout conditions. The heated tube maintains the humidification all the way from the machine to the mask.

    System One Humidity Control Technology System One Humidity Control Technology
    What is ThermoSmart Technology?
    ThermoSmart technology is a rainout reduction feature created by Fisher & Paykel. ThermoSmart technology is a unique heated hose which maintains the warm environment for the airflow to prevent condensation.

    With conventional humidification, as air flows from the heated humidifier through the CPAP hose, the surrounding air cools the air inside the CPAP hose. As the air cools, it releases moisture in the tube and mask. The heated hose creates a continuous heated environment to help the air hold its moisture and be delivered effectively to the user.

    Conventional Humidification Conventional Humidification ThermoSmart Technology ThermoSmart Technology
    What is Ambient Tracking Technology?
    Ambient Tracking technology is a rainout reduction feature created by Fisher & Paykel. Ambient Tracking Technology monitors the ambient temperature and adjusts heat to maintain the most effective humidification, given the ambient conditions. The Ambient Tracking Technology uses an auto-adjusting heater plate to maximize humidity delivered while adjusting for room temperature. The level of humidity delivered is dependent on room temperature.

    Effects of Ambient Temperature on Humidification Ambient Temperature
    Are prescriptions required for mask, machine and/or humidifier purchases?
    Yes. Federal law requires we have a valid prescription on file before we ship your mask, machine and/or humidifier.

    We provide many easy ways to get your prescription:
    • We can request your prescription for you! When you checkout, just let us know you would like us to request your prescription, or you can log into your account to have us request your prescription.
    • Fax your prescription to our toll free fax number: 866.353.2727, or our international fax number: 713.541.7370
    • Email your prescription to
    • Upload your prescription in your account, under the Prescriptions Section
    For more information on prescriptions, please see our Prescription Section of the Learning Center.
    What does a humidifier prescription need to say?
    A humidifier prescription must contain all of the following information:
    • One of the following words or phrases: "CPAP Humidifier", "Humidifier", "HH", "CPAP Supplies", "CPAP Mask", "CPAP", "Continuous Positive Airway Pressure", "APAP", "AutoPAP", "AutoSet", "Auto CPAP", "Auto Adjusting CPAP", "Self Adjusting CPAP", "BiPAP", "BiLevel", "VPAP", "BiPAP Auto", "BiPAP ST", "Synchrony ST", "VPAP ST"
    • Your physician's contact information
    • Your physician's signature
    • The patient's full name
    Does this product contain BPA?
    Yes, all CPAP masks and CPAP humidifier chambers either contain BPA or their manufacturer has not released a statement calling their products BPA free. Here is a statement released by Respironics:

    Government of Canada Takes Action on Another Chemical of Concern: Bisphenol A

    April 25th 2008

    To Whom It May Concern

    This document represents Respironics' position regarding the use of Bisphenol A in Respironics Sleep and Home Respiratory Devices. On April 18, 2008, the Government of Canada, banned the use of Bisphenol A (BPA) in polycarbonate baby bottles, claiming that the exposure to BPA on newborns and infants up to 18 months of age, could potentially present a health risk to this patient group when the polycarbonate baby bottles are exposed to high temperatures.

    At this time, we are able to provide the following information to our customer: NONE of our Sleep and Home Respiratory products which are either breathable or skin contacting are intended for use with newborns or infants under 18 months of age. Therefore, Respironics is in compliance with Health Canada's position for exposure for the identified at risk patient population.

    Although Health Canada's restriction for BPA does not include products used for ages above 18 months at this time, Respironics is evaluating its product portfolio and will take the appropriate actions to determine and mitigate any potential risk from use of its products or potential exposure to BPA. It should be noted that NOT all polycarbonate resins contain BPA. In response to the direction provided by Health Canada's device licensing division, Respironics will be evaluating all of our Class II and III medical devices to determine if the resins used in the manufacturer of its products contain BPA.

    Further, none of our products or accessories using polycarbonate are labeled for exposure.

    In closing, it is Respironics position that our products do not pose any increased risk of exposure to BPA for our users and thus our products remain safe for use.

    If you have any further question regarding this topic, please feel free to contact me at or at 724-387-4120.


    Zita Yurko Director, Regulatory Affairs Sleep and Home Respiratory Division Respironics, Inc.
    What are the CPAP, BiPAP and Sleep Apnea related HCPCS, CPT or billing codes?
    • A7034 is Nasal Mask
    • A7034 is Nasal Pillow Mask
    • A7030 is Full Face Mask
    • A7027 is Hybrid Mask
    • A7044 is Oral Interface Mask (Oracle)
    • A7035 is Headgear for Mask - Any Style
    • A7036 is Chinstrap - Any Style
    • A7032 is Replacement Nasal Mask Cushion
    • A7033 is Replacement Nasal pillows
    • A7031 is Replacement Full Face Mask Cushion
    • A7028 is Replacement Hybrid Mask Cushion
    • A7029 is Replacement Hybrid Mask Nasal Pillow
    • A7046 is Replacement Humidifier Chamber
    • A7037 is Tubing / Hose - Long & Short Tubes
    • A4604 is Heated Tubing
    • A7038 is Disposable Filter (White / Paper)
    • A7039 is Washable Filter (Gross Particle / Foam/ Black)
    • E0601 NU is CPAP Purchase
    • E0601 NU is APAP Purchase
    • E0470 NU is BiPAP Purchase
    • E0470 NU is BiPAP Auto Purchase
    • E0471 NU is BiPAP ST Purchase
    • E0471 NU is BiPAP Auto SV Purchase
    • E0562 NU is Heated CPAP Humidifier
    • E0561 NU is Passover or Cool CPAP Humidifier
    • E0601 RR is CPAP Rental
    • E0601 NU is APAP Rental
    • E0470 RR is BiPAP Rental
    • E0470 RR is BiPAP Auto Rental
    • E0471 RR is BiPAP ST Rental
    • E0471 RR is BiPAP Auto SV Rental

    E1399 is Miscellaneous and is used for other CPAP items.

    Did You Know, CPAP Humidification

    • Distilled water is recommended for use in your humidifier as it has less minerals and may be more sanitary.
    • Humidifiers add moisture to the air you breathe so your airways don't get dried out from the pressurized air.
    • The amount of humidification to your air will depend on your humidifier heat settings.
    • CPAP users who use humidification are more likely to stick with their therapy.

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