Frequently Asked Questions


Why does the amount of water used vary so much night to night?

Mouth breathing or mouth leak. can make you use more water from your heated humidifier. All the escaped air through the mouth (which can vary from night to night), uses up the water more quickly.

I can′t use my humidifier during some nights because my hose fills up with water condensation. What can I do about it and why does this happen?

This condensation is called “rainout.” If your room is cold, the warmed, humidified air hits the colder room temperature and cools. When air cools, the amount of humidity (water vapour) that it can hold is reduced, which causes the humidity to “rain out.” The amount of water air can carry varies with temperature: warmer air can carry more water while cold air can carry less. As warm air becomes cooler (eg, overnight), it has less capacity to carry water, so water condenses and forms droplets. There are a couple of ways to deal with this situation. (1) You can try turning your humidity level down. (2) You can raise the temperature of your bedroom at night to lessen the difference between the room temperature and the humidifier—make sure that your bedroom window is closed. (3) You can run the air tubing beneath your blankets to keep it warm. The goal is to keep the tube and its air warm.

What are the overall benefits of humidification?

Up to 40% of positive airway pressure (PAP) users experience nasal congestion and dryness of the nose and throat. These symptoms can be severe enough to prevent patients from continuing their treatment. A ResMed heated humidifier, like the HumidAire 3i, adds moisture and warmth to the air delivered by a continuous positive airway pressure (CPAP) or bilevel system. This reduces symptoms of dryness and congestion, improving comfort and compliance. Heated humidification can prevent the large increase in nasal resistance that results in mouth breathing and leaks and additional dryness.

Can I put my CPAP on top of the humidifier? Or should it only go next to it?

The CPAP should always be placed either at the same level or above the humidifier to reduce the risk of water entering the CPAP machine. To further ensure water does not enter your CPAP machine, empty the water chamber and disconnect the humidifier from your CPAP machine before transporting it.

Does heated humidification wear out my mask and hoses faster?

No, the tubing supplied with CPAP machines can withstand far higher temperatures than the heat generated by the humidifier.

How often do I need to clean the water chamber on my humidifier?

It is recommended that you wash your humidifier and tubing daily in warm water, using a mild detergent. Rinse them thoroughly with clean water and allow them to dry away from direct sunlight. Inspect the water chamber weekly for wear and deterioration. Replace the water chamber if any component has cracked, become cloudy or pitted. If you notice white powder or deposits in the water chamber: (1) Fill the water chamber to the maximum water level and mark with a solution of one part vinegar to ten parts water (2) Let the solution soak for ten minutes (3) Discard the solution and rinse the water chamber with clean water.

Should I turn on my humidifier before I go to bed to make sure the water is warm first?

If you find the air dry and irritating, then you may want to turn your humidifier on 20 minutes prior to going to bed.

What are the benefits of using a heated air humidifier vs. cold? Nasal pillows vs. mask? Which is a better choice when using humidification?

Because you can adjust the level of heat, heated humidification offers greater flexibility and reduces more severe symptoms. Both nasal pillows and masks are a viable option when using humidification; however, “rainout” (moisture caused by having the humidifier turned up too high) when using nasal pillows may become more of an issue as the moisture is directed into the nostrils.

How much water should a humidifier use during a night?

The amount of water needed varies from one humidifier to the next, from one patient to the next, and with the temperature and humidity of the bedroom. If you are concerned, please consult your health professional.

I have a full face mask. Will I need more water during the night?

A full face mask should not change the amount of water used each night. If you had a mouth leak before, you could have been losing lots of air and humidity through your mouth, in which case you should use less water now.

I have heard that wrapping the continuous positive airway pressure (CPAP) hose with fabric will help with ″rainout.″ Is this true?

Yes. Wrapping the hose helps to insulate your treatment air from the lower temperature of the room, reducing “rain out.”

How often should I change the water in the chamber? I never seem to use it all in one night′s time.

The water should be changed for each use.

How do I know what temperature setting to use with my humidifier?

The setting on your humidifier will set how much moisture you receive to alleviate your symptoms. The higher the setting, the more moisture, and this is best checked first with your Clinician and User Guide. If you start your setting for example at a midway point, and if your symptoms are not resolved, you may need to turn it up another setting. Continue in this manner until your symptoms are resolved. If you start to experience moisture in the mask tube, you need to turn it down or heat the room.

If I run out of distilled water, is it ok to use tap water once in a while?

Using distilled water will maximize the life of the water chamber and reduce mineral deposits. However, it is ok to occasionally use tap water to clean your humidifier. Do not use: bleach, alcohol, chlorine or ammonia-based solutions; moisturizing, antibacterial or glycerine based soaps; and water softening and unapproved descaling agents.

I usually use my humidifier during only the winter months when the heat is on in house and, therefore, the air is dryer. Am I shortchanging myself? Should I be using it all year round?

If you are finding that you have nasal symptoms at other times of the year, then you should probably use your humidifier. The added humidification will probably increase the comfort of the air as it is more fully moisturized.

Is humidification helpful for Upper Airway Resistance Syndrome (UARS)?

Humidification doesn’t really help with OSA or UARS. It helps with side effects caused by CPAP. If you are already on CPAP treatment and experiencing nasal dryness/symptoms, then humidification should help decrease the symptoms. The nasal symptoms are due to the increased flow of air through the nasal passages. Humidification adds moisture to the air breathed and helps the nasal passages cope with the increased flow of air.


Can I use my ResMed CPAP system in other countries?

All ResMed CPAP systems have a power supply that automatically adjusts to the various power supplies in different parts of the world. All devices will accept 100-240V, 50-60Hz, without any special adjustment. Please note that you will still need to use the correct adapter for the power supply socket of the country you are visiting.

Can my CPAP run from the 400Hz power supply on the aircraft?

Yes. Even though the rating plate on the CPAP specifies 50-60Hz, the switch mode power supply in the flow generator is compatible with the 110 volts 400Hz power supply on the aircraft. Remember to book a seat close to a power outlet on the aircraft. The number and availability varies from one aircraft type to another.

Will the x-ray scanners at the airport security affect my CPAP device?

No, the x-ray scanners will not harm the device. However, security may require you to show the medical statement from your physician verifying that you are carrying medical equipment. Make sure this is handy.

What are an inverter and a converter, what do they do and where can I get them?

An inverter is a device that turns a low voltage (usually 12 volt) DC into a mains level AC voltage – either 110 or 240 volts – so that domestic appliances can be run from a battery supply. The S8 CPAP range have a 12V or 24V power input via ResMed’s DC-12 converter.

Can I use my CPAP system in-flight on a commercial airline?

Some airlines allow passengers to use their CPAP in-flight; some do not. Make sure you check with the airline before you book your flight. Please note: Do not use humidifiers while on an aircraft.

Will I need to have my CPAP adjusted if I travel to high altitudes?

Our AutoSet Spirit device will automatically compensate for altitude changes. Our Escape device may require manual adjustment for altitude changes. Failure to make the adjustment may result in ineffective therapy. Consult your sleep specialist/clinic to discuss this if you have any questions.

Can I go camping and use my CPAP system?

With the use of a suitable inverter or converter unit, your ResMed CPAP can operate from a battery supply (in a truck or recreational vehicle for example). The inverter should be capable of supplying voltage in the 100-300V range and should be of sufficient capacity. The ResMed S8 CPAP range can use either an inverter or converter, however all machines prior to the S8 range only work with inverters. All flow generators with a humidifier need a pure sine inverter with a power rating of 200 Watts or more. A flow generator without a humidifier needs a modified sine wave inverter with a power rating of 150 Watts or more. Choose an auxiliary marine or deep cycle battery (used in 4WD vehicles and boats), as these are better suited to frequent discharge.

Do I need to take my machine with me if I need hospitalisation?

Yes. If you are having surgery, it is very important that you tell both the surgeon and the anaesthetist that you are being treated with CPAP. You should also inform the attending physician that you have been diagnosed with obstructive sleep apnea (OSA).


Why and how often should I replace my mask cushion?

You should replace your mask cushion periodically because as it becomes worn, it becomes less effective. The life of a mask cushion depends on use, the oils from your skin, and cleaning. It is always a good idea to inspect your mask routinely; poor care may adversely affect the fit of the cushion and thus performance. To get the longest life from your mask, be sure to wash your face each night before putting on your mask, and wash your mask after each use. Use only original washing up liquid, nothing with perfumes, moisturizers, antibacterial agents, bleaches, etc, and always dry your mask and cushion out of direct sunlight. Poor performance is often the first clue that your cushion may need replacement. Check for small tears or pinholes, anything that might cause a leak. Cats have been known to damage cushions by playing with them and so have children, so you may want to keep your mask out of reach. Also, be sure you don’t leave your mask somewhere that receives direct sunlight during the day.

If the mask is strapped on so tight (to get a seal) that it is painful, does this indicate the wrong size mask?

It probably means you have an incorrectly fit mask. When using a ResMed mask, it is important not to over-tighten the mask system. If you can only get a good seal by tightening the headgear, you probably have the wrong size cushion or an incorrectly adjusted forehead support.

Can the headgear and/or other individual parts be purchased separately?

Yes. All ResMed mask parts can be purchased separately through our accredited partners. Please make contact with the place you purchased our products or health professional. Part numbers (codes used to order) for each part are available on this Website.

I have been having problems keeping my mask on at night—I often wake up to find out that I′ve removed it in my sleep. Any suggestions? It′s usually more prevalent when my allergies and sinuses are acting up.

This type of problem is likely occurring due to nasal congestion. With a history of sinus and allergy problems, you may be better treated with a full face mask and/or humidification. You should discuss this with your sleep specialist/clinic.

Who benefits from wearing a full face mask?

Some people just prefer a full face mask, but those who get a therapeutic advantage are those who mouth breathe or experience mouth leaks. Mouth breathing and mouth leak can lead to less effective therapy.

Is there any other benefit to using a full face mask other than for mouth breathers?

Even if you don’t mouth breathe, you may still experience mouth leaks. Mouth leaks can contribute to decreased treatment effectiveness and consequent symptoms of poor therapy.

Does a heated humidifier work as well with a full face mask?

Yes, and switching to a full face mask may eliminate or reduce your need for humidification.

Is a full face mask more or less comfortable than a nasal mask?

Everyone is different. Some people find that they prefer a full face mask while others prefer a nasal mask. It is really personal preference. However, both our nasal and full face masks utilize the same cushion technology that inflates to form a floating seal, maximizing patient comfort.

Does headgear need to be replaced?

Yes, you will need to replace your headgear occasionally. Like mask cushions, the life of headgear depends on use, the oils from your skin, and care (cleaning etc). Taking good care of your mask is the key to maintaining the best performance and mask fit. Wash your headgear at least once per week and dry it out of direct sunlight. The headgear should be washed by hand, the use of a washing machine will shorten its life. If you have oily skin, you may need to wash it more often. Headgear should last longer than a cushion, but it will depend on use and environment.

Are the Mirage masks suitable for use with a moustache?

Mirage masks have a very thin membrane, which will typically seal even with a moustache. The shallow cushion in particular is ideal for patients with a moustache, as they may need to adjust the cushion in closer to the top lip. The shallow cushion allows the user to angle the cushion more and maintain the seal at the bridge of the nose.

When is a full face mask preferable to a nasal mask?

If you mouth breathe or have mouth leaks, then a ResMed full face mask will provide a number of benefits over a nasal mask. A full face mask will stop air loss that can compromise treatment, and it can resolve dry throat and nose problems. If you mouth breathe or have leaks, you will not be receiving your full treatment pressure and thus may not be getting the full benefits of your treatment.

My doctor says that my nose is totally blocked on one side from a deviated septum. Does that mean I can use a full face mask, but can′t use a nasal mask?

With a deviated septum, you are likely breathing through your mouth due to your nasal passage being blocked. A full face mask will certainly work for you and would allow you the option of breathing through you nose and/or mouth. If your mouth is dry in the morning, you are probably breathing through your mouth.

If I have a nasal mask for my CPAP, can I use a full face mask when I have a cold or nasal congestion/stuffiness?

Yes, however the thing to remember is that every mask has slightly different flow characteristics, so if you’re using a ResMed AutoSetTM device, you’ll need to change the mask setting on the user menu when you switch masks.

Does bilevel therapy work with a full face mask?

Yes. Based on one recent study, one could argue that people using bilevel therapy are more likely to benefit from a full face mask because they are more prone to mouth leak and mouth breathing. In the study, data showed that nearly ALL patients on non-invasive positive pressure ventilation (NPPV) experienced some degree of mouth leak and/or mouth breathing. Mouth leak reduces the quality of your sleep and causes sleep fragmentation.

What if the electricity goes off? Will I still be able to breathe using the full face mask

Yes, ResMed full face masks have a special anti-asphyxia valve that opens if your PAP device loses power. This feature allows you to breathe room air in the event of a power failure.

Can the ResMed mask family be used with just about any other brand of CPAP?

It should be fine, but if you’re using a non-ResMed APAP device, you may want to check with the manufacturer.

What does a leaking mask indicate?

This may indicate one of several things:

  1. Incorrect adjustment
  2. Incorrect assembly
  3. Incorrect size

Skin Iritation Advice

Allergic reactions to silicone

ResMed mask cushions are made from silicone which is a hypoallergenic material used in medical appliances and devices. True allergic reactions to silicone are extremely rare. In fact, skin irritation, sores (pressure sores) and blisters are more commonly caused by other associated factors rather than the silicone material itself.

Possible causes of skin irritation:

  • Headgear strap adjustment too loose or too tight
  • A poorly fitting mask (either unsuited style or incorrect mask size)
  • Worn out mask
  • Dirty mask – Silicone can absorb contaminants such as oils, sweat, dirt and creams from your skin. Extended contact with these contaminants during the night may irritate the skin.

If you are experiencing skin irritation, try one of the following suggested solutions:

  • Readjust headgear straps. The mask should be as loose as possible while still creating a seal
  • Consult your mask user guide or quick-fitting guide, alternatively consult your continuous positive airway pressure (CPAP) therapist for a mask fitting. A different style of mask may provide a better fit
  • Inspect mask cushion and frame for wear, stiffness, cracks or breaks. Replace either the mask or parts that are worn out
  • Wash mask daily according to user guide instructions, diluted liquid detergent and warm water (30°C/86°F)
  • Wash face before bed (suggested – pH neutral) to remove excess facial oils
  • Avoid using facial lotions and creams where your mask comes into contact with your face, as these products may interfere with mask seal and potentially degrade the quality of the cushion over time.
  • Place some porous hypoallergenic skin tape (consult your local pharmacy) over sensitive or irritated areas to create a barrier between the skin and the mask

Nasal irritation

Constant air flow, especially at high treatment pressures, can lead to dryness, nasal irritation and nosebleeds. Humidifiers provide relief from nasal irritation and dryness by adding warmth and moisture to the air delivered by the CPAP or bilevel system. There are also nasal oil products available in most chemists and pharmacies to help treat and prevent dryness.

Note: If skin irritation problems persist then consult a doctor.

Automatic Positive Airway Pressure (APAP)

What are the advantages of ResMed AutoSetTM devices?

AutoSet devices adjust pressure on a breath-by-breath basis to suit patient needs as they change throughout the night. As a result, patients receive the minimum pressure required for effective therapy. The lower average pressures improve comfort, reduce pressure-related side effects, and lead to more consistent use of therapy.

How do AutoSet devices know to adjust pressure?

After you fall asleep and your pressure needs begin to vary, your AutoSet device responds to three separate parameters: inspiratory flow limitation, snore, and apnea. AutoSet devices act pre-emptively by increasing pressure in response to inspiratory flow limitation and snore, both of which typically precede obstructive apneas. The AutoSet device calculates the pressure you need based on the severity of the event. This early intervention prevents obstructive apneas and reduces respiratory arousals.

I am looking to purchase an APAP. Why should I choose the AutoSet device over any others?

The AutoSet algorithm has been clinically validated in numerous third-party tests and peer-reviewed journals over more than past 11 years.

How fast do AutoSet devices evaluate and respond to changes?

AutoSet devices evaluate flow limitation on a breath-by-breath basis and adjust pressure according to a five-breath average.

How do the AutoSet devices handle hypopnea events?

AutoSet devices respond to obstructive hypopnea events when they are associated with flow limitation or snoring. Hypopneas that are central in origin (related to your central nervous system, not physical obstruction) should not be treated with increased pressure.

Why do AutoSet devices work with only some masks? Why not all masks?

This is a more difficult question to answer. The short answer is that all masks have different physical characteristics and an AutoSet device needs to know the specific characteristics of a mask for best performance. AutoSet devices respond to conditions like leak, snore, and inspiratory flow limitation. To properly treat a person with obstructive sleep apnea (OSA), an AutoSet device needs to know exactly how much of the conditions it detects come from the mask. All masks have some degree of leak to ensure users get fresh air. All masks also have some degree of resistance by virtue of their materials, contours, and leak. So using a mask that is “unknown” to the AutoSet device won’t let it do its job properly.

I hear that APAPs work only for people on low to moderate pressures, is this true?

Actually, the opposite is true. According to a recent study, AutoSet technology provides the greatest benefits for people on 10 cm H2O or more.

Plastic used in CPAP equipment

Is bisphenol A used in the manufacture of ResMed CPAP Equipment and is it safe?

  • Bisphenol A is an industrial chemical used to make a hard, clear plastic known as polycarbonate.
  • Polycarbonate is used in many consumer products, including reusable water bottles and baby bottles.
  • Many of ResMed’s products include polycarbonates in which bisphenol A is a raw material.
  • ResMed is confident in the safety of its polycarbonate containing products for their intended use.
  • The use of polycarbonates in these ResMed products is approved in every country where these products are sold, including Canada. In addition, these products are not intended for use by newborns or infants.



Diagnostic Devices


Calibration RESMED Device

Maintenance RESMED Device

Rental Resmed Device

Sleep Diagnostic Test: Apnealink™

Sleep Diagnostic Test: ApneaLink™ Plus

Sleep Diagnostic Test: SOMNOscreen™ Plus

Sleep Diagnostic Test: SOMNOtouch™ RESP

SOMNOtouch™ NIBP Monitoring Test

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