CPAP FAQ: all your questions answered

CPAP FAQ: All Your Questions Answered

Are you starting CPAP therapy, or have you been using your device for a while and questions keep coming up? This page gathers the questions CPAP users ask most often, with clear and practical answers.

What CPAP pressure is right for me?

Your CPAP pressure is set by your sleep physician after a titration study carried out in a sleep centre. It is expressed in centimetres of water (cmH₂O) and typically ranges from 4 to 20 cmH₂O depending on the patient.

If you use an auto-adjusting CPAP (APAP), the device sets the pressure by itself within a prescribed range, and that is the setting recommended today for most new patients. To check that your pressure is right, look at your residual AHI in the device data: an AHI below 5 means the treatment is working. Never change the pressure yourself without medical advice.

Do I need to use distilled water in the humidifier?

Yes, distilled water is strongly recommended in the humidifier tub of your CPAP. Tap water contains limescale and minerals that build up in the tub, encourage bacterial growth and damage the equipment over time.

Distilled water is sold in pharmacies and supermarkets, usually in 1.5 litre bottles. Empty and rinse the tub every morning, and fill it with fresh water every evening. Never let water sit in the tub for several days.

How do I clean my CPAP mask and device?

Regular care is essential, both for the lifespan of the equipment and for your own hygiene.

• Every morning: wipe the mask cushion with a soft damp cloth. Empty and rinse the humidifier tub.
• Once a week: wash the complete mask (cushion, frame, headgear) in lukewarm water with a mild soap, neither antibacterial nor moisturising. Rinse thoroughly and let it air dry away from direct sunlight. Wash the tubing as well by soaking it in lukewarm soapy water, then rinse and let it dry.
• To avoid at all costs: alcohol-based products, antibacterial wipes, moisturising or antibacterial soaps, hot air dryers. They degrade the silicone of the mask. The dishwasher needs a nuance: the water tub of the HumidAir 10 and 11 is allowed in it, top rack, delicate cycle; the air tubing, never, as both ResMed manuals explicitly forbid it.

Automatic CPAP cleaning devices, using ozone or UV light, are sold online. The US FDA has authorised none of them to clean, disinfect or sterilise a CPAP, and it has received reports of asthma attacks, headaches and shortness of breath after use. The ozone concentration inside the equipment can stay above safety limits for several hours after the cycle ends, and the patient then breathes through that circuit all night; UV light, for its part, does not reach every surface of a circuit. ResMed also excludes from its warranty any damage caused by an ozone device on machines sold since 1 February 2020. Lukewarm water and mild soap remain the only method recommended by the manufacturers.

How long does a CPAP mask last?

The lifespan of a CPAP mask depends on how it is cared for and how much it is used. As a general rule:

• Silicone cushion: 1 to 3 months in practice, but it is the condition of the silicone that decides. ResMed gives no calendar interval and asks you to inspect the cushion and replace it when needed. It is the part that wears out fastest: a tired cushion no longer seals and causes leaks.
• Mask frame: 6 to 12 months
• Headgear (straps): 6 to 12 months, as it loses its elasticity
• Tubing: 12 months, or as soon as cracks appear

A mask in good condition is crucial for the treatment to work. Large leaks lower the therapeutic pressure and make CPAP much less effective.

Can I travel by plane with my CPAP?

Yes, absolutely. A CPAP is recognised as medical equipment by the vast majority of airlines. It is generally allowed in the cabin in addition to your standard hand luggage. Tell the airline when you book, and take your prescription with you.

Important points for travelling with your CPAP:

• Empty the distilled water tub before going through security, as water is not allowed in the cabin in quantities above 100 ml
• Carry your prescription or your doctor's letter in English if you travel outside Belgium
• Most modern CPAP devices run on 100-240 V, so check your adapter against your destination
• For frequent travel or hiking, consider the ResMed AirMini, the most compact travel CPAP on the market

I have a beard - which mask should I choose?

A beard is one of the main causes of CPAP mask leaks, because silicone cannot seal against hair. Several solutions exist:

• Nasal pillows mask: the pillows sit directly at the nostrils and never touch the beard. This is the best option for beard wearers. The ResMed AirFit P10 is particularly well suited.
• High nasal mask: some models with a fabric or foam skirt cope with a beard better than a classic silicone seal.
• Beard oil: to be avoided, as it degrades the silicone.
• Adapting how you wear the mask: depending on the shape of your beard (moustache only, full beard, goatee) the constraints differ. You can try several models.

How do I get used to sleeping with the mask?

Getting used to the CPAP mask is often the hardest part of the first few weeks. Here is the advice that helps most:

• Wear the mask while awake: put it on 20 to 30 minutes before lights out, with the machine running. Watch television or read. Your brain gradually associates the mask with relaxing, not with being forced to fall asleep.
• Turn the ramp on: the pressure starts very low and rises gradually while you fall asleep. Far more comfortable at bedtime.
• Adjust the straps lying down: the geometry of the face changes with position. Adjust in your usual sleeping position.
• Do not overtighten: a mask that is too tight causes more leaks, not fewer. Slide a finger under the strap; if you cannot, it is too tight.
• Keep going beyond three weeks: the vast majority of patients who persist past the third week become faithful long-term users.

My CPAP is noisy - is that normal?

Modern CPAP devices are very quiet: between 25 and 30 dB in normal operation, which is less than a fridge. If yours is louder, here are the frequent causes:

• Mask leaks: the typical whistling almost always comes from mask leaks, not from the machine. Check the fit and the condition of the cushion.
• Clogged filter: a blocked air filter increases noise and reduces efficiency. Clean or replace it regularly.
• Tubing touching the bedding: vibrations of the tube against the bed amplify the noise. A tube holder can help.
• Ageing device: after 5 to 7 years of use, the internal parts wear and the noise can increase.

Does the INAMI convention reimburse my CPAP?

The INAMI/RIZIV convention does not reimburse the purchase of a CPAP: it organises the provision of the device by an accredited sleep centre. The patient uses the device but does not own it. The cost to the patient is 0.25 € per day, roughly 7.50 € per month.

VivaRespire is an alternative to the convention: you buy and own your CPAP directly, without going through an accredited centre. You choose the model freely, there is no compliance requirement, and the device belongs to you.

For all the details on the INAMI convention: CPAP reimbursement in Belgium.

My residual AHI is still high - what should I do?

A residual AHI, meaning the AHI measured by your CPAP during treatment, above 5 deserves attention. The most frequent causes:

• Mask leaks: leaks distort the AHI measurement and reduce the therapeutic effect. Check your mask.
• Insufficient pressure: a pressure that is too low does not clear every apnoea. Contact your provider or your doctor for an adjustment.
• Sleeping position: sleeping on your back raises the AHI. Try sleeping on your side.
• Central apnoeas: some patients develop central apnoeas under CPAP, which calls for a reassessment.

If your residual AHI stays above 10 despite good usage, see your sleep physician.