Sleep - Humidification for CPAP and Bi-Level Machines

Disclaimer: This fact sheet is for education purposes only. Please consult with your doctor or other health professional to make sure this information is right for your child.

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When we breathe through our nose or mouth, the air is warmed and moistened by the lining of our nose and mouth.  When children use a CPAP or Bi-level machine, the air enters their nose quickly and this does not allow time for it to be warmed or to collect moisture. 

Why use humidification?

The main purpose of humidification is to stop drying of the nasal and airway lining. Humidification may help improve comfort by keeping the airways moist, and by doing so, your child should be able to tolerate the machine more often. Humidification can benefit children who have dry mucus membranes or nose bleeds. Humidification must always be used when CPAP or Bi-level is delivered via tracheostomy.


The humidifier chamber is either inside the machine or added as an external device. This varies depending on the type of machine your child has. Distilled water (supplied by chemists) is the best water to use in the chambers and must be used for children with a tracheostomy. Boiled and cooled tap water can be used for children who use CPAP/Bi-level via a mask, if distilled water is unavailable. When filled, the water level must be below the marker for the maximum level on the chamber.

The chamber should sit next to the bed and be at a level lower than your child to stop water flowing through the tube to your child. Check the level of water in the chamber each time before you turn the machine on. Top up the chamber as needed to the marker. 


Some humidifiers have a range of settings. A low setting should be used when the room air is warm and moist and a higher setting can be used in cold, dry air. Most often the humidifier is set at level ‘2’. If too much water collects in the tube, try turning the humidification setting down. If you are unable to do this, please contact the Sleep Medicine Service on the number below.

Care and maintenance

The water in the chamber must be changed every day. The water chamber should be cleaned with warm soapy water once a week and rinsed thoroughly before refilling with fresh water.

Moving the machine and humidifier

The humidifier must be emptied before moving the CPAP or Bi-level machine, because movement can cause water to spill from the chamber back into the machine where it destroys electrical circuits. If you think this has happened turn the machine off immediately and contact the Sleep Medicine Service for advice.

Trouble shooting

If water builds up in the tubing, the machine should be stopped. Remove the mask from your child and the other end of the tubing from the machine and tip the extra water out. If there is a filter on the tubing, check carefully to make sure the filter is not wet. Replace if needed. Contact the Sleep Medicine Service or manufacturer if problems continue.


Sleep Medicine Scientific Officers                    (02) 9845 1851 / 9845 2107                                                                                     

Sleep Medicine Clinical Nurse Consultant        (02) 9845 2572                                                                                               

Sleep Medicine Clinical Nurse Specialist          (02) 9845 0230                                                                         

Biomedical Engineering Department                (02) 9845 2602

Acknowledgement for images                  

Philips Home Healthcare - customer care number          1300 766 488

ResMed                                                1800 658 189

The Children's Hospital at Westmead

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