CPAP mask fitting

Mrs Susan P Bradbury, Senior Chief Medical Technical Officer, North Staffordshire Hospital lets us into the finer points of mask fitting that she shares regularly with other professionals who attend courses on sleep study at North Staffordshire Hospital.

The most important factor in complying with CPAP therapy following correct pressure setting is ensuring that there is no mask discomfort. If the mask is uncomfortable inevitably CPAP usage will fall or stop completely, rendering treatment ineffective. There is a huge range of masks and headgear available in a variety of sizes. You do not have to use the mask which is supplied with a particular machine or the headgear which is made for that mask. Many types of headgear are interchangeable or with a little adaptation can be made to fit different masks.

The most comfortable headgear has in my experience been the cap style which is produced by Respironics, Sullivan, Tiara Medical, or the four-strap headgear from DeVilbiss. The mask does not move during the night causing leaks if a four or five-strap placement is used. If sweating under the cap is a problem, the Sullivan Rescap, Cool Cap from Tiara Medical, or strap headgear from DeVilbiss will often alleviate this problem.

The choice and fitting of the mask needs time and patience. If after a 20 minute trial there are obvious pressure marks on the face, change to a different make of mask and try again for 20 minutes. Check that there are no leaks into the eyes or above the upper lip. With Respironics type masks, spacers will often help if a pressure area on the nose occurs. Always choose a spacer which feels slightly too big as they compress quite quickly and then lose their effectiveness. Thin foam ribbon (used on wards to secure catheter bags) if wrapped around the mask frame to the required thickness to ensure comfort, is often more effective than spacers. This is fastened with Velcro supplied with the foam. If pressure areas, sweating under the mask, or a minor leak around the eyes cause problems, self adhesive towelling strips used for tennis racquet handgrips is amazingly effective. Three strips need to be cut, one for either side of the mask and one for the bottom (see diagram 1). The sticky paper backing is removed and the towelling is applied to the area of the mask in contact with the face. The towelling can be secured more permanently by sticking Micropore around the outside edge.

Diagram 1 – Towelling strips applied to mask

The Sullivan bubble masks, especially the type with the firm inner and outside bubble, can be particularly useful if leaks around the eyes are a problem.

Some people have problems with a feeling of claustrophobia when a nasal mask is used. Nasal pillows can often remedy this problem. I’ve personally had more success with those produced by Nellcor Puritan Bennett. (See diagram 2).

Diagram 2 – nasal pillows / Adams circuit

During CPAP titration the sleep technician will normally pick up the problem of leaks via the mouth due to the mouth falling open during the night. This can also occur a few months after issue and the user will complain of a return of daytime symptoms and waking with a dry mouth. A chin strap will often cure this problem. If this is unsuccessful then a full face mask or nose and face mask will need to be tried. I have also had success using the long narrow Respironics nasal mask as a full face mask in patients with small or medium small noses.

The new silicone gel masks have gone some way to help with severe leakage and discomfort. Problems have been encountered with spreading and occasional leakage of the silicone gel.

Sometimes despite trying all types of masks, problems cannot be overcome. These tend to be leakage into the eyes, pressure sores on the nose, or leakage above the top lip and cheeks. We have developed custom collars which in most cases have solved all of these problems.

Brief details of custom collar construction are as follows:

1. Choose a standard CPAP mask that is slightly too large.
2. If an upper denture is worn at night remove before moulding collar
3. Mix the silicone as per instructions, use approximately 3 scoops, and mix for 40 seconds. Make into a ball, flatten to a disk approximately 15 mm thick, and then make into polo shape
4. Mould to a triangular shape and place onto the face as shown in diagram 3 with enough pressure to mould the silicone to the face but not enough to squash through the silicone (preferred thickness approximately 4 mm). Fit the mask to the patient making sure the mask is vertical in all planes
5. Remove the mask and collar from the face when set (about 3-4 minutes) and leave for a further 5 minutes
6. Remove the collar from the mask and trim away any excess with scalpel (e.g., corners of eyes and base of the nose). Edges can be smoothed using soft-lining stones
7. Before gluing the collar to the mask, perform a working test – if everything is satisfactory de-grease the collar and mask surfaces using acetone and glue together with superglue
8. Less pressure is usually needed with the headgear to hold the mask securely on to the face without leaks
9. This type of custom collar construction is not possible on bubble masks. I have been extremely lucky in the production of custom collars having a husband who works in the maxillo-facial department. He developed the method of making the collars described above and is available to make the custom collars for CPAP users attending this department.

Diagram 3 – mould the silicone to the face

The final problem which can easily be overcome is if the Respironics type mask is lifting and causing air leakage between the nose and the upper lip, when movement occurs. Replacement of the straight connection between the mask and CPAP hose with a flexible bubble connector will give the required flexibility without lifting the mask.

Many simple problems with CPAP masks are easily overcome and users themselves often develop ways of dealing with problems. One user reported using small sections of pipe lagging around the CPAP hose, which enabled flexibility to be maintained, but this overcame the problem of cold air affecting his nasal passages and disturbing his sleep. I am sure many users have useful tips which would benefit others. We would be pleased to hear ways in which you have adapted your mask or headgear to ensure comfort.