In the July edition of the Sleep Journal is an article about using different types of CPAP masks during CPAP calibration studies. Currently most patients with suspected obstructive sleep apnea (OSA) have the diagnosis confirmed by a sleep study. If that patient will be using CPAP for treatment, than usually the patient spends a second night in the sleep lab to have the CPAP calibrated (or titrated) to the optimal settings while the patient is asleep. During this titration study, the mask(s) used can make a big difference. But, as the study authors point out, there are few studies done to help sleep technologists decide which type of mask to use on the titration study - over the nose (nasal) or over the nose and mouth (FFM) mask.
In this study, researchers randomly assigned 24 patients with OSA to two separate titration nights - one with the nasal mask and the other with the FFM. For the nasal mask titrations, the researchers had the patient wear a chin strap to keep the patient's mouth from opening which would prevent mouth leak. These patients were titrated using "smart" CPAP machines in the lab, which are capable of finding the optimal pressure settings automatically. In other words, these patients' CPAP's were not calibrated manually, as is the standard. This was on purpose to minimize human variability. The final pressure determination though was chosen by a sleep physician after they reviewed the titration study.
The results showed that the optimal pressure chosen by the sleep physician was no different for the nasal vs the FFM. Also, the automatic CPAP chose similar pressures whether it was a nasal or FFM. Fifty-four percent of patients had pressure differences that were less than 2 cm whereas 46% had pressure differences of 2 cm or greater between the two mask types.
Patients also rated nasal masks as better fitting and more comfortable than FFM, which has been my clinical experience. Perceived sleep quality was not different for the nasal mask vs FFM. Titrations done with the FFM, compared to the nasal mask, did have increased mask leak, more mouth dryness, increased residual respiratory disturbance and arousal indexes, decreased slow wave sleep, and decreased total amount of total sleep time on the titration night.
The results of this study support using nasal masks rather than FFM for titration studies. This has been my experience as well. Sometimes, sleep technologists have to use a FFM because the patient has persistent mouth leak on a nasal mask, even with the chin strap. Using the best type of mask may improve CPAP compliance as patients early experiences with CPAP tend to predict long-term usage.