Unfortunately, electronic monitoring of CPAP adherence was not performed. We would have liked to monitor the time spent at the prescribed CPAP level, but this was not available on all CPAP units that were used in the study. Although the units did have a chronometer, we were unable to find a reliable way to record hours of use on each CPAP unit as patients frequently forgot to read the time meter on their unit or neglected to bring their CPAP units to their follow-up visits; we did not have the resources to perform home visits. Ultimately, we believed that the best measurement of CPAP adherence that was available on all patients was to use self-reporting, acknowledging the limitations of that measurement. If there was a systematic error in this measurement, we anticipate that it applied equally to all patient groups.

Heated humidification plays an important role in CPAP therapy, and it is particularly important in patients who are using the Oracle mask. Although heated humidification was not standardized across groups in terms of the level of humidity that was set, the vast majority of patients in all groups did use heated humidification. This study was not designed to address the efficacy of humidification in different CPAP masks. In fact, we were concerned that using the same level of humidification in all patients would confound the interpretation of our results. We know from previous experience that oral masks require a higher level of humidification than nasal masks; consequently, limiting the level of humidification to patients who chose the Oracle mask could have biased our results by increasing the level of discomfort due to suboptimal humidification alone.

Similarly, excessive humidification may have produced rain-out in some patients (regardless of the mask they chose), which could have limited their use of CPAP for reasons not specifically related to the mask they chose. We wanted to assess the efficacy of different masks assuming that comfort was optimized by all conventional means including adequate humidification. We also feel this provides a more accurate reflection of patients’ experience in everyday practice, and consequently patients were given the opportunity to titrate their level of humidification to optimize comfort buy kamagra online.