[Optimising CPAP accommodation time by feedback-supported training phases in patients with obstructive sleep apnea...

Mask fitting and accommodation of CPAP-devices are of great importance. Only by accommodation over several hours, problems concerning mask size and fixation of mask are recognised and solved. Many patients overestimate the time they needed for achieving accommodation. We therefore asked whether by visualizing the time required for accommodation the accommodation time can be prolonged. Additionally we compared the subjective estimation on the time with the objectively measured time. We studied 20 patients with sleep apnoea syndrome, 13 men and 7 women, age 53 +/- 4 years, apnoea/hypopnoea index 32 +/- 16, lowest O2 saturation 83 +/- 6%. In a randomized cross-over study, a clock with a large 7 segment-display was either not visible in one setting, so that the patient had no control of the training-time, or the time was visible on the display. Thus the patient could possibly be motivated to increase his time of CPAP-accommodation during the day. The pressure-controlled clock counted only the time during which the pressure was above 4 HPa. In the setting with visible time-counter the accommodation time was 265.8 +/- 114 min, if the counter was not visible, time was only 210.8 +/- 91 min. If the patient cannot observe the time-counter he over-estimates the objectively measured time by half an hour (247.2 +/- 97.5 estimated vs. 210.8 +/- 91.0 actually). Thus the self-control of CPAP-accommodation by a visible clock leads to a significant prolongation of the exercise time. The estimation by the patient is only a limited means to evaluate the time of CPAP accommodation during the day.