Long term performance evaluation of an automatic airway positive pressure device

Long term studies of automatic continuous positive airway pressure (auto CPAP or APAP) device is presented. An APAP device is designed to eliminate OSA events automatically. It detects the pharyngeal wall vibration (PWV) signal and uses it as a feedback signal to adjust airway pressure. Two positively diagnosed obstructive sleep apnea patients participated in this study. A computer-based data acquisition system was used to collect the APAP pressure signal during the sleeping hours. Pressure trends for 182 nights for the first patient and 260 nights for the second patient were obtained. Both patients reported satisfaction with the APAP therapy. The pressure trends obtained from these two subjects revealed that the pressure level required for eliminating PWV changes thoughout the night and from night to night as well as the mean APAP pressure level was significant lower than the CPAP prescribed pressure (1st subject: 3.2 cm H₂O of mean APAP pressure vs. 7 cm H₂O of CPAP prescribed pressure; 2nd subject: 3.7 cm H₂O of mean APAP pressure vs. 15 cm H₂O of CPAP prescribed pressure). Therefore, adjusting the blower pressure automatically based on PWV signal detection may provide comparable treatment to that of a conventional CPAP device with lower airway pressure