A sleep laboratory evaluation of an automatic positive airway pressure system for treatment of obstructive sleep apnea

Study Objectives: This paper compares the performance of an experimental nasal positive airway pressure device that automatically adjusts the level of applied pressure (APAP) with the performance of a conventional continuous positive airway pressure (CPAP) in a sleep laboratory study. Design: In a randomized sequence, conventional CPAP therapy was applied for I night (CPAP night) and APAP therapy the following night (APAP night). Setting: The study was conducted in an accredited sleep disorders center. Patients or Participants: Twenty-six men and 5 women between the ages of 35 to 73 (51+/-9.6) years with body mass index 35.82+/-8.35 (kg/m(2)) who were diagnosed (using standard nocturnal polysomnography [NPSG] methods) as having OSA syndrome were studied. The subjects were treated with conventional CPAP for approximately 8 (7.79+/-3.16) weeks at home prior to their participation in this study. Measurements and Results: All standard polysomnography data and nasal mask pressures were recorded using a computer-based data acquisition system. Sleep and respiratory data were scored by a registered polysomnographer. The mean apnea-hypopnea index (AHI) for subjects for the NPSG night was 55.2+/-33.7. It dropped to 4.2+/-3.8 for the CPAP night and to 5.4+/-5.4 for the APAP night. There was no significant (p=0.05) difference between mean AHI indices, sleep stages, sleep stage shifts, and snore arousals for CPAP night and APAP night. However, all the measures showed significant (p=0.05) improvement over NPSG night. The mean of APAP applied pressure (8.4+/-3.3 cm H2O) was significantly (p=0.05) lower than the prescribed pressure (11.5+/-3.1 cm H2O), but there was no significant (p=0.05) difference between the maximum APAP applied pressure (12.8+/-4.3 cm H2O) and the prescribed pressure (11.5+/-3.1 cm H2O). All mean comparison tests were carried out using two-tailed statistics. Conclusions: APAP appears to be as effective as CPAP in treating OSA patients. APAP delivers the same level of therapy as CPAP, but it reduces the average airway pressure while providing needed peak pressures.