The measurement of impedance permits reliable detection of obstructive apneas, hypopneas and upper airways resistance syndrome.

To establish whether impedance-controlled self-adjusting positive airway pressure therapy (APAP_FOT) is equally as good as constant continuous positive airway pressure (CPAP) in the treatment of sleep apnea syndrome (OSAS).

Twenty men and five women with OSAS (age 52.8±9.0 years, body mass index (BMI) 31.4±5.0 kg/m², AHI 32.2±18.1/h (mean±SD)) underwent baseline polysomnography, manual CPAP titration and two nights of treatment, one with APAP_FOT, one with constant CPAP.

With both modes, a significant reduction in respiratory disturbances was seen (apnea/hypopnea index (AHI) baseline 32.2±18.1/h, constant CPAP 6.6±8.7, APAP_FOT 5.5±3.8/h, P<0.001 baseline vs. each treatment mode). Under APAP_FOT, the sleep profile was normalized (S3/4 baseline 16.3±13.9% total sleep time (TST), APAP_FOT 21.6±10.9% TST, P<0.05, rapid eye movement (REM) 14.2±6.7% TST vs. 20.3±7.3% TST, P<0.01), while with constant CPAP, a tendency towards improvement was found. The mean treatment pressure with APAP_FOT was significantly lower than the constant CPAP (5.7±2.1 vs. 8.3±1.6 mbar, P<0.001).

We conclude that APAP_FOT is at least as effective as constant CPAP in normalizing sleep and breathing in OSAS.