A NONINVASIVE TECHNIQUE FOR DETECTING OBSTRUCTIVE AND CENTRAL SLEEP-APNEA

A new noninvasive method to detect obstructive and central sleep apnea [(OSA) and (CSA)] events is described. Data were collected from ten v olunteer subjects with a previous diagnosis of OSA while they were tit rated for continuous positive airway pressure (CPAP) therapy. Apneic e vents were identify by analyzing of estimated airway impedance determi ned from pressure and airflow signals delivered from CPAP. To enhance performance of this technique, a single-frequency (5 Hz with 0.5 cmH(2 )O peak-to-peak amplitude) probing signal was superimposed on the appl ied CPAP pressure. The results indicated that estimated airway impedan ce during OSA (mean: 17.9, SD: 3.4, N = 50) was significantly higher t hen during CSA (mean: 4.1, SD: 1.7, N = 50). When the estimated impeda nce of OSA and CSA events were compared to a fixed threshold, 100% of all events can be correctly categorized. These results indicate that i t may be possible to diagnose OSA and CSA noninvasively based upon thi s technique. The instrument and the algorithm required are relatively simple and can be incorporated in a home-based device. If this method was used for prescreening apnea patients, it could reduce cost, waitin g time, and discomfort associated with traditional diagnostic procedur es.