Comparison Study between Micro Wave Radar and Conventional SpO₂ Measurement for Primary Screening of Sleep Apnea Syndrome

Abstract

It is particularly important to detect early stage Sleep Apnea Syndrome(SAS) in patients. Conventional screening method for SAS measures peripheral oxygen saturation (SpO₂) using pulse oximeter. The SpO₂ sensor needs to be attached to a fingertip and the main unit is mounted to the wrist. We have developed a non-contact Doppler radar respirometry method, where our Doppler radars are located beneath the bed mattress and are not burdensome to the subjects. In order to evaluate the effectiveness of the Doppler radar respirometry, we have conducted clinical test to make a comparison between the proposed non-contact method and conventional SpO₂ sensor. The twenty subjects were suspected to have SAS( male 17, female 3, age 40 to 60, average 54.6 ± 5.3 years old). We tested whether if we can determine SpO₂ reduction less than 90% using the radar respirometry method. The proposed method detected 308 SpO₂ reductions out of 358 events which is about 86%. Our method appears promising. However, the radar measurement sometimes detected 4 or 5 times many events than SpO₂ measurement. Authors are continuing the studies to find the reason why radar detects so many events using Polysomnography (PSG) simultaneously.