Non-contact monitoring of respiratory rate including sleep apnea using millimeter wave radar.

Respiratory rate (RR) is a critical vital sign, but it is affected by metabolic and behavior controls while awake. In addition, the prevalence of sleep apnea (SA) is high. Therefore, a non-contact respiratory monitor that can measure RR and SA is desired. A millimeter wave radar (MWR) was used for RR monitoring of persons with suspected SA in several positions while awake in addition to detecting the apnea hypopnea index (AHI). AHI by polysomnography (PSG) was compared with a 1-hour respiratory event (REI) determined by MWR, portable monitor (PM) and 3% oxygen desaturation index (ODI). From data on the first 30 participants, we made algorithms to measure RR and AHI by MWR and validated them in the next 30. While awake, the correlations in each position between RR by MWR and PSG were very high (0.92~0.99) (n=60). Non, mild, moderate and severe SA were identified in 7, 8, 6, and 9 test group participants and 8, 9, 6, and 7 validation participants, respectively. The Bland-Altman plot of REI by MWR revealed a low percentage of data points outside of the 95%CI as well as compared with PM and ODI (Figure 1). Mean AHI, ODI, REI by PM or MWR were 31.5 {quartile points：5.3-26.2}, 25.8 [4.3-21.5], 30.2 [6.9-23.3] and 25.9 [8.0-17.9], respectively. A non-contact MWR monitoring device can be useful during wakefulness and sleep and to detect apnea and hypopnea. This monitoring system could be used in multiple medical settings. <fig><object-id>erj;64/suppl_68/PA1751/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>