Ambulatory detection of sleep apnea using a non-contact biomotion sensor

The high prevalence of obstructive sleep apnea has led to increasing interest in ambulatory diagnosis. The SleepMinder (TM) (SM) is a novel non-contact device that employs radiofrequency wave technology to assess the breathing pattern, and thereby estimate obstructive sleep apnea severity. We assessed the performance of SleepMinder (TM) in the home diagnosis of obstructive sleep apnea. One-hundred and twenty-two subjects were prospectively recruited in two protocols, one from an unselected sleep clinic cohort (n = 67, mean age 51 years) and a second from a hypertension clinic cohort (n = 55, mean age 58 years). All underwent 7 consecutive nights of home monitoring (SMHOME) with the SleepMinder (TM) as well as inpatient-attended polysomnography in the sleep clinic cohort or cardiorespiratory polygraphy in the hypertension clinic cohort with simultaneous SleepMinder (TM) recordings (SMLAB). In the sleep clinic cohort, median SMHOME apnea-hypopnea index correlated significantly with polysomnography apnea-hypopnea index (r = .68; p < .001), and in the hypertension clinic cohort with polygraphy apnea-hypopnea index (r = .7; p < .001). The median SMHOME performance against polysomnography in the sleep clinic cohort showed a sensitivity and specificity of 72% and 94% for apnea-hypopnea index >= 15. Device performance was inferior in females. In the hypertension clinic cohort, SMHOME showed a 50% sensitivity and 72% specificity for apnea-hypopnea index >= 15. SleepMinder (TM) classified 92% of cases correctly or within one severity class of the polygraphy classification. Night-to-night variability in home testing was relatively high, especially at lower apnea-hypopnea index levels. We conclude that the SleepMinder (TM) device provides a useful ambulatory screening tool, especially in a population suspected of obstructive sleep apnea, and is most accurate in moderate-severe obstructive sleep apnea.