Classification of breathing events using load cells under the bed

Abstract

Sleep disturbances are prevalent, financially taxing, and have a negative effect on health and quality of life. One of the most common sleep disturbances is obstructive sleep apnea-hypopnea syndrome (OSAHS) which frequently goes undiagnosed. The gold standard for diagnosing OSAHS is polysomnography (PSG)-a procedure that is inconvenient, time-consuming, and interferes with normal sleep patterns. We are investigating an alternative to PSG in which unobtrusive load cells fitted under the bed are used to monitor movement, heart rate, and respiration. In this paper we describe how load cell data can be used to distinguish between clinically relevant disordered breathing (apneas and hypopneas) and normal respiration. The method correctly classified disordered breathing segments with a sensitivity of 0.77 and a specificity of 0.91.

Fig. 1

Patient data from three different 30 second epochs during the sleep study. The left column depicts an epoch of normal breathing, the middle column depicts a central apnea, and the right column depicts a hypopnea. The upper row contains decimated data from the load cell placed under the upper middle support of the bed. The middle row contains filtered load cell data from the same sensor. The bottom row contains data from the PSG respiratory inductive plethysmography abdomen belt during the 30 second epoch. The vertical line indicates the time point where the respective respiratory event was scored by an OHSU sleep lab technician.