Heart Rate and Breathing Rate Calculated from Cheeks and Lips Using Green and Derived Colors from Video

Abstract

There has been considerable interest in the development of non-contact measurement of heart rate (HR) and breathing rate (BR). Some researchers have focused the heart rate (HR) and breathing rate (BR) measurement on the cheek region extracted from the face. The physiological rationale behind selecting the face and facial parts such as cheeks rely on the concept of photoplethysmography (PPG), which is the absorption of light by blood cells. A PPG signal contains information about HR and BR. Several studies have used PPG from the cheek portion extracted from the videos as many capillaries lie underneath the cheeks. Lips also carry a rich bed of blood vessels underneath. Because of the difference in innervation of the lips from the cheeks, there is the possibility that non-contact measurement from the lips may also contain information about subtle changes in autonomic function. Therefore, we explored whether lips might contain information about HR and BR comparable or better than cheeks in measuring HR and BR. Towards this goal data were collected from 5 subjects. Our results showed that while measurements from lips generally were comparable to those from cheeks, for wider use, lips may not be a viable location to calculate non-contact HR and BR due to possible confounding factors.