Noncontact Monitoring Breathing Pattern, Exhalation Flow Rate and Pulse Transit Time

• Published in: IEEE transactions on biomedical engineering Vol. 61; no. 11; pp. 2760 - 2767
• Main Authors: Shao, Dangdang, Yang, Yuting, Liu, Chenbin, Tsow, Francis, Yu, Hui, Tao, Nongjian
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.11.2014; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adult; Algorithms; Biomedical monitoring; Cameras; Exhalation - physiology; Female; Flow rates; Frequency measurement; Heart beat; Heart rate; Heart Rate - physiology; Humans; Living conditions; Male; Mobile health; Monitoring, Physiologic - methods; Noise; photoplethysmography (PPG); Photoplethysmography - methods; physiological signal detection; Physiology; pulse transit time (PTT); Pulse Wave Analysis - methods; remote sensing; Remote Sensing Technology - methods; respiration; Signal Processing, Computer-Assisted; Telemedicine - methods; Young Adult; photoplethysmography (PPG); pulse transit time (PTT); remote sensing; respiration; Mobile health; physiological signal detection
• ISSN: 0018-9294; 1558-2531; 1558-2531
• DOI: 10.1109/TBME.2014.2327024

We present optical imaging-based methods to measure vital physiological signals, including breathing frequency (BF), exhalation flow rate, heart rate (HR), and pulse transit time (PTT). The breathing pattern tracking was based on the detection of body movement associated with breathing using a differential signal processing approach. A motion-tracking algorithm was implemented to correct random body movements that were unrelated to breathing. The heartbeat pattern was obtained from the color change in selected region of interest (ROI) near the subject's mouth, and the PTT was determined by analyzing pulse patterns at different body parts of the subject. The measured BF, exhaled volume flow rate and HR are consistent with those measured simultaneously with reference technologies (r = 0.98, p <; 0.001 for HR; r = 0.93, p <; 0.001 for breathing rate), and the measured PTT difference (30-40 ms between mouth and palm) is comparable to the results obtained with other techniques in the literature. The imaging-based methods are suitable for tracking vital physiological parameters under free-living condition and this is the first demonstration of using noncontact method to obtain PTT difference and exhalation flow rate.