Title: Phase tracking of the breathing cycle in sleeping subjects by frequency analysis of acoustic data

Authors: Hisham Alshaer, Geoffrey R. Fernie, T. Douglas Bradley

Addresses: Toronto Rehabilitation Institute Sleep Research Laboratory, Institute of Biomaterials and Biomedical Engineering, University of Toronto, 550 University Avenue, Toronto, ON, M5G 2A2, Canada. ' Toronto Rehabilitation Institute, 12029, 550 University Avenue, Toronto, ON, M5G 2A2, Canada. ' Toronto Rehabilitation Institute Sleep Research Laboratory, Toronto General Hospital/UHN, 9N-943, 200 Elizabeth St., Toronto, ON, M5G 2C4, Canada

Abstract: We tested the hypothesis that the inspiratory and expiratory phases of breathing could be identified from breath sound recordings during sleep. Breath sounds were digitally recorded from 10 subjects during sleep. Frequency spectra of inspiration and expiration were determined. The ratio of frequency magnitude bins between 400-1000 Hz to frequency bins between 10-400 Hz was calculated for inspiration (Ri) and expiration (Re) for each breath. The Ri/Re ratio was significantly greater than the thresholds of 1.5 (p < 0.001) and 2-fold (p < 0.001). Breathing phases were correctly identified in 90% and 73% of cases using the 1.5 and 2.0 thresholds, respectively.

Keywords: breath sounds; respiratory monitoring; sleep; healthcare technology; phase tracking; breathing cycle; sleeping subjects; frequency analysis; acoustic data.

DOI: 10.1504/IJHTM.2010.034087

International Journal of Healthcare Technology and Management, 2010 Vol.11 No.3, pp.163 - 175

Available online: 12 Jul 2010 *

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