Investigating the stationarity of paediatric aspiration signals.
An aspiration signal is the time-varying anterior-posterior acceleration measured infero-anterior to the thyroid notch when foreign material enters the airway during inspiration. The hypothesis of weak stationarity is tested on aspiration signals by the reverse arrangements test. Results indicate that aspiration signals cannot be uniformly regarded as weakly stationary. Forty-five percent of the examined signals violated the stationarity hypothesis. For these signals, time-varying variance and spectral density structure are identified as major sources of nonstationarity. Stationarity test results generally corroborate qualitative clinical descriptions of aspiration. However, stationarity analysis indicates that aspiration signals are highly heterogenous, a finding which poses significant challenges to the automatic detection of aspirations by accelerometry.
Chau
Tom
T
Bloorview MacMillan Children's Centre and the Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M4G 1R8, Canada. ttkchau@ieee.org
Chau
Doug
D
Casas
Michael
M
Berall
Glenn
G
Kenny
David J
DJ
D000054:Acceleration; D000465:Algorithms; D002648:Child; D003680:Deglutition Disorders / Q000175:diagnosis* / Q000503:physiopathology*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005260:Female; D006801:Humans; D001239:Inhalation; D008297:Male; D010808:Physical Examination / Q000379:methods*; D013223:Statistics as Topic; D013269:Stochastic Processes