title: Time-varying signal analysis to detect high-altitude periodic breathing in climbers ascending to extreme altitude.
abstract: This work investigates the performance of cardiorespiratory analysis detecting periodic breathing (PB) in chest wall recordings in mountaineers climbing to extreme altitude. The breathing patterns of 34 mountaineers were monitored unobtrusively by inductance plethysmography, ECG and pulse oximetry using a portable recorder during climbs at altitudes between 4497 and 7546 m on Mt. Muztagh Ata. The minute ventilation (VE) and heart rate (HR) signals were studied, to identify visually scored PB, applying time-varying spectral, coherence and entropy analysis. In 411 climbing periods, 30-120 min in duration, high values of mean power (MP(VE)) and slope (MSlope(VE)) of the modulation frequency band of VE, accurately identified PB, with an area under the ROC curve of 88 and 89%, respectively. Prolonged stay at altitude was associated with an increase in PB. During PB episodes, higher peak power of ventilatory (MP(VE)) and cardiac (MP(LF)(HR) ) oscillations and cardiorespiratory coherence (MP(LF)(Coher)), but reduced ventilation entropy (SampEn(VE)), was observed. Therefore, the characterization of cardiorespiratory dynamics by the analysis of VE and HR signals accurately identifies PB and effects of altitude acclimatization, providing promising tools for investigating physiologic effects of environmental exposures and diseases.
authors.affiliation: Biomedical Signal Processing and Interpretation (BIOSPIN) Group, Department of ESAII, Institut de Bioenginyeria de Catalunya (IBEC) and CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Universitat Politècnica de Catalunya (UPC), C/Baldiri Reixac, 4, 08028, Barcelona, Spain, ainara.garde@upc.edu.
authors.forename: A
authors.initials: A
authors.lastname: Garde
authors.forename: B F
authors.initials: BF
authors.lastname: Giraldo
authors.forename: R
authors.initials: R
authors.lastname: Jané
authors.forename: T D
authors.initials: TD
authors.lastname: Latshang
authors.forename: A J
authors.initials: AJ
authors.lastname: Turk
authors.forename: T
authors.initials: T
authors.lastname: Hess
authors.forename: M M
authors.initials: MM
authors.lastname: Bosch
authors.forename: D
authors.initials: D
authors.lastname: Barthelmes
authors.forename: T M
authors.initials: TM
authors.lastname: Merz
authors.forename: J Pichler
authors.initials: JP
authors.lastname: Hefti
authors.forename: O D
authors.initials: OD
authors.lastname: Schoch
authors.forename: K E
authors.initials: KE
authors.lastname: Bloch
mesh_terms: D000328:Adult; D000368:Aged; D000531:Altitude; D015716:Electrocardiography, Ambulatory; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D009051:Mountaineering; D010092:Oximetry; D010991:Plethysmography; D012372:ROC Curve; D056152:Respiratory Rate / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted
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