title: eAMI: a qualitative quantification of periodic breathing based on amplitude of oscillations.
abstract: OBJECTIVE
  Periodic breathing is sleep disordered breathing characterized by instability in the respiratory pattern that exhibits an oscillatory behavior. Periodic breathing is associated with increased mortality, and it is observed in a variety of situations, such as acute hypoxia, chronic heart failure, and damage to respiratory centers. The standard quantification for the diagnosis of sleep related breathing disorders is the apnea-hypopnea index (AHI), which measures the proportion of apneic/ hypopneic events during polysomnography. Determining the AHI is labor-intensive and requires the simultaneous recording of airflow and oxygen saturation. In this paper, we propose an automated, simple, and novel methodology for the detection and qualification of periodic breathing: the estimated amplitude modulation index (eAMI).
  
  
  METHODS
  Antarctic Cohort (3800 meters): 13 normal individuals. Sleep Clinic Cohort: 39 different patients suffering from diverse sleep-related pathologies.
  
  
  RESULTS
  When tested in a population with high levels of periodic breathing (Antarctic Cohort), eAMI was closely correlated with AHI (r = 0.95, P < 0.001). When tested in the clinical setting, the proposed method was able to detect portions of the signal in which subclinical periodic breathing was validated by an expert (n = 93; accuracy = 0.85). Average eAMI was also correlated with the loop gain for the combined clinical and Antarctica cohorts (r = 0.58, P < 0.001).
  
  
  CONCLUSIONS
  In terms of quantification and temporal resolution, the eAMI is able to estimate the strength of periodic breathing and the underlying loop gain at any given time within a record. The impaired prognosis associated with periodic breathing makes its automated detection and early diagnosis of clinical relevance.
authors.affiliation: Vrije Universiteit Brussel, Human Physiology & Sportsmedicine Department, Brussels, Belgium.|Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium.
authors.forename: Helio Fernandez
authors.initials: HF
authors.lastname: Tellez
authors.affiliation: Vrije Universiteit Brussel, Human Physiology & Sportsmedicine Department, Brussels, Belgium.|Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium.|Vrije Universiteit Brussels, Biological Psychology Department, Brussels, Belgium.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Pattyn
authors.affiliation: Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium.|Vrije Universiteit Brussels, Biological Psychology Department, Brussels, Belgium.|Sleep Laboratory & Unit for Chronobiology - Brugmann University Hospital Free University of Brussels, Brussels, Belgium.
authors.forename: Olivier
authors.initials: O
authors.lastname: Mairesse
authors.affiliation: Clinical Institute of Clinical Neurophysiology, University Clinical Centre, Ljubljana, Slovenia.
authors.forename: Leja
authors.initials: L
authors.lastname: Dolenc-Groselj
authors.affiliation: Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden.
authors.forename: Ola
authors.initials: O
authors.lastname: Eiken
authors.affiliation: Deptartment of Automation, Biocybernetics, and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.
authors.forename: Igor B
authors.initials: IB
authors.lastname: Mekjavic
authors.affiliation: Université Libre de Bruxelles, Erasmus Hospital, Brussels, Belgium.
authors.forename: P F
authors.initials: PF
authors.lastname: Migeotte
authors.affiliation: The Princess Alexandra Hospital NHS Trust, Harlow, UK.|Institut polaire français Paul-Emile Victor, France.
authors.forename: Em
authors.initials: E
authors.lastname: Macdonald-Nethercott
authors.affiliation: Vrije Universiteit Brussel, Human Physiology & Sportsmedicine Department, Brussels, Belgium.
authors.forename: Romain
authors.initials: R
authors.lastname: Meeusen
authors.affiliation: Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium.|CISS Department, Royal Military Academy of Brussels, Brussels, Belgium.
authors.forename: Xavier
authors.initials: X
authors.lastname: Neyt
mesh_terms: D000328:Adult; D000864:Antarctic Regions; D001331:Automation; D062485:Breath Holding; D015331:Cohort Studies; D042241:Early Diagnosis; D006801:Humans; D008297:Male; D010507:Periodicity; D017286:Polysomnography; D011379:Prognosis; D015203:Reproducibility of Results; D012119:Respiration; D012891:Sleep Apnea Syndromes / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D012893:Sleep Wake Disorders / Q000150:complications
keywords: Cheyne-Stokes respiration; loop gain; modulating index; periodic breathing; quantification