title: Robust detection of sleep apnea from Holter ECGs. Joint assessment of modulations in QRS amplitude and respiratory myogram interference.
abstract: BACKGROUND
  This article is part of the Focus Theme of Methods of Information in Medicine on "Biosignal Interpretation: Advanced Methods for Studying Cardiovascular and Respiratory Systems".
  
  
  OBJECTIVE
  Detect presence of sleep-related breathing disorders (SRBD) in epochs of 1 min by signal analysis of Holter ECG recordings.
  
  
  METHODS
  In 121 patients, 140 synchronized polysomnograms (PSGs) and 8-channel Holter ECGs were recorded. The only excluded condition was persistent arrhythmias. Respiratory events as scored from the PSGs were mapped to a 1 min grid and served as reference for ECG-based detection. Moreover, 69/70 recordings of the Physionet Sleep Apnea ECG Database (PADB) were included. We performed receiver operating characteristics analysis of a single, novel time-domain feature, the joint local similarity index (jLSI). Based on cross-correlation, the jLSI quantifies the time-locked occurrence of characteristic low-frequency (LF) modulations in ECG respiratory myogram interference (RMI), QRS amplitude (QRSA) and heart rate.
  
  
  RESULTS
  Joint oscillations in QRSA, RMI and the envelope of RMI identified positive epochs with a sensitivity of 0.855 (PADB: 0.873) and a specificity of 0.86 (PADB: 0.88). Inclusion of heart rate did not improve detection accuracy.
  
  
  CONCLUSIONS
  Joint occurrence of LF-modulations in QRSA and RMI is a characteristic feature of SRBD that is robustly quantified by the jLSI and permits reliable and reproducible detection of sleep apnea in very heterogeneous settings.
authors: Christoph Maier, Institute of Medical Biometry and Informatics, Department of Medical Informatics, Heidelberg University Hospital, Im Neuenheimer Feld 305, 69120 Heidelberg, Germany, E-mail: christoph.maier@med.uni-heidelberg.de.
authors: C
authors: C
authors: Maier
authors: H
authors: H
authors: Wenz
authors: H
authors: H
authors: Dickhaus
mesh_terms: D015716:Electrocardiography, Ambulatory / Q000706:statistics & numerical data*; D045853:Exhalation / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D001239:Inhalation / Q000502:physiology; D017286:Polysomnography / Q000706:statistics & numerical data*; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000503:physiopathology
keywords: ECG; ECG-derived respiration; heart rate; respiratory myogram interference; sleep related breathing disorders