title: Circulation detection using the electrocardiogram and the thoracic impedance acquired by defibrillation pads.
abstract: OBJECTIVE
  To develop and evaluate a method to detect circulation in the presence of organized rhythms (ORs) during resuscitation using signals acquired by defibrillation pads.
  
  
  METHODS
  Segments containing electrocardiogram (ECG) and thoracic impedance (TI) signals free of artifacts were used. The ECG corresponded to ORs classified as pulseless electrical activity (PEA) or pulse-generating rhythm (PR). A first dataset containing 1091 segments was split into training and test sets to develop and validate the circulation detector. The method processed ECG and TI to obtain the impedance circulation component (ICC). Morphological features were extracted from ECG and ICC, and combined into a classifier to discriminate between PEA and PR. The performance of the method was evaluated in terms of sensitivity (PR) and specificity (PEA). A second dataset (86 segments from different patients) was used to assess two application of the method: confirmation of arrest by recognizing absence of circulation during ORs and detection of return of spontaneous circulation (ROSC) during resuscitation. In both cases, time to confirmation of arrest/ROSC was determined.
  
  
  RESULTS
  The method showed a sensitivity/specificity of 92.1%/90.3% and 92.2%/91.9% for training and test sets respectively. The method confirmed cardiac arrest with a specificity of 93.3% with a median delay of 0s after the first OR annotation. ROSC was detected with a sensitivity of 94.4% with a median delay of 57s from ROSC onset.
  
  
  CONCLUSIONS
  The method showed good performance, and can be reliably used to distinguish perfusing from non-perfusing ORs.
authors.affiliation: Communications Engineering Department, University of the Basque Country UPV/EHU, Alameda Urquijo S/N, 48013 Bilbao, Spain.
authors.forename: Erik
authors.initials: E
authors.lastname: Alonso
authors.affiliation: Communications Engineering Department, University of the Basque Country UPV/EHU, Alameda Urquijo S/N, 48013 Bilbao, Spain.
authors.forename: Elisabete
authors.initials: E
authors.lastname: Aramendi
authors.affiliation: Department of Emergency Medicine, Oregon Health & Science University, 97239-3098 Portland, OR, United States.
authors.forename: Mohamud
authors.initials: M
authors.lastname: Daya
authors.affiliation: Communications Engineering Department, University of the Basque Country UPV/EHU, Alameda Urquijo S/N, 48013 Bilbao, Spain.
authors.forename: Unai
authors.initials: U
authors.lastname: Irusta
authors.affiliation: Communications Engineering Department, University of the Basque Country UPV/EHU, Alameda Urquijo S/N, 48013 Bilbao, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Chicote
authors.affiliation: Department of Emergency Medicine, Oregon Health & Science University, 97239-3098 Portland, OR, United States.
authors.forename: James K
authors.initials: JK
authors.lastname: Russell
authors.affiliation: Knight Cardiovascular Institute, Oregon Health & Science University, 97239-3098 Portland, OR, United States.
authors.forename: Larisa G
authors.initials: LG
authors.lastname: Tereshchenko
mesh_terms: D001775:Blood Circulation; D016887:Cardiopulmonary Resuscitation; D047548:Defibrillators; D017097:Electric Impedance; D004562:Electrocardiography; D006323:Heart Arrest / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D013909:Thorax
keywords: Circulation detection; Defibrillator; Pulse; Pulse-generating rhythm; Pulseless electrical activity; Thoracic impedance