title: Feasibility of automated rhythm assessment in chest compression pauses during cardiopulmonary resuscitation.
abstract: OBJECTIVE
  To demonstrate the feasibility of doing a reliable rhythm analysis in the chest compression pauses (e.g. pauses for two ventilations) during cardiopulmonary resuscitation (CPR).
  
  
  METHODS
  We extracted 110 shockable and 466 nonshockable segments from 235 out-of-hospital cardiac arrest episodes. Pauses in chest compressions were already annotated in the episodes. We classified pauses as ventilation or non-ventilation pause using the transthoracic impedance. A high-temporal resolution shock advice algorithm (SAA) that gives a shock/no-shock decision in 3s was launched once for every pause longer than 3s. The sensitivity and specificity of the SAA for the analyses during the pauses were computed.
  
  
  RESULTS
  We identified 4476 pauses, 3263 were ventilation pauses and 2183 had two ventilations. The median of the mean duration per segment of all pauses and of pauses with two ventilations were 6.1s (4.9-7.5s) and 5.1s (4.2-6.4s), respectively. A total of 91.8% of the pauses and 95.3% of the pauses with two ventilations were long enough to launch the SAA. The overall sensitivity and specificity were 95.8% (90% low one-sided CI, 94.3%) and 96.8% (CI, 96.2%), respectively. There were no significant differences between the sensitivities (P=0.84) and the specificities (P=0.18) for the ventilation and the non-ventilation pauses.
  
  
  CONCLUSIONS
  Chest compression pauses are frequent and of sufficient duration to launch a high-temporal resolution SAA. During these pauses rhythm analysis was reliable. Pre-shock pauses could be minimised by analysing the rhythm during ventilation pauses when CPR is delivered at 30:2 compression:ventilation ratio.
authors: Communications Engineering Department, University of the Basque Country UPV/EHU, Alameda Urquijo S/N, 48013 Bilbao, Spain.
authors: J
authors: J
authors: Ruiz
authors: U
authors: U
authors: Ayala
authors: S
authors: S
authors: Ruiz de Gauna
authors: U
authors: U
authors: Irusta
authors: D
authors: D
authors: González-Otero
authors: E
authors: E
authors: Alonso
authors: J
authors: J
authors: Kramer-Johansen
authors: T
authors: T
authors: Eftestøl
mesh_terms: D000465:Algorithms; D002307:Cardiography, Impedance / Q000379:methods; D016887:Cardiopulmonary Resuscitation / Q000379:methods* / Q000401:mortality; D015331:Cohort Studies; D016208:Databases, Factual; D047548:Defibrillators; D004562:Electrocardiography / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D006336:Heart Massage / Q000379:methods* / Q000401:mortality; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality* / Q000628:therapy*; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome
keywords: Automated external defibrillator (AED); Cardiopulmonary resuscitation (CPR); Defibrillation; Hands-off; Out-of-hospital cardiac arrest (OHCA); Ventilation