title: Chest compression rate feedback based on transthoracic impedance.
abstract: BACKGROUND
  Quality of cardiopulmonary resuscitation (CPR) is an important determinant of survival from cardiac arrest. The use of feedback devices is encouraged by current resuscitation guidelines as it helps rescuers to improve quality of CPR performance.
  
  
  OBJECTIVE
  To determine the feasibility of a generic algorithm for feedback related to chest compression (CC) rate using the transthoracic impedance (TTI) signal recorded through the defibrillation pads.
  
  
  METHODS
  We analysed 180 episodes collected equally from three different emergency services, each one using a unique defibrillator model. The new algorithm computed the CC-rate every 2s by analysing the TTI signal in the frequency domain. The obtained CC-rate values were compared with the gold standard, computed using the compression force or the ECG and TTI signals when the force was not recorded. The accuracy of the CC-rate, the proportion of alarms of inadequate CC-rate, chest compression fraction (CCF) and the mean CC-rate per episode were calculated.
  
  
  RESULTS
  Intervals with CCs were detected with a mean sensitivity and a mean positive predictive value per episode of 96.3% and 97.0%, respectively. Estimated CC-rate had an error below 10% in 95.8% of the time. Mean percentage of accurate alarms per episode was 98.2%. No statistical differences were found between the gold standard and the estimated values for any of the computed metrics.
  
  
  CONCLUSIONS
  We developed an accurate algorithm to calculate and provide feedback on CC-rate using the TTI signal. This could be integrated into automated external defibrillators and help improve the quality of CPR in basic-life-support settings.
authors.affiliation: Department of Communications Engineering, University of the Basque Country, UPV/EHU, 48013 Bilbao, Spain.
authors.forename: Digna M
authors.initials: DM
authors.lastname: González-Otero
authors.affiliation: Department of Communications Engineering, University of the Basque Country, UPV/EHU, 48013 Bilbao, Spain. Electronic address: sofia.ruizdegauna@ehu.es.
authors.forename: Sofía
authors.initials: S
authors.lastname: Ruiz de Gauna
authors.affiliation: Department of Communications Engineering, University of the Basque Country, UPV/EHU, 48013 Bilbao, Spain.
authors.forename: Jesus
authors.initials: J
authors.lastname: Ruiz
authors.affiliation: Oregon Health & Science University, 97239-3098 Portland, OR, USA.
authors.forename: Mohamud R
authors.initials: MR
authors.lastname: Daya
authors.affiliation: Norwegian National Advisory Unit on Prehospital Emergency Medicine, Oslo University Hospital, Oslo, Norway.
authors.forename: Lars
authors.initials: L
authors.lastname: Wik
authors.affiliation: Russell Biomedical Research Consulting, Seattle, USA.
authors.forename: James K
authors.initials: JK
authors.lastname: Russell
authors.affiliation: Norwegian Centre for Prehospital Emergency Care (NAKOS), Oslo University Hospital and University of Oslo, 0424 Oslo, Norway.
authors.forename: Jo
authors.initials: J
authors.lastname: Kramer-Johansen
authors.affiliation: Department of Electrical Engineering and Computer Science, Faculty of Science and Technology, University of Stavanger, 4036 Stavanger, Norway.
authors.forename: Trygve
authors.initials: T
authors.lastname: Eftestøl
authors.affiliation: Department of Communications Engineering, University of the Basque Country, UPV/EHU, 48013 Bilbao, Spain.
authors.forename: Erik
authors.initials: E
authors.lastname: Alonso
authors.affiliation: Department of Communications Engineering, University of the Basque Country, UPV/EHU, 48013 Bilbao, Spain.
authors.forename: Unai
authors.initials: U
authors.lastname: Ayala
mesh_terms: D000465:Algorithms; D002307:Cardiography, Impedance / Q000379:methods*; D016887:Cardiopulmonary Resuscitation / Q000295:instrumentation / Q000379:methods / Q000592:standards; D047548:Defibrillators; D004562:Electrocardiography / Q000379:methods; D004632:Emergency Medical Services / Q000592:standards*; D005240:Feasibility Studies; D005246:Feedback; D006323:Heart Arrest / Q000628:therapy*; D006801:Humans; D011237:Predictive Value of Tests; D011312:Pressure; D011785:Quality Assurance, Health Care / Q000379:methods; D058996:Quality Improvement; D015203:Reproducibility of Results
keywords: Automated external defibrillator; Basic life support; CPR quality; Chest compression; Transthoracic impedance