title: Minimizing pre-shock chest compression pauses in a cardiopulmonary resuscitation cycle by performing an earlier rhythm analysis.
abstract: BACKGROUND
  Guidelines recommend 2min of CPR after defibrillation attempts followed by ECG analysis during chest compression pause. This pause may reduce the likelihood of return of spontaneous circulation (ROSC) and survival. We have evaluated the possibility of analysing the rhythm earlier in the CPR cycle in an attempt to replace immediate pre-shock rhythm analysis.
  
  
  RESULTS
  The randomized Circulation Improving Resuscitation Care (CIRC) trial included patients with out of hospital cardiac arrest of presumed cardiac aetiology. Defibrillator data were used to categorize ECG rhythms as shockable or non-shockable 1min post-shock and immediately before next shock. ROSC was determined from end-tidal CO2, transthoracic impedance (TTI), and patient records. TTI was used to identify chest compressions. Artefact free ECGs were categorized during periods without chest compressions. Episodes without ECG or TTI data or with undeterminable ECG rhythm were excluded. Data were analyzed using descriptive statistics. Of 1657 patients who received 3409 analysable shocks, the rhythm was shockable in 1529 (44.9%) cases 1min post-shock, 13 (0.9%) of which were no longer shockable immediately prior to next possible shock. Of these, three had converted to asystole, seven to PEA and three to ROSC.
  
  
  CONCLUSIONS
  While a shockable rhythm 1min post-shock was present also immediately before next possible defibrillation attempt in most cases, three patients had ROSC. Studies are needed to document if moving the pre-shock rhythm analysis will increase shocks delivered to organized rhythms, and if it will increase shock success and survival.
authors.affiliation: Medical Student Research Program, University of Oslo, Oslo, Norway; Norwegian National Advisory Unit on Prehospital Emergency Medicine, Oslo University Hospital, Oslo, Norway. Electronic address: mikkelts@studmed.uio.no.
authors.forename: Mikkel T
authors.initials: MT
authors.lastname: Steinberg
authors.affiliation: Norwegian National Advisory Unit on Prehospital Emergency Medicine, Oslo University Hospital, Oslo, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
authors.forename: Jan-Aage
authors.initials: JA
authors.lastname: Olsen
authors.affiliation: Department of Statistics and Epidemiology, Oslo University Hospital, Oslo, Norway.
authors.forename: Cathrine
authors.initials: C
authors.lastname: Brunborg
authors.affiliation: Houston Fire Department and the Baylor College of Medicine, Houston, TX, United States.
authors.forename: David
authors.initials: D
authors.lastname: Persse
authors.affiliation: Department of Emergency Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Fritz
authors.initials: F
authors.lastname: Sterz
authors.affiliation: Hillsborough County Fire Rescue, Tampa, FL, United States; Department of Emergency Medicine, Lake Erie College, Bradenton, FL, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Lozano
authors.affiliation: Heart Lung Center, Department of Cardiology, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.
authors.forename: Marc A
authors.initials: MA
authors.lastname: Brouwer
authors.affiliation: Gold Cross Ambulance Service, Appleton Neenah-Menasha and Grand Chute Fire Departments, Neenah, WI, United States; Theda Clark Regional Medical Center, Neenah, WI, United States.
authors.forename: Mark
authors.initials: M
authors.lastname: Westfall
authors.affiliation: Houston Fire Department and the Baylor College of Medicine, Houston, TX, United States.
authors.forename: Chris M
authors.initials: CM
authors.lastname: Souders
authors.affiliation: Regional Ambulance Service Gelderland-Zuid, Nijmegen, The Netherlands.
authors.forename: Pierre M
authors.initials: PM
authors.lastname: van Grunsven
authors.affiliation: Hillsborough County Fire Rescue, Tampa, FL, United States.
authors.forename: David T
authors.initials: DT
authors.lastname: Travis
authors.affiliation: Department of Emergency Medicine, Medical College of Wisconsin, Milwaukee, WI, United States.
authors.forename: E Brooke
authors.initials: EB
authors.lastname: Lerner
authors.affiliation: Norwegian National Advisory Unit on Prehospital Emergency Medicine, Oslo University Hospital, Oslo, Norway.
authors.forename: Lars
authors.initials: L
authors.lastname: Wik
mesh_terms: D000368:Aged; D002307:Cardiography, Impedance / Q000379:methods; D047548:Defibrillators; D004554:Electric Countershock / Q000379:methods*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006336:Heart Massage / Q000295:instrumentation / Q000379:methods; D006339:Heart Rate; D006801:Humans; D008297:Male; D058687:Out-of-Hospital Cardiac Arrest / Q000175:diagnosis / Q000209:etiology / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000150:complications*
keywords: Cardiopulmonary resuscitation; Defibrillation; Guidelines; Ventricular fibrillation