title: Interruptions of chest compressions during emergency medical systems resuscitation.
abstract: BACKGROUND
  Survival after nontraumatic out-of-hospital (OOH) cardiac arrest in Tucson, Arizona, has been flat at 6% (121/2177) for the decade 1992 to 2001. We hypothesized that interruptions of chest compressions occur commonly and for substantial periods during treatment of OOH cardiac arrest and could be contributing to the lack of improvement in resuscitation outcome.
  
  
  RESULTS
  Sixty-one adult OOH cardiac arrest patients treated by automated external defibrillator (AED)-equipped Tucson Fire Department first responders from November 2001 through November 2002 were retrospectively reviewed. Reviews were performed according to the code arrest record and verified with the AED printout. Validation of the methodology for determining the performance of chest compressions was done post hoc. The median time from "9-1-1" call receipt to arrival at the patient's side was 6 minutes, 27 seconds (interquartile range [IQR, 25% to 75%], 5 minutes, 24 seconds, to 7 minutes, 34 seconds). An additional 54 seconds (IQR, 38 to 74 seconds) was noted between arrival and the first defibrillation attempt. Initial defibrillation shocks never restored a perfusing rhythm (0/21). Chest compressions were performed only 43% of the time during the resuscitation effort. Although attempting to follow the 2000 guidelines for cardiopulmonary resuscitation, chest compressions were delayed or interrupted repeatedly throughout the resuscitation effort. Survival to hospital discharge was 7%, not different from that of our historical control (4/61 versus 121/2177; P=0.74).
  
  
  CONCLUSIONS
  Frequent interruption of chest compressions results in no circulatory support during more than half of resuscitation efforts. Such interruptions could be a major contributing factor to the continued poor outcome seen with OOH cardiac arrest.
authors.affiliation: Emergency Medicine Research Center, University of Arizona, Tucson, AZ, USA.
authors.forename: Terence D
authors.initials: TD
authors.lastname: Valenzuela
authors.forename: Karl B
authors.initials: KB
authors.lastname: Kern
authors.forename: Lani L
authors.initials: LL
authors.lastname: Clark
authors.forename: Robert A
authors.initials: RA
authors.lastname: Berg
authors.forename: Marc D
authors.initials: MD
authors.lastname: Berg
authors.forename: David D
authors.initials: DD
authors.lastname: Berg
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Hilwig
authors.forename: Charles W
authors.initials: CW
authors.lastname: Otto
authors.forename: Daniel
authors.initials: D
authors.lastname: Newburn
authors.forename: Gordon A
authors.initials: GA
authors.lastname: Ewy
mesh_terms: D000328:Adult; D000368:Aged; D016887:Cardiopulmonary Resuscitation; D047548:Defibrillators; D005260:Female; D006323:Heart Arrest / Q000401:mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000628:therapy