title: Effect of timing and duration of a single chest compression pause on short-term survival following prolonged ventricular fibrillation.
abstract: BACKGROUND
  Pauses during chest compressions are thought to have a detrimental effect on resuscitation outcome. The Guidelines 2005 have recently eliminated the post-defibrillation pause. Previous animal studies have shown that multiple pauses of increasing duration decrease resuscitation success. We investigated the effect of varying the characteristics of a single pause near defibrillation on resuscitation outcome.
  
  
  METHODS
  Part A: 48 swine were anesthetized, fibrillated for 7min and randomized. Chest compressions were initiated for 90s followed by defibrillation and then resumption of chest compressions. Four groups were studied-G2000: 40s pause beginning 20s before, and ending 20s after defibrillation, A1: a 20s pause just before defibrillation, A2: a 20s pause ending 30s prior to defibrillation, and group A3: a 10s pause ending 30s prior to defibrillation. Part B: 12 swine (Group B) were studied with a protocol identical to Part A but with no pause in chest compressions. Primary endpoint was survival to 4h.
  
  
  RESULTS
  The survival rate was significantly higher for groups A1, A2, A3, and B (5/12, 7/12, 5/12, and 5/12 survived) than for the G2000 group (0/12, p<0.05). Survival did not differ significantly among groups A1, A2, A3, and B.
  
  
  CONCLUSIONS
  These results suggest that the Guidelines 2005 recommendation to omit the post-shock pulse check and immediately resume chest compressions may be an important resuscitation protocol change. However, these results also suggest that clinical maneuvers further altering a single pre-shock chest compression pause provide no additional benefit.
authors.affiliation: University of Alabama, B140 Volker Hall, 1670 University Blvd., Birmingham, AL 35294, United States. gpw@crml.uab.edu
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Walcott
authors.forename: Sharon B
authors.initials: SB
authors.lastname: Melnick
authors.forename: Robert G
authors.initials: RG
authors.lastname: Walker
authors.forename: Isabelle
authors.initials: I
authors.lastname: Banville
authors.forename: Fred W
authors.initials: FW
authors.lastname: Chapman
authors.forename: Cheryl R
authors.initials: CR
authors.lastname: Killingsworth
authors.forename: Raymond E
authors.initials: RE
authors.lastname: Ideker
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D004195:Disease Models, Animal; D004554:Electric Countershock / Q000379:methods*; D005260:Female; D006323:Heart Arrest / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D006336:Heart Massage / Q000379:methods*; D006339:Heart Rate / Q000502:physiology; D008297:Male; D010507:Periodicity; D013552:Swine; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000150:complications / Q000503:physiopathology / Q000628:therapy*