title: Witnessed arrest, but not delayed bystander cardiopulmonary resuscitation improves prehospital cardiac arrest survival.
abstract: BACKGROUND
  This study correlated the effect of witnessing a cardiac arrest and instituting bystander CPR (ByCPR), as a secondary end point in a study evaluating the effect of bicarbonate on survival.
  
  
  METHODS
  This prospective, randomised, double blinded clinical intervention trial enrolled 874 prehospital cardiopulmonary arrest patients encountered in a prehospital urban, suburban, and rural regional emergency medical service (EMS) area. This group underwent conventional advanced cardiac life support intervention followed by empiric early administration of sodium bicarbonate (1 mEq/l), monitoring conventional resuscitation parameters. Survival was measured as presence of vital signs on emergency department (ED) arrival. Data were analysed using chi(2) with Pearson correlation and odds ratio where appropriate.
  
  
  RESULTS
  The overall survival rate was 13.9% (110 of 792) of prehospital cardiac arrest patients. The mean (SD) time until provision of bystander cardiopulmonary resuscitation (ByCPR) by laymen was 2.08 (2.77) minutes, and basic life support (BLS) by emergency medical technicians was 6.62 (5.73) minutes. There was improved survival noted with witnessed cardiac arrest-a 2.2-fold increase in survival, 18.9% (76 of 402) versus 8.6% (27 of 315) compared with unwitnessed arrests (p<0.001) with a decreased risk ratio of mortality of 0.4534 (95% CI, 0.0857 to 0.1891). The presence of ByCPR occurred in 32% (228 of 716) of patients, but interestingly did not correlate with survival. The survival rate was 18.2% (33 of 181) if ByCPR was performed within two minutes and 12.8% (6 of 47), if performed >two minutes (p = 0.3752).
  
  
  CONCLUSIONS
  Survival after prehospital cardiac arrest is more likely when witnessed, but not necessarily when ByCPR was performed by laymen.
authors.affiliation: University of Pittsburgh Medical Center-Northwest, One Spruce Street, Franklin, PA 16323, USA. rbvmd@comcast.net
authors.forename: R B
authors.initials: RB
authors.lastname: Vukmir
mesh_terms: D000328:Adult; D016887:Cardiopulmonary Resuscitation; D004311:Double-Blind Method; D004632:Emergency Medical Services; D005392:First Aid; D006323:Heart Arrest / Q000628:therapy*; D006801:Humans; D011379:Prognosis; D011446:Prospective Studies; D017693:Sodium Bicarbonate / Q000627:therapeutic use*; D015996:Survival Rate; D013997:Time Factors
chemical_list: D017693:Sodium Bicarbonate