title: Impact of changes in resuscitation practice on survival and neurological outcome after out-of-hospital cardiac arrest resulting from nonshockable arrhythmias.
abstract: BACKGROUND
  Out-of-hospital cardiac arrest (OHCA) claims millions of lives worldwide each year. OHCA survival from shockable arrhythmias (ventricular fibrillation/ tachycardia) improved in several communities after implementation of American Heart Association resuscitation guidelines that eliminated "stacked" shocks and emphasized chest compressions. "Nonshockable" rhythms are now the predominant presentation of OHCA; the benefit of such treatments on nonshockable rhythms is uncertain.
  
  
  RESULTS
  We studied 3960 patients with nontraumatic OHCA from nonshockable initial rhythms treated by prehospital providers in King County, Washington, over a 10-year period. Outcomes during a 5-year intervention period after adoption of new resuscitation guidelines were compared with the previous 5-year historical control period. The primary outcome was 1-year survival. Patient demographics and resuscitation characteristics were similar between the control (n=1774) and intervention (n=2186) groups, among whom 471 of 1774 patients (27%) versus 742 of 2186 patients (34%), respectively, achieved return of spontaneous circulation; 82 (4.6%) versus 149 (6.8%) were discharged from hospital, 60 (3.4%) versus 112 (5.1%) with favorable neurological outcome; 73 (4.1%) versus 135 (6.2%) survived 1 month; and 48 (2.7%) versus 106 patients (4.9%) survived 1 year (all P≤0.005). After adjustment for potential confounders, the intervention period was associated with an improved odds of 1.50 (95% confidence interval, 1.29-1.74) for return of spontaneous circulation, 1.53 (95% confidence interval, 1.14-2.05) for hospital survival, 1.56 (95% confidence interval, 1.11-2.18) for favorable neurological status, 1.54 (95% confidence interval, 1.14-2.10) for 1-month survival, and 1.85 (95% confidence interval, 1.29-2.66) for 1-year survival.
  
  
  CONCLUSIONS
  Outcomes from OHCA resulting from nonshockable rhythms, although poor by comparison with shockable rhythm presentations, improved significantly after implementation of resuscitation guideline changes, suggesting their potential to benefit all presentations of OHCA.
authors.affiliation: Department of Medicine, Division of Cardiology, Box 356422, University of Washington, 1959 NE Pacific St, Seattle, WA 98195-6422, USA. kudenchu@u.washington.edu
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Kudenchuk
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Redshaw
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Stubbs
authors.forename: Carol E
authors.initials: CE
authors.lastname: Fahrenbruch
authors.forename: Florence
authors.initials: F
authors.lastname: Dumas
authors.forename: Randi
authors.initials: R
authors.lastname: Phelps
authors.forename: Jennifer
authors.initials: J
authors.lastname: Blackwood
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Rea
authors.forename: Mickey S
authors.initials: MS
authors.lastname: Eisenberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000150:complications*; D016887:Cardiopulmonary Resuscitation; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D012189:Retrospective Studies