Survival from out-of-hospital cardiac arrest in New Zealand following the 2005 resuscitation guideline changes

Aims: The effect of cardiopulmonary resuscitation guideline changes on out-of-hospital survival rates and defibrillation efficacy was investigated. The guideline changes were those recommended by the International Liaison Committee on Resuscitation in 2005.

Methods: A retrospective comparative study was undertaken of out-of-hospital cardiac arrests in the Wellington region. The effect of guideline changes between the periods of 1st July 2005-30th June 2006 and 1st June 2007-31st May 2008 was examined. Data was collected from Wellington Free Ambulance and hospital records in accordance with the Utstein template. The primary outcome measure was survival to hospital discharge. Additional end points included individual shock success, return of spontaneous circulation (ROSC) and survival to hospital admission.

Results: There was no significant increase in survival to hospital discharge with 11% (18/162) pre-change and 12% (20/170) post-change (p=0.5). First-shock efficacy decreased from 68% (65/96) to 62% (57/92) (p=0.75). Second shock efficacy decreased from 47% (14/30) to 27% (9/33) (p=0.12). The proportion of patients with ROSC increased from 34% (55/162) to 42% (72/170) (p=0.07, Chi squared). The proportion surviving to hospital increased significantly from 22% (36/162) to 36% (61/170) (p=0.006). Withdrawal of atropine in 2005 had no adverse effect on the outcome.

Conclusion: This study suggests that in the Wellington Region of New Zealand, the new guidelines have improved survival to hospital but not to discharge. Whilst the guideline changes have resulted in a trend towards decreased shock success rates, ROSC and survival to hospital admission have both increased.