The impact of partial resuscitation attempts on the reported outcomes of out-of-hospital cardiac arrest in Victoria, Australia: implications for Utstein-style outcome reports

Background: Success rates from cardiopulmonary resuscitation (CPR) are often quantified by Utstein-style outcome reports in populations who receive an attempted resuscitation. In some cases, evidence of futility is ascertained after a partial resuscitation attempt has been administered, and these cases reduce the overall effectiveness of CPR. We examine the impact of partial resuscitation attempts on the reported outcomes of out-of-hospital cardiac arrest (OHCA) in Victoria, Australia.

Methods: Between 2002 and 2012, 34,849 adult OHCA cases of presumed cardiac aetiology were included from the Victorian Ambulance Cardiac Arrest Registry. Resuscitation attempts lasting ≤10min in cases which died on scene were defined as a partial resuscitation. We used logistic regression to identify factors associated with a partial resuscitation attempt in the emergency medical service (EMS) treated population. Survival outcomes with and without partial resuscitations were compared across included years.

Results: The proportion of partial resuscitations in the overall EMS treated population increased significantly from 8.6% in 2002 to 18.8% in 2012 (p for trend<0.001), and were largely supported by documented evidence of irreversible death. Partial resuscitations were independently associated with older age, female gender, initial non-shockable rhythm, prolonged downtime, and lower skill level of EMS personnel. Selectively excluding partial resuscitations increased event survival by 7.6% (95% CI 4.1-11.2%), and survival to hospital discharge increased by 3.1% (95% CI 0.5-5.7%) in 2012 (p<0.001 for both).

Conclusion: In our EMS system, evidence of futility was often identified after the commencement of a partial resuscitation attempt. Excluding these events from OHCA outcome reports may better reflect the overall effectiveness of CPR.