Purpose
There is increasing community interest in the long-term prognosis after out-of-hospital cardiac arrest (OHCA). We examine the impact of cardiopulmonary resuscitation (CPR) duration on 12-month functional outcomes after OHCA.

Methods
Between 2010 and 2016, consecutive adult non-traumatic OHCA patients where identified from the Victorian Ambulance Cardiac Arrest Registry. Survivors to hospital discharge underwent follow-up at 12 months post-arrest to determine functional outcome using the Glasgow Outcome Scale–Extended (GOSE). CPR duration was defined as the total CPR time either before return of spontaneous circulation or termination of resuscitation. Adjusted logistic regression was used to assess the effect of CPR duration on 12-month survival with good functional outcome (GOSE≥7).

Results
Of the 13,898 attempted resuscitations, 710 (5.1%) survived to 12 months with good functional outcome. The median CPR duration was 17 minutes overall (interquartile range: 9, 33), but was lower in 12-month survivors with good functional outcome (7 vs. 20 minutes; p<0.001). Every minute increase in CPR duration was associated with a 10.9% reduction in the risk-adjusted odds of good functional recovery at 12 months among all arrests (OR 0.89, 95% CI: 0.88, 0.90, p<0.001), and a 2.9% reduction in the subgroup of 12-month survivors (OR 0.97, 95% CI: 0.96, 0.98; p<0.001). Increasing CPR duration also reduced the risk-adjusted odds of living at home without care and returning to work (both p<0.001). The 99th cumulative proportion of 12-month survivors with good functional outcome was reached at a CPR duration of 41 minutes overall (95% CI: 34, 47), 42 minutes (95% CI: 35, 48) in patients with initial shockable rhythms, and 26 minutes (95% CI: 20, 26) in patients with initial non-shockable rhythms.

Conclusion
Increasing CPR duration is associated with poorer long-term functional recovery after OHCA. However, long-term favourable outcomes are possible with CPR durations exceeding 40 minutes.

2 - Impact of resuscitation duration on the long-term functional outcome of out-of-hospital cardiac arrest patients.