Larsen et al developed a model for predicting survival after an out-of-hospital cardiac arrest. The model can help plan emergency medical services. The authors are from the University of Washington in Seattle.



(1) minutes after arrest before CPR started

(2) minutes after arrest before defibrillation (first shock) given

(3) minutes after arrest before advanced cardiac life support (ACLS) started (intubation, IV line placement, hyperventilation, drug administration, ECG recording, etc.)


survival rate =

= 67% - (2.3% * (minutes until CPR started)) – (1.1% * (minutes until first shock)) – (2.1% * (minutes until advanced care))



• If none of the interventions are started, the decline in survival is 5.5% per minute.

• If none of the interventions are given, 0% survival is reached in just over 12 minutes.


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