system
Given the following post, respond as if you're commenting on Reddit:
human
How effective is CPR if applied immediately after cardiac arrest?

So, according to the statistics, the vast majority of patients don't make it, despite CPR (<5 percent survivors), and I wonder if that's the case because it's simply administered too late to be effective.

Are the chances significantly higher if emergency measures are taken immediately?
gpt
One way to look at this is to compare the survival rates of cardiac arrests which happen outside of hospital compared to those that happen within the hospital. Although the in hospital population may be sicker, it is also reasonable to assume that CPR will be started sooner, and be more effective, for an in hospital arrest. 


Not surprisingly, outcome for in hospital arrest is better; survival to hospital discharge has been given at around 17%, compared to 8% for out of hospital arrest 

(source:BMJ 2012;345 Published 3 October 2012)