While this is anecdotal, it shows that perhaps the people you gave CPR to were very unlucky. Alternatively, it might be due to the delay before the CPR starts. If you're a first responder, you're probably too late unless the person had someone right next to her capable of administering CPR.
Radiolab did a podcast a few months ago[1] which looked at a John Hopkins survey of doctors that has been going on for decades now. 90% of all doctors surveyed said they would not want to be given CPR as a life saving intervention.
In TV and film, CPR is shown as being highly effective - well over 50%. But in reality, CPR can have a survival rate as low as 2%. The best survival rate I could find was 30%, which is where CPR is given immediately by a trained first aider. And that's the survival rate - the majority of people who survive CPR are unable to live normal lives, and may require medical care for life.
And that is not to say that people don't make complete recoveries and live long lives after CPR - it's just that the odds are overwhelmingly against them. It's telling that doctors would prefer not to receive CPR.
[1]: http://www.radiolab.org/blogs/radiolab-blog/2013/jan/15/bitt...
Look, CPR is a last ditch effort and there are reasons people get DNRs. But please don't go around spreading fear and confusion because of some radiolab factoid you heard.
In all the cases, not a single patient had been given CPR prior to our arrival. So right there, you can assume at least 5-10 minutes without any circulation. The (very rough) formula they taught us back then: every 1 minute without circulation -> 10% less chance to a successful CPR. When you go into cardiac arrest, you need CPR immediately or that's it.
In Germany the statistics at the time suggested roughly the following success rates:
- < 3 % with no CPR prior to arrival of EMT/paramedic
- ~ 20 % with immediate layman's CPR, fast emergency call, fast response
- ~ 30 - 40% when EMTs where on scene during the event (immediate application of drugs, intubation, excellent ventilation, good CPR)
- up to 70% when the patient went into cardiac arrest while in intensive care unit
The elephant in the room is, that when you end up being CPR'd in the street by the EMS after no circulation for 5 - 10 minutes, you better wish that you don't end up with ROSC. Because in all likelyhood you will (if you don't die after a few days in hospital / they kindly pull the plug) end with about as much brain activity as the chair you are sitting on right now.
Again: YMMV and I personally know a guy who was successfully resuscitated and became a paramedic after that. But I try to base life decisions on statistics and not anecdotes, so I personally prefer having a living will set up.
There's your killer factor right there... The article did talk about people receiving CPR right away from a bystander. And that was the case of my colleague's mother too - they were sitting at the dinner table together when his mom's heart went into cardiac arrest, and one of them had been trained to do CPR.
It sounds like CPR is absolutely worthwhile, based on the statistics you quoted - there's a 10x or more improvement in success rate from immediate CPR. However, that CPR needs to be immediate. The obvious conclusion is that more people should be trained in CPR techniques.