In my humble opinion, the patient were not "unlucky" (which to me suggests that most would have faired much better on average), they were a very good representation of how the situation is/was (~10 years ago now).

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

Now, here's the thing: "Success" in all those cases means nothing more than 'Return Of Spontaneous Circulation' (ROSC). In layman's terms: the heart would start beating. That - of course - tells you next to nothing about brain damage.

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.