There was this interesting discussion on CPR and defib in response to the question "Why can't we defibrillate the heart within 1 minute after ventricular fibrillation by electroshock?".
Now I was wondering "How long can the brain cope without O2?".
And to specify this question to a realistic situation: "How long can the brain survive a cardiac arrest without (gross) neurological symptomatic consequences?"
I would define "gross symptomatic consequences" as "noticeable and debilitating" in one way or another to the subject. This opposed to minute changes in, e.g., motor response latencies measured in a laboratory task designed to pick up the slightest results of asphyxia.
As background: I did these CPR and defib courses and the first thing they tell you to do is (1) call 911 / 000 whatever alarm number and (2) arrange a partner in crime to help with CPR; or in case of a defib situation, (call alarm nr), make your way to the defib, unpack, apply electrodes, look at the manual, casually wait for instructions/warning lights etc. But..but... there is a person here without oxygen supply to his brain! And I know professional staff should be brought to the scene, but what struck me most is that starting up the defib (which inherently takes time) is more important than CPR (which is immediate)? In other words, loosing precious minutes is advantageous over diving straight away into CPR and pumping blood around?