Has it been reported how soon a defibrillator was used after he collapsed? CPR probably continued after he was defibbed.
Per guidelines, CPR typically would be resumed immediately after defibrillation, and continued for at least two minutes before pausing briefly to check for a pulse. Resuscitation efforts are simply continued until return of spontaneous circulation or a decision is made to stop.
Some reports said Hamlin was resuscitated on the field twice — I’m thinking that plus the continuous CPR must have given his system enough circulation to carry him through.
Most interesting info. here — it’s the carbonic acid buildup that gets you even before the low oxygen level:
https://www.verywellhealth.com/respiratory-or-cardiac-arrest-1298194
Also, breathing MAY continue as long as a minute after the heart stops, but, of course, without CPR there’s little or no blood circulation to clear out the CO2 / carbonic acid..