I have had CPR but in hospital. My heart stopped three times, and when my parents arrived (which took them about 45 minutes) they were still working on me.
They don’t actually always use the defibrillator, but they usually administer Adrenalin as well as giving CPR I have also been defibrilated (different occasion).
And I have seen the crash team in hospital do CPR on a patient for over 25 minutes, Not a nice thing to witness, but when I went up for the test I was going to he was being taken up to ICU and they said he was going to be ok.
In my case I was fitted with a temporary pacemaker and then kept on a ventilator overnight. When I woke up I spent a couple of days in ICU and was then transferred back down to coronary care....
I have ongoing heart problems so my story doesn’t end there but I am here now and doing well.
If it’s any consolation, he will be completely unaware of anything that is happening to him. In my case they started compressions before my heart actually stopped to try to prevent it from doing so (heart rate had dropped to 5BPM and I remember that bit vividly, but once I arrested there was just nothing.
Just another thing, if they are successful he will likely be in pain. The impact on your chest and ribs is immense, so it’s likely he wil have bruising and possibly even fractured/broken ribs. But it does pass I promise.
Fingers crossed that you get some news soon.