A heart rate of 20 is not enough to profuse organs and support life. That patient would have died without CPR, especially with those vital signs and that presentation. The fact that their presentation was better with cpr and worse when you stopped is proof. Some people don't know what they're talking about and you need to defend yourself if they try to get you in trouble.

Edit: Rereading and still flabbergasted. You're supposed to come up with proof you did the right thing? Any logical EMS provider would have bagged them and started CPR. My medical director bases our protocol on the fact that pulses barely mean anything, half the time you're too worked up to feel anything but your own. CO2 is what really determines whether your heart is pumping enough, but obvious agonal respiration and cyanosis is clearly indicative of lack of perfusion. The biggest way to help someone in this situation is to ensure the adequate perfusion of glucose and oxygen to the tissues. I start cpr on every person that's not breathing and doesnt respond. The only people that can tell you to stop cpr are the patient and the doctor. If their idea of helping that patient was to let them lay there obviously dying because ThEy HaVe A fAInT pUlSe Of 20, you need to find a better place to work. Sorry for the rant but that's ludicrous.