Bradycardia with Bigeminal pulse

This is sad. Last night, we were on duty. The patient in ICU-A was bradycardic with bigeminal pulse (due to PVCs). So the resident on duty gave atropine. After a while, the patient complained of difficulty of breathing and suddenly desaturated from 89% of oxygen to absolutely 0%. My co-clerk shouted: "Mayday!" So we went to the ICU to do CPR. The chief resident put the endotracheal tube while all of us were alternately compressing. We did it for more than 30 minutes with an interval of 3 rounds of defibrillator. We lost her. What's sadder is the patient's relatives were blaming us. We can't blame them, they lost a loved one. But they should also remember that we are not God. We don't decide whether we let the patient live or die. We're only humans.