my 85 year old daddy died 11/3 in er, 5 hospitalizations w/pneumonia & nursing/rehab for ot, pt & st since 8/1, hx copd, pneumonia, dementia, aorta stenosis, when he was brought into er his O2 was 76, very low b/p 70-80/30-40, death cert cause of death cardiac arrest, although er had to stop his pacemaker, he stopped breathing on his own, was on a ventilator in er for about 3 hrs, i'm trying to understand, did he really die because of chronic pneumonia that he never recovered from that led to the cardiac arrest cause of lack of O2 & lo b/p