title: Witnessed collapse and bystander cardiopulmonary resuscitation: what is really going on?
mesh_terms: D000368:Aged; D016887:Cardiopulmonary Resuscitation / Q000592:standards / Q000639:trends; D004632:Emergency Medical Services / Q000379:methods / Q000639:trends; D004634:Emergency Medical Technicians / Q000592:standards / Q000639:trends; D017809:Fatal Outcome; D006323:Heart Arrest / Q000175:diagnosis / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged