Pre-arrival Instructions Effect on Bystander Cardiopulmonary Resuscitation (CPR).

Inclusion Criteria: * Patients 21 years old or older * Presumed cardiac origin as indicated on the Milwaukee County Emergency Medical Services (MCEMS) report * Non-Emergency Medical Services (EMS) witnessed arrest Exclusion Criteria: * Patients younger than 21 years old * Patients who are "obviously dead" (decomposition, rigor mortis, decapitation, or other) * Trauma victims, including hanging and burns * Patients with cardiac arrests clearly of other non-cardiac origin including drug overdose, carbon monoxide poisoning, drowning, exsanguination, electrocution, asphyxia, hypoxia related to respiratory disease, cerebrovascular accident and documented terminal illness * Patients determined to be a do-not-resuscitate (DNR) upon arrival of Emergency Medical Services (EMS) providers * Cardiopulmonary Resuscitation (CPR) by someone other than Emergency Medical Services (EMS) who is a trained first responder or health care provider with a predetermined duty to provide care.