Inclusion Criteria:  Suspected out-of-hospital cardiac arrest Use of ZOLL AED 3 public-access defibrillator (running software v.1.03.602 or newer (US) or v. 6.03.006 or newer(OUS)) with Uni-padz III Unconsciousness Absence of breathing Absence of pulse and other signs of circulation  Exclusion Criteria:  Pre-existing Do Not Attempt Resuscitation (DNAR) orders No evidence of cardiac arrest