• Hospital admission defined as being alive four hours after the call for assistance to the emergency dispatch center.
  

• ROSC (a pulse in any vessel) at any time
  
• ROSC at arrival to emergency department
  
• Admittance to the hospital
  
• Discharge from the hospital
  
• CPC score at discharge from the hospital
  
• Survival at 3 months post hospital discharge
  

Extensive early experience yielded no reliably validated instances of out-of-hospital arrest associated with tachyarrhythmia being resuscitated without successful defibrillatory shock. This together with the increasing availability of automated external defibrillators (AEDs), at increasingly attractive prices, led, in the past decade, to a strong emphasis on early defibrillation. This emphasis may have inadvertently resulted in a decreased emphasis on cardiopulmonary resuscitative techniques, particularly in light of publications decrying the uniformly poor quality of CPR performed by laymen, medical professionals, and even EMS personnel. However, recent research strongly suggests that assisted reperfusion prior to defibrillation may actually significantly improve survival rates. These reports, based on clinical studies, have received substantial confirmation from carefully controlled laboratory studies, particularly in pigs.

If assisted reperfusion prior to defibrillation (and subsequent to failed shock) is important, it is reasonable to suppose that the benefit is related to quality of chest compressions. Observations of resuscitative efforts in the field indicate that maintaining compressions is one of the more difficult tasks, for a variety of reasons. Observations in the laboratory with trained paramedics show that the depth of compression and the compression rate diminish rapidly with time from the onset of CPR, without the participant being aware that his/her effort is actually diminished.

The desire to provide consistent and quality compressions has led to the development of a mechanical compression assist device called the AutoPulse. It is a self-contained, portable chest compression device that is rapidly field deployable.

Inclusion Criteria:

• All persons with out-of-hospital cardiac arrest who are attended by a vehicle involved in the randomization process and who are treated by the emergency medical service (EMS).

Exclusion Criteria:

• Persons under the age of 18
• Victims with traumatic arrest
• Less than the legal age of consent
• Resuscitation attempt discontinued because of do not resuscitate (DNR) orders or on request of authorized decision-maker
• Wards of the state, including prisoners
• Chest or abdominal surgery within 6 weeks
• Site specific exclusions