Improving Cardiac Arrest Diagnostic Accuracy of Emergency Medical Dispatchers

Cardiac arrest is a leading cause of death in Canada; it is defined as the sudden cessation of cardiac mechanical activity. It is uniformly fatal if not treated within minutes. More than 85% of out-of-hospital cardiac arrest (OOHCA) occur in residential locations so public access to automatic external defibrillators, to restart the heart, are not helpful. The overall rate of survival for OOHCA rarely exceeds 8%.

Bystander cardiopulmonary resuscitation (CPR) is chest compression and ventilations provided by someone not on the emergency response team. A victim or cardiac arrest is almost 4 times more likely to survive when receiving bystander CPR. However, despite various attempts to improve bystander rates they have remained low, not exceeding 15% in Ontario. It has been shown that since the ambulance dispatch centres in Ontario implemented dispatch-assisted CPR instructions (given to callers while emergency vehicles were on the way), there was a significant increase in use.

Emergency medical dispatchers can identify about 70% of OOHCA cases over the phone. Agonal breathing (laboured breathing preceding death) may be misinterpreted as a sign of life, and is responsible for as much as 50% of missed diagnoses. There is no specific training on the significance of this sign, and minimal information about recognizing cardiac arrest. An educational intervention designed to better understand the significance of agonal breathing and to clarify the existing CPR instruction protocol will most likely increase the frequency of CPR instructions, bystander CPR rates, and potentially survival of victims of cardiac arrest.

Inclusion criteria

• presumed cardiac origin
• event occurs in the catchment area of Training or Control Site
• resuscitation is attempted by a bystander and/or the emergency responders

Exclusion criteria

• patients younger than 16 years old
• patients who are "obviously dead" as defined by the Ambulance Act of Ontario (decomposition, rigor mortis, decapitation, or other)
• trauma victims including hanging and burns
• cardiac arrest of non-cardiac origin including drug overdose, carbon monoxide poisoning, drowning, exsanguination, electrocution, asphyxia, hypoxia related to respiratory disease, cerebrovascular accident, and documented terminal illness