Many of us remember the day when out-of-hospital defibrillation was delivered exclusively by Paramedic units and even then, in some areas, they had to request an order from a physician to shock! Thank God those days are gone. Paramedics today have a wide range of autonomy with regard to defibrillation. Unfortunately, paramedics represent the minority of EMS workers and in many cases, can not get to a patient in time.
With the advent of modern, high-speed microprocessors and EKG interpretation algorithms, machines that "read" the EKG can diagnose Ventricular fibrillation and administer appropriate life-saving shocks in the absence of a paramedic. With well designed protocols where EMTs and the lay public only apply the device on a pulseless patient, the risks of inappropriate shock are exceedingly low. Lay public/EMTs should not monitor pre-arrested patients with AEDs. This is because they do not have the interpretive skills or judgement nor will the device provide adequate frequency response to benefit the paramedic or physician. In addition, the screen and paper output is sufficient only to say Vf/VT or more normal rhythms exist. finally, monitoring defeats the most important safety issue...If the machine malfunctions, it will not shock a living person. Unfortunately unethical sales people take advantage of eager, naive EMTs by telling them they should monitor the patient. It would be tragic if a patient or the patients family thought they were in the care of a paramedic because a "cardiac monitor" was applied to the patient.
We know that for every minute after the Vf/VT cardiac arrest, the chances of survival diminish 20% for every minute without defibrillation.
It is important that paramedics support rapid defibrillation programs and work with the community to educate the initial responders. Paramedics should also be familiar with various AED devices for training purposes as well as off duty use.
AEDs are not a panacea. Successfully defibrillated patients often go back into Vf within the next 5 to 10 minutes. Paramedics can stabilize these hearts with medication to reduce the chances of a second cardiac arrest.
AEDs may be life saving even when no paramedics are available (as in Rural America). Approximately 18% of patients will not re-fibrillate.