Automated External Defibrillation

“Chain of Survival”

• Early access

• Early CPR

• Early defibrillation

• Early advanced life support

Defibrillation is “Part of BLS”

• Basic Life Support includes CPR and defibrillation

• Early defibrillation with an automated external defibrillator (AED) has established benefit

• The principle of early defibrillation suggests that the first person to arrive at the scene of a cardiac arrest should have a defibrillator

• This principle is now internationally accepted

Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care p. I-68

Early Defibrillation Effectiveness

• Rural and urban U.S. studies

• Substantial increases in survival

Textbook of Advanced Cardiac Life Support, Chapter 20, 1990, p. 289

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25

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0King CountyWashington

Iowa SoutheastMinnesota

NortheastMinnesota

Wisconsin

Before

After

% S

urvi

val

Early Defibrillation by Police and Paramedics—Rochester, MN

Survival to Number hospital discharge

First shocked 31 18 (58%)by police

First shocked 53 23 (43%)by paramedics

Overall survival to hospital discharge = 49%

White RD, et al. Annals of Emerg Med. 1996;28:480–485.

Electrical Conduction System of the Heart

Left AtriumAtrioventricular Node

Bundle of His

Left Bundle Branch

Left Ventricle

Purkinje FibersRight Ventricle

Right Bundle Branch

Right Atrium

Sinoatrial Node

Internodal Pathways

Normal Conduction Pathway in the Heart and the ECG

Sinoatrial (SA) Node Atrioventricular (AV) Node

Left Bundle Branches

Right Bundle Branch

Purkinje Fibers

P = Atrial DepolarizationQRS = Ventricular DepolarizationT = Ventricular Repolarization

P T

QRS

Normal Sinus Rhythm

Sinoatrial Node

12:56 29MAR96 PADDLES X1.0 HR = 74

Ventricular Fibrillation

12:57 29MAR96 PADDLES X1.0 HR = ---

Defibrillation: The Only Effective Treatment for Ventricular Fibrillation

300 JOULES DEFIB 20:29 01APR96 PADDLES X1.0 HR = ---

“Thanks, I needed that!”

Why Early Defibrillation?

• VF most frequent initial rhythm in sudden cardiac arrest

• Defibrillation most effective treatment

• Probability of defibrillation success diminishes with time

• VF tends to rapidly deteriorate into asystole

Textbook of Advanced Cardiac Life Support, Chapter 20, 1990; p. 287.

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0 1 2 3 4 5 6 7 8 9

% Success

Time (minutes)

Success rates decrease 7-10% each minute

* Non-linearAdapted from text: Cummins RO, Annals Emerg Med. 1989, 18:1269-1275.

Resuscitation Success vs. Time*

Ventricular Tachycardia

12:57 29MAR96 PADDLES X1.0 HR = 214

Asystole

15:17 29MAR96 PADDLES X1.0 HR = ---

Automated External Defibrillators

• Analyze patient ECG– only for unconscious, pulseless victims with

no spontaneous breathing and no signs of circulation

• Determine via computer algorithm shockable or non-shockable rhythm

• Advise operator “SHOCK” or “NO SHOCK”

• Shock ventricular fibrillation and certain ventricular tachycardias

LIFEPAK® 500Automated External Defibrillators

Defibrillation Electrode Placement

Anterior-lateral placement

Lateral

Anterior

Next time, remove his shirt!

Defibrillation Electrode Placement

• Correct electrode position optimizes the amount of current flowing through the ventricles

Correct electrode position Incorrect electrode position

How to Defibrillate

• Verify the victim is unconscious, not breathing, without a pulse or signs of circulation

• Turn on AED and attach electrodes

• ANALYZE heart rhythm

• Follow the voice prompts and screen messages

Safety First

• Attach the defibrillator only to someone not breathing and without a pulse or signs of circulation

• Make sure no one is touching the victim

• Be sure the electrodes are firmly adhered to the victim’s chest

• Move oxygen away from the rescue effort before defibrillation

You should have said “clear”!

Who is Using AEDs Today?

• Flight Attendants

• Firefighters

• EMTs

• Corporate Emergency Response Teams

• Security Officers

• Police

• Golf Pros

• Lifeguards

• Health Club Employees

Advantages of AEDs

• Eliminates need to recognize rhythms

• Personnel with less training can defibrillate

• May reduce time to therapy—access to more treatable rhythms

• Makes early defibrillation practical and achievable