Download Advances In ResuscitationÑAutomated External Defibrillators

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
30
Before
25
% Survival
After
20
15
10
5
0
King County
Washington
Iowa
Southeast
Minnesota
Northeast
Minnesota
Textbook of Advanced Cardiac Life Support, Chapter 20, 1990, p. 289
Wisconsin
Early Defibrillation by Police and
Paramedics—Rochester, MN
Survival to
Number hospital discharge
First shocked
by police
31
18 (58%)
First shocked
by paramedics
53
23 (43%)
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 Atrium
Atrioventricular Node
Bundle of His
Internodal Pathways
Left Bundle Branch
Sinoatrial Node
Right Atrium
Left Ventricle
Right Bundle Branch
Right Ventricle
Purkinje Fibers
Normal Conduction Pathway in the
Heart and the ECG
Sinoatrial (SA) Node
Atrioventricular (AV) Node
Left Bundle Branches
Right Bundle Branch
Purkinje Fibers
P
T
QRS
P=
Atrial Depolarization
QRS = Ventricular Depolarization
T=
Ventricular Repolarization
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.
Resuscitation Success vs. Time*
100
90
Success rates decrease
7-10% each minute
80
70
60
%
Success
50
40
30
20
10
* Non-linear
0
1
2
3
4
5
6
Time (minutes)
7
8
9
Adapted from text: Cummins
RO, Annals Emerg Med. 1989,
18:1269-1275.
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® 500
Automated External
Defibrillators
Defibrillation Electrode Placement
Anterior
Lateral
Anterior-lateral placement
Next time, remove his shirt!
Defibrillation Electrode Placement
Correct electrode position
Incorrect electrode position
• Correct electrode position optimizes the amount of
current flowing through the ventricles
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
• Police
• Firefighters
• Golf Pros
• EMTs
• Lifeguards
• Corporate Emergency
• Health Club Employees
Response Teams
• Security Officers
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