AUTOMATIC EXTERNAL DEFIBRILLATION
INTRODUCTION
Nearly one million people die annually from cardiovascular disease. Most episodes of sudden cardiac arrest occur outside the hospital. Although sudden cardiac death occurs most often in patients with previously recognized ischemic heart disease, it is also the first manifestation of underlying heart disease in up to 20% of patients. The majority of adults with sudden cardiac arrest are found to be in ventricular fibrillation. In order to provide optimal care to these patients, it is necessary that the EMT-I understand general principles of rapid defibrillation. The following topics will be discussed:
· Cardiovascular anatomy and physiology
· Basic electrophysiology
· Importance of early defibrillation
· Overview of automated external defibrillator and operational procedures
· Coordination of EMT-I with ALS providers
· Importance of CPR and airway management
· AED protocol to include defibrillation, post-defibrillation care and monitoring, and documentation
LESSON OBJECTIVES
See attachment "A" - County of Los Angeles Department of Health Services EMT-I Defibrillation Program Objectives.
1. Describe the basic anatomy and physiology of the heart.
2. Describe the basic electrophysiology of the heart.
3. Describe BLS and airway management procedures.
4. Recognize a patient requiring defibrillation and provide management.
5. Describe the basic operational principles of the defibrillator.
6. Describe the sequence for patient assessment, defibrillation, reassessment, reporting, and documentation in a cardiac arrest situation.
7. Describe appropriate procedures to interface with ALS response.
SKILLS:
1. Rhythm Recognition
2. Airway Management and one/two rescuer CPR
3. Use of the Forerunner
4. Case Scenarios
KEY VOCABULARY
The following terms will be used during this lesson:
· Acute myocardial infarction:
Severe and sustained oxygen deprivation of the myocardium resulting in death of the heart cells; commonly known as a heart attack.
· Sudden cardiac death:
Sudden arrhythmic death due to cardiac arrest or death due to myocardial failure such as stroke, hemorrhage, or infarction.
· Ventricular fibrillation:
A chaotic quivering of the heart caused by the firing of multiple ectopic sites throughout the ventricle that results in cardiac arrest.
· Automatic external defibrillator:
Defibrillator that interprets the electrocardiogram of the patient and automatically initiates or advises defibrillation as needed.
KEY CONCEPTS
The following section provides information and space for taking notes on the key concepts discussed by the instructor.
COUNTY OF LOS ANGELES/DEPARTMENT OF HEALTH SERVICES
ATTACHMENT “A”
EMT-I DEFIBRILLATION (EMT-ID)
Program Objectives
Overall
Program
Goals: Upon completion of this course, the participant will be able to:
1. Discuss the "Chain of Survival" and the fundamentals of early defibrillation.
2. Describe BLS and airway management procedures according to the American Heart Association and L.A. County EMT-I skills protocols.
3. Recognize a patient requiring defibrillation and provide management according to the L.A. County policies and procedures for the EMT-ID.
4. Identify the roles and responsibilities of the EMT-ID and the local EMS Agency as well as the laws governing the EMT-IDs practice.
Cardiac Anatomy/Electrophysiology and Monitoring/Dysrhythmia Recognition
Objectives: Upon completion of this lesson, the participant will be able to:
1. Describe the basic anatomy and physiology of the heart.
2. Describe the basic electrophysiology of the heart.
3. Identify each part of the electrical conduction system.
4. Describe the basic function of the electrocardiogram (EKG) and environmental factors affecting monitoring.
Defibrillator Operation and Defibrillation
Objectives: Upon completion of this lesson, the participant will be able to:
1. Describe the standard operational procedures for the automated external defibrillator (AED).
2. When applicable, identify and describe the function of the following on the automated defibrillator (AED)
a. "on" switch
b. monitor screen
c. medical control module/PCMCIA card
d. cassette tape
e. microphone
f. battery
g. patient cable
h. analyze button indicator
i. change energy button
j. shock button
k. status button
1. date/time set button
m. key convertor
3. Demonstrate removal and replacement of the following:
a. medical control module
b. cassette tape or PCMCIA card
c. battery
4. Describe and demonstrate battery charging procedures for the following:
a. quick charge
b. regular charge
5. Identify procedures for care and troubleshooting of the following:
a. battery
b. cassette tape/PCMCIA card
c. medical control module
d. patient cable
e. protective case
f. monitor screen
g. routine maintenance
h. electrode placement
6. Describe and demonstrate proper electrode placement for defibrillation.
7. Identify initial and repeat joules (watts/seconds) to be used for defibrillation.
8. Describe and demonstrate the proper technique for performing defibrillation.
9. Given selected patient situations, standard operational procedures, for performing the defibrillation skill.
10. Identify the step-by-step approach to a patient in cardiac arrest.
11. Describe and demonstrate the sequence for initial assessment, defibrillation, ongoing assessment, reporting, and documentation in a cardiac arrest situation.
Standard Operational Procedures of EMT-IDs
Objectives: Upon completion of this lesson, the participant will be able to:
1. State the indications and contraindications for the use of the automated external defibrillator.
2. Identify the key action and specific actions to be taken under all conditions described in the EMT-ID Protocols.
3. Identify limits for interruption of CPR during defibrillation.
4. Describe the appropriate procedures to interface with ALS response.
5. Describe environmental factors, which may be hazardous during defibrillation.
6. Describe safety precautions to be taken when performing defibrillation.
Roles and Responsibilities of the EMT-ID
Objectives: Upon completion of this lesson, the participant will be able to:
1. Identify those procedures or practices authorized for an EMT -ID.
2. Identify State requirements for EMT-ID accreditation.
3. Identify the EMT-ID accrediting authority in L.A. County.
4. Describe circumstances that might warrant disciplinary action or loss of accreditation
as an EMT-ID.
5. Identify documentation requirements of the EMT-ID.
6. Describe procedures for proper disposition of cassette tape recordings or PCMCIA card
and documentation.
7. Describe methods of maintaining medical control associated with EMT-ID.
8. Identify continuing education requirements for maintenance of EMT-ID accreditation.
9. Discuss the purpose of a continuous quality improvement program.
Los Angeles County EMS Agency---Revised: September 1996
EMT-I DEFIBRILLATION ACCREDITATION PROCESS
Eligibility Requirements:
· Current EMT-I certification in the State of California
· Completion of an EMT-I Defibrillation Program approved by
the local EMS Agency
· Successful passage of EMT-I written and skills examination
approved by DHS
THE ACCREDITATING AGENCY FOR THE AED PROGRAM IS THE
LOS ANGELES COUNTY DEPARTMENT OF HEALTH SERVICES.
Reaccreditation Process:
· Must maintain continuous certification as an EMT- I
· Demonstrates skill proficiency every 6 months
· Must work for a local provider agency
*Dr Shea is the Program Medical Director for the AED program for
Long Beach Fire Department
Contraindications in the AED:
· Less than 8 years or under 55 pounds (25kg)
· Obviously dead criteria
· Honoring Prehospital DNR orders
Relative Contraindication:
· Traumatic full arrest is a relative contraindication.
· If the patient appears to be more medical than trauma, proceed with
the AED protocol.
KEY POINTS:
· Always deliver in stacks of 3, unless directed by the defibrillator
· Pulses should not be checked within a series of 3 shocks.
· CPR should be interrupted only for the maximum amount of time
needed to give 3 shocks or up to 90 seconds.
CARDIOVASCULAR ANATOMY AND PHYSIOLOGY
Heart
A muscular pump that generates the driving forces for blood to flow to all parts
of the body: the force must be sufficient to open the vessels so that blood can
pass through and then perfuse the organs and tissues.
Chambers
The inner portion of the heart is divided into four chambers:
· Left Atrium-receives blood from the lungs
· Right Atrium-receives blood from the rest of the body
· Right Ventricle-delivers blood to the lungs
· Left Ventricle-delivers oxygenated blood to the rest of the body;
picks up carbon dioxide and other waste products of metabolism
Cardiac Anatomy
· The four chambers of the heart are also divided by four valves:
Tricuspid valve-(three cusps) valve between the right atrium
and ventricle
Bicuspid valve-(two cusps) valve located between the left atrium
and ventricle
Aortic semilunar valve-guards the orifice between the
left ventricle and the aorta
Pulmonary semilunar valve-guards the orifice between
the right ventricle and the pulmonary artery.
Coronary Circulation
·The four pulmonary veins bring oxygenated blood to the left side of the heart.
·The coronary arteries are the exclusive suppliers of arterial blood to the
heart muscle. The left coronary artery carries approximately 85% of the
blood supply to the myocardium, and the right carries the remainder.
·The coronary arteries originate just above the aortic valve and divide into
smaller vessels that encircle the heart.
Cardiac Physiology
· Two-pumps in one:
Low-pressure pump (right atrium and right ventricle)
High-pressure pump (left atrium and left ventricle)
· Cardiac Cycle:
The pumping action of the heart is a product of rhythmic,
alternate contraction (systole) and relaxation (diastole) of the
atria and ventricles.
· Stroke Volume:
Amount of blood ejected from each ventricle with one contraction.
· Preload:
The amount of blood returning to the ventricle.
· Afterload:
The total resistance against which the blood must be pumped.
· Cardiac Output:
The volume of blood pumped by the heart each minute.
BASIC ELECTROPHYSIOLOGY
Conduction System
A series of specialized tissues which order the rhythmic relaxation and
contraction of the heart's cells.
· Sino atrial node: Also known as the "pacemaker." Sets the pace
of the contraction by sending an electrical current which causes
the atria to contract.
· Atrioventricular junction: Carries the impulse across from the
atria to the ventricles and into the Bundle of His.
· Bundle of His: Divides into small branches and carries the
impulse to the right and left bundle branches.
· Purkinje fibers: Fine conducting fibers at the anterior and
posterior portions of the left bundle branch.
The EKG Rhythm
· P Wave: First positive upward deflection on the EKG tracing,
representing atrial depolarization.
· PR Interval: The time it takes for an electrical impulse to be
conducted through the atria and the AV node up to ventricular
depolarization.
· QRS Complex: Follows the P Wave and represents ventricular
depolarization.
· ST Segment: Represents the early part of repolarization of the
ventricles. It immediately follows the QRS complex and ends
with the onset of the T wave.
· T Wave: Follows the QRS Complex and
represents repolarization of the ventricles.
IMPORTANCE OF EARLY DEFIBRILLATION
General Statistics
· Six hundred thousand people die each year of cardiovascular disease
· One-half of these deaths occur outside the hospital
· Collapse with sudden death is the first sign of heart disease in many of
these patients
Chain of Survival
· Early access to 911:
Recognizing the need for help and calling 911 is designed to get
a defibrillator to the patient's side as quickly as possible
· Early CPR:
CPR is used to sustain life by circulating oxygenated blood to the
brain; CPR cannot reverse ventricular fibrillation, that can only
be achieved by prompt defibrillation
· Early defibrillation:
The prompt use of automatic external defibrillator by the first
responder, provides the patient with an optimal chance for survival
· Early advanced cardiac care:
Supports the patient after defibrillation
Rationale for early defibrillation
· The most frequent initial rhythm in sudden cardiac arrest is
ventricular fibrillation
· The most effective treatment for ventricular fibrillation is
electrical defibrillation
· The probability of successful defibrillation diminishes rapidly
over time
· Ventricular fibrillation tends to convert to asystole within a
few minutes
OVERVIEW OF AUTOMATIC EXTERNAL DEFIBRILLATOR
Types of Automated Defibrillators
· Fully automated- defibrillator operates without action by EMT-I,
except to turn on power.
· Semi-automated- defibrillator uses a computer voice synthesizer
to advise EMT-I as to the steps to take based upon its analysis of
the patient's cardiac rhythm.
The Forerunner
·