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
· Automatically interprets the patient's heart rhythm, identifies
ventricular fibrillation, and advises the operator whether or not
a shock is appropriate.
· Notebook-sized tool weighs about four pounds and is exceptionally
durable.
· Delivers energy in a biphasic waveform in which the direction of
the current is reversed midway through the pulse. The biphasic
waveform requires less energy than the monophasic waveform to
achieve comparable defibrillation efficacy.
Specifications
· Defibrillator
Operating Mode--Semi-automatic or manual
Energy selection--Single energy output
Charge time from shock advised--typically less than
10 seconds
Shock-to-shock cycle time--typically less than 20
seconds (including analysis time)
Voice and text prompts--extensive text prompts and
audible messages guide user through protocol
Protocol--follows pre-configured settings, can be
modified with the optional set-up card
Shock delivery--via pads placed in the anterior-
anterior position
Controls-on/off switch, screen contrast, manual
over-ride, manual charge, and disarm
· Battery
Capacity--typically 100 shocks or 5 hours of
operating time
Standby life-typically more than one year under
standby environmental conditions
Standard Operational Procedures
· Attach AEDs only to people in apparent cardiac arrest
to avoid
delivering inappropriate shocks.
· No defibrillator is capable of working without properly
functioning batteries.
Special Considerations
· Medicated skin patches need to be removed prior to using the AED
· Nitroglycerin paste needs to be removed with a gloved hand
· Use caution if the patient is wet or in any wet conditions
· Excessive chest hair may need to be shaved prior to application
· Do not apply pads over a pacemaker or internal defibrillator
Causes of Artifact
· Patient movement
· Loose electrodes
· Electric blankets
· Muscle tremors
· Vehicle movement
Inappropriate delivery of shocks
· Human error
· Mechanical error-such as battery failure
Interruption of
CPR
· No CPR performed at times shocks are delivered.
· No person should be touching the patient when rhythm is being
analyzed and when shocks are delivered.
· Chest compressions and artificial ventilations are stopped when
the rhythm is being analyzed and when shocks are delivered.
· Defibrillation is more effective than CPR, so stopping CPR
during process is more beneficial to patient outcome.
· CPR may be stopped up to 90 seconds if three shocks are necessary.
· Resume CPR only after up to the first three shocks are delivered.
Advantages of automated external defibrillation
· Learning to use and operate an AED is easier than learning to perform CPR
· Speed of operation- first shock can be delivered within 60-90 seconds
of arrival at the patient's side
· Hands-off defibrillation-promotes a safer method
· Adhesive defibrillatory pads may offer consistently better paddle
placement during a lengthy resuscitation attempt
Use of the Forerunner-Preparation
· Initiate basic life support
· Begin one or two-rescuer CPR
· Position defibrillator next to the patient
· Turn on machine and follow voice prompts
· Apply defibrillation pads in the anterior-anterior position
· Plug in the connector
Use of the Forerunner-Procedure
· Stop CPR-the Forerunner will automatically begin to analyze
the patients rhythm
· If "Deliver shock now" is displayed--warn bystanders to stand
back and press the shock button to deliver
· Repeat this sequence to deliver a total of three shocks if necessary
· After the 3rd shock, check for return of pulse
· Resume CPR for 60 seconds if no pulse
· May repeat a series of three shocks if needed
· Check for return of the carotid pulse;
if absent resume CPR
· Check for spontaneous respiration;
if absent perform rescue breathing
· If pulse and breathing present:
monitor patient
· If return of pulse then loss of pulse;
repeat protocol as if new arrest
Post Resuscitation Care
If the patient regains a pulse:
· Proper airway control and ventilatory management
· Supplemental oxygen
· Appropriate airway clearance if vomitus occurs
· Continued monitoring of vital signs
· Physical stabilization and transport
· Continued support while waiting the arrival of the ALS team
Documentation
Mandatory Items for Voice Recording
· Assessment--what is observed
· Action--what is done
· Results--how the patient responded
Coordination of ALS with EMT-ID
· On arrival, ALS providers should ask for a quick report from the
automated defibrillation providers and direct them to proceed
with their protocols.
· ALS providers should use the AED for additional shocks and
rhythm monitoring. They can direct the providers to operate the
AED. To save time, avoid disorganization, and allow a
coordinated transfer of care, ALS providers should not remove
the AED and attach a separate conventional defibrillator.
· If EMT-Is and EMT-Ps arrive simultaneously, use the EMT-I
for 3 shocks while the EMT-Ps initiate ALS care.
· If EMT-Ps arrive during any series of 3 shocks, EMT-Is shall
complete that series as indicated.
Documentation
· All information normally recorded on the EMS Report form shall
continue to be documented.
· The following information shall be included in specific sections of
the EMS Report Form:
"Comments" section:
Amount of time lapsed from patient collapse to arrival
of EMT-I
Amount of time lapsed from patient collapse to initiation
of citizen CPR (if applicable)
"Drugs/EKG" section:
Time of each defibrillation
The effect of the defibrillation on the patient
Identification of team member performing
defibrillation by placing Team Member #
"Signature" section:
The EMT-I performing the defibrillation skill on run shall
record his/her name in one of the team member boxes and
EMT in box labeled CERT #
Quality Improvement Program
Indicators to be monitored:
· 911 access to time of dispatch
· Dispatch time to time at patient's side
· Time from at patient's side to first defibrillation
· Witnessed arrest and unwitnessed arrest:
Bystander CPR
Restoration of pulse
Discharged from hospital
Initial rhythm and if defibrillated
Event Review Storage and Retrieval
· Use only Heartstream PC data card
· Install the data card before use
· Replace the PC data card after each use
· Notify EMS Staff when used
· Deliver the card to the appropriate EMS Staff member
via inter-office mall
Maintaining the Forerunner
Self Tests:
· The AED performs periodic self tests when a battery is
installed
Automatic External Defibrillator Check Sheet
· FF/EMT-I must complete daily and after each use
Troubleshooting:
· Confirm that the battery is securely in place
· Listen to voice prompts
· Are the training modes inactivated?
· Notify EMS Staff
CARDIAC RHYTHMS
Normal Sinus Rhythm
· Usual rhythm in healthy individuals
· Originates in the sinoatrial node
· Characteristics:
Distinct P waves can be identified
Pattern is very regular
Normal, narrow QRS complexes
Rate is 60-100 beats/minute
Ventricular Fibrillation
· Most common rhythm in cardiac arrest
· Chaotic quivering of the heart
· Characteristics
No distinguishable P waves
Wavy, chaotic, no organized pattern
No QRS complexes
Rate is indeterminate
Ventricular Tachycardia
· Atrioventricular dissociation usually is present
· Three or more beats of ventricular origin occur in succession
· May be well tolerated or associated with life-threatening
hemodynamic compromise
· Characteristics
No distinguishable P waves
Rhythm may be slightly irregular
Wide, bizarre complexes
Rapid rhythm-100-220 beats/minute
Aysto1e
· Total absence of ventricular activity
· No rate, no rhythm, no electrical activity
· Characteristics
P waves may occur
No distinguishable complexes
Complete absence of ventricular activity
No rhythm
Pulseless Electrical Activity
· Absence of a detectable pulse and the presence
of some type of electrical activity other than
ventricular tachycardia or ventricular fibrillation
· Characteristics
P waves may or may not occur
Rhythm may appear viable
May have normal QRS complexes
Rate may be variable--no pulses
Shockable Rhythms
· Ventricular Fibrillation
· Pulseless Ventricular Tachycardia
Non-Shockable Rhythms
· Normal Sinus Rhythm
· Asystole
· Pulseless Electrical Activity
BLS REVIEW AND AIRWAY MANAGEMENT
Anatomy and Physiology Review
Upper airway structures:
· Nasopharynx:
air passes into the nasal cavity through the nostrils
· Oropharynx:
anteriorly, the oropharynx opens into the oral cavity
which contains the lips, cheek, teeth, tongue, hard and
soft palates, and tonsils
· Laryngopharynx:
extends from the tip of the epiglottis to the glottis and
the esophagus
· Larynx:
lies in the anterior neck
Lower airway structures:
· Trachea:
air passage from the larynx to the lungs
· Bronchial tree:
trachea divides into the right and left primary bronchi
· Lungs:
large, paired, spongy organs whose principle function is
respiration
Manual Maneuvers for Opening the Airway
· Head tilt/chin lift:
fingers of one hand are placed under the lower jaw on the
bony part near the chin and lifted to bring the chin forward,
supporting the jaw and helping to tilt the head back
· Jawthrust:
method of choice for the trauma patient since you may do
this procedure while stabilizing the neck; place hands on
either side of neck to stabilize and use your fingers to push
up on the angles of the jaw to open the airway
AIRWAY ADJUNCTS
Oropharyngeal Airway
For use in the unconscious patient without a gag reflex
· Complications:
If the airway is too long, it may press the epiglottis against the
entrance of the larynx producing complete airway obstruction
Placement of an oropharyngeal airway—Review
· Determine the appropriate size by measuring:
earlobe to the corner of the mouth
midline of the lip to the angle of the jaw
· Open the airway
medical-head tilt/chin lift
trauma-jaw thrust
· Open the mouth using thumb pressure on the chin
· Insert the oropharyngeal airway
point tip upwards toward roof of mouth and rotate
· Reassess the airway
Nasopharyngeal Airway
Indicated when the patient still has a gag
· Complications:
If the tube is too long, it may enter the esophagus causing
gastric distention and hypoventilation
Placement of a nasopharyngeal airway--Review
· Select the appropriate size
diameter-slightly smaller than the diameter of nares
length-measure from tip of nose to tragus of ear
· Lubricate the airway
· Insert airway with bevel towards septum
advance tip along the floor of nasal cavity
rotate tube while inserting
· Reassess the airway
Bag-Valve-Mask
First line method for ventilating patients in the prehospital setting
· Complications:
Inability to provide adequate ventilatory volumes to a patient
who is not intubated
Bag-valve-mask ventilation--Review
· Select appropriate size mask/bag
· Open the airway
medical--head tilt/chin lift
trauma--jaw thrust
· Insert appropriate airway adjunct
· Secure mask to face, using C-grip
apply slight pressure on mask to establish adequate seal
One rescuer/two rescuer CPR-Review
· Establish unresponsiveness
· Open airway (head tilt/chin lift)
· Check for spontaneous respirations
· Give 2 slow breaths
· Palpate the carotid pulse
· Establish correct hand position
· Compress the chest 1 ˝ to 2 inches at a rate of 100
· One rescuer-continue procedure by alternating 2 slow breaths
and 15 compressions
· Two-rescuer-continue procedure by alternating two
breaths and 15 compressions, with a pause for ventilation
The Forerunner
· Initiate basic life support
Establish unresponsiveness, pulselessness, and apnea
Begin one or two-rescuer CPR
· Position the defibrillator next to the patient
Ensure that PC card for voice recording is in unit
Ensure that the battery is installed
· Turn the Forerunner on and follow the monitor messages and
verbal prompts
· Apply the defibrillator pads to the patient in the
anterior-anterior position and plug in connector
· Rhythm analysis is automatic once the device is turned on
· Stop CPR during rhythm analysis
MESSAGE AND VERBAL PROMPTS DURING PROCEDURE:
Rhythm Analysis
· Message Screen
"Analyzing"
· Verbal Prompt
"Analyzing heart rhythm. Do not touch patient.
· It will take 9-14 seconds to analyze electrical activity
If the patient is touched, moved, or disturbed in any way during
rhythm analysis:
· Message Screen
"Analyzing stopped. Do not touch patient"
· Verbal Prompt
"Analyzing interrupted. Do not touch the patient.
Patient and device must remain still"
· When a "Shock advised" prompt occurs in a motion
environment, patient movement and vibration must be
minimized for at least 15 seconds to allow reconfirmation
of EKG analysis before delivering a shock
CAUTION:
CPR SHOULD NOT BE PERFORMED ON THE PATIENT
WHILE THE DEFIBRILLATOR IS ANALYZING. THIS
REPRESENTS A POSSIBLE SHOCK HAZARD.
Shockable Rhythm
· Message Prompt
"Shock advised. Charging"
· Verbal Prompt
"Shock advised, charging Stay clear of patient."
· When the defibrillator is armed (charged)
"Deliver shock now. Press orange button."
· The EMT-I should warn all bystanders to stand back.
· Energy will be immediately transferred to the patient
"Shock delivered" will be displayed.
Note: When in semi-automated mode, the shock button will remain armed
until it is pressed, unless the rhythm becomes nonshockable,
the defibrillation pads are not adequately attached, or the device
is turned off.
Non-shockable Rhythm
· Message Prompt
“No shock advised. Monitoring."
· Verbal Prompt
"No shock advised. It is safe to touch the patient.
Check airway, check breathing, check pulse."
· At this point, the patient's pulse should again be checked and verbalized.
If pulseless, then perform CPR.
Note: During the monitoring period following a "No shock advised"
message, the analysis continues automatically, but there are no
voice prompts (quiet monitoring). If the rhythm changes to one
which the Forerunner suspects may be a shockable rhythm, it
will transition to the type of analysis in which prompts are again heard.