Automated External Defibrillation

“Chain of Survival” Early access Early CPR Early defibrillation Early advanced life support The chain of survival concept represents the sequence of four events that must occur quickly to optimize a person's chance of surviving a cardiac arrest. The four links of the chain: • Early Access, the first link, has two components: educating citizens to recognize cardiac arrest and having an emergency dispatch system in place to send trained personnel and equipment to the scene quickly. • Early CPR should be initiated by the person discovering the cardiac arrest. CPR buys time for the patient until arrival of the defibrillator and advanced care. • Early Defibrillation can establish a normal heart rhythm to a person suffering a cardiac arrest. It is most effective when it is performed in the first few minutes of a cardiac arrest. • Early Advanced Cardiac Life Support means that more advanced support such as drugs and intubation can be quickly given if necessary by more advanced care providers such as paramedics, nurses and physicians.

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 Basic Life Support (BLS) once included only CPR. The American Heart Association (AHA) now includes defibrillation as part of BLS. Defibrillation was once provided only by advanced practitioners such as physicians, nurses, and paramedics. With the introduction of automated external defibrillators (AEDs) responders not trained in rhythm recognition were able to defibrillate. Emergency Medical Technicians (EMTs), firefighters, police, security guards, flight attendants, lifeguards and lay responders have been trained to defibrillate. According to the AHA, the goal for early defibrillation at the community level is for the victim of sudden cardiac arrest (SCA) to receive a shock within 5 minutes from EMS call receipt. Not all Emergency Medical Systems (EMS) can reach the SCA victim within this time limit. Therefore, “every community should assess its capability to provide this intervention and institute whatever measures are necessary to make this goal a reality.” (AHA Guidelines 2000 for CPR and ECC). 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 After 20 % Survival In many communities when early defibrillation programs were introduced, survival rates doubled and tripled. 15 10 5 King County Washington Iowa Southeast Minnesota Northeast Minnesota Wisconsin Textbook of Advanced Cardiac Life Support, Chapter 20, 1990, p. 289

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% In Rochester, MN early defibrillation by police and paramedics was made a community objective in 1990 and survival to hospital discharge from sudden cardiac arrest, rose to 49% by 1995. Of the thirty-one victims who were first shocked by police, 18 (58%) survived. Fifty-three were first shocked by paramedics and 23 (43%) survived to hospital discharge. White RD, et al. Annals of Emerg Med. 1996;28:480–485.

Electrical Conduction System of the Heart Atrioventricular Node Left Atrium Bundle of His Internodal Pathways Left Bundle Branch Sinoatrial Node Right Atrium The heart has a network of specialized conductive fibers that conduct electrical impulses to the cardiac muscle tissues. This is the heart's "electrical" system. The network delivers electrical impulses directly to the cardiac muscle tissues which are stimulated to contract and pump blood. The pumping of the heart is the "mechanical" activity of the heart which results in a pulse. Left Ventricle Right Bundle Branch Purkinje Fibers Right Ventricle

Normal Conduction Pathway in the Heart and the ECG Sinoatrial (SA) Node Atrioventricular (AV) Node Left Bundle Branches Right Bundle Branch The heart's primary impulse generator is the sinoatrial (SA) node located in the right atrium. The impulse is carried through the cardiac muscle tissue of the atria. This causes the atria to contract. The impulse then travels through the network to the ventricles causing them to contract. The resulting action causes blood to be pumped through the body via connecting blood vessels. Purkinje Fibers P T QRS P = Atrial Depolarization QRS = Ventricular Depolarization T = Ventricular Repolarization

Normal Sinus Rhythm Sinoatrial Node The electrocardiogram (ECG) is a measurement of the electrical activity in the heart. The impulses from the heart pass through body tissues and reach the skin where they can be detected by disposable electrodes placed on the skin. The ECG of a healthy heart shows an organized, uniform rhythm called normal sinus rhythm (NSR). 12:56 29MAR96 PADDLES X1.0 HR = 74

Ventricular Fibrillation Sudden cardiac arrest (SCA) means the heart has unexpectedly stopped beating. The most common abnormal rhythm associated with SCA is ventricular fibrillation (VF). VF is an unorganized rhythm of chaotic electrical activity resulting in uncoordinated and ineffective cardiac muscle contractions which prevent the circulation of blood. There is no pulse or blood pressure. A heart in VF looks like a quivering bowl of jelly. If left untreated VF will virtually always result in death. 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 = --- Defibrillation is the delivery of a strong electrical shock to the heart. The goal of defibrillation is to reorganize the chaotic electrical activity of VF and return the heart to a normal rhythm. After a shock the SA node or another area of the heart can regain control as the primary pacemaker.

Cartoon, "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 Defibrillation must be delivered within minutes of a cardiac arrest in order to have the best chance of success. If not done quickly the rhythm will deteriorate into a rhythm which cannot be treated. Textbook of Advanced Cardiac Life Support, Chapter 20, 1990; p. 287.

Resuscitation Success vs. Time* 10 20 30 40 50 60 70 80 90 100 Success rates decrease 7-10% each minute % Success Success rates decrease by about 7-10% each minute. The actual relationship between defibrillation success and time is a non-linear one, with the best chance for success probably occurring in the first 3–4 minutes. 1 2 3 4 5 6 7 8 9 Adapted from text: Cummins RO, Annals Emerg Med. 1989, 18:1269-1275. * Non-linear Time (minutes)

Ventricular Tachycardia Pulseless ventricular tachycardia (VT) is a rhythm that often precedes VF. It occurs when a site in the ventricular muscle fires rapidly and takes over as the dominant pacemaker. As the heart rate increases, there is less time for the ventricles to fill with blood. This reduces the amount the heart can pump and blood pressure falls. If the blood pressure drops severely, consciousness and pulse will be lost. Like VF, if left untreated, pulseless VT will result in death within minutes. Both VF and VT are treated with electrical shocks called defibrillation. 12:57 29MAR96 PADDLES X1.0 HR = 214

Asystole 15:17 29MAR96 PADDLES X1.0 HR = --- Not all rhythms of cardiac arrest can be treated with electrical shocks. Asystole (“flat line” or no electrical activity of the heart) and pulseless electrical activity (“PEA”—electrical activity but no pumping of the heart) are examples of dysrhythmias that do not respond to external shocks.

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 An automated external defibrillator or AED is a type of defibrillator which analyzes the patient’s rhythm and advises the operator when a shockable rhythm is detected. It is not necessary for the AED operator to be skilled in rhythm recognition. AEDs should only be applied to patients who are unconscious, not breathing, and pulseless with no signs of circulation.

LIFEPAK® 500 Automated External Defibrillators Picture of LIFEPAK® 500 AED. LIFEPAK® 500 Automated External Defibrillators

Defibrillation Electrode Placement Anterior Disposable defibrillation electrodes are placed on the patient's bare chest in the anterior-lateral position. Remove excessive chest hair, sweat, and medication patches before applying the electrodes. Place electrodes by following the diagrams on the electrodes: On the victim’s left ribs—between the nipple and armpit. Press the electrode firmly to the skin. Above the victim’s right nipple, below the collarbone and beside the breast bone (sternum). Do not place over the breast bone. Bone is a poor conductor of electricity. Lateral Anterior-lateral placement

Next time, remove his shirt! Cartoon, “Next time, remove his shirt!” Next time, remove his shirt!

Defibrillation Electrode Placement Correct electrode placement allows more current to pass through the heart. Avoid placing the electrode over large bones such as the breast bone (sternum) which block the flow of current. 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 Defibrillation is easy because screen messages and voice prompts coach the operator through the procedure. The operator must only confirm cardiac arrest, turn on the AED, attach the electrodes, and 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 Safety for the patient and those associated with the rescue effort should be of primary importance. First attach the defibrillator only to someone in full cardiac arrest. Make sure no one is touching the victim during analysis and shock. The electrodes should be firmly adhered to clean dry skin to prevent sparking and fire. Chest hair should be quickly removed only if it is excessive and prevents the electrodes from firmly sticking to the chest. Be careful to remove oxygen from the victim during defibrillation and move it away from the rescue effort to help prevent a fire hazard.

You should have said “clear”! Cartoon, "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 AEDs can be used anywhere. The portability of the AED allows the user to bring it to the victim. Time to defibrillation, the most critical link to survival, can be reduced if an AED is “on-site” or can be brought to the victim quickly. AEDs are designed to be used safely by people who are not medically trained. In most states, anyone who has taken a CPR and AED instruction course can use an AED. Training courses are offered by the American Heart Association, the American Red Cross and other local organizations.

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 AEDs have eliminated the need to teach rhythm recognition and thus make is easier for those responders with less training to defibrillate. This may reduce the time to therapy. Unfortunately, even with the best efforts, not every person can be saved, but by combining early CPR with early defibrillation, the chance to save a life greatly increases.

“Happy Hearts” cartoon.

AED use by BLS trained nurses trained in hospital.

AED mounted on wall in healthclub, gym or exercise facility

AED carried by bike patrol (police, EMT or paramedic)

AED use by targeted responders in industrial setting.

AED in office building for use by security officers.

AED use by police officers.

AED use by firefighters.

AED use by airline flight attendants on aircraft.