Sudden cardiac arrest (SCA) is the abrupt loss of heart function leading to sudden cardiac death (SCD). Most cardiac arrests occur when the electrical impulses in the diseased heart become rapid (ventricular tachycardia) or chaotic (ventricular fibrillation [VF]), or both.1 This irregular heart rhythm (arrhythmia) may cause the heart to suddenly stop beating. As a result, the arterial pressure suddenly drops to critically low levels. Death usually ensues within less than 10 minutes due to the lack of oxygen supply to vital organs. Application of a therapeutic dose of electrical shock to the affected heart with a defibrillator within a few minutes of onset of VF can depolarize the heart muscle, reestablishing normal electrical activity.
SCD is a major health problem worldwide and is the leading cause of death in many developed countries.2-5 In North America, the annual incidence of out-of-hospital SCA is about 0.55 per 1,000.6 In Europe, about 275,000 individuals suffer from cardiac arrest annually, while the reported incidence of SCD in the United States varies from 180,000 to 250,000 annually.7-9 Approximately 70% to 80% of all cardiac arrests occur at home, often while the victim is alone or asleep.10 The reported incidence of out-of-hospital pediatric cardiac arrest varies widely from 2.6 to 19.7 annual cases per 100,000.11 The actual number of SCDs that occur in the general population is large, even though the incidence is lower compared to the number of SCDs in the high-risk population.12 Thus, the cost of SCA and SCD to society is not easily calculable.
Chain of Survival
The 1960 recommendation of closed-chest cardiac massage by Kouwenhoven is generally considered to be the advent of the modern era of cardiopulmonary resuscitation (CPR).13 The concept of “chain of survival” was fully described in the 1992 guidelines for CPR and emergency cardiac care of the American Heart Association (AHA).14 Chain of survival refers to a series of critical interventions that reduce the mortality from SCA. If one of these actions is neglected, it is unlikely the victim will survive. The chain of survival has four interdependent links: 1) early access, 2) early basic CPR, 3) early defibrillation, and 4) early advanced cardiac life support (ACLS). The guidelines were revised in 2005 to create a single international version of evidence-based, scientific resuscitation guidelines. However, the most critical element is that the effectiveness of an emergency cardiac care system does not depend on an individual link; instead the whole system must be taken into consideration, and survival rates will drop when there is any inadequacy in the chain.15 Nevertheless, recognition of the emergency and initiation of the chain remains the most critical point—if no one recognizes the emergency and no action is taken, the possibility of survival plummets to zero.
Early Access: Early access refers to the actions taken from the time the victim collapses until emergency medical service (EMS) personnel arrive. When someone suffers from SCA, the most important actions a bystander can take are to recognize the critical nature of the situation and call an emergency service number. However, recognition of early warning signs, such as chest pain, shortness of breath, and patient activation of the emergency response system can significantly increase the rate of survival. This is the compelling reason that the AHA stresses education concerning the importance of recognizing the signs and symptoms of cardiac arrest, acute myocardial infarction, and stroke, and initiating the action plan for survival.
Early CPR: Research confirms that the survival rate is higher in victims who receive early CPR than in those who receive delayed CPR.16-18 CPR helps preserve cerebral and myocardial viability. CPR alone cannot stand as the sole important link to increased survival, as a significant barrier to successful CPR is the complexity of the skills required. However, the primary reason for poor outcomes with CPR is most often due to delays in initiating defibrillation.19
Early Defibrillation: The survival rate from SCA is poor if the victim does not receive electrical therapy within a few minutes to restore normal electrical cardiac activity. Reports suggest that early defibrillation is critical in improving survival.20 The most critical factor in survival from VF is the time difference between the onset of fibrillation and administration of defibrillation.2 Studies find that the probability of survival is reduced by about 50% for each three-minute delay in administration of defibrillation.21 Further, survival rates for SCA can rise as high as 90% when immediate defibrillation is administered.19 Thus, the AHA and other health advocate groups recognize early defibrillation as a critical component in the chain of survival.22
However, early defibrillation is not the only important aspect of treatment. Defibrillation works best when CPR is provided until the shock is applied, followed by advanced care. In line with this, the AHA stresses that early CPR coupled with rapid defibrillation is critical to survival of adult victims of SCA; delays in the initiation of CPR or defibrillation can reduce survival.22 Moreover, the AHA emphasizes that all personnel must be trained to operate a defibrillator if their job description includes responding to persons in cardiac arrest. Therefore, all ambulances and other emergency vehicles that respond to or transport cardiac patients should be equipped with a defibrillator.
Early ACLS: ACLS is an enhancement of basic life support (BLS). Professional EMS personnel provide this advanced life support, which includes airway and breathing management, medications, and, in some cases, inducing hypothermia, as well as arranging follow-up care when necessary. Establishing a meaningful ACLS program requires extensive medical knowledge and rigorous hands-on training and practice. Arguments have been advanced both for and against ACLS for treating out-of-hospital cardiac arrest in comparison to BLS with a defibrillator. For victims who do not respond to initial CPR or do not have a rapid response to early defibrillation, ACLS may be of limited or no benefit, as it does not improve survival.23
Automated External Defibrillators
A defibrillator is a device that applies therapeutic electric shocks to the heart in order to restore normal heart rhythms before the malfunctioning heart suffers SCA followed by SCD. Defibrillators can be external, transvenous, or implanted. Some external devices, known as automated external defibrillators (AEDs), are capable of accurately analyzing cardiac rhythms and advising about and delivering therapeutic electric shocks when needed. Practical defibrillators were first developed in the early 1900s and the first AED was introduced in 1979.24 AEDs use internal computer algorithms to analyze cardiac rhythms and detect VF. Unlike earlier devices, modern AEDs deliver biphasic, effective, low-energy waveform shocks of 120 to 200 joules.
The current generation of AEDs is safe, effective, lightweight, easy to use and maintain, and relatively inexpensive (~$1,500 each).25 They require only four simple steps: 1) turning on the device, 2) attaching two electrodes, 3) pressing a button for rhythm analysis, and 4) pressing another button to administer the shocks. If further shocks are required, the device will instruct accordingly. However, the operator must carefully follow all instructions.
Studies report positive outcomes with early defibril lation in public places, as it saves precious minutes and improves survival rates for cardiac arrest victims.26 It is critical to have trained lay rescuers equipped with AEDs in all public places where large numbers of people congregate, such as airports, airplanes, schools, sports arenas, golf courses, hotels, concert halls, high-rise buildings, manufacturing plants, and shopping malls. All can benefit from obtaining AEDs and training employees to use them as part of a public access defibrillation (PAD) program. President Bush signed Public Law 107-188 on June 12, 2002, which authorized $30 million in federal grants to be made available to states and localities for the purchase and placement of AEDs in public places where cardiac arrests are likely to occur.27 Grant funds can be used to train first responders to administer immediate life-saving care, including AED use and CPR. As a result, more cities across the U.S. are becoming involved in PAD programs.
Properly designed AEDs can be used to deliver an effective defibrillation shock in a timely manner by bystanders with only basic knowledge and training. It is expected that a PAD program will target nonmedical or minimally trained personnel. Therefore, AEDs must be accurate in diagnosing arrhythmias, simple to operate, safe to the patient and rescuer, lightweight, portable, and cost-effective.
Program Goals
The primary goal of an AED or PAD program is to sustain the patient’s previous quality of life by preserving normal neurologic functioning. The program enables rescuers to deliver early defibrillation to victims within three to five minutes of collapse, the first critical moments after an SCA. However, the AED program should not replace the care provided by EMS personnel, but rather provide a lifesaving bridge during the first few critical minutes it takes for advanced life support providers to arrive. Care of the patient should be transferred to the EMS personnel upon their arrival. Furthermore, the program must comply with all applicable state regulations.
Role of the Pharmacist
Pharmacists asked to help convince public or private entities to institute a PAD program should press the following points. First, many people die from SCA every year. A well-established program in all public places will serve as a safety net to guard against death or disability. With public awareness and the availability of AEDs in community settings, the number of deaths from SCA is expected to undergo significant reductions by ensuring more timely access to defibrillation. Proven efficacy of AEDs in preventing death and disability from SCA in public places, coupled with the advent of user-friendly devices, has led to the development of the first nonprescription AED for home use (see sidebar).
Sudden cardiac arrest occurs when a person’s heart stops beating effectively for some reason. Unless swift action is taken, the patient may suffer lifelong disability or death. This is the reason that people are taught such lifesaving techniques as cardiopulmonary resuscitation, also known as CPR. Carrying out CPR can help the patient survive until emergency medical personnel arrive. However, CPR alone is not considered the best therapy in all cases.
New Devices Save Lives
Many people are familiar with the fact that patients whose hearts are not beating effectively are often administered electric shocks to correct and normalize the heart’s rhythms. Movies and television shows often illustrate this technique being carried out in the hospital setting. It is less well known that this procedure has become much more widespread and useful now that these devices, known asautomated external defibrillators (AEDs), have become portable and lightweight.
New Public Law
Most people who suffer cardiac arrest do so nowhere near a hospital or medical facility. They may be in a casino, at a sporting event, at a religious gathering, or in a university classroom. Perhaps a bystander tries to administer CPR until medical personnel arrive. Studies show that many patients would also benefit from the use of an AED if it were available. Modern AEDs are lightweight and portable and have an internal program that determines whether a shock is needed before it is administered. For these reasons, a public law was passed in 2002 with the goal of making AEDs widely available. The law authorized funds for states and localities to purchase and place AEDs in public places. The funds were also used to train people to use the devices and to deliver lifesaving cardiac treatment simply and with minimal training.Should You Participate?
People lose consciousness while in cardiac arrest; thus, they cannot administer shocks to themselves. A life is in jeopardy, and you may actually save someone by learning to use an AED. If an organization you belong to has placed AEDs in its building, learn where the devices are located. At some point, the organization should offer training. Do not hesitate to take part, as the devices are virtually foolproof. Their internal computer program will not allow you to deliver a shock unless it is actually needed. You should also learn how to check the battery for a full charge.The Home AED
Some readers are already familiar with the concept of AEDs and the benefits they can provide. They may be surprised to learn that the FDA has approved the first nonprescription AED for use at home. It is known as the Philips HeartStart Home Defibrillator. It comes with a training video that can be used to become familiar with the device. Everyone in the home who might conceivably need to use the AED on a loved one should watch the video. The company offers several flexible payment plans. You may go to www.heartstarthome.com to learn more, or you may also contact the company by calling 1-866-333-4246.Remember, if you have questions, Consult Your Pharmacist.
REFERENCES
1. Jalife J. Ventricular fibrillation: mechanisms of initiation and maintenance. Annu Rev Physiol. 2000;62:25-50.
2. Varon J, Marik P. Treatment of cardiac arrest with automated external defibrillators: impact on outcome. Am J Cardiovasc Drugs. 2003;3:265-270.
3. Turakhia M, Tseng ZH. Sudden cardiac death: epidemiology, mechanisms, and therapy. Curr Probl Cardiol. 2007;32:501-546.
4. Montagnana M, Lippi G, Franchini M, et al. Sudden cardiac death: prevalence, pathogenesis, and prevention. Ann Med. 2008;40:360-375.
5. Filippi A, Sessa E, Mazzaglia G, et al. Out of hospital sudden cardiac death in Italy. J Cardiovasc Med. 2008;9:595-600.
6. Vaillancourt C, Stiell IG. Cardiac arrest care and emergency medical services in Canada. Can J Cardiol. 2004;20:1081-1090.
7. Atwood C, Eisenberg MS, Herlitz J, Rea TD. Incidence of EMS-treated out-of-hospital cardiac arrest in Europe. Resuscitation. 2005;67:75-80.
8. Chugh SS, Reinier K, Teodorescu C, et al. Epidemiology of sudden cardiac death: clinical and research implications. Prog Cardiovasc Dis. 2008;51:213-228.
9. Mell HK, Sayre MR. Public access defibrillators and fire extinguishers: are comparisons reasonable? Prog Cardiovasc Dis. 2008;51:204-212.
10. Rho RW, Page RL. The automated external defibrillator. J Cardiovasc Electrophysiol. 2007;18: 896-899.
11. Donoghue A, Nadkarni V, Berg RA, et al. Out-of-hospital pediatric cardiac arrest: an epidemiologic review and assessment of current knowledge. Ann Emerg Med. 2005;46:512-522.
12. Smith T, Cain M. Sudden cardiac death: epidemiologic and financial worldwide perspective. J Interv Card Electrophysiol. 2006;17:199-203.
13. Gullo A. Cardiac arrest, chain of survival and Utstein style. Eur J Anaesthesiol. 2002;19:624-633.
14. Guidelines for cardiopulmonary resuscitation and emergency cardiac care. Emergency Cardiac Care Committee and Subcommittees, AHA. Part I. Introduction. JAMA. 1992;268:2171-2183.
15. Emergency Cardiac Care Guidelines Part 12: From science to survival: strengthening the chain of survival in every community. Circulation. 2000;102:I-358–I-370.
16. Cummins RO, Eisenberg MS, Hallstrom AP, Litwin PE. Survival of out-of-hospital cardiac arrest with early initiation of cardiopulmonary resuscitation. Am J Emerg Med. 1985;3:114-119.
17. Iwami T, Kawamura T, Hiraide A, et al. Effectiveness of bystander-initiated cardiac-only resuscitation for patients with out-of-hospital cardiac arrest. Circulation. 2007;16:2900-2907.
18. Ong ME, Anushia P, Tham LP, et al. Comparison of chest compression only and standard cardiopulmonary resuscitation for out-of-hospital cardiac arrest in Singapore. Resuscitation. 2008;78:119-126.
19. Ramaswamy K, Page R. The automated external defibrillator: critical link in the chain of survival. Annu Rev Med. 2003;54:235-243.
20. Marenco JP, Wang PJ, Link MS, et al. Improving survival from sudden cardiac arrest: the role of the automated external defibrillator. JAMA. 2001;285:1193-1200.
21. Koster RW. Automatic external defibrillator: key link in the chain of survival. J Cardiovasc Electrophysiol. 2002;13(suppl 1):S92-S95.
22. 2005 AHA guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Part 5: electrical therapies. Circulation. 2005;112(suppl 1):IV-35–IV-46.
23. Isenberg DL, Bissell R. Does advanced life support provide benefits to patients? Prehosp Disaster Med. 2005;20:265-270.
24. Diak AW, Welborn WS, Rullman RG, et al. An automatic cardiac resuscitator for emergency treatment of cardiac arrest. Med Instrum. 1979;13:78-83.
25. AED Programs Q&A. American Heart Association.
www.americanheart.org/
26. Brady GH, Lee KL, Mark DB, et al. Rationale and design of the Home Automatic External Defibrillator Trial (HAT). Am Heart J. 2008;155:445-454.
27. State laws on heart attacks, cardiac arrest & defibrillators.
www.ncsl.org/programs/health/
28. HeartStart Home Defibrillator.
www.heartstarthome.com. Accessed December 15, 2008.
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