Lay Rescuer Automated External Defibrillator ("Public Access Defibrillation") Programs
http://www.100md.com
《循环学杂志》
Abstract
Lay rescuer automated external defibrillator (AED) programs may increase the number of people experiencing sudden cardiac arrest who receive bystander cardiopulmonary resuscitation (CPR), can reduce time to defibrillation, and may improve survival from sudden cardiac arrest. These programs require an organized and practiced response, with rescuers trained and equipped to recognize emergencies, activate the emergency medical services system, provide CPR, and provide defibrillation. To determine the effect of public access defibrillation (PAD) programs on survival and other outcomes after SCA, the National Heart, Lung, and Blood Institute, the American Heart Association (AHA), and others funded a large prospective randomized trial. The results of this study were recently published in The New England Journal of Medicine and support current AHA recommendations for lay rescuer AED programs and emphasis on planning, training, and practice of CPR and use of AEDs. The purpose of this statement is to highlight important findings of the Public Access Defibrillation Trial and summarize implications of these findings for healthcare providers, healthcare policy advocates, and the AHA training network.
Key Words: AHA Science Advisory ; defibrillation ; heart arrest ; fibrillation ; cardiopulmonary resuscitation
Introduction
Since 1995, the American Heart Association (AHA) has promoted the development of lay rescuer automated external defibrillator (AED) programs to improve survival from out-of-hospital sudden cardiac arrest (SCA).1–3 These programs are also known as "public access" defibrillation (PAD) programs. The AHA has emphasized the importance of organization, planning, and training to maximize effectiveness of these programs.4
To determine the effect of PAD programs on survival and other outcomes after SCA, the National Heart, Lung and Blood Institute (NHLBI), the AHA, and others funded a large prospective randomized trial. The results of this study were published recently in The New England Journal of Medicine.5 The purpose of the present statement is to highlight important findings of the Public Access Defibrillation (PAD) trial and summarize implications of these findings for healthcare providers, healthcare policy advocates, and the AHA training network.
Background
Although estimates of the annual number of deaths caused by out-of-hospital SCA in the United States vary widely,6–9 the AHA estimates that 250 000 people die in the United States each year from SCA outside the hospital setting.10 At the time of first heart rhythm analysis, 40% of SCA victims demonstrate ventricular fibrillation (VF), an abnormal heart rhythm that causes the heart to quiver so that it is unable to pump blood effectively.8 It is likely that an even higher proportion of people with SCA have VF at the time of collapse. Many people who experience sudden VF cardiac arrest can survive if bystanders act immediately. If VF is untreated, then cardiac standstill will develop, and successful resuscitation will be unlikely.11
The AHA has traditionally used 4 links in a chain to illustrate the important actions that can create a "chain of survival" for victims of VF SCA.12 These links are as follows:
Early recognition of the emergency and activation of the emergency medical services (EMS) system ("9-1-1").
Early bystander cardiopulmonary resuscitation (CPR).
Early delivery of a shock with a defibrillator.
Early advanced life support.
Bystanders can now perform 3 of the links in this chain. Bystander recognition of the emergency and EMS activation are critical first steps in response to an SCA, ensuring that basic and advanced life support providers are dispatched to the site of the arrest. In most communities, the time interval from collapse to the arrival of EMS personnel is 7 to 8 minutes or longer. This means that the victim depends on the actions of bystanders and local rescuers to perform the first 2 or 3 links in the chain of survival during the first minutes after SCA.
Bystanders need to provide immediate CPR for victims of SCA. CPR provides blood flow to the heart and brain. In addition, CPR increases the likelihood that a shock delivered by a defibrillator will terminate the VF and that the heart will resume an effective rhythm after defibrillation. These effects of CPR appear to be particularly important if shock delivery does not occur for 4 minutes after collapse.13 Defibrillation does not "restart" the heart; defibrillation stops VF and allows the heart to resume a normal rhythm. In the first few minutes after defibrillation, the heart rhythm may be slow and the heart may not pump blood effectively. CPR may be needed for several minutes after defibrillation until adequate heart function resumes.14
Lay rescuers can use computerized devices called AEDs to deliver a shock to victims of VF cardiac arrest. The rescuer attaches the AED to the victim with adhesive pads or electrodes. The AED records and analyzes the victim’s ECG rhythm, informs the rescuer if a shock is needed, and provides voice and audio prompts to guide the rescuer through all steps of AED use. The AED computerized algorithms that are used to analyze the victim’s heart rhythm are accurate. AEDs will deliver a shock only when VF or its precursor, rapid ventricular tachycardia, is present and will not deliver a shock to a person with a normal heart rhythm.15
The success of the actions of rescuers at the scene of an SCA is time critical. Several studies have documented the effects of time to defibrillation and the effects of bystander CPR on survival from SCA. For every minute that passes between collapse and defibrillation, survival from witnessed VF SCA falls 7% to 10% if no CPR is provided.11 When bystander CPR is provided, the fall in survival is more gradual and averages 3% to 4% per minute from collapse to defibrillation.11,16 CPR can double11,16 or triple17 survival from witnessed SCA at any interval to defibrillation.
Lay rescuer AED programs may increase the number of SCA victims who receive bystander CPR and can reduce time to defibrillation. These programs require an organized and practiced response with rescuers trained and equipped to recognize emergencies, activate the EMS system, provide CPR, and provide defibrillation. Small studies of lay rescuer AED programs in airports18 and casinos19,20 and with police officers14,21–23 have demonstrated a 49% to 74% survival rate from out-of-hospital witnessed VF SCA when immediate bystander CPR is provided and defibrillation occurs within 3 to 5 minutes of collapse. These high survival rates, however, are attained only in programs that reduce time to defibrillation.24
The PAD Trial
The PAD trial involved 993 facilities in 24 urban and suburban regions in North America and reported outcomes from 239 episodes of out-of-hospital SCA with attempted resuscitation.5 A facility was included if it had a history of at least 1 out-of-hospital cardiac arrest every 2 years or if at least 1 out-of-hospital cardiac arrest was predicted during the study period. Each study site was required to have clearly defined geographic boundaries and a typical EMS response interval of 3 to 15 minutes.
Methods
Participating sites were urban and suburban communities served by EMS systems that provide advanced life support. Each site identified distinct units within their service area (eg, buildings, public areas). These units were randomly allocated to train and equip volunteers to provide either CPR only or CPR plus AED response. All of the volunteer rescuers received rigorous, standard training to recognize SCA, phone 9-1-1, and perform CPR according to AHA recommendations. Volunteers at the sites offering CPR plus AED response also were trained and equipped to use AEDs. At CPR-plus-AED sites, AEDs were placed to enable volunteers to retrieve and deliver an AED to a victim of SCA within 3 minutes of collapse.
The trial was conducted from July 2000 through September 2003. Approximately 20 000 volunteers received training in programs that offered frequent retraining and refresher drills. More than 1600 AEDs were placed to conduct the trial. Most (84%) of the study facilities were in public locations such as recreational facilities and shopping centers. Additional details of the study design and methodology have been published.25
Results
In the units providing only bystander CPR, 15 of 107 persons experiencing definite cardiac arrest (ie, an arrest of cardiac origin with rhythm identification) survived to hospital discharge. In the units providing bystander CPR plus AED response, 30 of 128 victims of definite cardiac arrest survived to discharge. This increase in the number of survivors of definite cardiac arrest in units with CPR plus AED response compared with the number of survivors in the units providing CPR response alone was statistically significant (P<0.05).26
In this study, nearly two thirds of all victims of SCA in both groups received bystander CPR. Compared with sites with CPR-only response, sites with CPR plus AED response had a shorter interval from collapse to first rhythm assessment (6 versus 8.7 minutes) and a higher incidence of VF (57% versus 47%). These differences were statistically significant. No inappropriate shocks were delivered. Adverse events were rare and consisted chiefly of stolen AEDs and transient psychological stress among rescuers.
It is important to note that residential sites represented 16% of the study sites and accounted for 28% of the cardiac arrests but <5% of the survivors. The study lacked statistical power to detect whether lay rescuer AED programs increase survival from SCA in residential settings.
Implications for Public Policy
Estimates of the incidence of SCA in the United States vary widely because SCA is not a reportable disease or cause of death. In the PAD study, the observed number of cardiac arrests during the study period was substantially lower (<50%) than the number predicted. This correlates with recent data suggesting that the incidence of SCA may be 0.5 per 1000 adults >35 years old.6,7 To quantify the problem and evaluate the effect of any interventions designed to reduce death from SCA, this cause of death must be reportable.
EMS databases may enable the identification of sites of cardiac arrests to better pinpoint priority sites for lay rescuer AED programs. Although the organization of information in state EMS databases varies widely, recent attempts to collect national EMS data have been encouraging.
The PAD trial5 confirms the value of the elements of the chain of survival in improving the outcome of SCA. The trial supports current AHA recommendations for lay rescuer AED programs and the emphasis on planning, training, practice of CPR, and use of AEDs. Early recognition, early CPR, and early defibrillation all contribute to an increased chance of survival from out-of-hospital SCA. The authors note that if the increased number of survivors from the PAD trial is extrapolated to all episodes of out-of-hospital SCA that occur in public locations annually in the United States, then 2000 to 4000 additional lives can be saved every year with widespread implementation of lay rescuer community AED programs. This would require the placement of AEDs in those public locations with a high incidence or likelihood of SCA (see the Figure).27
Public locations with high incidence of SCA in Seattle and King County, Washington, 1990 to 1994 (n=134). Adapted with permission from Becker et al.27 Copyright 1998 American Heart Association.
In the PAD trial, survival with structured lay rescuer programs that included bystander CPR response was higher than previously reported by traditional EMS systems.5 This implies that public sites that do not provide AED programs may still improve survival from SCA by training volunteers to recognize cardiac arrest, phone 9-1-1, and give bystander CPR before the arrival of EMS providers.
Lay rescuer AED programs will be most cost effective if they are present at sites where at least 1 witnessed SCA is likely to occur every few years. In the PAD trial, sites were enrolled if there were at least 250 adults >50 years old present at the site during waking hours (16 hours per day). Other criteria (eg, presence of high-risk persons) that can be used to select AED program sites are posted on the AED website (http://www.americanheart.org/ecc/PAD).
It is important to note that the PAD trial was not designed to evaluate home defibrillation or defibrillation provided by untrained rescuers. A national study is under way to evaluate home defibrillation, and the results of this study are expected to provide additional information about the potential benefits of home AED programs.
The AHA recommends critical elements for lay rescuer AED programs: healthcare provider oversight and planning, training of anticipated rescuers in CPR and use of the AED, link with the EMS system, and a plan for maintenance and quality improvement monitoring.4 The AHA has particularly emphasized the importance of training rescuers and the development and practice of a structured response plan. Even in the PAD trial, with rescuers trained to respond to SCA, resuscitation was attempted for only half of the witnessed SCA victims, and the on-site AED was used for only about one third of SCA victims. These findings suggest that rescuers may need more training or practice than that offered in the study and document that the mere presence of an AED does not ensure that it will be used when SCA occurs.
The selection of sites for potential lay rescuer AED programs and the placement of the AEDs within the site are important in the planning for the program. Published data about the most likely sites of SCA in the community27 can be used to identify potential sites for these lay rescuer AED programs (see the Figure). The AHA recommends that the AEDs be placed in the site so that they can be reached within a 1- to 1.5-minute brisk walk from any location.
Implications for Future AHA Activities
The promotion of PAD programs is an important component of the AHA’s comprehensive strategy to prevent heart disease and stroke through risk factor prevention, identification and control, early identification and treatment of acute events, and prevention of recurrent events. The PAD trial results validate the importance of the AHA chain of survival in improving outcome from out-of-hospital witnessed SCA. The results document the importance of program planning, rescuer training, the link with the local EMS system, and a system of device maintenance and quality improvement monitoring in lay rescuer AED programs to improve outcome from SCA.
All states have passed legislation or regulations that allow lay rescuer AED programs, but the heterogeneity of the state laws has created confusion for lay rescuers and has complicated attempts to establish lay rescuer AED programs. An AHA scientific statement is being developed that will delineate critical state legislative components and implementation strategies for lay rescuer AED programs.
The PAD trial results are being carefully reviewed by AHA resuscitation experts to refine recommendations for resuscitation and lay rescuer AED programs. In addition, the researchers gained experience in obtaining community informed consent and institutional review board approval.28 For further information about lay rescuer AED programs, see http://www.americanheart.org/ecc/PAD.
Acknowledgments
Writing Group Disclosures
Reviewer Disclosures
Footnotes
The American Heart Association makes every effort to avoid any actual or potential conflicts of interest that may arise as a result of an outside relationship or a personal, professional, or business interest of a member of the writing panel. Specifically, all members of the writing group are required to complete and submit a Disclosure Questionnaire showing all such relationships that might be perceived as real or potential conflicts of interest.
This statement was approved by the American Heart Association Science Advisory and Coordinating Committee on April 11, 2005. A single reprint is available by calling 800-242-8721 (US only) or writing the American Heart Association, Public Information, 7272 Greenville Ave, Dallas, TX 75231-4596. Ask for reprint No. 71-0325. To purchase additional reprints: up to 999 copies, call 800-611-6083 (US only) or fax 413-665-2671; 1000 or more copies, call 410-528-4121, fax 410-528-4264, or e-mail kgray@lww.com. To make photocopies for personal or educational use, call the Copyright Clearance Center, 978-750-8400.
Expert peer review of AHA Scientific Statements is conducted at the AHA National Center. For more on AHA statements and guidelines development, visit http://www.americanheart.org/presenter.jhtml;identifier=3023366.
References
Weisfeldt M, Kerber R, McGoldrick RP, Moss AJ, Nichol G, Ornato JP, Palmer DG, Riegel B, Smith SC Jr. Public access defibrillation: a statement for healthcare professionals from the American Heart Association Task Force on Automatic External Defibrillation. Circulation. 1995; 92: 2763.
Weisfeldt ML, Kerber RE, McGoldrick RP, Moss AJ, Nichol G, Ornato JP, Palmer DG, Riegel B, Smith SC Jr. American Heart Association Report on the Public Access Defibrillation Conference December 8–10, 1994. Automatic External Defibrillation Task Force. Circulation. 1995; 92: 2740–2747.
Nichol G, Hallstrom AP, Kerber R, Moss AJ, Ornato JP, Palmer D, Riegel B, Smith S Jr, Weisfeldt ML. American Heart Association report on the second public access defibrillation conference, April 17–19, 1997. Circulation. 1998; 97: 1309–1314.
Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Part 4: the automated external defibrillator: key link in the chain of survival. The American Heart Association in Collaboration with International Liaison Committee on Resuscitation. Circulation. 2000; 102 (suppl I): I-60–I-76.
PAD Trial Investigators. Public-access defibrillation and survival after out-of-hospital cardiac arrest. N Engl J Med. 2004; 351: 637–646.
Rea TD, Eisenberg MS, Sinibaldi G, White RD. Incidence of EMS-treated out-of-hospital cardiac arrest in the United States. Resuscitation. 2004; 63: 17–24.
Chugh SS, Jui J, Gunson K, Stecker EC, John BT, Thompson B, Ilias N, Vickers C, Dogra V, Daya M, Kron J, Zheng ZJ, Mensah G, McAnulty J. Current burden of sudden cardiac death: multiple source surveillance versus retrospective death certificate-based review in a large U.S. community. J Am Coll Cardiol. 2004; 44: 1268–1275.
Cobb LA, Fahrenbruch CE, Olsufka M, Copass MK. Changing incidence of out-of-hospital ventricular fibrillation, 1980–2000. JAMA. 2002; 288: 3008–3013.
Zheng ZJ, Croft JB, Giles WH, Mensah GA. Sudden cardiac death in the United States, 1989 to 1998. Circulation. 2001; 104: 2158–2163.
American Heart Association. Heart Disease and Stroke Statistics—2005 Update. Dallas, Tex: American Heart Association; 2004.
Larsen MP, Eisenberg MS, Cummins RO, Hallstrom AP. Predicting survival from out-of-hospital cardiac arrest: a graphic model. Ann Emerg Med. 1993; 22: 1652–1658.
Cummins RO, Ornato JP, Thies WH, Pepe PE. Improving survival from sudden cardiac arrest: the "chain of survival" concept: a statement for health professionals from the Advanced Cardiac Life Support Subcommittee and the Emergency Cardiac Care Committee, American Heart Association. Circulation. 1991; 83: 1832–1847.
Cobb LA, Fahrenbruch CE, Walsh TR, Copass MK, Olsufka M, Breskin M, Hallstrom AP. Influence of cardiopulmonary resuscitation prior to defibrillation in patients with out-of-hospital ventricular fibrillation. JAMA. 1999; 281: 1182–1188.
White RD, Russell JK. Refibrillation, resuscitation and survival in out-of-hospital sudden cardiac arrest victims treated with biphasic automated external defibrillators. Resuscitation. 2002; 55: 17–23.
Kerber RE, Becker LB, Bourland JD, Cummins RO, Hallstrom AP, Michos MB, Nichol G, Ornato JP, Thies WH, White RD, Zuckerman BD. Automatic external defibrillators for public access defibrillation: recommendations for specifying and reporting arrhythmia analysis algorithm performance, incorporating new waveforms, and enhancing safety: a statement for health professionals from the American Heart Association Task Force on Automatic External Defibrillation, Subcommittee on AED Safety and Efficacy. Circulation. 1997; 95: 1677–1682.
Valenzuela TD, Roe DJ, Cretin S, Spaite DW, Larsen MP. Estimating effectiveness of cardiac arrest interventions: a logistic regression survival model. Circulation. 1997; 96: 3308–3313.
Holmberg M, Holmberg S, Herlitz J. Effect of bystander cardiopulmonary resuscitation in out-of-hospital cardiac arrest patients in Sweden. Resuscitation. 2000; 47: 59–70.
Caffrey SL, Willoughby PJ, Pepe PE, Becker LB. Public use of automated external defibrillators. N Engl J Med. 2002; 347: 1242–1247.
Valenzuela TD, Bjerke HS, Clark LL, Hardman R, Spaite DW, Nichol, G. Rapid defibrillation by nontraditional responders: the Casino project. Acad Emerg Med. 1998; 5: 414–415.Abstract.
Valenzuela TD, Roe DJ, Nichol G, Clark LL, Spaite DW, Hardman RG. Outcomes of rapid defibrillation by security officers after cardiac arrest in casinos. N Engl J Med. 2000; 343: 1206–1209.
White R, Asplin B, Bugliosi T, Hankins D. High discharge survival rate after out-of-hospital ventricular fibrillation with rapid defibrillation by police and paramedics. Ann Emerg Med. 1996; 28: 480–485.
White RD. Early out-of-hospital experience with an impedance-compensating low-energy biphasic waveform automatic external defibrillator. J Interv Card Electrophysiol. 1997; 1: 203–210.
White RD, Hankins DG, Bugliosi TF. Seven years’ experience with early defibrillation by police and paramedics in an emergency medical services system. Resuscitation. 1998; 39: 145–151.
Groh WJ, Newman MM, Beal PE, Fineberg NS, Zipes DP. Limited response to cardiac arrest by police equipped with automated external defibrillators: lack of survival benefit in suburban and rural Indiana—the police as responder automated defibrillation evaluation (PARADE). Acad Emerg Med. 2001; 8: 324–330.
Ornato JP, McBurnie MA, Nichol G, Salive M, Weisfeldt M, Riegel B, Christenson J, Terndrup T, Daya M; PAD Trial Investigators. The Public Access Defibrillation (PAD) trial: study design and rationale. Resuscitation. 2003; 56: 135–147.
Sayre MR, Travers AH, Daya M, Greene HL, Salive ME, Vijayaraghavan K, Craven RA, Groh WJ, Hallstrom AP; PAD Investigators. Measuring survival rates from sudden cardiac arrest: the elusive definition. Resuscitation. 2004; 62: 25–34.
Becker L, Eisenberg M, Fahrenbruch C, Cobb L. Public locations of cardiac arrest: implications for public access defibrillation. Circulation. 1998; 97: 2106–2109.
Mosesso VN Jr, Brown LH, Greene HL, Schmidt TA, Aufderheide TP, Sayre MR, Stephens SW, Travers A, Craven RA, Weisfeldt ML; PAD Trial Investigators. Conducting research using the emergency exception from informed consent: the Public Access Defibrillation (PAD) Trial experience. Resuscitation. 2004; 61: 29–36.(Mary F. Hazinski, RN, MSN)
Lay rescuer automated external defibrillator (AED) programs may increase the number of people experiencing sudden cardiac arrest who receive bystander cardiopulmonary resuscitation (CPR), can reduce time to defibrillation, and may improve survival from sudden cardiac arrest. These programs require an organized and practiced response, with rescuers trained and equipped to recognize emergencies, activate the emergency medical services system, provide CPR, and provide defibrillation. To determine the effect of public access defibrillation (PAD) programs on survival and other outcomes after SCA, the National Heart, Lung, and Blood Institute, the American Heart Association (AHA), and others funded a large prospective randomized trial. The results of this study were recently published in The New England Journal of Medicine and support current AHA recommendations for lay rescuer AED programs and emphasis on planning, training, and practice of CPR and use of AEDs. The purpose of this statement is to highlight important findings of the Public Access Defibrillation Trial and summarize implications of these findings for healthcare providers, healthcare policy advocates, and the AHA training network.
Key Words: AHA Science Advisory ; defibrillation ; heart arrest ; fibrillation ; cardiopulmonary resuscitation
Introduction
Since 1995, the American Heart Association (AHA) has promoted the development of lay rescuer automated external defibrillator (AED) programs to improve survival from out-of-hospital sudden cardiac arrest (SCA).1–3 These programs are also known as "public access" defibrillation (PAD) programs. The AHA has emphasized the importance of organization, planning, and training to maximize effectiveness of these programs.4
To determine the effect of PAD programs on survival and other outcomes after SCA, the National Heart, Lung and Blood Institute (NHLBI), the AHA, and others funded a large prospective randomized trial. The results of this study were published recently in The New England Journal of Medicine.5 The purpose of the present statement is to highlight important findings of the Public Access Defibrillation (PAD) trial and summarize implications of these findings for healthcare providers, healthcare policy advocates, and the AHA training network.
Background
Although estimates of the annual number of deaths caused by out-of-hospital SCA in the United States vary widely,6–9 the AHA estimates that 250 000 people die in the United States each year from SCA outside the hospital setting.10 At the time of first heart rhythm analysis, 40% of SCA victims demonstrate ventricular fibrillation (VF), an abnormal heart rhythm that causes the heart to quiver so that it is unable to pump blood effectively.8 It is likely that an even higher proportion of people with SCA have VF at the time of collapse. Many people who experience sudden VF cardiac arrest can survive if bystanders act immediately. If VF is untreated, then cardiac standstill will develop, and successful resuscitation will be unlikely.11
The AHA has traditionally used 4 links in a chain to illustrate the important actions that can create a "chain of survival" for victims of VF SCA.12 These links are as follows:
Early recognition of the emergency and activation of the emergency medical services (EMS) system ("9-1-1").
Early bystander cardiopulmonary resuscitation (CPR).
Early delivery of a shock with a defibrillator.
Early advanced life support.
Bystanders can now perform 3 of the links in this chain. Bystander recognition of the emergency and EMS activation are critical first steps in response to an SCA, ensuring that basic and advanced life support providers are dispatched to the site of the arrest. In most communities, the time interval from collapse to the arrival of EMS personnel is 7 to 8 minutes or longer. This means that the victim depends on the actions of bystanders and local rescuers to perform the first 2 or 3 links in the chain of survival during the first minutes after SCA.
Bystanders need to provide immediate CPR for victims of SCA. CPR provides blood flow to the heart and brain. In addition, CPR increases the likelihood that a shock delivered by a defibrillator will terminate the VF and that the heart will resume an effective rhythm after defibrillation. These effects of CPR appear to be particularly important if shock delivery does not occur for 4 minutes after collapse.13 Defibrillation does not "restart" the heart; defibrillation stops VF and allows the heart to resume a normal rhythm. In the first few minutes after defibrillation, the heart rhythm may be slow and the heart may not pump blood effectively. CPR may be needed for several minutes after defibrillation until adequate heart function resumes.14
Lay rescuers can use computerized devices called AEDs to deliver a shock to victims of VF cardiac arrest. The rescuer attaches the AED to the victim with adhesive pads or electrodes. The AED records and analyzes the victim’s ECG rhythm, informs the rescuer if a shock is needed, and provides voice and audio prompts to guide the rescuer through all steps of AED use. The AED computerized algorithms that are used to analyze the victim’s heart rhythm are accurate. AEDs will deliver a shock only when VF or its precursor, rapid ventricular tachycardia, is present and will not deliver a shock to a person with a normal heart rhythm.15
The success of the actions of rescuers at the scene of an SCA is time critical. Several studies have documented the effects of time to defibrillation and the effects of bystander CPR on survival from SCA. For every minute that passes between collapse and defibrillation, survival from witnessed VF SCA falls 7% to 10% if no CPR is provided.11 When bystander CPR is provided, the fall in survival is more gradual and averages 3% to 4% per minute from collapse to defibrillation.11,16 CPR can double11,16 or triple17 survival from witnessed SCA at any interval to defibrillation.
Lay rescuer AED programs may increase the number of SCA victims who receive bystander CPR and can reduce time to defibrillation. These programs require an organized and practiced response with rescuers trained and equipped to recognize emergencies, activate the EMS system, provide CPR, and provide defibrillation. Small studies of lay rescuer AED programs in airports18 and casinos19,20 and with police officers14,21–23 have demonstrated a 49% to 74% survival rate from out-of-hospital witnessed VF SCA when immediate bystander CPR is provided and defibrillation occurs within 3 to 5 minutes of collapse. These high survival rates, however, are attained only in programs that reduce time to defibrillation.24
The PAD Trial
The PAD trial involved 993 facilities in 24 urban and suburban regions in North America and reported outcomes from 239 episodes of out-of-hospital SCA with attempted resuscitation.5 A facility was included if it had a history of at least 1 out-of-hospital cardiac arrest every 2 years or if at least 1 out-of-hospital cardiac arrest was predicted during the study period. Each study site was required to have clearly defined geographic boundaries and a typical EMS response interval of 3 to 15 minutes.
Methods
Participating sites were urban and suburban communities served by EMS systems that provide advanced life support. Each site identified distinct units within their service area (eg, buildings, public areas). These units were randomly allocated to train and equip volunteers to provide either CPR only or CPR plus AED response. All of the volunteer rescuers received rigorous, standard training to recognize SCA, phone 9-1-1, and perform CPR according to AHA recommendations. Volunteers at the sites offering CPR plus AED response also were trained and equipped to use AEDs. At CPR-plus-AED sites, AEDs were placed to enable volunteers to retrieve and deliver an AED to a victim of SCA within 3 minutes of collapse.
The trial was conducted from July 2000 through September 2003. Approximately 20 000 volunteers received training in programs that offered frequent retraining and refresher drills. More than 1600 AEDs were placed to conduct the trial. Most (84%) of the study facilities were in public locations such as recreational facilities and shopping centers. Additional details of the study design and methodology have been published.25
Results
In the units providing only bystander CPR, 15 of 107 persons experiencing definite cardiac arrest (ie, an arrest of cardiac origin with rhythm identification) survived to hospital discharge. In the units providing bystander CPR plus AED response, 30 of 128 victims of definite cardiac arrest survived to discharge. This increase in the number of survivors of definite cardiac arrest in units with CPR plus AED response compared with the number of survivors in the units providing CPR response alone was statistically significant (P<0.05).26
In this study, nearly two thirds of all victims of SCA in both groups received bystander CPR. Compared with sites with CPR-only response, sites with CPR plus AED response had a shorter interval from collapse to first rhythm assessment (6 versus 8.7 minutes) and a higher incidence of VF (57% versus 47%). These differences were statistically significant. No inappropriate shocks were delivered. Adverse events were rare and consisted chiefly of stolen AEDs and transient psychological stress among rescuers.
It is important to note that residential sites represented 16% of the study sites and accounted for 28% of the cardiac arrests but <5% of the survivors. The study lacked statistical power to detect whether lay rescuer AED programs increase survival from SCA in residential settings.
Implications for Public Policy
Estimates of the incidence of SCA in the United States vary widely because SCA is not a reportable disease or cause of death. In the PAD study, the observed number of cardiac arrests during the study period was substantially lower (<50%) than the number predicted. This correlates with recent data suggesting that the incidence of SCA may be 0.5 per 1000 adults >35 years old.6,7 To quantify the problem and evaluate the effect of any interventions designed to reduce death from SCA, this cause of death must be reportable.
EMS databases may enable the identification of sites of cardiac arrests to better pinpoint priority sites for lay rescuer AED programs. Although the organization of information in state EMS databases varies widely, recent attempts to collect national EMS data have been encouraging.
The PAD trial5 confirms the value of the elements of the chain of survival in improving the outcome of SCA. The trial supports current AHA recommendations for lay rescuer AED programs and the emphasis on planning, training, practice of CPR, and use of AEDs. Early recognition, early CPR, and early defibrillation all contribute to an increased chance of survival from out-of-hospital SCA. The authors note that if the increased number of survivors from the PAD trial is extrapolated to all episodes of out-of-hospital SCA that occur in public locations annually in the United States, then 2000 to 4000 additional lives can be saved every year with widespread implementation of lay rescuer community AED programs. This would require the placement of AEDs in those public locations with a high incidence or likelihood of SCA (see the Figure).27
Public locations with high incidence of SCA in Seattle and King County, Washington, 1990 to 1994 (n=134). Adapted with permission from Becker et al.27 Copyright 1998 American Heart Association.
In the PAD trial, survival with structured lay rescuer programs that included bystander CPR response was higher than previously reported by traditional EMS systems.5 This implies that public sites that do not provide AED programs may still improve survival from SCA by training volunteers to recognize cardiac arrest, phone 9-1-1, and give bystander CPR before the arrival of EMS providers.
Lay rescuer AED programs will be most cost effective if they are present at sites where at least 1 witnessed SCA is likely to occur every few years. In the PAD trial, sites were enrolled if there were at least 250 adults >50 years old present at the site during waking hours (16 hours per day). Other criteria (eg, presence of high-risk persons) that can be used to select AED program sites are posted on the AED website (http://www.americanheart.org/ecc/PAD).
It is important to note that the PAD trial was not designed to evaluate home defibrillation or defibrillation provided by untrained rescuers. A national study is under way to evaluate home defibrillation, and the results of this study are expected to provide additional information about the potential benefits of home AED programs.
The AHA recommends critical elements for lay rescuer AED programs: healthcare provider oversight and planning, training of anticipated rescuers in CPR and use of the AED, link with the EMS system, and a plan for maintenance and quality improvement monitoring.4 The AHA has particularly emphasized the importance of training rescuers and the development and practice of a structured response plan. Even in the PAD trial, with rescuers trained to respond to SCA, resuscitation was attempted for only half of the witnessed SCA victims, and the on-site AED was used for only about one third of SCA victims. These findings suggest that rescuers may need more training or practice than that offered in the study and document that the mere presence of an AED does not ensure that it will be used when SCA occurs.
The selection of sites for potential lay rescuer AED programs and the placement of the AEDs within the site are important in the planning for the program. Published data about the most likely sites of SCA in the community27 can be used to identify potential sites for these lay rescuer AED programs (see the Figure). The AHA recommends that the AEDs be placed in the site so that they can be reached within a 1- to 1.5-minute brisk walk from any location.
Implications for Future AHA Activities
The promotion of PAD programs is an important component of the AHA’s comprehensive strategy to prevent heart disease and stroke through risk factor prevention, identification and control, early identification and treatment of acute events, and prevention of recurrent events. The PAD trial results validate the importance of the AHA chain of survival in improving outcome from out-of-hospital witnessed SCA. The results document the importance of program planning, rescuer training, the link with the local EMS system, and a system of device maintenance and quality improvement monitoring in lay rescuer AED programs to improve outcome from SCA.
All states have passed legislation or regulations that allow lay rescuer AED programs, but the heterogeneity of the state laws has created confusion for lay rescuers and has complicated attempts to establish lay rescuer AED programs. An AHA scientific statement is being developed that will delineate critical state legislative components and implementation strategies for lay rescuer AED programs.
The PAD trial results are being carefully reviewed by AHA resuscitation experts to refine recommendations for resuscitation and lay rescuer AED programs. In addition, the researchers gained experience in obtaining community informed consent and institutional review board approval.28 For further information about lay rescuer AED programs, see http://www.americanheart.org/ecc/PAD.
Acknowledgments
Writing Group Disclosures
Reviewer Disclosures
Footnotes
The American Heart Association makes every effort to avoid any actual or potential conflicts of interest that may arise as a result of an outside relationship or a personal, professional, or business interest of a member of the writing panel. Specifically, all members of the writing group are required to complete and submit a Disclosure Questionnaire showing all such relationships that might be perceived as real or potential conflicts of interest.
This statement was approved by the American Heart Association Science Advisory and Coordinating Committee on April 11, 2005. A single reprint is available by calling 800-242-8721 (US only) or writing the American Heart Association, Public Information, 7272 Greenville Ave, Dallas, TX 75231-4596. Ask for reprint No. 71-0325. To purchase additional reprints: up to 999 copies, call 800-611-6083 (US only) or fax 413-665-2671; 1000 or more copies, call 410-528-4121, fax 410-528-4264, or e-mail kgray@lww.com. To make photocopies for personal or educational use, call the Copyright Clearance Center, 978-750-8400.
Expert peer review of AHA Scientific Statements is conducted at the AHA National Center. For more on AHA statements and guidelines development, visit http://www.americanheart.org/presenter.jhtml;identifier=3023366.
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