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Public Access Defibrillators and Fire Extinguishers: Are Comparisons Reasonable?
Public Access Defibrillators and Fire Extinguishers: Are Comparisons Reasonable? Howard K. Mell and Michael R. Sayre
Sudden cardiac death is a major cause of mortality in the United States of America (Circulation 2008;117:e25-146) with approximately 310000 deaths related to coronary heart disease occurring in emergency departments or in the prehospital environment annually. Several organizations have directed resources toward the treatment of sudden cardiac arrest through a paradigm that has come to be known as the “chain of survival”—prompt activation of emergency response by telephone 911, early bystander cardiopulmonary resuscitation, early defibrillation, and timely advanced cardiac life support (Circulation 1991;83:1832-1847). The ready availability of automated external defibrillators (AEDs) has been advocated as a key component of this chain. Some authors have suggested a “fire extinguisher model” for AED deployment (Circulation 1998;98:2334-2351; Resuscitation 1995;30:151-156; Ann Intern Med 2001;135:990-998). In this model, AEDs are prominently displayed in public places for use by laypersons, much like fire extinguishers. For example, in Chicago's O'Hare Airport, AEDs are placed alongside fire extinguishers in the public concourses (N Engl J Med 2002;347:1242-1247). Advocates of this model suggest that advancing this practice would be a means to widely disburse lifesaving technology that is easy to use. Several experts have questioned this model, suggesting that the costeffectiveness of distributing AEDs this widely would be prohibitive (BMJ 2002;325:515; Curr Opin Cardiol 2007;22:5-10; BMJ 2003;326:162; Int J Technol Assess Health Care 2007;23:362-367) and may not be more effective than more targeted distribution of AEDs. This literature review will examine the
From the Department of Emergency Medicine, College of Medicine, The Ohio State University, Columbus, OH. Address reprint requests to Michael R. Sayre, MD, Department of Emergency Medicine, College of Medicine, The Ohio State University, 141 Means Hall, 1654 Upham Drive, Columbus, OH 43210-1228, USA. E-mail: [email protected] 0033-0620/$ - see front matter n 2008 Elsevier Inc. All rights reserved. doi: doi:10.1016/j.pcad.2008.05.003
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available data on both AEDs and fire extinguishers to determine if these comparisons are reasonable as a means of guiding public policy. n 2008 Elsevier Inc. All rights reserved.
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ublicly accessible fire-fighting equipment is a tradition that extends to the “bucket brigades” present in the 1700s. Homeowners used to place leather buckets on their doorsteps, and when a fire alarm sounded, each man would race from his home, bucket in hand to help extinguish a fire.1 British Captain George William Manby is generally credited with the invention of the “Extincteur,” a copper vessel filled with soda ash propelled by compressed air—the first modern fire extinguisher, in 1816.2 A United States Patent was issued to Almon M. Granger in 1880 for a fire extinguisher that relied on a chemical reaction to generate a gas to propel water from a tank3 in a design quite similar to today's fire extinguishers. Modern fire extinguishers in the United States are generally classified as type A, B, C, or D (or some combination thereof).4 This classification system is based on the types of fires expected to be extinguished.4 Type A fires are those fueled by common flammable goods (eg, paper, wood, etc).4 Type B fires involve flammable liquids such as gasoline.4 Type C fires are complicated by the presence of energized electrical equipment.4 Type D fires are those involving heavy metals—where use of water may prove harmful.4 Fire extinguishers are generally required to be placed in public buildings at set intervals, according to the building's purpose, construction, and expected occupancy.4,5 The rules for fire extinguisher placement are contained within a “building code”—a set of life safety rules adopted by a state or local government to guide building construction.5 Because these codes are extensive and involve a high degree of expertise in fire protection engineering, building design, architecture, and ergonomics, most entities with the
Progress in Cardiovascular Diseases, Vol. 51, No. 3 (November/December), 2008: pp 204-212
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authority to enact and enforce codes purchase the right to use a model code from specialty groups (such as the National Fire Protection Association [NFPA] or the International Code Council [formerly known as the Building Officials and Code Administrators International]) and adapt them as needed for local use. The Occupational Health and Safety Administration also regulates the placement and availability of fire extinguishers in the workplace (eg, 29 CFR 1910.157). Interestingly, neither Occupational Health and Safety Administration1, International Code Council, nor the NFPA mandate the placement, or even availability, of automated external defibrillators (AEDs) in their codes or regulations. As early as 1979,6 scientists recognized the potential for AEDs to save lives. Over time, advances in technology have increased the portability, diagnostic accuracy, and therapeutic efficacy of these devices.7 In their most modern form, these devices are capable of highly accurate cardiac rhythm analysis and delivery of a biphasic electrical shock with a minimum of operator input or action.7 Some models even prompt and instruct the rescuer on the provision of cardiopulmonary resuscitation (CPR). Since 1991, the American Heart Association (AHA) has supported the idea that survival from out-of-hospital sudden cardiac arrest (SCA) could be markedly improved by layperson rescuers using AEDs.8 The AHA has emphasized the importance of a coordinated approach of planning, organizing, and training as a means to maximize the effectiveness of these programs.9 The National Heart Lung and Blood Institute, the AHA, and others supported the creation of a large prospective randomized trial of public access defibrillation programs named the Public Access Defibrillation (PAD) Trial.10 The findings of this study resoundingly support public access defibrillation.9,10 The results of this trial, and other studies, provide considerable guidance for medical professionals on the topic of public access defibrillation. Although the potential impact of widespread access to AEDs is as yet unclear, there 1 While OSHA recommends AED availability in the workplace, and hosts a website of AED resources for employers (http://www.osha.gov/SLTC/aed/index.html), no federal regulation or standard interpretation of regulations mandates AED availability.
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exists a wide body of literature supporting the integration of AEDs into layperson and professional rescuer CPR.11 There are commonalities between fire extinguishers and AEDs that invite comparison. Both are relatively portable devices designed to save lives. Each requires some level of maintenance or inspection to ensure proper function when needed.5,12 Each requires a person to directly act and intervene against the perceived life threat (as opposed to an automatic sprinkler system). Each provides a “bridge” until professional assistance (ie, fire service or Emergency Medical Services) can arrive. However, there are some common misperceptions regarding fire extinguishers that make comparisons between them and AEDs problematic. First, there is a significant difference in the amount of fire that a trained firefighter can extinguish with any given fire extinguisher and the amount that a layperson can extinguish.4 Automated external defibrillators are nearly equally as effective in the hands of experts as they are when used by laypersons.13,14 Second, firefighting, even in small, incipient fires, is hazardous.15 Four percent of all fire deaths in the United States reported through the National Fire Incident Reporting System occurred while the decedent was attempting to extinguish the fire, whereas no significant injuries have been reported from using an AED.15 Third, there is an inference, through the basis of the comparisons alone, that fire extinguishers represent a “cost-effective” public health intervention. Given that the number of fire deaths in the United States is extremely low (when compared with other causes of death) and has been for many decades, the costs per life saved are not necessarily “effective.”16 Lastly, there are questions of time constraints and alternatives. If a fire is discovered at its incipient stage (when it would be safe for a layperson to extinguish it), evacuation is an effective option to prevent mortality. However, early defibrillation is key in the prevention of mortality from SCA and is more effective than CPR alone.11 This question can be extended to assess the effects of time until professional rescuers can respond. Is there a definable period before a fire is “out of control” and escape impossible without a fire extinguisher or professional assistance? There is
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such a time sensitivity defined in SCA.17-20 This review will analyze the data available on the training needed, risks of using, cost-effectiveness, and time sensitivity of both AEDs, and fire extinguishers to assess the validity of their increasingly frequent comparisons.
Training Automated external defibrillators are extremely easy to use. The time to defibrillation using an AED was compared between untutored sixth grade children and paramedics trained in AED use, and the difference in mean time to defibrillation was only 23 seconds.14 A more recent study by Kelley et al21 found that eighth grade public school students could be taught continuous chest compression CPR and AED use in a 1-hour program with excellent retention at 4 weeks. Interactive computer training or interactive computer training plus instructor-led practice was compared with traditional classroom instruction in teaching CPR and AED use to high school students.22 The mean scores for “key AED actions” were greater than 80% for all groups in both initial testing and follow-up evaluation. All groups scored better than 95% at turning on the AED and pressing the shock button if indicated, both on initial training and reevaluation at 2 months.22 All groups also scored better than 80% at knowing to continue CPR until an AED was available both on initial training and reevaluation.22 These studies were performed using children who were likely comfortable with technology. Although this may color the results somewhat, AED use is simple enough that reasonable results can be expected by the naive user and skills are retained by those trained in its use. In an evaluation of skill retention of more than 3700 adults trained in CPR and AED use, 84% were able to adequately demonstrate AED use skills as remote as 17 months after their training.23 Interestingly, an evaluation of the English National Defibrillator Programme suggested that although significant skill deterioration was demonstrated between 7 and 12 months in terms of CPR performance, the time to first shock with AED use did not significantly change.24 This suggests that AED use skill retention persists longer than that of CPR.
Unfortunately, fire extinguishers are not as simple to use. A nonexpert user is expected to extinguish only 40% of the square footage of fire that an expert can using the same extinguisher.4 For example, in a class A fire (the most common type), a nonexpert user is most likely to only be capable of extinguishing 1 to 4 square feet of fire (using one of the more common types of extinguishers) vs the 2 1/2 to 10 square feet that a trained firefighter would be able to extinguish with the same equipment.4 The International Fire Service Training Association suggests that successful operation of fire extinguishers depends on the following: ○ Extinguisher is properly located. ○ Extinguisher is properly placed and in working order. ○ Extinguisher is of proper type for the fire which may occur. ○ Fire is discovered while still small enough for the extinguisher to be effective. ○ Fire is discovered by a person, ready, willing, and trained to use the extinguisher. {emphasis added} ○ Smoke created by burning materials allows approach. ○ Fire is accessible for a close approach with portable extinguishers.”5 This difficulty in use creates a problem in directly comparing AEDs to fire extinguishers. A nonexpert user can only be expected to put out a small, relatively contained fire producing minimal smoke. Such a fire does not immediately represent a serious threat to life. An AED only delivers a shock when a life is at risk. Nonexperts are reasonably as proficient as medical experts in the use of AEDs,13,14 and the machine is capable of determining if the proper conditions for use exist in a patient.25
Safety The safety of AEDs is supported by a study of 1654 businesses and private citizens who had owned AEDs for at least 1 year. The devices were applied to patients 213 times with no reports of rescuer or patient injuries resulting from AED use.26 Although patient outcome was not always known by the participants in the study, 4 persons resuscitated by
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laypersons were known to have survived to hospital admission and 2 of these known to survive to discharge.26 In an examination of adverse events related to public access defibrillators among the 1260 public and residential facilities in the United States and Canada during the PAD trial (spanning 26389 months of public availability and 3952 emergency episodes of which 649 were presumed cardiac arrests), only 36 adverse events were confirmed.27 Of these, 27 were related to the AED itself (20 cases of theft, 3 of the AED not being in an assigned location, and 4 “incidents of mechanical difficulty or battery failure”).27 No inappropriate shocks were delivered, and no device failed to shock when indicated.27 The remaining 7 adverse events involved the lay rescue personnel. One pulled a muscle during rescue efforts.27 Two reported feeling pressured by their employers to participate as first responders.27 Four individuals reported increased stress levels directly related to their rescue efforts that required follow-up or intervention.27 The most severely affected person reported responding to 2 events involving victims known to her personally, and she declined further participation in the study.27 A study of the psychological consequences to layperson responders in public access defibrillation found that the responders “demonstrated an apparently innate resilience to the adverse psychological effects of responding with an AED in a PAD scheme.”28 This study suggested that self protective mechanisms occurred naturally, outside of formal training.28 Placement of an AED in the home after an acute ischemic event was associated with a perceived decrease in quality of life for both patients and family members.29 Of the 158 families studied, 92 received training in CPR and AED use and were provided an AED, and 66 families were trained in CPR alone.29 Interestingly, those who received the AEDs and training in their use reported lower quality of life as measured on a standard tool; but this negative effect was small and not likely to be clinically significant.29 In contrast, attempting to extinguish a fire has been clearly demonstrated to be hazardous.15 A report from the NFPA indicates that of civilians killed by fire in the United States between 1999 and 2002, 4% perished while trying to fight fire.15 More telling are the statistics for nonfatal fire-related
civilian injuries. “Attempting to fight fire” was the leading activity at time of injury during both the 1999 to 2002 period as well between 1994 and 1998 (35% and 32%, respectively).15 In addition, studies have demonstrated that carrying and deploying a fire extinguisher causes an increased metabolic demand.30 When actually fighting a fire, this increased demand occurs in an atmosphere that may be oxygen depleted.4 A person attempting to extinguish a fire should be in a reasonable state of physical fitness to safely proceed.30 In a comparison to AEDs and fire extinguishers, the very real possibility of injury to the rescuer must be considered. Although no data were found to suggest that fire extinguishers encourage laypersons to attempt to fight fires, to use one places the operator at increased risk of injury or death.15 No such risks have been demonstrated with AED use.
Placement The AHA states, “lay rescuer AED programs will have the greatest potential impact on survival from SCA if the programs are created in locations where SCA is likely to occur.”31 The Public Access Defibrillation Trial placed AEDs in community facilities where a pool of potential volunteer responders existed and had the ability to deliver an AED within 3 minutes to a person having a cardiac arrest.10 Facilities in the study were “expected” to be the location of at least 1 out-ofhospital cardiac arrest during the study period and were those that had a history of at least one witnessed out-of-hospital cardiac arrest an average of every 2 years or those where the equivalent of at least 250 adults more than 50 years of age were present for at least 16 hours a day.10 Optimization of EMS systems to provide for rapid response by public safety first responders equipped with AEDs may be insufficient in many cases. Studies indicate that the outcome of defibrillation is time dependant.17–20 Different studies have examined various “cutoff” times for improved survivability; 2 (in hospital),17 4,18 5,19 and 6 minutes20 have all been identified as possible points after which outcomes appreciably worsen. A previous EMS industry standard of an EMS response in less than 8 minutes is insufficient.32 When analyzing the need for a public access defibrillator based on public safety first
208 responder response time to a given location, several factors besides distance from the first responders' post must be considered. A first responder unit must be dispatched, travel to the scene, travel to the patient, assess the situation, and deliver the necessary defibrillation. Campbell et al33 found a call receipt to vehicle at scene time of 5.98 minutes (95% confidence interval [CI], 4.4-7.3 minutes). The vehicle at scene to defibrillation was 3.6 minutes (95% CI, 2.5-4.6 minutes).33 It should be noted that although Campbell's study is from 1995 and one could perhaps assume that the vehicle at scene to defibrillation interval could be dropped with the current renewed emphasis on defibrillation, it is unlikely that call receipt to vehicle at scene will have changed much since the time of their study. This interval alone may account for all of the “ideal” time interval to defibrillation. An average of 1.3 minutes elapses between an EMS unit's arrival on scene and patient contact.34 Combining these studies, one could safely assume that on average, more than 7 minutes elapses before even the possibility of EMS defibrillation occurs. A different study examining a tiered response system (one where EMS providers of different levels arrive separately) found that just over 5 minutes elapsed from the time of the initial 911 call until the first emergency response vehicle arrived “on scene” and almost 6 1/2 minutes elapsed until an ambulance was present.35 Nearly 2 minutes elapsed in the interval between vehicle arrival and first analysis of the patient's rhythm.35 Although dated, these studies are important to the question of AED placement. Patients that experience out-of-hospital cardiac arrest where defibrillation occurred more than 10 minutes after the initial collapse had almost no chance of survival.36 This mirrors the findings of a 1999 meta-analysis that suggested dismal outcomes for patients defibrillated more than 11 minutes after their SCA.20 The Ontario Prehospital Advanced Life Support (OPALS) study suggested that defibrillation in less than or equal to 8 minutes was associated with an adjusted odds ratio of 3.4 (95% CI, 1.4-8.4) of survival to hospital discharge.20 Given these findings, a strong case for public access defibrillation is made. If, on average, it takes public safety first responders more than 7 minutes to reach a patient and be ready to defibrillate (ie, have attached electrocardiogram leads and analyzed the
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rhythm), defibrillation must routinely occur before EMS arrival to improve outcomes. This assumes an “average” distance between the first responder vehicle and the patient. There certainly exist public structures where a cardiac arrest patient may be found greater than 4 minutes walking distance from the door at which first response personnel arrive. Examples would include office buildings, shopping malls, sports arenas, or outdoor recreational areas not readily accessible by motorized vehicles (eg, golf courses). For this reason, the AHA and American College of Sports Medicine encourage all health and fitness facilities to be equipped with AEDs.37 Likewise, The National Athletic Trainers' Association convened an expert consensus panel that recommended AEDs be deployed at any school where defibrillation by EMS personnel in less than 5 minutes is unlikely.38 That panel acknowledged this would describe most US schools.38 Many states have passed or are considering legislation mandating AED placement. Arizona, California, Nevada, New Jersey, and New York require placement in specific public buildings.39 Arkansas, California, Illinois, Louisiana, New York, and Rhode Island require them in specific health clubs.39 California, Delaware, Florida, Georgia, Illinois, Maine, Massachusetts, New Jersey, New York, Nevada, Pennsylvania, Rhode Island, and Virginia require placement in public schools.39 The building codes regarding the distribution of fire extinguishers are generally based on the occupancy hazards of the areas to be protected. Building codes specify the type, size, and number of extinguishers to be present as well as defining classes of occupancy hazards. 5 The NFPA's Standard Number 10 classifies occupancies as light, ordinary, or extra hazards.5 Light hazards are occupancies such as offices, schoolrooms, houses of worship, and places of assembly where combustibles exist in small enough amounts that only fires of small size are expected.5 Ordinary hazard occupancies are those where moderate fires might be expected such as retail stores and storage as well as light manufacturing.5 Occupancies deemed “extra hazard” are those where combustible materials or flammable liquids are present in sufficient amount that significant fires may be expected, such as auto or aircraft service shops and buildings where industrial processes using flammable liquids are housed.5 As the
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hazard levels increase, so does the size of the required extinguisher.5 In all occupancies, the NFPA recommends that a fire extinguisher never be more than 75 ft from any given location and that no extinguisher, regardless of size or hazard class, can protect greater than 11250 square feet.5 Firefighting, like SCA, is time sensitive; however, the intervals are generally longer. Depending on building construction, combustible materials present, and so on, a rule of thumb in firefighting is that a building in which a heavy body of fire has been out of control on 2 or more floors for greater than 15 to 20 minutes is at risk for structural collapse.40 Many SCA events happen in the home. Although research suggests that individuals at high risk of SCA would accept the devices in their homes41 and that family members are willing to be trained in AED use, the results of the Home Automatic External Defibrillator Trial (HAT) suggest that “for survivors of anterior-wall myocardial infarction who were not candidates for implantation of a cardioverter-defibrillator, access to a home AED did not significantly improve overall survival, as compared with reliance on conventional resuscitation methods.”42 Similarly, although 71% of US homes are estimated to have at least 1 fire extinguisher,43 no data were found to suggest that these extinguishers reduced morbidity or mortality. A study of burn injuries in children found no difference in the rates of burn injuries in homes with fire extinguishers compared with those without one.44 Interestingly, one study suggests that obtaining a fire extinguisher is the most common fire prevention step taken in rural households after reporting a fire.45 Given the time intervals needed to maximize the chance of return of spontaneous circulation after SCA using a defibrillator, there is little question that public access to these devices is necessary. The available data clearly demonstrate that, in most cases, professional rescuers cannot respond quickly enough.20,33-35 However, there are no data to support the model often cited in the popular press of placing an AED with every fire extinguisher in a public structure. Several airports have adopted a model where an AED is placed “a brisk 60-to-90–second walk apart throughout passenger terminals.”46 No study was found that has proven a need to place an
AED every 75 ft within a structure nor was any found that suggested square footage is an accurate means to determine the need for AED availability. Data suggest that neither AEDs nor fire extinguishers are effective tools for tertiary prevention in the home setting.42,44
Costs The cost of fire protection equipment purchased annually by businesses in the United States is staggering. A report from the NFPA suggests that the “construction expenditures that are needed solely because of fire safety and fire protection considerations” totaled $27.2 billion for nonresidential construction in 2004.47 An earlier report attempted to break these costs down and found the costs to businesses in the United States of “system maintenance, industrial fire brigades, and training programs for occupational fire protection and fire safety” was $6.5 billion in 1991 (adjusted value $8.39 billion in 2004).16 According to the NFPA, the total (residential and nonresidential) fire prevention–related construction-related expenditures (the category containing the costs of fire extinguishers) rose from $30.6 billion (inflation adjusted) in 1995 to $41.3 billion in 2004.47 Beyond these reports, few publicly available data exist as to the expenditures toward fire prevention. To put these numbers in perspective; according to the United States Fire Administration, there were approximately 3900 civilian fatalities from fires and 17875 injuries in 2004.48 The same report lists 4585 fire-related civilian fatalities and 25775 injuries in 1995.48 Several authors have attempted to estimate the costs of PAD programs. Walker et al49 calculated a cost per quality-adjusted life year (QALY) to be $68924 if AEDs were to be placed in all major airports, train stations, and bus terminals in Scotland. The study was limited by a relatively low number of arrests (38 over the 7-year study period) in the study sites and the retrospective chart review study design.49 Improved survival rates were calculated based on expected improvements in survival.49 Although the authors concluded that more wide dispersal would decrease cost-effectiveness, more directed placement in areas where SCA is more likely to occur would likely increase cost-effectiveness.
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Another study calculated the cost-effectiveness of public access defibrillators in the United States. Using a Markov Decision Model and an assumption that a given AED would be deployed in such a fashion as to be used once every 5 years, the cost per QALY was calculated at approximately $30000.50 To reach a cost per QALY of $50000 (a generally accepted level of cost-effectiveness in medical interventions), AEDs would need to be deployed so as to have a 12% annual probability of use.50 The authors concede that their results were based on the assumption that if an AED is present, it will be used.50 However, the authors concluded that if a goal cost per QALY of $50000 is assumed, the placement scheme used in the PAD Trial is likely too conservative.50 An additional variable to be considered in cost analyses of public access defibrillation is the cost savings based on time to defibrillation.51 One study concluded “the point estimates of the incremental cost-effectiveness ratios of reduction of time to shock of 2, 4, and 6 minutes compared with baseline were €17 508, €14 303, and €12 708 per life saved, respectively.”51 Thus, when comparing PAD to EMS-based defibrillation, the reduction of time to defibrillation may add to cost-effectiveness. There are no readily available data on the costeffectiveness in terms of cost per QALY for fire extinguishers. Any attempt to calculate these data would be complicated by the question of defining the lives saved by fire extinguisher use. An argument could be made that using a fire extinguisher saves the lives of all occupants in a building. However, an opposite view could also be considered, which is that if a fire is small, producing little smoke and is readily accessible enough to be extinguised with a publicly available extinguisher, no lives are saved when compared with the alternative action of building evacuation as such a fire is unlikely to hinder evacuation.
Alternative Actions As described above, in terms of life safety (as opposed to preventing material losses), attempting to extinguish a fire is not effective. For a fire extinguisher to work, a fire must be small, accessible, and not producing large quantities of smoke.5 In the face of such a fire, the safest course of action is to evacuate the area.
A recent meta-analysis of available data comparing CPR alone vs CPR coupled with AED concluded that the risk ratio of survival to hospital admission was 1.22 (95% CI, 1.04-1.43) in persons treated with CPR and AED vs those given CPR alone.11 The risk ratio of survival to hospital discharge was found to be 1.39 (95% CI, 1.06-1.83) in a comparison of the same groups.11 The authors calculated that “the number of out-ofhospital cardiac arrests to be treated by trained non–health care professionals by CPR + AED to gain one survival to hospital admission was 17 (NNT = 17). The number of out-of-hospital cardiac arrests to be treated by trained non–health care professionals by CPR + AED use to gain one survival to hospital discharge was 24 (NNT = 24).”11 These findings suggest that AED use with CPR is the most effective action to take in the face of SCA.
Conclusion Although some authors draw parallels between the deployment of PADs and that of fire extinguishers, these comparisons are problematic. Fire extinguisher placement is not designed for life safety but rather to protect property by extinguishing small, incipient fires. Fire extinguishers require extensive training to be used effectively.5 Using a fire extinguisher exposes the operator to physical danger15 and in terms of life safety— evacuation, as opposed to attempting to extinguish the fire probably represents the best option. The cost-effectiveness of fire extinguishers in terms of QALY remains undefined, and data suggest they may not effectively prevent injury.44 When compared to fire extinguishers, AEDs are easy to use,13,14 safe,27,28 and represent the best course of action to take when faced with the emergency they are designed to mitigate.11 The most cost-effective placement model for PADs has not yet been determined. However, using fire extinguisher placement as a template would likely be inefficient and expensive.
References 1. Cote A, Bugbee P: Principles of fire protection. Quincy, MA: National Fire Protection Association; 1988 2. Lee S (ed): The dictionary of national biography, vol. XII. New York: The MacMillan Company, 1909
PUBLIC ACCESS DEFIBRILLATORS AND FIRE EXTINGUISHERS 3. Granger AM: U.S. patent no. 248,733. Washington, DC: U.S. Patent and Trademark Office; 1881 4. International Fire Service Training Association: Essentials of fire fighting. 3rd ed. Stillwater, OK: Fire Protection Publications, Oklahoma State University; 1992 5. International Fire Service Training Association: Private fire protection and detection. 1st ed. Stillwater, OK: Fire Protection Publications, Oklahoma State University; 1979 6. Diack A, Welborn W, Rullman R, et al: An automatic cardiac resuscitator for emergency treatment of cardiac arrest. Med Instrum 13:78-83, 1979 7. 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 the International Liaison Committee on Resuscitation. Circulation, 102(8 Suppl), I60-I76, 2000. 8. Cummins R, Ornato J, Thies W, et al: 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 83:1832-1847, 1991 9. Hazinski M, Idris A, Kerber R, et al: Lay rescuer automated external defibrillator (“public access defibrillation”) programs: lessons learned from an international multicenter trial: advisory statement from the American Heart Association Emergency Cardiovascular Committee; the Council on Cardiopulmonary, Perioperative, and Critical Care; and the Council on Clinical Cardiology. Circulation 111:3336-3340, 2005 10. Richardson L, Gunnels M, Groh W, et al: Implementation of community-based public access defibrillation in the PAD trial. Acad Emerg Med 12:688-697, 2005 11. Sanna T, La Torre G, de Waure C, et al: Cardiopulmonary resuscitation alone vs. cardiopulmonary resuscitation plus automated external defibrillator use by non-healthcare professionals: a meta-analysis on 1583 cases of out-of-hospital cardiac arrest. Resuscitation 76:226-232, 2008 12. Brown J, Kellermann A: The shocking truth about automated external defibrillators. JAMA 284: 1438-1441, 2000 13. Domanovits H, Meron G, Sterz F, et al: Successful automatic external defibrillator operation by people trained only in basic life support in a simulated cardiac arrest situation. Resuscitation 39:47-50, 1998 14. Gundry J, Comess K, DeRook F, et al: Comparison of naive sixth-grade children with trained professionals in the use of an automated external defibrillator. Circulation 100:1703-1707, 1999 15. Hall JR: Characteristics of Home Fire Victims. Quincy, MA: National Fire Protection Association; 2005 16. Meadeoup: A first pass at computing the cost of fire safety in a modern society. Fire Technology 27:341, 1991 17. Chan P, Krumholz H, Nichol G, et al: Delayed time to defibrillation after in-hospital cardiac arrest. N Engl J Med 358:9-17, 2008
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18. Valenzuela T, Roe D, Nichol G, et al: Outcomes of rapid defibrillation by security officers after cardiac arrest in casinos. N Engl J Med 343:1206-1209, 2000 19. Wik L, Hansen T, Fylling F, et al: Delaying defibrillation to give basic cardiopulmonary resuscitation to patients with out-of-hospital ventricular fibrillation: a randomized trial. JAMA 289:1389-1395, 2003 20. Nichol G, Stiell I, Laupacis A, et al: A cumulative metaanalysis of the effectiveness of defibrillator-capable emergency medical services for victims of out-ofhospital cardiac arrest. Ann Emerg Med 34(4 Pt 1): 517-525, 1999. 21. Kelley J, Richman P, Ewy G, et al: Eighth grade students become proficient at CPR and use of an AED following a condensed training programme. Resuscitation 71:229-236, 2006 22. Reder S, Cummings P, Quan L: Comparison of three instructional methods for teaching cardiopulmonary resuscitation and use of an automatic external defibrillator to high school students. Resuscitation 69:443-453, 2006 23. Riegel B, Nafziger S, McBurnie M, et al: How well are cardiopulmonary resuscitation and automated external defibrillator skills retained over time? Results from the Public Access Defibrillation (PAD) Trial. Acad Emerg Med 13:254-263, 2006 24. Woollard M, Whitfield R, Newcombe R, et al: Optimal refresher training intervals for AED and CPR skills: a randomised controlled trial. Resuscitation 71:237-247, 2006 25. Marenco J, Wang P, Link M, et al: Improving survival from sudden cardiac arrest: the role of the automated external defibrillator. JAMA 285:1193-1200, 2001 26. Jorgenson D, Skarr T, Russell J, et al: AED use in businesses, public facilities and homes by minimally trained first responders. Resuscitation 59:225-233, 2003 27. Peberdy M, Ottingham L, Groh W, et al: Adverse events associated with lay emergency response programs: the public access defibrillation trial experience. Resuscitation 70:59-65, 2006 28. Davies E, Maybury B, Colquhoun M, et al: Public Access Defibrillation: psychological consequences in responders. Resuscitation 77:201-206, 2008 29. Cagle A, Diehr P, Meischke H, et al: Psychological and social impacts of automated external defibrillators (AEDs) in the home. Resuscitation 74:432-438, 2007 30. Bilzon J, Scarpello E, Smith C, et al: Characterization of the metabolic demands of simulated shipboard Royal Navy fire-fighting tasks. Ergonomics 44: 766-780, 2001 31. 2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 112(24 Suppl), IV-35 – IV-46. 32. De Maio V, Stiell I, Wells G, et al: Optimal defibrillation response intervals for maximum out-of-hospital cardiac arrest survival rates. Ann Emerg Med 42:242-250, 2003 33. Campbell J, Kroshus K, Lindholm D, et al: Measuring the call-receipt-to-defibrillation interval: evaluation of
212 34.
35.
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prehospital methods. Ann Emerg Med 26:697-701, 1995 Campbell J, Gratton M, Girkin J, et al: Vehicle-atscene-to-patient-access interval measured with computer-aided dispatch. Ann Emerg Med 25:182-186, 1995 Stiell I, Wells G, Field B, et al: Improved out-of-hospital cardiac arrest survival through the inexpensive optimization of an existing defibrillation program: OPALS study phase II. Ontario Prehospital Advanced Life Support. JAMA 281:1175-1181, 1999 Vilke G, Chan T, Dunford J, et al: The threephase model of cardiac arrest as applied to ventricular fibrillation in a large, urban emergency medical services system. Resuscitation 64: 341-346, 2005 Balady G, Chaitman B, Foster C, et al: Automated external defibrillators in health/fitness facilities: supplement to the AHA/ACSM Recommendations for Cardiovascular Screening, Staffing, and Emergency Policies at Health/Fitness Facilities. Circulation 105: 1147-1150, 2002 Drezner J, Courson R, Roberts W, et al: Interassociation task force recommendations on emergency preparedness and management of sudden cardiac arrest in high school and college athletic programs: a consensus statement. Heart Rhythm 4: 549-565, 2007 England H, Weinberg P, Estes III NA: The automated external defibrillator: clinical benefits and legal liability. JAMA 295:687-690, 2006 Fried E: Fireground tactics. Chicago: H. M. Ginn Corp.; 1972 Chen M, Eisenberg M, Meischke H: Impact of inhome defibrillators on postmyocardial infarction
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42. 43.
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45. 46. 47. 48. 49.
50.
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patients and their significant others: an interview study. Heart Lung 31:173-185, 2002 Bardy G, Lee K, Mark D, et al: Home use of automated external defibrillators for sudden cardiac arrest. N Engl J Med 358:1793-1804, 2008 Runyan C, Johnson R, Yang J, et al: Risk and protective factors for fires, burns, and carbon monoxide poisoning in U.S. households. Am J Prev Med 28:102-108, 2005 LeBlanc J, Pless I, King W, et al: Home safety measures and the risk of unintentional injury among young children: a multicentre case-control study. CMAJ 175:883-887, 2006 Allareddy V, Peek-Asa C, Yang J, et al: Risk factors for rural residential fires. J Rural Health 23:264-269, 2007 Caffrey S, Willoughby P, Pepe P, et al: Public use of automated external defibrillators. N Engl J Med 347: 1242-1247, 2002 Hall JR: The total cost of fire in the United States. Quincy, MA: National Fire Protection Association; 2006 U.S. Fire Administration/National Fire Data Center: Fire in the United States1995-2004. 14th ed. Emmitsburg, MD: U.S. Fire Administration; 2007 Walker A, Sirel J, Marsden A, et al: Cost effectiveness and cost utility model of public place defibrillators in improving survival after prehospital cardiopulmonary arrest. BMJ 327:1316, 2003 Cram P, Vijan S, Fendrick A: Cost-effectiveness of automated external defibrillator deployment in selected public locations. J Gen Intern Med 18: 745-754, 2003 van Alem A, Dijkgraaf M, Tijssen J, et al: Health system costs of out-of-hospital cardiac arrest in relation to time to shock. Circulation 110:1967-1973, 2004
Sudden cardiac death is a major cause of mortality in the United States of America (Circulation 2008;117:e25-146) with approximately 310000 deaths related to coronary heart disease occurring in emergency departments or in the prehospital environment annually. Several organizations have directed resources toward the treatment of sudden cardiac arrest through a paradigm that has come to be known as the “chain of survival”—prompt activation of emergency response by telephone 911, early bystander cardiopulmonary resuscitation, early defibrillation, and timely advanced cardiac life support (Circulation 1991;83:1832-1847). The ready availability of automated external defibrillators (AEDs) has been advocated as a key component of this chain. Some authors have suggested a “fire extinguisher model” for AED deployment (Circulation 1998;98:2334-2351; Resuscitation 1995;30:151-156; Ann Intern Med 2001;135:990-998). In this model, AEDs are prominently displayed in public places for use by laypersons, much like fire extinguishers. For example, in Chicago's O'Hare Airport, AEDs are placed alongside fire extinguishers in the public concourses (N Engl J Med 2002;347:1242-1247). Advocates of this model suggest that advancing this practice would be a means to widely disburse lifesaving technology that is easy to use. Several experts have questioned this model, suggesting that the costeffectiveness of distributing AEDs this widely would be prohibitive (BMJ 2002;325:515; Curr Opin Cardiol 2007;22:5-10; BMJ 2003;326:162; Int J Technol Assess Health Care 2007;23:362-367) and may not be more effective than more targeted distribution of AEDs. This literature review will examine the
From the Department of Emergency Medicine, College of Medicine, The Ohio State University, Columbus, OH. Address reprint requests to Michael R. Sayre, MD, Department of Emergency Medicine, College of Medicine, The Ohio State University, 141 Means Hall, 1654 Upham Drive, Columbus, OH 43210-1228, USA. E-mail: [email protected] 0033-0620/$ - see front matter n 2008 Elsevier Inc. All rights reserved. doi: doi:10.1016/j.pcad.2008.05.003
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available data on both AEDs and fire extinguishers to determine if these comparisons are reasonable as a means of guiding public policy. n 2008 Elsevier Inc. All rights reserved.
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ublicly accessible fire-fighting equipment is a tradition that extends to the “bucket brigades” present in the 1700s. Homeowners used to place leather buckets on their doorsteps, and when a fire alarm sounded, each man would race from his home, bucket in hand to help extinguish a fire.1 British Captain George William Manby is generally credited with the invention of the “Extincteur,” a copper vessel filled with soda ash propelled by compressed air—the first modern fire extinguisher, in 1816.2 A United States Patent was issued to Almon M. Granger in 1880 for a fire extinguisher that relied on a chemical reaction to generate a gas to propel water from a tank3 in a design quite similar to today's fire extinguishers. Modern fire extinguishers in the United States are generally classified as type A, B, C, or D (or some combination thereof).4 This classification system is based on the types of fires expected to be extinguished.4 Type A fires are those fueled by common flammable goods (eg, paper, wood, etc).4 Type B fires involve flammable liquids such as gasoline.4 Type C fires are complicated by the presence of energized electrical equipment.4 Type D fires are those involving heavy metals—where use of water may prove harmful.4 Fire extinguishers are generally required to be placed in public buildings at set intervals, according to the building's purpose, construction, and expected occupancy.4,5 The rules for fire extinguisher placement are contained within a “building code”—a set of life safety rules adopted by a state or local government to guide building construction.5 Because these codes are extensive and involve a high degree of expertise in fire protection engineering, building design, architecture, and ergonomics, most entities with the
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authority to enact and enforce codes purchase the right to use a model code from specialty groups (such as the National Fire Protection Association [NFPA] or the International Code Council [formerly known as the Building Officials and Code Administrators International]) and adapt them as needed for local use. The Occupational Health and Safety Administration also regulates the placement and availability of fire extinguishers in the workplace (eg, 29 CFR 1910.157). Interestingly, neither Occupational Health and Safety Administration1, International Code Council, nor the NFPA mandate the placement, or even availability, of automated external defibrillators (AEDs) in their codes or regulations. As early as 1979,6 scientists recognized the potential for AEDs to save lives. Over time, advances in technology have increased the portability, diagnostic accuracy, and therapeutic efficacy of these devices.7 In their most modern form, these devices are capable of highly accurate cardiac rhythm analysis and delivery of a biphasic electrical shock with a minimum of operator input or action.7 Some models even prompt and instruct the rescuer on the provision of cardiopulmonary resuscitation (CPR). Since 1991, the American Heart Association (AHA) has supported the idea that survival from out-of-hospital sudden cardiac arrest (SCA) could be markedly improved by layperson rescuers using AEDs.8 The AHA has emphasized the importance of a coordinated approach of planning, organizing, and training as a means to maximize the effectiveness of these programs.9 The National Heart Lung and Blood Institute, the AHA, and others supported the creation of a large prospective randomized trial of public access defibrillation programs named the Public Access Defibrillation (PAD) Trial.10 The findings of this study resoundingly support public access defibrillation.9,10 The results of this trial, and other studies, provide considerable guidance for medical professionals on the topic of public access defibrillation. Although the potential impact of widespread access to AEDs is as yet unclear, there 1 While OSHA recommends AED availability in the workplace, and hosts a website of AED resources for employers (http://www.osha.gov/SLTC/aed/index.html), no federal regulation or standard interpretation of regulations mandates AED availability.
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exists a wide body of literature supporting the integration of AEDs into layperson and professional rescuer CPR.11 There are commonalities between fire extinguishers and AEDs that invite comparison. Both are relatively portable devices designed to save lives. Each requires some level of maintenance or inspection to ensure proper function when needed.5,12 Each requires a person to directly act and intervene against the perceived life threat (as opposed to an automatic sprinkler system). Each provides a “bridge” until professional assistance (ie, fire service or Emergency Medical Services) can arrive. However, there are some common misperceptions regarding fire extinguishers that make comparisons between them and AEDs problematic. First, there is a significant difference in the amount of fire that a trained firefighter can extinguish with any given fire extinguisher and the amount that a layperson can extinguish.4 Automated external defibrillators are nearly equally as effective in the hands of experts as they are when used by laypersons.13,14 Second, firefighting, even in small, incipient fires, is hazardous.15 Four percent of all fire deaths in the United States reported through the National Fire Incident Reporting System occurred while the decedent was attempting to extinguish the fire, whereas no significant injuries have been reported from using an AED.15 Third, there is an inference, through the basis of the comparisons alone, that fire extinguishers represent a “cost-effective” public health intervention. Given that the number of fire deaths in the United States is extremely low (when compared with other causes of death) and has been for many decades, the costs per life saved are not necessarily “effective.”16 Lastly, there are questions of time constraints and alternatives. If a fire is discovered at its incipient stage (when it would be safe for a layperson to extinguish it), evacuation is an effective option to prevent mortality. However, early defibrillation is key in the prevention of mortality from SCA and is more effective than CPR alone.11 This question can be extended to assess the effects of time until professional rescuers can respond. Is there a definable period before a fire is “out of control” and escape impossible without a fire extinguisher or professional assistance? There is
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such a time sensitivity defined in SCA.17-20 This review will analyze the data available on the training needed, risks of using, cost-effectiveness, and time sensitivity of both AEDs, and fire extinguishers to assess the validity of their increasingly frequent comparisons.
Training Automated external defibrillators are extremely easy to use. The time to defibrillation using an AED was compared between untutored sixth grade children and paramedics trained in AED use, and the difference in mean time to defibrillation was only 23 seconds.14 A more recent study by Kelley et al21 found that eighth grade public school students could be taught continuous chest compression CPR and AED use in a 1-hour program with excellent retention at 4 weeks. Interactive computer training or interactive computer training plus instructor-led practice was compared with traditional classroom instruction in teaching CPR and AED use to high school students.22 The mean scores for “key AED actions” were greater than 80% for all groups in both initial testing and follow-up evaluation. All groups scored better than 95% at turning on the AED and pressing the shock button if indicated, both on initial training and reevaluation at 2 months.22 All groups also scored better than 80% at knowing to continue CPR until an AED was available both on initial training and reevaluation.22 These studies were performed using children who were likely comfortable with technology. Although this may color the results somewhat, AED use is simple enough that reasonable results can be expected by the naive user and skills are retained by those trained in its use. In an evaluation of skill retention of more than 3700 adults trained in CPR and AED use, 84% were able to adequately demonstrate AED use skills as remote as 17 months after their training.23 Interestingly, an evaluation of the English National Defibrillator Programme suggested that although significant skill deterioration was demonstrated between 7 and 12 months in terms of CPR performance, the time to first shock with AED use did not significantly change.24 This suggests that AED use skill retention persists longer than that of CPR.
Unfortunately, fire extinguishers are not as simple to use. A nonexpert user is expected to extinguish only 40% of the square footage of fire that an expert can using the same extinguisher.4 For example, in a class A fire (the most common type), a nonexpert user is most likely to only be capable of extinguishing 1 to 4 square feet of fire (using one of the more common types of extinguishers) vs the 2 1/2 to 10 square feet that a trained firefighter would be able to extinguish with the same equipment.4 The International Fire Service Training Association suggests that successful operation of fire extinguishers depends on the following: ○ Extinguisher is properly located. ○ Extinguisher is properly placed and in working order. ○ Extinguisher is of proper type for the fire which may occur. ○ Fire is discovered while still small enough for the extinguisher to be effective. ○ Fire is discovered by a person, ready, willing, and trained to use the extinguisher. {emphasis added} ○ Smoke created by burning materials allows approach. ○ Fire is accessible for a close approach with portable extinguishers.”5 This difficulty in use creates a problem in directly comparing AEDs to fire extinguishers. A nonexpert user can only be expected to put out a small, relatively contained fire producing minimal smoke. Such a fire does not immediately represent a serious threat to life. An AED only delivers a shock when a life is at risk. Nonexperts are reasonably as proficient as medical experts in the use of AEDs,13,14 and the machine is capable of determining if the proper conditions for use exist in a patient.25
Safety The safety of AEDs is supported by a study of 1654 businesses and private citizens who had owned AEDs for at least 1 year. The devices were applied to patients 213 times with no reports of rescuer or patient injuries resulting from AED use.26 Although patient outcome was not always known by the participants in the study, 4 persons resuscitated by
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laypersons were known to have survived to hospital admission and 2 of these known to survive to discharge.26 In an examination of adverse events related to public access defibrillators among the 1260 public and residential facilities in the United States and Canada during the PAD trial (spanning 26389 months of public availability and 3952 emergency episodes of which 649 were presumed cardiac arrests), only 36 adverse events were confirmed.27 Of these, 27 were related to the AED itself (20 cases of theft, 3 of the AED not being in an assigned location, and 4 “incidents of mechanical difficulty or battery failure”).27 No inappropriate shocks were delivered, and no device failed to shock when indicated.27 The remaining 7 adverse events involved the lay rescue personnel. One pulled a muscle during rescue efforts.27 Two reported feeling pressured by their employers to participate as first responders.27 Four individuals reported increased stress levels directly related to their rescue efforts that required follow-up or intervention.27 The most severely affected person reported responding to 2 events involving victims known to her personally, and she declined further participation in the study.27 A study of the psychological consequences to layperson responders in public access defibrillation found that the responders “demonstrated an apparently innate resilience to the adverse psychological effects of responding with an AED in a PAD scheme.”28 This study suggested that self protective mechanisms occurred naturally, outside of formal training.28 Placement of an AED in the home after an acute ischemic event was associated with a perceived decrease in quality of life for both patients and family members.29 Of the 158 families studied, 92 received training in CPR and AED use and were provided an AED, and 66 families were trained in CPR alone.29 Interestingly, those who received the AEDs and training in their use reported lower quality of life as measured on a standard tool; but this negative effect was small and not likely to be clinically significant.29 In contrast, attempting to extinguish a fire has been clearly demonstrated to be hazardous.15 A report from the NFPA indicates that of civilians killed by fire in the United States between 1999 and 2002, 4% perished while trying to fight fire.15 More telling are the statistics for nonfatal fire-related
civilian injuries. “Attempting to fight fire” was the leading activity at time of injury during both the 1999 to 2002 period as well between 1994 and 1998 (35% and 32%, respectively).15 In addition, studies have demonstrated that carrying and deploying a fire extinguisher causes an increased metabolic demand.30 When actually fighting a fire, this increased demand occurs in an atmosphere that may be oxygen depleted.4 A person attempting to extinguish a fire should be in a reasonable state of physical fitness to safely proceed.30 In a comparison to AEDs and fire extinguishers, the very real possibility of injury to the rescuer must be considered. Although no data were found to suggest that fire extinguishers encourage laypersons to attempt to fight fires, to use one places the operator at increased risk of injury or death.15 No such risks have been demonstrated with AED use.
Placement The AHA states, “lay rescuer AED programs will have the greatest potential impact on survival from SCA if the programs are created in locations where SCA is likely to occur.”31 The Public Access Defibrillation Trial placed AEDs in community facilities where a pool of potential volunteer responders existed and had the ability to deliver an AED within 3 minutes to a person having a cardiac arrest.10 Facilities in the study were “expected” to be the location of at least 1 out-ofhospital cardiac arrest during the study period and were those that had a history of at least one witnessed out-of-hospital cardiac arrest an average of every 2 years or those where the equivalent of at least 250 adults more than 50 years of age were present for at least 16 hours a day.10 Optimization of EMS systems to provide for rapid response by public safety first responders equipped with AEDs may be insufficient in many cases. Studies indicate that the outcome of defibrillation is time dependant.17–20 Different studies have examined various “cutoff” times for improved survivability; 2 (in hospital),17 4,18 5,19 and 6 minutes20 have all been identified as possible points after which outcomes appreciably worsen. A previous EMS industry standard of an EMS response in less than 8 minutes is insufficient.32 When analyzing the need for a public access defibrillator based on public safety first
208 responder response time to a given location, several factors besides distance from the first responders' post must be considered. A first responder unit must be dispatched, travel to the scene, travel to the patient, assess the situation, and deliver the necessary defibrillation. Campbell et al33 found a call receipt to vehicle at scene time of 5.98 minutes (95% confidence interval [CI], 4.4-7.3 minutes). The vehicle at scene to defibrillation was 3.6 minutes (95% CI, 2.5-4.6 minutes).33 It should be noted that although Campbell's study is from 1995 and one could perhaps assume that the vehicle at scene to defibrillation interval could be dropped with the current renewed emphasis on defibrillation, it is unlikely that call receipt to vehicle at scene will have changed much since the time of their study. This interval alone may account for all of the “ideal” time interval to defibrillation. An average of 1.3 minutes elapses between an EMS unit's arrival on scene and patient contact.34 Combining these studies, one could safely assume that on average, more than 7 minutes elapses before even the possibility of EMS defibrillation occurs. A different study examining a tiered response system (one where EMS providers of different levels arrive separately) found that just over 5 minutes elapsed from the time of the initial 911 call until the first emergency response vehicle arrived “on scene” and almost 6 1/2 minutes elapsed until an ambulance was present.35 Nearly 2 minutes elapsed in the interval between vehicle arrival and first analysis of the patient's rhythm.35 Although dated, these studies are important to the question of AED placement. Patients that experience out-of-hospital cardiac arrest where defibrillation occurred more than 10 minutes after the initial collapse had almost no chance of survival.36 This mirrors the findings of a 1999 meta-analysis that suggested dismal outcomes for patients defibrillated more than 11 minutes after their SCA.20 The Ontario Prehospital Advanced Life Support (OPALS) study suggested that defibrillation in less than or equal to 8 minutes was associated with an adjusted odds ratio of 3.4 (95% CI, 1.4-8.4) of survival to hospital discharge.20 Given these findings, a strong case for public access defibrillation is made. If, on average, it takes public safety first responders more than 7 minutes to reach a patient and be ready to defibrillate (ie, have attached electrocardiogram leads and analyzed the
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rhythm), defibrillation must routinely occur before EMS arrival to improve outcomes. This assumes an “average” distance between the first responder vehicle and the patient. There certainly exist public structures where a cardiac arrest patient may be found greater than 4 minutes walking distance from the door at which first response personnel arrive. Examples would include office buildings, shopping malls, sports arenas, or outdoor recreational areas not readily accessible by motorized vehicles (eg, golf courses). For this reason, the AHA and American College of Sports Medicine encourage all health and fitness facilities to be equipped with AEDs.37 Likewise, The National Athletic Trainers' Association convened an expert consensus panel that recommended AEDs be deployed at any school where defibrillation by EMS personnel in less than 5 minutes is unlikely.38 That panel acknowledged this would describe most US schools.38 Many states have passed or are considering legislation mandating AED placement. Arizona, California, Nevada, New Jersey, and New York require placement in specific public buildings.39 Arkansas, California, Illinois, Louisiana, New York, and Rhode Island require them in specific health clubs.39 California, Delaware, Florida, Georgia, Illinois, Maine, Massachusetts, New Jersey, New York, Nevada, Pennsylvania, Rhode Island, and Virginia require placement in public schools.39 The building codes regarding the distribution of fire extinguishers are generally based on the occupancy hazards of the areas to be protected. Building codes specify the type, size, and number of extinguishers to be present as well as defining classes of occupancy hazards. 5 The NFPA's Standard Number 10 classifies occupancies as light, ordinary, or extra hazards.5 Light hazards are occupancies such as offices, schoolrooms, houses of worship, and places of assembly where combustibles exist in small enough amounts that only fires of small size are expected.5 Ordinary hazard occupancies are those where moderate fires might be expected such as retail stores and storage as well as light manufacturing.5 Occupancies deemed “extra hazard” are those where combustible materials or flammable liquids are present in sufficient amount that significant fires may be expected, such as auto or aircraft service shops and buildings where industrial processes using flammable liquids are housed.5 As the
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hazard levels increase, so does the size of the required extinguisher.5 In all occupancies, the NFPA recommends that a fire extinguisher never be more than 75 ft from any given location and that no extinguisher, regardless of size or hazard class, can protect greater than 11250 square feet.5 Firefighting, like SCA, is time sensitive; however, the intervals are generally longer. Depending on building construction, combustible materials present, and so on, a rule of thumb in firefighting is that a building in which a heavy body of fire has been out of control on 2 or more floors for greater than 15 to 20 minutes is at risk for structural collapse.40 Many SCA events happen in the home. Although research suggests that individuals at high risk of SCA would accept the devices in their homes41 and that family members are willing to be trained in AED use, the results of the Home Automatic External Defibrillator Trial (HAT) suggest that “for survivors of anterior-wall myocardial infarction who were not candidates for implantation of a cardioverter-defibrillator, access to a home AED did not significantly improve overall survival, as compared with reliance on conventional resuscitation methods.”42 Similarly, although 71% of US homes are estimated to have at least 1 fire extinguisher,43 no data were found to suggest that these extinguishers reduced morbidity or mortality. A study of burn injuries in children found no difference in the rates of burn injuries in homes with fire extinguishers compared with those without one.44 Interestingly, one study suggests that obtaining a fire extinguisher is the most common fire prevention step taken in rural households after reporting a fire.45 Given the time intervals needed to maximize the chance of return of spontaneous circulation after SCA using a defibrillator, there is little question that public access to these devices is necessary. The available data clearly demonstrate that, in most cases, professional rescuers cannot respond quickly enough.20,33-35 However, there are no data to support the model often cited in the popular press of placing an AED with every fire extinguisher in a public structure. Several airports have adopted a model where an AED is placed “a brisk 60-to-90–second walk apart throughout passenger terminals.”46 No study was found that has proven a need to place an
AED every 75 ft within a structure nor was any found that suggested square footage is an accurate means to determine the need for AED availability. Data suggest that neither AEDs nor fire extinguishers are effective tools for tertiary prevention in the home setting.42,44
Costs The cost of fire protection equipment purchased annually by businesses in the United States is staggering. A report from the NFPA suggests that the “construction expenditures that are needed solely because of fire safety and fire protection considerations” totaled $27.2 billion for nonresidential construction in 2004.47 An earlier report attempted to break these costs down and found the costs to businesses in the United States of “system maintenance, industrial fire brigades, and training programs for occupational fire protection and fire safety” was $6.5 billion in 1991 (adjusted value $8.39 billion in 2004).16 According to the NFPA, the total (residential and nonresidential) fire prevention–related construction-related expenditures (the category containing the costs of fire extinguishers) rose from $30.6 billion (inflation adjusted) in 1995 to $41.3 billion in 2004.47 Beyond these reports, few publicly available data exist as to the expenditures toward fire prevention. To put these numbers in perspective; according to the United States Fire Administration, there were approximately 3900 civilian fatalities from fires and 17875 injuries in 2004.48 The same report lists 4585 fire-related civilian fatalities and 25775 injuries in 1995.48 Several authors have attempted to estimate the costs of PAD programs. Walker et al49 calculated a cost per quality-adjusted life year (QALY) to be $68924 if AEDs were to be placed in all major airports, train stations, and bus terminals in Scotland. The study was limited by a relatively low number of arrests (38 over the 7-year study period) in the study sites and the retrospective chart review study design.49 Improved survival rates were calculated based on expected improvements in survival.49 Although the authors concluded that more wide dispersal would decrease cost-effectiveness, more directed placement in areas where SCA is more likely to occur would likely increase cost-effectiveness.
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Another study calculated the cost-effectiveness of public access defibrillators in the United States. Using a Markov Decision Model and an assumption that a given AED would be deployed in such a fashion as to be used once every 5 years, the cost per QALY was calculated at approximately $30000.50 To reach a cost per QALY of $50000 (a generally accepted level of cost-effectiveness in medical interventions), AEDs would need to be deployed so as to have a 12% annual probability of use.50 The authors concede that their results were based on the assumption that if an AED is present, it will be used.50 However, the authors concluded that if a goal cost per QALY of $50000 is assumed, the placement scheme used in the PAD Trial is likely too conservative.50 An additional variable to be considered in cost analyses of public access defibrillation is the cost savings based on time to defibrillation.51 One study concluded “the point estimates of the incremental cost-effectiveness ratios of reduction of time to shock of 2, 4, and 6 minutes compared with baseline were €17 508, €14 303, and €12 708 per life saved, respectively.”51 Thus, when comparing PAD to EMS-based defibrillation, the reduction of time to defibrillation may add to cost-effectiveness. There are no readily available data on the costeffectiveness in terms of cost per QALY for fire extinguishers. Any attempt to calculate these data would be complicated by the question of defining the lives saved by fire extinguisher use. An argument could be made that using a fire extinguisher saves the lives of all occupants in a building. However, an opposite view could also be considered, which is that if a fire is small, producing little smoke and is readily accessible enough to be extinguised with a publicly available extinguisher, no lives are saved when compared with the alternative action of building evacuation as such a fire is unlikely to hinder evacuation.
Alternative Actions As described above, in terms of life safety (as opposed to preventing material losses), attempting to extinguish a fire is not effective. For a fire extinguisher to work, a fire must be small, accessible, and not producing large quantities of smoke.5 In the face of such a fire, the safest course of action is to evacuate the area.
A recent meta-analysis of available data comparing CPR alone vs CPR coupled with AED concluded that the risk ratio of survival to hospital admission was 1.22 (95% CI, 1.04-1.43) in persons treated with CPR and AED vs those given CPR alone.11 The risk ratio of survival to hospital discharge was found to be 1.39 (95% CI, 1.06-1.83) in a comparison of the same groups.11 The authors calculated that “the number of out-ofhospital cardiac arrests to be treated by trained non–health care professionals by CPR + AED to gain one survival to hospital admission was 17 (NNT = 17). The number of out-of-hospital cardiac arrests to be treated by trained non–health care professionals by CPR + AED use to gain one survival to hospital discharge was 24 (NNT = 24).”11 These findings suggest that AED use with CPR is the most effective action to take in the face of SCA.
Conclusion Although some authors draw parallels between the deployment of PADs and that of fire extinguishers, these comparisons are problematic. Fire extinguisher placement is not designed for life safety but rather to protect property by extinguishing small, incipient fires. Fire extinguishers require extensive training to be used effectively.5 Using a fire extinguisher exposes the operator to physical danger15 and in terms of life safety— evacuation, as opposed to attempting to extinguish the fire probably represents the best option. The cost-effectiveness of fire extinguishers in terms of QALY remains undefined, and data suggest they may not effectively prevent injury.44 When compared to fire extinguishers, AEDs are easy to use,13,14 safe,27,28 and represent the best course of action to take when faced with the emergency they are designed to mitigate.11 The most cost-effective placement model for PADs has not yet been determined. However, using fire extinguisher placement as a template would likely be inefficient and expensive.
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