SKYAID
New 
Mission
Overview   
Details    
Medical   
Watch   
Heart attack  
Stroke    
World health  
Emergency
Cost effective
Media 
- Site Map 

SKYCAR   
Details   
Overview  
VTOL   
Airline   
Military   
Transportation
Images 
- Site Map

Search

Translate 
  8 languages
 

                                                                              
Improving Survival From Sudden Cardiac Arrest: The Role of the Automated External Defibrillator.

JAMA, The Journal of the American Medical Association, March 7,2001 v285 i9 p1193.
  John P. Marenco, Paul J. Wang, Mark S. Link, Munther K. Homoud and N. A. Mark Estes III
                                                                              

 Abstract:  Automated external defibrillators are so small and easy to use
that even non-medical personnel can be trained to use them. Defibrillators are
used to deliver an electric shock to the heart of a person in cardiac arrest.
This will allow these patients to be treated sooner, which may improve their
prognosis.
                Full Text COPYRIGHT 2001 American Medical Association

Context Sudden cardiac death is a major public health problem in the United
States, and improving survival after out-of-hospital cardiac arrest has been
the subject of intense study. Early defibrillation has been shown to be
critical to improving survival. Use of automated external defibrillators
(AEDs) has become an important component of emergency medical systems, and
recent advances in AED technology have allowed expansion of AED use to
nontraditional first responders and the lay public.

Objectives To examine advancements in AED technology, review the impact of
AEDs on time to defibrillation and survival, and explore the future role of
AEDs in the effort to improve survival following sudden cardiac arrest.

Data Sources MEDLINE was searched for articles from 1966 through December 2000
(Medical Subject Headings: electric countershock, heart arrest, resuscitation,
emergency medical services; keywords: automatic external defibrillator,
automated external defibrillator, public access defibrillation). Reference
lists of relevant articles, news releases, and product information from
manufacturers were also reviewed.

Study Selection Initial MEDLINE search produced 4816 articles, from which 101
articles were selected for referencing based on having been published in a
peer-reviewed journal and on relevance to the subject of the manuscript as
determined by all 5 authors.

Data Extraction All studies were critically reviewed for relevance, accuracy,
and quality of data and study design by all authors.

Data Synthesis Recent advances in AED technology and design have resulted in
marked simplification of AED operation, improvements in accuracy and
effectiveness, and reductions in cost. Use of AEDs by first responders and
laypersons has reduced time to defibrillation and improved survival from
sudden cardiac arrest in several communities. Initial studies of the
cost-effectiveness of AED use in comparison with other commonly used
treatments are favorable.

Conclusion The AED represents an efficient method of delivering defibrillation
to persons experiencing out-of-hospital cardiac arrest and its use by both
traditional and nontraditional first responders appears to be safe and
effective. The rapidly expanding role of AEDs in traditional emergency medical
systems is supported by the literature, and initial studies of public access
to defibrillation offer hope that further improvements in survival after
sudden cardiac death can be achieved.

CARDLOVASCULAR DISEASE IS THE major cause of death in the United States,
resulting in nearly 1 million deaths a year. Nearly half of these deaths
(250,000 to 500,000) are sudden and unexpected. [1-3] Most sudden deaths from
cardiac arrest occur outside the hospital, and survival rates have
traditionally been poor--only 1% to 5% of these patients are estimated to
survive to hospital discharge. [4,5] When first-responders arrive early,
ventricular tachycardia and ventricular fibrillation are the rhythms they most
commonly encounter initially. [1,2,7] Most persons experiencing cardiac arrest
have no history of severe heart disease, and sudden cardiac death is
frequently the first manifestation of cardiovascular disease (FIGURE 1).
[1,6,7] This has complicated efforts at prevention and has led to a shift in
emphasis to improvements in prehospital care.

In an effort to improve prehospital care, the American Heart Association (AHA)
has promoted the "Chain of Survival" concept, describing a sequence of
interventions (links) that when implemented result in improved survival
following sudden cardiac arrest. [8] Early defibrillation has emerged as the
single most important intervention. There are data from both animal and human
studies showing that defibrillation immediately after witnessed ventricular
fibrillation results in survival rates greater than 90%. [12,15] Each minute
of ventricular fibrillation, however, leads to a nearly 10% reduction in
survival. Although cardiopulmonary resuscitation (CPR) prior to defibrillation
in prolonged arrests ([greater than]4 minutes) may improve survival, [16]
chances of long-term survival of patients defibrillated after 10 minutes are
dismal (FIGURE 2). [7,9-11] Early use of external defibrillation by emergency
medical technicians (EMTs) in selected communities with rapid response times
has been shown to improve survival. [17,18] However, many communities, both
rural and urban, continue to have poor survival rates, presumably due to
longer response times of emergency personnel. Studies of persons experiencing
sudden cardiac arrest in New York City and Chicago, where emergency medical
system (EMS) response times are prolonged by heavy traffic and tall buildings,
have demonstrated survival rates of 2% or less. [5,19]

In an effort to overcome these limitations, the AHA has promoted the concept
of public access defibrillation (PAD). [20,21] This concept promotes the
expansion of the role of defibrillation to both minimally trained
first-responders (police officers, firefighters, security guards, flight
attendants) and to trained laypersons who witness an arrest. It also promotes
the placement of automated external defibrillators (AEDs) in such areas as
airports, convention centers, sporting arenas, casinos, shopping malls, and
large office buildings. Some have envisioned a future where the AED is as
commonplace as the fire extinguisher. [2] One of the keys to making PAD
feasible has been advances in technology over the past 2 decades that have
made AED use by nonmedical personnel safe and effective. Although there is
growing literature to suggest that PAD is greatly improving survival from
sudden cardiac arrest, many questions remain. We will examine the important
advances in AED technology over the past 2 decades, review the existing
literature on the effectiveness of the AED, and explore the future role of the
AED in our effort to improve survival from sudden cardiac arrest.

METHODS

We used MEDLINE to identify all English-language publications on AEDs from
1966 to December 2000. The medical subject headings used were electric
countershock, heart arrest, resuscitation, and emergency medical services.
Automatic external defibrillator, automated external defibrillator, and public
access defibrillation were searched as keywords. All relevant publications
were reviewed. Data quality was determined by publication in peer-reviewed
literature. In addition, all 5 authors reviewed relevant abstracts and
presentations from the official 1999 and 2000 annual meetings of the American
College of Cardiology, the AHA, and the North American Society of Pacing and
Electrophysiology. Product information was obtained from each AED
manufacturer's official Web site and official specification sheets were
provided by each of the manufacturers at our request.

RESULTS

Technology

Automated external defibrillators were developed in the 1970s and first
introduced for clinical use in 1979. [22,23] The AED is a lightweight portable
device containing a battery, capacitors, and circuitry designed to analyze
cardiac rhythm and inform the operator whether a shock is indicated.
Information is transmitted to the device by electrode pads used for both
monitoring and shock therapy (FIGURE 3). Manufacturers were challenged to
develop an AED so reliable and easy to use that fears of misuse and
inappropriate shocks would be unfounded. Reductions in size, weight, cost, and
maintenance were also essential if PAD were to be logistically and
economically feasible. Several advances in AED technology over the past decade
have been instrumental in the effort to achieve these goals.

Ease of Use

Laypersons trained to use an AED may go months or years without witnessing an
arrest or operating an AED. Operation of an AED, therefore, needs to be nearly
intuitive for timely delivery of therapy. Several important changes have
resulted in marked simplification of AED use. Self-adhesive electrode pads are
provided with diagrams on how to apply them (Figure 3). Once activated, AEDs
have voice and text prompts to guide the user through the few simple steps. An
arrhythmia analysis algorithm automatically interprets the rhythm and either
recommends countershock, to be given by the push of a button, or no
countershock. The device immediately reevaluates the rhythm and determines
whether to recommend an additional shock. Cardiac rhythms are automatically
recorded for review. These simplifications in AED operation have resulted in a
marked reduction in defibrillation times and have minimized the need for
retraining. A study examining the use of the AED in out-of-hospital cardiac
arrests showed that trained first responders had an average time from
power-on to first defibrillation of only 25 seconds. [24] One recent study of
mock cardiac arrest showed that mean time to defibrillation from arrival at
the scene was only 90 seconds for a group of untrained sixth-grade students
and 67 seconds for trained EMTs and paramedics. [25]

Arrhythmia Analysis Algorithms

Taking advantage of innovations in computer technology and detection algorithm
design in the 1980s and 1990s, manufacturers have developed arrhythmia
analysis algorithms that can interpret complex cardiac rhythms and deliver
appropriate therapy with impressive accuracy (FIGURE 4). In 1997, the AHA
Subcommittee on AED Safety and Efficacy recommended specific performance goals
for arrhythmia analysis algorithms. Current AEDs have consistently exceeded
these goals. [23] Several studies have demonstrated 100% sensitivity and
specificity for the detection of ventricular fibrillation. [24,26-29]

Energy Delivery and Storage

External defibrillation requires the delivery of energy, in the form of
current, to the myocardium. This process has been made more efficient through
the use of impedance-based defibrillation, larger electrode pad sizes, and
biphasic waveforms. Impedance-based defibrillation refers to the adjustment of
shock waveform features or shock energy based on patient impedance
(resistance). Because defibrillation thresholds vary substantially from
patient to patient, this feature results in a more efficient use of energy.
[30-33] Larger electrode pad sizes have been shown to reduce transthoracic
impedance and improve defibrillation success rates. [34,35]

Early AEDs and most external defibrillators used monophasic waveforms, in
which current is delivered to the patient in a single direction (polarity).
Two conventional monophasic waveforms exist: damped sinusoidal, in which a
high peak current is delivered with the current returning to zero gradually;
and truncated exponential, in which current returns to zero instantaneously
after delivery of the selected energy. More recently, biphasic waveforms, in
which the direction of current flow is reversed part way through the pulse
(FIGURE 5), have been used extensively in implantable cardiac defibrillators
(ICDs) and found to achieve equivalent or superior defibrillation rates at
relatively lower energy levels ([less than]200 J) than the previously used
monophasic waveforms. [36-38] While direct comparison of biphasic with
monophasic waveforms in the out-of-hospital setting are lacking, evidence that
lower energy shocks using biphasic waveforms have comparative efficacy and are
safe and clinically effective has led some AED manufacturers to use a fixed
150-J shock energy. [23,30,48] Poole et a1 [29] demonstrated a first-shock
defibrillation rate of 89% using low-energy (150 J) biphasic waveforms in
patients with out-of-hospital cardiac arrest found to be in ventricular
fibrillation, while Gliner et a1 [26] achieved a rate of 83%. Ventricular
fibrillation was successfully terminated by fewer than 3 shocks in 97% of
patients. [26] Animal studies suggest that these lower energies result in
improved postshock myocardial function. [49,50] Such data have resulted in
biphasic waveforms becoming the most common waveform offered in AEDs, and the
manufacturers of standard external defibrillators have begun to market
biphasic waveform devices as well.

Nonrechargeable lithium-based batteries that can last up to 5 years with-out
requiring service are rapidly replacing larger lead and nickel cadmium
batteries as the energy source for the AED. At present, most devices
automatically perform self-tests on a daily or weekly basis, alerting users
when service is required. Such innovations in energy delivery and storage have
led to marked reductions in maintenance requirements and reductions in both
the size and cost ($3000-$4500 each) of AEDs (TAHLE 1).

Use of the AED Within the Traditional EMS System

Several studies have demonstrated that EMTs and paramedics can safely and
effectively use manual external defibrillators. [51-54] Subsequent studies of
AED use by these trained personnel demonstrated that the AED was equally safe
and effective and suggested a possible survival advantage over use with the
manual external defibrillator (TABLE 2). [17,18,55] These data, along with
improved portability and ease of use of the AED, have led to AEDs becoming
standard equipment in many EMSs. Several communities have documented improved
survival with the addition of EMT defibrillation using the AED, [56-59] while
2 meta-analyses have demonstrated that defibrillation by basic life support
providers reduced the relative risk of death for persons experiencing
out-of-hospital cardiac arrest who are in ventricular fibrillation. [60,61]

In an effort to further reduce time to defibrillation and in response to
evidence demonstrating the safety and ease of use of the AED, many communities
expanded the role of defibrillation to trained first-responders (eg, police
officers and firefighters) who often arrive at the scene of an arrest before
paramedics. Studies of the use of the AED by such personnel have shown
dramatically reduced time to defibrillation and enhanced survival in select
communities (TABLE 3) [62-68] Weaver et a1 [62] showed that firefighters could
deliver defibrillation with an AED 5 minutes earlier than paramedics could
with a standard defibrillator. A study by White et a1 [63] found that survival
to hospital discharge in Rochester, Minn, was increased from 26% to 58% when
patients in ventricular fibrillation were defibrillated by police. Mossesso et
a1 [64] showed that police use of the AED in Allegheny County, Pennsylvania,
decreased time to defibrillation and was an independent predictor of survival
to hospital discharge.

Despite these impressive results, several studies indirectly point out the
inability of early defibrillation alone to overcome other deficiencies in the
chain of survival. Kellermann et a1 [69] showed that the impact on survival of
adding first responder defibrillation to a fast-response urban EMS system was
small despite a reduction in time to defibrillation. Low rates of bystander
CPR (12%) were felt likely to have contributed to poor survival rates in this
study. Sweeney et al [70] also showed that the addition of AEDs to their EMS
system in North Carolina failed to improve survival rates. Bystander CPR was
impressively frequent, but delays in calling for EMS support and long
call-processing times were noted. A large study by Stiell et al, [71]
involving more than 19 different communities in Ontario in which survival
rates had previously been low (2.5%), showed implementation of a rapid
defibrillation program to be an effective and inexpensive approach to
improving out-of-hospital cardiac arrest survival. [71,72] Much of the benefit
to survival in this study, however, came from patients unlikely to benefit
from early defibrillation--those initially found with pulse-less electrical
activity and asystole--suggesting that shorter response times and early CPR
were important determinants of improved survival. [73] A meta-analysis by
Nichol et a1 [74] concluded that while early defibrillation had the greatest
relative impact on survival, increased rates of bystander CPR and the presence
of advanced cardiac life support-capable EMSs are also important determinants
of survival. In summary, while each component of the chain of survival remains
critical to improved survival, the AED is a vital addition to an EMS and a
powerful tool in the effort to reduce time to defibrillation and improve
survival from sudden cardiac death.

Outside the Traditional EMS System

Because the majority of cardiac arrests occur at home, several studies have
examined the use of AEDs by family members of high-risk patients. [75,76]
Although these studies demonstrated the feasibility of training laypersons
(eg, family members) to use an AED, researchers had difficulty with patient
recruitment and obtained disappointing results. There is mounting evidence for
the efficacy of ICDs in patients at increased risk for sudden cardiac death.
[77-79] This has limited enthusiasm for the placement of AEDs in the home of
high-risk patients and primarily limited the role of the AED in the home to
high-risk patients who either refuse an ICD or have a contraindication to ICD
placement. However, these studies used earlier-generation AEDs and, given the
lower costs and ease of use of the current devices, further study with the
newer technology is warranted.

In 1991, Quantas Airlines initiated a program using AEDs on overseas flights
and at major terminals. Quantas documented 46 cardiac arrests in a 64-month
period in which long-term survival from arrests was 26%, comparable with the
most effective prehospital emergency services. [80] In data from American
Airlines over a 2-year period, the AED was used on 200 patients. Of those with
ventricular fibrillation, 6 of 15 (40%) were shocked and survived to hospital
discharge with full neurologic and functional recovery. Specificity and
sensitivity for ventricular fibrillation were 100%. [81] Based on these
experiences, several US and international airlines have installed AEDs or are
planning to do so. [82,83]

Valenzuela et a1 [84] looked at use of the AED by security personnel in
casinos, a setting in which a large population is closely monitored. Use of
the AED resulted in survival to discharge in 53% (56/105) of patients whose
initial rhythm was ventricular fibrillation. Mean time to first defibrillation
was only 4.4(2.9) minutes while mean time for arrival of paramedics was
9.8(4.3) minutes.

Public Access Defibrillation

How widespread the availability of the AED should be is unknown and whether
AEDs should be placed in shopping malls, conventions centers, and large office
buildings is largely untested. Becker et al, [85] however, retrospectively
looked at the potential benefit of placing AEDs in the higher-incidence sites
of cardiac arrest in Seattle and King County, Washington and estimated that
134 cardiac arrest patients would have been provided treatment, with 8 to 32
lives saved over 5 years. The National Heart, Lung, and Blood Institute and
the AHA are jointly supporting a multicenter, controlled, prospective clinical
trial of PAD that should answer some of these important questions. [86-88]

In the Hospital

The use of the AED is not limited to pre-hospital patient care. While cardiac
arrest survival rates in the coronary care unit can be as high as 90%,
survival outside of these units falls off dramatically. Several minutes can
elapse before conventional in-hospital code teams first attempt
defibrillation. [89,90] It has been shown that non--critical care nurses can
learn to use the AED and retain the knowledge and skill over time. [91] The
use of the AED has made it possible to reduce time to defibrillation in
non--critical care locations and, as a result, in-hospital AED programs are
increasingly being encouraged. [92-96] The AED has been used intraoperatively
in high-risk patients with success. Advantages of the AED in the operating
room included rapid response to ventricular arrhythmia; safe, hands-free
operation; and minimal disruption of the surgical procedure. [97]

Cost to the Health Care System

Although based on multiple assumptions of cost and improvements in survival,
initial cost-effectiveness analyses have suggested that PAD and
first-responder defibrillation are economical in comparison to other common
treatments for life-threatening illnesses. [98,99] Nichol et al [99] estimated
that implementation of PAD by laypersons in an urban EMS system was associated
with a median cost of $44,000 per additional quality-adjusted life-year saved
and that the same program for police use was associated with a median cost of
$27,200 per additional quality-adjusted life-year saved, consistent with the
cost of other common medical interventions (ie, [less than] $50,000 per
quality-adjusted life-year). These data are based on multiple assumptions,
including the cost to implement a PAD program and the survival rate from
cardiac arrest, and must be evaluated with caution. Prospective randomized
trials are needed to better answer these questions. The AHA Guidelines 2000
for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care currently
call for PAD programs in areas where response times of fewer than 5 minutes,
from EMS call to countershock, cannot be reliably achieved, and in areas where
there exists a reasonable probability of at least 1 AED use in 5 years. [86]

Barriers to PAD

Physicians and legislators were initially slow to accept the concept of PAD.
Recently, however, both state and federal governments have taken a more active
role in promoting efforts at reduction of sudden cardiac death. In 1997 the
106th Congress passed the Cardiac Arrest Survivor Act of 1997, amending the
Public Health Service Act to establish at the National Heart, Lung, and Blood
Institute a program regarding lifesaving interventions for individuals who
experience cardiac arrest. The success of manufacturers in developing more
advanced AEDs has reduced concerns over inappropriate shocks and potential
harm of defibrillation by laypersons. These improvements have buoyed the
efforts to pass Good Samaritan laws, and currently 45 states have passed
legislation protecting laypersons who use an AED in good faith. [100] On May
20, 2000, the president proposed an initiative directing the creation of
criteria for the placement of AEDs in federal buildings and on all commercial
airlines in an effort to save up to 20 000 lives each year. [101] These
initiatives at the state and federal levels are paving the way for more
widespread access to defibrillation as legal barriers to PAD, both perceived
and real, are slowly eliminated.

CONCLUSION

Sudden cardiac death remains a major public health issue. Animal and human
data demonstrate that early defibrillation improves survival, and that
reductions in time to defibrillation can increase survival following sudden
cardiac arrest. However, there are limitations to how quickly the EMSs can
respond in many communities, particularly in rural and urban centers. The AED
represents a major advance in the effort to achieve early defibrillation and
further improve survival following out-of-hospital sudden cardiac arrest. By
responding to the challenge to develop an AED that is more accurate,
lightweight, affordable, and easy to use, AED manufacturers have helped make
public access to defibrillation feasible. With help from the state and federal
governments, manufacturers have helped overcome many of the obstacles to AED
implementation. Automated external defibrillators are quickly becoming an
integral part of the EMS and their presence in the community is increasing at
a rapid rate. Additional studies are need ed to determine how widespread the
deployment of these lifesaving devices should be, provide more data on the
cost-effectiveness of PAD, and further define the role of the AED in children
and infants.

Author Affiliations: New England Cardiac Arrhythmia Center. Division of
Cardiology. Department of Medicine, New England Medical Center, Boston, Mass.

Corresponding Author and Reprints: N. A. Mark Estes III, MD, New England
Cardiac Arrhythmia Center, Division of Cardiology, New England Medical Center,
750 Washington St, Boston, MA 02111 (e-mail: nestes@lifespan.org).

Clinical Cardiology Section Editor: Michael S. Lauer, MD, Contributing Editor, JAMA.

REFERENCES

(1.) Gillum RF. Sudden coronary death in the United States: 1980-1985.Circulation. 1989;79:756-765.

(2.) Zipes DP, Wellens HJ. Sudden cardiac death. Circulation.1998:98:2334-2351.

(3.) National Center for Health Statisics. Advance report of final mortality
statistics, 1995. Monthly Vital Stat Rep. 1997:45:S2.

(4.) Becker LB, Ostrander MP, Barrett J, et al. Outcome of CPR in a large
metropolitan area: where are the survivors? Ann Emerg Med. 1991:20:355-361.

(5.) Lombardi G, Gallagher J, Gennis P. Outcome of out-of-hospital cardiac
arrest in New York City: the pre-hospital arrest survival evaluation study. JAMA. 1994: 271:678-683.

(6.) Myerburg RJ, Kessler KM. Castellanos A. Sudden cardiac death: structure,
function, and time dependence of risk. Circulation. 1992:85(suppl 1): 12-110.

(7.) Eisenberg MS, Bergner L, Hallstrom AP, Cummins RO. Sudden cardiac death.Sci Am. 1986;254:37-43.

(8.) Cummins RO, Ornato JP, Thies WH, Pepe PE. Improving survival from sudden
cardiac arrest: the chain of survival concept. Circulation. 1991:83:1832-1847.

(9.) Weaver WD, Cobb LA, Hallstrom AP. Factors influencing survival after
out-of-hospital cardiac arrest. J Am Coll Cardiol. 1986:7:752-775.

(10.) Nichol G, Stiell IG, Laupacis A, et al. A cumulative mete-analysis of
the effectiveness of defibrillator capable emergency medical services for
victims of out-of-hospital cardiac arrest. Ann Emerg Med. 1999:34:517-525.

(11.) Eisenberg MS, Hallstrom A, Bergner L. The ACLS score: predicting
survival from out-of-hospital cardiac arrest. JAMA. 1981;246:50-52.

(12.) Kouwenhoven WB. The development of the defibrillator. Ann Intern Med.1969:71:449-458.

(13.) Haskell WL. Cardiovascular complications during exercise training of cardiac patients. Circulation. 1978:57:920-924.

(14.) Hossack KF, Hartwig R. Cardiac arrest associated with supervised cardiac
rehabilitation. J Card Rehabil. 1982:2:402-408.

(15.) Van Camp SP, Peterson RA. Cardiovascular complications of outpatient
cardiac rehabilitation programs. JAMA. 1986;256:1160-1163.

(16.) Cobb LA, Fahrenbruch CE, Walsh TR, et al. Influence of cardiopulmonary
resuscitation prior to defibrillation in patients with out-of-hospital
ventricular fibrillation. JAMA. 1999;281:1182-1188.

(17.) Weaver WD, Hill D, Fahrenbuch CE, et al. Use of automated external
defibrillators in the management of out-of-hospital cardiac arrest. N Engl J
Med. 1988;319:661-666.

(18.) Stults KR, Brown DD, Kerber RE. Efficacy of an automated external
defibrillator in the management of out-of-hospital cardiac arrest: validation
of the diagnostic algorithm and the clinical experience in a rural
environment. Circulation. 1986;73:701-709.

(19.) Becker LB. Han BH, Meyer PM, et al. Racial differences in the incidence
of cardiac arrest and subsequent survival. N Engl J Med. 1993;329:600-606.

(20.) Weisfeldt ML, Kerber RE, McGoldrick RP, et al, for the American Heart
Association Task Force on Automatic External Defibrillation. Public access to
defibrillation. Circulation. 1995;92:2763.

(21.) Nichol G, Hallstrom AP, Kerber R. et al. American Heart Association
Report on the Second Public Access Defibrillation Conference, April 17-19,
1997. Circulation. 1998;97:1309-1314.

(22.) Diack AW, Welborn WS, Rullman RG. Use of an automatic cardiac
resuscitator for emergency treatment of arrest. Med Instrum. 1979;13:78-81.

(23.) Kerber RE, Becker LB. Bourland JD, et al. Automatic external
defibrillators for public access defibrillation: recommendation for specifying
and reporting arrhythmia analysis algorithm performance, incorporating new
waveforms, and enhancing safety. Circulation. 1997;95:1677-1682.

(24.) Cummins RO, Eisenberg M, Bergner L, Murray JA Sensitivity, accuracy, and
safety of an automatic external defibrillator. Lancet. 1984;2:318-320.

(25.) Gundry JW, Comess KA, DeRook FA, Jorgenson D, Bardy GH. Comparison of
naive sixth-grade children with trained professionals in the use of an
automated external defibrillator. Circulation. 1999;100:1703-1707.

(26.) Gliner BE, Jorgenson DB, Poole JE, et al, for the LIFE Investigators.
Treatment of out-of hospital cardiac arrest with low-energy
impedance-compensating biphasic waveform automatic external defibrillators.
Biomed Instrum Technol. 1998;32:631-644.

(27.) Stults KR, Brown DD, Cooley F, et al. Self adhesive
monitor/defibrillator pads improve pre-hospital defibrillation success. Ann
Emerg Med. 1987:16:872-877.

(28.) Carlson MD, Freeman CS, Garan H, Ruskin IN. Sensitivity of an automatic
external defibrillator for ventricular tachyarrhythmias in patients undergoing
electrophysiologic studies. Am J Cardiol. 1988;61:787-790.

(29.) Poole JE, White RD. Kanz KG, et al. Low-energy impedance-compensating
biphasic waveforms terminate ventricular fibrillation at high rates in victims
of out-of-hospital cardiac arrest. J Cardiovasc Electro physiol. 1997;8:1373-1385.

(30.) White RD. Gliner BE. Transthoracic impedance does not affect
defibrillation efficacy in cardiac arrest victims when shocks are delivered
with an impedance compensating biphasic waveform. Circulation. 1997;96(suppl 1):1-561.

(31.) DaIzell GWN, Adgey AAJ. Determinants of successful transthoracic
defibrillation. Br Heart J. 1991: 65:311-316.

(32.) Kerber RE, Martins JB, Kienzle MG, et al. Energy, current, and success
in defibrillation and cardioversion: clinical studies using an automated
impedance based method of energy adjustment. Circulation. 1988;77:1038-1046.

(33.) Kerber RE. Electrical treatment of cardiac arrythmias: defibrillation
and cardioversion. Ann Emerg Med. 1993;22:296-301.

(34.) Dalzell GWN, Cunningham SR. Anderson J, Adgey AA. Electrode pad size,
transthoracic impedance and success of external ventricular defibrillation. Am J Cardiol. 1989;64:741-744.

(35.) Hoyt R, Grayzel J, Kerber RE. Determinants of intracardiac current in
defibrillation: experimental studies in dogs. Circulation. 1981;64:818-823.

(36.) Bardy GH, Marchlinski FE, Sharma AD, et al. Multicenter comparison of
truncated biphasic shocks and standard damped sine wave monophasic shocks for
transthoracic ventricular defibrillation. Circulation. 1996;94:2507-2514.

(37.) Bardy GH, Gliner BE, Kudenchuk PJ, et al. Truncated biphasic pulses for
transthoracic defibrillation. Circulation. 1995;91:1768-1774.

(38.) Walcott GP, Melnick SB, Chapman FW, et al. Relative efficacy of
monophasic and biphasic waveforms for transthoracic defibrillation after short
and long durations of ventricular fibrillation. Circulation.
1998;98:2210-2215.

(39.) Greene HL, DiMarco JP, Kudenchuk PJ, et al, for the Biphasic Waveform
Defibrillation Investigators. Comparison of monophasic and biphasic
defibrillating pulse waveforms for transthoracic cardioversion. Am J Cardiol. 1995:75:1135-1139.

(40.) Wilson CM, Bailey A, Allen JD, Anderson J, Adgey AA. Transthoracic
defibrillation threshold of sine and trapezoidal waveforms in defibrillation.
I Electocardial. 1989;22:241-247.

(41.) Swartz JF, Fletcher RF, Karasik PJ, et al. Optimization of biphasic
waveforms for human nonthoracotomy defibrillation. Circulation. 1993;88:2646-2654.

(42.) Bardy GH, Gliner BE, White RD. Comparison of human defibrillation
efficacy rates in short duration and long duration ventricular fibrillation
using monophasic and biphasic transthoracic shocks. Circulation. 1997;96(suppl):1-560.

(43.) Kerber RE, Spencer KT, Kallok MJ et al. Overlapping sequential pulses: a
new waveform for transthoracic defibrillation. Circulation. 1994;89:2369-2379.

(44.) Peleska B. Optimal parameters of electrical impulses for defibrillation
by condenser discharges. Circ Res. 1966;18:10-17.

(45.) Yamanouchi Y, Brewer JE, Olson KF, et al. Fully discharging phases: a
new approach to biphasic waveforms for external defibrillation. Circulation. 1999;100:826-831.

(46.) Yamanouchi Y, Brewer JE, Mowrey KA, Donohoo AM, Wilkoff BL, Tchou P. The
optimal small capacitor biphasic waveform for external defibrillation:
influence of phase-1 tilt and phase-2 voltage. Circulation. 1998;98:2487-2493.

(47.) Cummins RO, Hazinski F, Kerber RE, et al, for the American Heart
Association Committee on Emergency Cardiovascular Care. Low-energy biphasic
waveform defibrillation: evidence-based review applied to emergency cardiac
care guidelines. Circulation. 1998;97:1654-1667.

(48.) Ideker RE, Charbonnier F. Established and alternative waveforms.
Workshop report presented at: Second American Heart Association Public Access
Defibrillation Conference; April 19, 1997; Washington, DC.

(49.) Tang W, Weil MH, Sun S, et al. Low-energy biphasic waveform
defibrillation reduces the severity of postresuscitation myocardial
dysfunction after prolonged arrest. Crit Care Med. 2000;11 (suppl): N222-224.

(50.) Tang W, Weil MH, Sun S, et al. The effects of biphasic and conventional
monophasic defibrillation on postresuscitation myocardial function. J Am Coll
Cardiol. 1999;34:815-822.

(51.) Bachman JW, McDonald GS, O'Brien PC. A study of out-of-hospital cardiac
arrests in northeastern Minnesota. JAMA. 1986;256:477-483

(52.) Olson DW, LaRochelle J, Fark D, et al. EMT-defibrillation: the Wisconsin
experience. Ann Emerg Med. 1989;18:806-811.

(53.) Eisenberg MS, Copass MK, Hallstrom AP. Treatment of out-of hospital
cardiac arrest with rapid defibrillation by emergency medical technicians. N
Engl J Med. 1980;302:1379-1383.

(54.) Stults KR, Brown DD, Schug VL. Prehospital defibrillation performed by
emergency medical technicians in rural communities. N Engl J Med. 1984;310:219-223.

(55.) Cummins RO, Eisenberg MS, Litwin PE. Automatic external defibrillators
used by emergency medical technicians: a controlled clinical trial. JAMA. 1987;27:1605-1610.

(56.) Gray AJ, Redmond AD, Martin MA. Use of the automatic external
defibrillator-pacemaker by ambulance personnel: the Stockport experience. BMJ.
1987;294:1133-1135.

(57.) Jakobsson J, Nyquist O, Rehnquist N. Effects of early defibrillation of
out-of-hospital cardiac arrest patients by ambulance personnel. Eur Heart J. 1987;8:1189-1194.

(58.) Eisenberg MS, Hallstrom AP, Copass MK. Treatment of ventricular
fibrillation: emergency medical technician defibrillation and paramedic
services. JAMA. 1984;251:1723-1726.

(59.) Vukov IF, White RD, Backman JW. New perspectives on rural EMT
defibrillation. Ann Emerg Med. 1988;17:318-321.

(60.) Watts DO. Defibrillation by basic emergency medical technicians: effect
on survival. Ann Emerg Med. 1995;26:635-639.

(61.) Auble TE, Menegazzi JL, Paris PM. Effect of out-of-hospital
defibrillation by basic life support providers on cardiac arrest mortality: a
meta-analysis. Ann Emerg Med. 1995;25:642-648.

(62.) Weaver WD, Copass MK, Bufi D, Ray R, Hallstrom AP, Cobb LA. Improved
neurologic recovery and survival after early defibrillation. Circulation. 1984;69:943-948.

(63.) White RD, Vukov LF, Bugliosi TF. Early defibrillation by police: initial
experience with measurement of critical time intervals and patient outcome.
Ann Emerg Med. 1994;23:1009-1013.

(64.) Mossesso VN Jr, Davis EA, Auble TE, Paris PM, Yealy DM. Use of automated
external defibrillators by police officers for treatment of out-of-hospital
cardiac arrest. Ann Emerg Med. 1998;32:200-207.

(65.) White RD, Asplin BR, Bugliosi TF, Hankins DG. High discharge survival
rate after out-of-hospital ventricular fibrillation with rapid defibrillation
by police and paramedics. Ann Emerg Med. 1996;28:480-485.

(66.) Shuster M, Keller JL. Effect of fire department first-responder
automated defibrillation. Ann Emerg Med. 1 1993;22-721-727.

(67.) Weaver WD, Copass MK, Hill D, Fahrenbruch C, Hallstrom AP, Cobb L
Cardiac arrest treated with a new automatic external defibrillator by
out-of-hospital first responders. Am J Cardiol. 1986;57:1017-1021.

(68.) Davis EA, Mosesso VN Jr. Performance of police first-responders in
utilizing automated external defibrillation on victims of sudden cardiac
arrest. Pre-hosp Emerg Care. 1998;2:101-107.

(69.) Kellermann AL, Hackman BB, Somes G, Kreth TK, Nail L, Dobyns P. Impact
of first-responder defibrillation in an urban emergency medical services
system. JAMA. 1993;270:1708-1713.

(70.) Sweeney TA, Runge JW, Gibbs JM, Schafermeyer RW, Norton HJ,
Boyle-Whitesel MJ. EMT defibrillation does not increase survival from sudden
cardiac death in a two-tiered urban-suburban EMS system. Ann Emerg Med. 1998;31:234-240.

(71.) Stiell IG, Wells GA, Field BJ, et al. Improved out-of-hospital cardiac
arrest survival through the inexpensive optimization of an existing
defibrillation program. JAMA. 1999;281:1175-1181.

(72.) Brison RJ, Davidson JR, Dreyer JF, et al. Cardiac arrest in Ontario:
circumstances, community response, role of prehospital defibrillation and
predictors of survival. CMAJ. 1992;147:191-199.

(73.) Asplin BR, Yealy DM, White RD. Improving survival following
out-of-hospital cardiac arrest. JAMA. 1999;282:1033-1034.

(74.) Nichol G, Stiell IG, Laupacis A, et al. A cumulative meta-analysis of
the effectiveness of defibrillator-capable emergency medical services for
victims of out-of-hospital cardiac arrest. Ann Emerg Med. 1999;34:517-525.

(75.) McDaniel CM, Berry VA, Haines DE, et al. Automatic external
defibrillation of patients after myocardial infarction by family members:
practical aspects and psychological impact of training. Pacing Clin Electrophysiol. 1988;11:155-160.

(76.) Eisenberg MS, Moore J, Cummins RO, et al. Use of the automatic external
defibrillator in homes of survivors of out-of-hospital ventricular
fibrillation. Am J Cardiol. 1989;63:443-446.

(77.) The Antiarrhythmics Versus Implantable Defibrillators (AVID)
Investigators. A comparison of antiarrhythmic-only therapy with implantable
defibrillators in patients resuscitated from near-fatal ventricular
arrythmias. N Engl J Med. 1997;337:1576-1583.

(78.) Siebels J, Kuck KH, for the CASH investigators. Implantable cardioverter
defibrillator compared with antiarrhythmic drug treatment in cardiac arrest
survivors (the Cardiac Arrest Study Hamburg). Am Heart J. 1994;127:1139-1144.

(79.) Moss AJ, Hall J, Cannom DS, et al. Improved survival with an implanted
defibrillator in patients with coronary disease at high risk for ventricular
arrhythmia: the Multi-Center Automatic Defibrillator Implantation Trial. N
Engl J Med. 1996;335:1933-1940.

(80.) O'Rourke MF, Donaldson EE, Geddes JS. An airline cardiac arrest program.
Circulation. 1997;96:2849-2853.

(81.) Page RL, Joglar JA, Kowal RC, et al. Use of automated external
defibrillators by a U.S. airline. N Engl J Med. 2000;343:1210-1216.

(82.) Zimmermann PG, Campbell L. Automatic external defibrillators on
commercial airplanes. J Emerg Nurs. 1997;23:340-342.

(83.) Smith SC, Hamburg RS. Automated external defibrillators; time for
federal and state advocacy and broader utilization. Circulation. 1998;97:1321-1324.

(84.) 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.

(85.) Becker L, Eisenberg M, Fahrenbruch C, Cobb L. Public locations of
cardiac arrest: implications for public access defibrillation. Circulation. 1998;97:2106-2109.

(86.) The American Heart Association in Collaboration with the International
Liaison Committee on Resuscitation. Guidelines 2000 for Cardiopulmonary
Resuscitation and Emergency Cardiovascular Care. Circulation. 2000;102(suppl 1):160-176.

(87.) Robertson RM. Sudden death from cardiac arrest: improving the odds. N Engl J Med. 2000;343:1259-1260.

(88.) Hallstrom AP. Public Access Defibrillation (PAD) Community Trial
[abstract] [CRISP database online]. Grant 1N01HC95177. Available at:
http://commons.cit.nih.gov/crisp/CRISP.generate_ticket. Access confirmed.

(90.) Dickey W, Adgey A. Mortality within hospital from ventricular
fibrillation outside the hospital. Br Heart J. 1992;67:334-338.

(89.) Lazzam C, McCans J. Predictors of survival of in-hospital cardiac arrest. Can J Cardiol. 1991;7:113-116.

(91.) Mancini ME, Kaye W. In-hospital first-responder automated external
defibrillation: what critical care practitioners need to know. Am J Crit Care. 1998;7:314-319.

(92.) Kaye W, Mancini ME, Guiliano KK, Richards N. Strengthening the
in-hospital chain of survival with rapid defibrillation by first responders
using automated external defibrillators: training and retention issues. Ann
Emerg Med. 1995;25:163-168.

(93.) Kaye W, Mancini ME, Richards N. Organizing and implementing a
hospital-wide first-responder automated external defibrillation program:
strengthening the in-hospital chain of survival. Resuscitation. 1995;30:151-156.

(94.) Kaye W, Mancini ME. Improving outcome from cardiac arrest in the
hospital with a reorganized and strengthened chain of survival: an American
view. Resuscitation. 1996;31:181-186.

(95.) Destro A, Marzaloni M, Sermasi S, Rossi F. Automated external
defibrillators in the hospital as well? Resuscitation. 1996;31:39-43.

(96.) Spearpoint KG, McLean CP, Zideman DA. Early defibrillation and the chain
of survival in "in-hospital" adult cardiac arrest: minutes count.
Resuscitation. 2000;44:165-169.

(97.) Jones FD, Fahy BG. Intraoperative use of automated external defibrillator. J Clin Anesth. 1999;11:336-338.

(98.) Jermyn BD. Cost-effectiveness analysis of a rural/urban first-responder
defibrillation program. Pre-hosp Emerg Care. 2000;4:43-47.

(99.) Nichol G, Hallstrom AP, Ornato JP, et al. Potential cost-effectiveness
of public access defibrillation in the United States. Circulation. 1998;97:1315-1320.

(100.) SoRelle R. States set to pass laws limiting liability far lay users of
automated defibrillators. Circulation. 1999;99:2606-2607.

(101.) President William Jefferson Clinton. White House press release. June 1, 2000.
                     Automated External Defibrillators
Manufacturer                          		Model           	Battery Type
Agilent Technologies, Seattle, Wash   	Heartstream FR2 	Lithium
Medtronic Physiocontrol,              	Lifepak 500     	Lithium or
  Redmond, Va                                           		lead-acid
Survivalink, Minneapolis, Minn        	Firstsave       	Lithium
Laerdal Medical, Wappingers Falls, NY 	Heartstart FR   	Lithium
Medical Research Laboratories,        	AEDefibrillator 	Lithium
  Buffalo Grove, Ill
Zoll Medical Corporation,             	Zoll M Series   	Lead-acid
  Burlington, Mass [ss]
Manufacturer                          		Waveform (Shock Energy, Joules)
Agilent Technologies, Seattle, Wash   	Nonescalation biphasic (150) [*]
Medtronic Physiocontrol,              	Escalating biphasic or
  Redmond, Va                           	monophasic (200, 300, 360)
Survivalink, Minneapolis, Minn        	Escalating biphasic or monophasic (140-360) [+]
Laerdal Medical, Wappingers Falls, NY 	Nonescalating biphasic (150) [*]
Medical Research Laboratories,        	Escalating biphasic [++] or monophasic
  Buffalo Grove, Ill
Zoll Medical Corporation,             	Monophasic (200, 300, 260) or
  Burlington, Mass [ss]                 	biphasic (120, 150, 200)
Manufacturer                          		Weight, kg
Agilent Technologies, Seattle, Wash      	2.1
Medtronic Physiocontrol,                 	3.2
  Redmond, Va
Survivalink, Minneapolis, Minn          	 3.4
Laerdal Medical, Wappingers Falls, NY    	2.1
Medical Research Laboratories,           	2.1
  Buffalo Grove, Ill
Zoll Medical Corporation,                	5.2
  Burlington, Mass [ss]

(*.)Shock waveform adjusted for impedance.

(+.)Shock energy adjusted for impedance.

(++.)Awaiting approval from the Food and Drug Administration.

(ss.)Includes electrocardiogram monitor and manual capability.
                     Comparison of Survival Rates From
                      Out-of-Hospital Cardiac Arrest
                       After Defibrillation With an
                     Automated External Defibrillator
                    (AED) vs a Manual Defibrillator [*]
                                     Survival, % (No.)
Study              	Location          Manual Defibrillator AED
Weaver et al [17]  	Seattle, Wash         17 (44/228)      30 (84/276)
Stults et al [18]  	Iowa                  13 (7/53)        17 (6/35)
Cummins et al [55] 	King County, Wash     23               28
Study                        	P Value
Weaver et al [17]     		[less than].001
Stults et al [18]  	[greater than].75
Cummins et al [55]                NS
(*.)NS indicates not significant.
               Comparison of First-Responder Defibrillation
                     With Paramedic/EMT Defibrillation
                                         Survival, % (No.)
Study               	Location             		First Responder   Paramedic/EMT
Mossesso et al [64] 	Allegheny County, Pa   	26 (12/46)        3 (1/29)
Weaver et al [17]   	Seattle, Wash          		30 (84/276)      19 (44/220)
Shuster et al [66]  	Hamilton, Ontario     		5.7 (8/140)      2.7 (4/147)
White et al [63]    	Rochester, Minn        		49 (41/84)       43 (23/53)
Weaver et al [67]   	Seattle, Wash          		30 (26/87)       28 (105/370)
                                         Call-to-Shock Time, min
                                                  First
Study                        	P Value            Responder
Mossesso et al [64]             	.01                8.7
Weaver et al [17]     [less than] .001               3.6
Shuster et al [66]                NA               8.5
White et al [63]                	.02                5.6
Weaver et al [67]                 	NS [+]           8.8
Study               		Paramedic/EMT
Mossesso et al [64]      	11.8
Weaver et al [17]         	5.1
Shuster et al [66]       		12
White et al [63]          	6.3
Weaver et al [67]        	11.5

(*.)EMT indicates emergency medical technician; CPR, cardiopulmonary
resusitation; and NS, not significant.

(+.)Subset of patients who had prolonged paramedic response times or in whom
initiation of CPR did demonstrate significant improvement in suvival.
                                                                              

                                -- End --