Antoni Martínez-Rubio, MD, FESC,
FACC and Gonzalo Barón-Esquivias, MD, FESC*
Departments of Cardiology . Hosp. de
Sabadell (Fund. Univ. Parc Taulí), Sabadell, Barcelona and University
Hospital Virgen del Rocio*, Seville, Spain.
Address for correspondence:
Antoni Martínez-Rubio, MD, FESC, FACC, Hospital de Sabadell – Cardiology,
Fund. Universitaria Parc Taulí, Parc Taulí s/n, E-08208 Sabadell,
Barcelona, Spain. Email:
22917amr@comb.es
Abstract:
In-hospital cardiac arrest remains a major problem but new technologies allowing
fully automatic external defibrillation are available. These technologies
allow the concept of “external therapeutic monitoring” of lethal arrhythmias.
Since early defibrillation improves outcome by decreasing morbidity and mortality,
the use of this device should improve the outcome of in-hospital cardiac
arrest victims. Furthermore, the use of these devices could allow safe monitoring
and treatment of patients at risk of cardiac arrest who not necessarily
must be in conventional monitoring units (Intensive or Coronary Care Units)
saving costs with a more meaningful use of resources. The capability to
provide early defibrillation within any patient-care areas should be considered
as an obligation (“standard of care”) of the modern hospital.
Key words: cardiac arrest, cost-effective, defibrillation,
ventricular arrhythmias, ventricular fibrillation and ventricular tachycardia.
Introduction
Cardiovascular
disease is the major cause of death in the majority of countries
1,2. In developed countries
(e.g. United States), nearly the half of these deaths are unexpected and
sudden
3,4. Although
the broad majority of sudden cardiac deaths occur outside the hospital and
very poor survival rates have been reported, in-hospital cardiac arrest remains
a major problem. The aim of this article is to review the actual knowledge
of the utility of “fully automatic” external defibrillators for treatment
of in-hospital cardiac arrest. The name “automated” external defibrillator
(AED) must be distinguished from fully “automatic” external defibrillator.
The automatic device is able to deliver a shock without intervention from
an operator whereas the automated device only “advises” by a voice or a text
to deliver the energy. Thus, the automated device requires operator intervention.
Physiological considerations of cardiac arrest
Cardiopulmonary
resuscitation maneuvers can sustain a patient for a certain time but is unlikely
to restore an organized rhythm of the heart. To achieve this goal defibrillation
and advanced cardiovascular care are necessary, which must be administered
in the shortest possible interval after the arrhythmic event. Furthermore,
the risk of ischemia and the defibrillation threshold increase with arrhythmia
duration
5. The time to defibrillation
is the single most important determinant of survival from cardiac arrest
6,7,8,9,10,11,12,13,14,15,16,17. In addition, ventricular
fibrillation (VF) tends to evolve to asystole within few minutes
18,19,20,21,22,23,24,25,26,27. Thus, survival rates after VF decrease
approximately 7% to 10% with every minute that defibrillation is delayed
18,19,20,21,22,23,24. In addition, the cerebral cortex is irreversibly
damaged if cardiac arrest is not quickly interrupted
18,28,29,30. Because of these facts, individual physicians
as well as the American Heart Association, the American College of Emergency
Physicians, the European Resuscitation Council and others have advocated
the widespread dissemination of defibrillators for decreasing mortality and
morbidity for victims of cardiac arrest
31,32,33,34.
In-hospital cardiac arrest
The classical reality
Sustained ventricular
tachycardia (VT) and VF, even in hospitalized patients, are major causes
of morbidity and mortality
28,35,36,37. In the best setting
(monitoring wards), continuous ECG monitoring allows identification of lethal
arrhythmias and alarm systems alert nursing and medical staff. However, a
time delay between the arrhythmic event and human intervention obviously
exists. This time delay may be prolonged in certain circumstances even in
monitoring wards. In addition, response time intervals for in-hospital resuscitation
events are often inaccurate and must be corrected before documented times
to defibrillation can be considered reliable
34.
Although major
evidence exists supporting the need for rapid defibrillation and important
advances in out-of-hospital cardiac arrest treatment have been achieved
(e.g. out-of hospital cardiac arrest quick response programs)
15,16,34,38,39,40,41,42,43,
in-hospital cardiac arrest is still a major problem without significant advances
(e.g. changing strategies) during the last 30 years. This leads to important
mortality, morbidity and social as well as economic costs
28,35,36,37. The scarcity of data
28,44 related to deployment
of AEDs in hospitals and its impact on patient outcome reflects the very
limited existence of in-hospital early defibrillation programs.
However, as stated
in major guidelines, early defibrillation is a high-priority goal in out-of
hospital as well as in-hospital cardiac arrest
31,32,33,34.
Clearly the earlier defibrillation occurs, the better the prognosis in adults
and children
18,19,20,21,23,24,25,27,45,46,47.
The capability
to provide early defibrillation within any patient-care areas should be
considered as an obligation (“standard of care”) of the modern hospital.
Furthermore, cardiac arrests often occur outside monitored areas. Recently,
Herlitz et al.
28 reported that
out of 557 patients suffering in-hospital cardiac arrest, only 292 patients
(53%) were in monitored wards and from those only 43.2% of the patients
could be discharged alive. They reported that the median interval between
collapse and first defibrillation was 1 minute in monitored wards and 5 minutes
in non-monitored wards. Only 31% of patients from non-monitored wards could
be discharged alive and with a cerebral performance inferior to that of survivors
of monitored wards. Other authors
48
present similar data showing better in-hospital survival for witnessed arrest
(25%) than for non-witnessed arrest (7%) but, in addition, they report a
disproportionately high incidence of non-witnessed arrests during the night
(12AM to 6 AM) resulting in a very poor survival rate (0%). Cardiac arrest
occurs in 4.8% of hospitalized patients because of acute myocardial infarction
49. The survival rate to hospital discharge
for these individuals was 29.4%
49.
Although ventricular tachycardia or fibrillation was documented in 34.7%
of patients, only 47.5% of those survived to discharge
49. Thus, the use of “automatic” defibrillators
had probably improved outcome of those patients presenting in-hospital cardiac
arrest. Furthermore, although survival to hospital discharge offers an objective
evaluation point and is used in the broad majority of reports, several patients
who survive a cardiac arrest present neurological damage, which is highly
dependent of the response time to cardiac arrest
18,28,29.
Therefore, the neurological status should also be considered when reporting
results of resuscitation procedures
30.
The new reality
Very early response
to lethal ventricular tachyarrhythmias is achievable now with fully “automatic”
external defibrillators. As occurs with implantable cardioverter defibrillators,
these devices may be individually programmed to intervene. Thus, as occurs
with other medical management strategies (e.g. drugs prescription), physicians
may and should decide under which circumstances and how the device will react
in presence of arrhythmias.
In a multicenter
European trial, Martínez-Rubio et al.
50
tested the safety and efficacy of an automatic external cardioverter-defibrillator
[Powerheart®; Cardiac Science Inc., Irvine (California, USA)]. Subjects
(n=117) included patients undergoing electrophysiologic testing (n=66; all
with suspected/documented VT/VF or undergoing implantation of implantable
cardioverter defibrillator) as well as patients in monitoring wards (n=51)
at risk of cardiac arrest. Patients with active implanted cardioverter-defibrillators
were excluded from the study.
The automatic
external cardioverter-defibrillator was connected to patients using self-adhesive
electrodes. Placement of the electrodes (either antero-posterior or
sternal-apex) was at the discretion of the investigators.
The automatic
external defibrillator was used for monitoring and treatment of patients
in the coronary care units or intensive care units. It was also used
as a “rescue” defibrillator during ICD implantations. This device operates
either in “advisory” or in “automatic” mode. In advisory mode, it will
detect the arrhythmia, alarm, charge the capacitors, and prompt the user to
deliver the shock. The energy (maximum of 360J monophasic) and time delay
(10s to 600s) for each shock could be programmed (up to 9 shocks per episode).
Shock delivery was non-committed such that therapy is automatically aborted
should the rhythm spontaneously convert to a non-shockable rhythm.
In addition, the device algorithm featured a modulation domain function which
allows to discriminate between ventricular and supraventricular rhythms.
The performance
of the device in detecting shockable and non-shockable rhythms was confirmed
by review of the simultaneously recorded Holter data and the programmed parameters.
A total of 1,240 hours of monitoring and 1,988 episodes of rhythm changes
were documented. The device detected ventricular arrhythmias with
a sensitivity of 100% and specificity of 97.6%. The mean response time
to shock was 14.4 seconds [evaluated in those episodes (sustained) that
were associated with a full capacitor charge cycle]. All false positives
were caused by T-wave oversensing during ventricular pacing. There
were no complications or adverse events. There were a total of 35 sustained
arrhythmic episodes treated by the device (12 in the EP lab and 23 in monitoring
wards). All 35 episodes were successfully (100% efficacy) converted
to normal sinus rhythm with a first shock success of 94.3% (
Figure 1).
This European study
50 confirms
the initial experience presented by Mattioni et al
51 in a multicenter American trail. These authors
reported a sensitivity and specificity of 100% and 99.4%, respectively, and
a response time of 22 seconds
51.
Click here to view larger images:
Upper Panel Lower Panel
Figure 1.
Upper panel: Recording of the automatic
external cardioverter-defibrillator response to spontaneous monomorphic ventricular
tachycardia. The device is programmed to detect the arrhythmia, to charge
and to delay 1 minute the shock delivery. After 24 seconds and spontaneously,
the tachycardia terminates. Observe that the device aborts the shock delivery.
The first circle indicates de beginning of charge (200 J) of the device. The
second circle indicates the full charge of the device (“ready to shock”).
Each line corresponds to 15 seconds of continuous ECG registration.
Lower panel: Recording of the automatic external cardioverter-defibrillator
response to spontaneous ventricular fibrillation in a patient with admitted
because of recurrent syncope. The first circle indicates de beginning of charge
(200 J) of the device. The second circle indicates the full charge of the
device. Note that the device terminates the arrhythmia when applies the shock.
Each line corresponds to 15 seconds of continuous ECG registration.
Although some differences
exist (e.g. sample size, hours of monitoring, software version, etc.) both
studies
50,51
lead to the same conclusions. Thus, both groups (European and American) of
investigators agree that the device is safe and highly effective in monitoring,
detecting and treating spontaneous rhythms. Therefore, with its wide use
a significant improvement in the treatment of in-hospital cardiac arrest should
be expected. In addition, the now available version of the described automated
external cardioverter-defibrillator has important improvements (compatibility
to commercially available patient monitoring systems, biphasic wave forms,
etc.).
References
1. Murray CJL, López AD. Alternative projections of mortality
and disability by cause 1990-2020: Global Burden of Disease Study. Lancet
1997; 349: 1498-1504.
2. Achutti A, Balaguer-Vintró,
Bayés de Luna A, Chalmers J, Chockalingam, Farinaro E, Lauzon RRJ,
Martin I, Papp JG, Postiglione A, Reddy KS. Profile and magnitude of the
problem. In: Chockalingam A, Balaguer-Vintró I eds. Impending global
pandemic of cardiovascular disease. Prous Science (Barcelona) and World Heart
Federation (Geneva) 1999:11-49.
3. Bayés de Luna A, Coumel
P, Leclercq JF et al. Ambulatory sudden death: mechanisms of production of
fatal arrhythmia on the basis of data from 157 cases. Am Heart J 1989;117:
151-59.
4. Zipes DP, Wellens HJ.
Sudden Cardiac Death. Circulation 1998; 98: 2334-51.
5. Winkle RA, Mead RH, Ruder MA,
et al. Effect of duration of ventricular fibrillation on defibrillation efficacy
in humans. Circulation 1990; 81: 1477-81.
6. Cummins
RO, Eisenberg MS, Bergner L, Hallstrom A, Hearne T, Murray JA. Automatic
external defibrillation: evaluations of its role in the home and in emergency
medical services. Ann Emerg Med 1984;13:798–801.
7. Cummins RO, Eisenberg MS, Moore JE,
Hearne TR, Andresen E, Wendt R, Litwin PE, Graves JR, Hallstrom AP, Pierce
J. Automatic external defibrillators: clinical, training, psychological,
and public health issues. Ann Emerg Med 1985;14:755–760.
8. Atkins
JM. Emergency medical service systems in acute cardiac care: state of the
art. Circulation 1986;74(suppl IV):IV-4–IV-8.
9. Cummins RO, Eisenberg MS, Stults KR. Automatic
external defibrillators: clinical issues for cardiology. Circulation 1986;73:381–38
10. Eisenberg MS, Cummins RO. Defibrillation
performed by the emergency medical technician. Circulation 1986;74(suppl
IV):IV-9–IV-12.
11. Jacobs L. Medical, legal, and
social implications of automatic external defibrillators. Ann Emerg Med 1986;15:863–864.
12.
Cummins RO. EMT-defibrillation: national
guidelines for implementation. Am J Emerg Med 1987;5:254–257.
13.
Newman
MM. The survival advantage: early defibrillation programs in the fire service.
J Emerg Med Serv 1987;12:40–46.
14.
Ruskin JN. Automatic external defibrillators
and sudden cardiac death. N Engl J Med 1988;319:713–715.
15.
Sedgwick ML, Watson J, Dalziel K, Carrington DJ, Cobbe SM. Efficacy
of out of hospital defibrillation by ambulance technicians using automated
external defibrillators: the Heartstart Scotland Project. Resuscitation 1992;24:73–87.
16.
Mols P, Beaucarne E, Bruyninx J, Labruyere JP,
De Myttenaere L, Naeije N, Watteeuw G, Verset D, Flamand JP. Early defibrillation
by EMTs: the Brussels experience. Resuscitation 1994;27:129–136.
17. Stapczynski JS, Svenson JE,
Stone CK. Population density, automated external defibrillator use, and survival
in rural cardiac arrest. Acad Emerg Med 1997;4:552–558.
18. 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.
19. Bachman JW, McDonald GS, O’Brien
PC. A study of out-of-hospital cardiac arrests in northeastern Minnesota.
JAMA 1986;256:477–483.
20. Cummins RO. From concept
to standard-of-care? Review of the clinical experience with automated external
defibrillators. Ann Emerg Med 1989;18:1269–1275.
21. Olson DW, LaRochelle J, Fark D, Aprahamian
C, Aufderheide TP, Mateer JR, Hargarten KM, Stueven HA. EMT-defibrillation:
the Wisconsin experience. Ann Emerg Med 1989;18:806–811.
22. Eisenberg
MS, Horwood BT, Cummins RO, Reynolds-Haertle R, Hearne TR. Cardiac arrest
and resuscitation: a tale of 29 cities. Ann Emerg Med 1990;19:179–186.
23. Eisenberg
MS, Cummins RO, Damon S, Larsen MP, Hearne TR. Survival rates from out-of-hospital
cardiac arrest: recommendations for uniform definitions and data to report.
Ann Emerg Med 1990;19:1249–1259.
24. Larsen MP, Eisenberg MS, Cummins
RO, Hallstrom AP. Predicting survival from out-of-hospital cardiac arrest:
a graphic model. Ann Emerg Med 1993;22:1652–1658.
Circulation. 1998;97:987-995.
25.
Valenzuela TD, Spaite DW, Meislin
HW, Clark LL, Wright AL, Ewy GA. Emergency vehicle intervals versus collapse-to-CPR
and collapse-to-defibrillation intervals: monitoring emergency medical services
system performance in sudden cardiac arrest. Ann Emerg Med 1993;22:1678–1683.
26. Valenzuela TD, Roe DJ, Cretin S, Spaite DW, Larsen
MP. Estimating effectiveness of cardiac arrest interventions: a logistic
regression survival model. Circulation 1997;96:3308–3313.
27. Holmberg M, Holmberg S, Herlitz J,
Gardelov B. Survival after cardiac arrest outside hospital in Sweden: Swedish
Cardiac Arrest Registry. Resuscitation 1998;36:29–36.
28.
Herlitz J, Bang A,
Aune S, Ekstrom L, Lundstrom G, Holmberg S. Characteristics and outcome
among patients suffering in-hospital cardiac arrest in monitored and non-monitored
areas. Resuscitation 2001; 48: 125-35.
29.
Jorgensen EO, Holm S. The course
of circulatory and cerebral recovery after circulatory arrest: influence
of prearrest, arrest and post-arrest factors. Resuscitation 1999; 42: 173-82.
30. Rosomoff HL, Kochanek PM,
Clark R, DeKosky ST, Ebmeyer U, Grenvik AN, Marion DW, Obrist W, Palmer AM,
Safer P, White RJ. Resuscitation from severe brain trauma. Crit Care Med.
1996;24:S48–S56.
31. McDowell R, Krohmer J, Spaite DW, Benson N, Pons P,
American College of Emergency Physicians. Guidelines for implementation of
early defibrillation/automated external defibrillator programs. Ann Emerg
Med 1993;22:740–741.
32. Kloeck W, Cummins RO, Chamberlain
D, Bossaert L, Callanan V, Carli P, Christenson J, Connolly B, Ornato JP,
Sanders A, Steen P. Early defibrillation: an advisory statement from the
Advanced Life Support Working Group of the International Liaison Committee
on Resuscitation. Circulation 1997;95:2183–2184.
33. Bossaert L, Handley A, Marsden
A, Arntz R, Chamberlain D, Ekstrom L, Evans T, Monsieurs K, Robertson C,
Steen P. European Resuscitation Council guidelines for the use of automated
external defibrillators by EMS providers and first responders: a statement
from the Early Defibrillation Task Force, with contributions from the Working
Groups on Basic and Advanced Life Support, and approved by the Executive Committee.
Resuscitation 1998;37:91–94.
34. Guidelines 2000 for Cardiopulmonary
Resuscitation and Emergency Cardiovascular Care. The American Heart Association
in Collaboration with the International Liaison Committee on Resuscitation.
Part 4: The automated External Defibrillator. Key link in the Chain of Survival.
Circulation 2000; 102(suppl 8): I60-76.
35. Bedell SE, Delbanco TL, Cook EF,
et al. Survival after cardiopulmonary resucitation in the hospital. N En
J Med 1983; 309: 569-76.
36. 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: 181-6.
37. Thel MC, O'Connor CM. Cardiopulmonary
resuscitation: historical perspective to recent investigations. Am
Heart J 1999;137(1):39-48.
38. O’Rourke MF, Donaldson E, Geddes
JS. An airline cardiac arrest program. Circulation 1997;96:2849–2853.
39. Page RL, Hamdan MH, McKenas DK. Defibrillation
aboard a commercial aircraft. Circulation 1998;97:1429–1430.
40. 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.
41. Karch SB, Graff J, Young S, Ho CH. Response times
and outcomes for cardiac arrests in Las Vegas casinos. Am J Emerg Med 1998;16:249–253.
42. Mosesso
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.
43. Davis EA, McCrorry J, Mosesso VN
Jr. Institution of a police automated external defibrillation program: concepts
and practice. Prehosp Emerg Care 1999;3:60–65.
44.
Destro A, Marzaloni M, Sermasi S, Rossi F. Automatic external
defibrillators in the hospital as well? Resuscitation 1996;31:39–43.
45.
Hickey RW, Cohen DM, Strausbaugh
S, Dietrich AM. Pediatric patients requiring CPR in the prehospital setting.
Ann Emerg Med. 1995;25:495–501.
46. Mogayzel C, Quan L, Graves
JR, Tiedeman D, Fahrenbruch C, Herndon P. Out-of-hospital ventricular fibrillation
in children and adolescents: causes and outcomes. Ann Emerg Med 1995;25:484–491.
47. Losek JD, Hennes H, Glaeser P, Hendley G, Nelson DB.
Prehospital care of the pulseless, nonbreathing pediatric patient. Am J Emerg
Med 1987;5:370–374.
48. Dumot JA, Burval DJ, Sprung J, Waters
JH, Mraovic B, Karafa MT, Mascha EJ, Bourke Dl. Outcome of adult cardiopulmonary
resuscitations at a tertiary referral center including results of “limited”
resuscitations. Archives of Internal Medicine 2001; 161: 1751-8.
49. Ornato JP, Peberdy MA, Tadler SC,
Strobos NC. Factors associated with the occurrence of cardiac arrest during
hospitalization for acute myocardial infarction in the Second National Registry
of Myocardial Infarction in the U.S.. Resuscitation 2001; 48: 117-23.
50. Martínez-Rubio A, Kanaan
N, Borggrefe M, Block M, Mäkijärvi M, Fedele F, Pappone C, Haverkamp
W, Merino JL, Barón Esquivias G, Cinca J. Advances for treating in-hospital
cardiac arrest: safety and effectiveness of a new automatic external cardioverter-defibrillator.
J Am Coll Cardiol 2003; 41: 627-32.
51. Mattioni TA, Nademanee K, Brodsky
M, Fisher J, Riggio D, Allen B, Welch S, Ybarra RA, Lin D, Dean E. Initial
clinical experience with a fully automatic in-hospital external cardioverter
defibrillator. PACE 1999; 22; 1648-55.
