Download Out-of-Hospital Cardiac Arrest in Taipei, Taiwan

Review Article
Acta Cardiol Sin 2006;22:53-7
Out-of-Hospital Cardiac Arrest in Taipei, Taiwan
Chien-Hua Huang, Matthew Huei-Ming Ma and Wen-Jone Chen
The occurrence of out-of-hospital cardiac arrest (OHCA) carries high mortality and morbidity even though
treatments for coronary heart disease and the practice of cardiopulmonary resuscitation (CPR) have been improving
for decades. The survival rate of all OHCA patients is still poor and is estimated to be below 5% from most reports
throughout the world. The prevalence of ventricular fibrillation as the initial rhythm recorded is lower in Taipei City
compared to western countries. The lower chance of coronary heart disease in Taiwan may account for it. Those
OHCA patients with initial rhythm of ventricular fibrillation have better prognosis. The community-wide use of
automatic external defibrillator was launched in 2000, utilizing the model of biphasic 150 joules of fixed energy.
The survival-to-discharge rate of the OHCA patients has been improved after the introduction of automatic external
defibrillators in Taipei City. The concepts of treating OHCA patients have been changing recently. The adequate
quality of cardiopulmonary resuscitation, especially effective cardiac compression, has been proved to be the key to
improving the outcomes of resuscitated patients. The concept of defibrillation first for patients with prolonged VF
has been challenged. The optimum in post-resuscitation care, including hypothermia treatment, is beneficial to the
long-term outcomes of the OHCA patients.
Key Words:
Out-of-hospital cardiac arrest · Ventricular fibrillation · Automatic external defibrillation ·
Cardiopulmonary resuscitation · Taipei City
tients.
The occurrence of out-of-hospital cardiac arrest
(OHCA) carries high mortality and morbidity even though
treatments for the coronary heart disease and the practice
of cardiopulmonary resuscitation (CPR) have been improving for decades. The survival rate of all OHCA patients is still poor and is estimated to be below 5% from
the reports throughout the world.1 For these sudden death patients, the events happen unexpectedly and carry
huge impact on their family and the society. Thus, it has
become an important issue to examine how to improve
outcome in such cases and to ultimately save more pa-
Less VF as the Initial OHCA Cardiac Rhythms
in Taipei City
Generally, ventricular fibrillation (VF) and ventricular tachycardia (VT) are not so common as the initial
rhythm recorded for OHCA in Taipei City compared to
western countries. A previous OHCA study in Taipei City in 1993 revealed that only 4.1% of victims presented
with VF when arriving at hospital. 2 By 2001, another
study in Taipei City noted that VF was the initial rhythm
in 11.8% of OHCA patients, with mean call-to-emergency medical technician (EMT) arrival time of 4.1 minutes
and mean call-to-first shock time of 9.3 minutes.3 This
prevalence rate is lower than in western countries, where
VF accounted for 25-70% of initial OHCA rhythms. 4
The proportion of VF as the initial rhythm was 16.2% of
cardiac-cause OHCA patients in Japan in a recent study,
with a mean 11 minutes of call-to-electrocardiography
recording interval.5 The lower VF prevalence in the Asia
Received: February 8, 2006 Accepted: April 19, 2006
Department of Emergency Medicine and Department of Internal
Medicine (Cardiology), National Taiwan University Hospital and
National Taiwan University Medical College, Taipei, Taiwan.
Address correspondence and reprint requests to: Dr. Wen-Jone Chen,
MD, PhD, Department of Emergency Medicine, National Taiwan
University Hospital, No. 7, Chung-Shan South Road, Taipei, Taiwan.
Tel: 886-2-2356-2831; Fax: 886-2-2322-3150; E-mail: jone@ha.
mc.ntu.edu.tw
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Acta Cardiol Sin 2006;22:53-7
Chien-Hua Huang et al.
shock or not after assessing the general condition of the
victim. It is easy to learn and operate the AED machine
correctly; laymen, even sixth-grade children, can use the
AED after a short period of training.9 The Taipei City
early defibrillation programs began in June 2000. AEDs,
using an impedance-compensated biphasic truncated exponential waveform with a fixed 150-joule (J) energy
protocol, have been deployed in all ambulances in the
emergency medical system (EMS) in Taipei City. All
EMTs receive a training course with American Heart
Association guidance. After the implementation of the
city-wide AED program, the overall survival rate for
OHCA victims in Taipei City was brought up to 3.9% in
2001 from 1.9% in the basic-life-support-only era in 1993.2
The survival-to-discharge rate was even up to 18.8% for
patients when initial rhythm was VT/VF. The chance of
survival to discharge for the witnessed VF/VT patients
was 25%. For those victims gaining return of spontaneous circulation (ROSC) after defibrillation on the scene,
the prognosis was good, with a more than 90% chance of
survival to discharge.3 Comparing with other Asian countries, the survival-to-discharge rate was 1.6% in Hong
Kong, 3.5% in Singapore for all OHCA patients and
6.0% for VF patients.10,11 The rates of survival to discharge were 17% and 30%, respectively, for VF/VT
patients after introducing the AED for the OHCA patients for Seattle and Iowa groups in the United States.8,12
The public accessible defibrillator program (PAD), which
deploys AED in public, well-marked areas and trains local employees how to use AED, improved markedly the
survival of OHCA patients in casinos and the Chicago
airport.13,14 The PAD program has been launched also in
the Haneda airport and at the Nagoya World Expo in Japan, where 4 patients were rescued by use of AED. The
treatment recommendation on AEDs made by the Internal Liaison Committee on Resuscitation (ILCOR) is
“Use of AEDs by trained lay and professional responders is recommended to increase survival rates in patients
with cardiac arrest. Use of AEDs in public settings (airports, casinos, sports facilities, etc.) where witnessed
cardiac arrest is likely to occur can be useful if an effective response plan is in place.”9
The accuracy of AED analysis and reading of cardiac rhythms in the field is an issue, since the AED is
used not only by medical doctors, but also by first responders, including personnel with patient contact in or
as compared with western countries may be linked to the
importance of different racial backgrounds or underlying
cardiovascular disease patterns. It is known that the prevalence of coronary heart disease is lower in Taiwan
compared to that in western countries, and this may account for the low VF rate in OHCA events.6 In addition
to OHCA patients, the low frequency of initial VF (13.6%)
and of pre-existing coronary heart disease (17%) also has
been documented in the in-hospital resuscitation setting
in Taiwan.7 It has also been found that the incidence of
VF as the initial OHCA rhythm is going down worldwide. A decrease from 45% in 1991 to 28% in 2001
was noted in a Swedish nation wide registry study and
from 61% in 1980 to 41% in 2000 in Seattle, Washington, United States.4,8 It is postulated that improvement
in treatment of coronary heart disease may partly account for the change in the incidence of ventricular
fibrillation as the primary arrhythmia in out-of-hospital
cardiac arrest patients. One hypothesis is that with the
introduction of new therapeutic regimes like coronary
interventions and medications, patients with ischemic
heart disease live longer, and once they suffer from cardiac arrest, they have reached end-stage heart disease
where asystole or pulseless electrical activity is more
common than ventricular fibrillation.4 However, VF is
thus far the most favorable survival cardiac rhythm for
OHCA patients.
Automatic External Defibrillator in Taipei City
Strengthening the chain of survival in emergency cardiac care, which is comprised of early access, early CPR,
early defibrillation and early advanced care, is the most
important way to improve the outcomes of sudden death
patients. Early defibrillation is the key manner in which
to save patients with cardiovascular diseases presenting
with life-threatening ventricular arrhythmia. Early defibrillation for the witnessed ventricular fibrillation (VF)
carries high survival rate of more than 90%.1 Each minute of delay when treating VF leads to a 10% reduction
of survival. The automatic external defibrillator (AED),
a small portable defibrillator which can analyze the cardiac rhythm utilizing a built-in computer program, has
been developed for decades to improve the survival of
sudden cardiac death patients. Defibrillation is suggested
when it recognizes shockable rhythm of VF or rapid ventricular tachycardia (VT). The operator can decide to
Acta Cardiol Sin 2006;22:53-7
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OHCA in Taipei
out of hospitals. From a study of OHCA patients in Taipei City, the overall specificity for detecting shockable
rhythms was 100% and the sensitivity was 90%. The
sensitivity for individual rhythm was as high as 97.5%
for detecting coarse VF as the shockable rhythm and as
low as 60% for slow VT, respectively.15 The results are
similar to a study in the Boston area showing high specificity (99.9%) and moderately high sensitivity (81%) in
detecting shockable unstable cardiac rhythms (VF or VT)
in the out-of-hospital setting.8 It is not surprising that the
sensitivity of detecting shockable rhythm is not perfect
in Taipei and Boston. It would be a dilemma to promote
both sensitivity and specificity for the AED machine.
The high specificity of the AED machine use by the
EMTs in the out-of-hospital setting prevents unnecessary
defibrillation for the non-indicated victim, which is unacceptable in medical practice.
revised in the new guidelines. The rule of 200-300/360360 joules (J) 3 shocks in a row has been changed to
use only one shock with 360 J for monophasic defibrillator or 150 J to 200 J for the initial shock with a
biphasic truncated exponential waveform for sudden
cardiac death patients. The reason is the current biphasic defibrillators have a high first shock efficacy,
with an average of more than 90%. If one shock fails
to eliminate VF, the VF may be of low amplitude and
the incremental benefit of another shock is low. In
such patients, immediate resumption of CPR, particularly effective chest compressions, is likely to confer a
greater value than an immediate second shock. 16 The
treatment recommendation of ILCOR is the following:
a one-shock strategy may improve outcome by reducing interruption of chest compressions. A three-stacked
shock sequence can be optimized by immediate resumption of effective chest compressions after each
shock (irrespective of the rhythm) and by minimizing
the hands-off time for rhythm analysis.9
Some of the “paradigms” are being challenged with
the rapid development of resuscitation science.16,19 The
concept of “defibrillate as soon as possible” for treating
the VF has been argued, although not conclusively,
since it is found that patients with short-term CPR before defibrillation have a better outcome than those
treated with standard “CPR first” strategies in prolonged out-of-hospital VF situation. There is no welldocumented effective anti-arrhythmia agent so far to
improve the long-term outcomes of out-of-hospital VF
patients. The new promising treatment for OHCA patients is therapeutic hypothermia, which has improved
the long-term survival and neurological recovery of
out-of-hospital VF patients by reducing the body temperature to 32 to 34 °C for 12 to 24 hours in welldesigned randomized control studies and is now formally suggested by American Heart Association in their
new guidelines.16
In conclusion, the outcomes of OHCA patients
have been improving worldwide, including Taipei City,
after great efforts to enhance resuscitation medicine.
Refining the resuscitation clinical practices, researching the pathophysiological changes and introducing
new concepts and instruments are key to promoting and
upgrading the level and quality of management for
OHCA patients.
Changing Concepts and Future Challenges for
Treating OHCA Patients
With the development of evidence-based medicine, many concepts and routine clinical practices have
been rechecked regarding improving outcomes. In addition to the shortening of the interval from patient
collapse to defibrillation, the quality of CPR is highly
stressed to improve the prognosis of OHCA patients in
the recent published guidelines for emergency cardiac
care of the American Heart Association. 16 With the
help of cardiac rhythm and voice recording by AED in
the field, the CPR quality was found to be a major
determinant for survival to discharge among OHCA patients in Taipei City. The patients with adequate CPR,
which is defined as more than 50 effective cardiac
compressions per minute and limited hands-off time,
had a 53% chance of survival to discharge compared
to only 8% for those without adequate CPR performance. 17 Using prompting devices, such as the audio
prompt, improved CPR quality by enhancing the cardiac compression rate and limiting the hands-off time
for OHCA patients in Taipei City. 18 The ratio of cardiac compression to ventilation has been brought to
30:2 in the new guidelines instead of 15:2 in the previous guidelines for CPR in basic life support, which
implicates the importance of adequate cardiac compression during resuscitation efforts.16 The traditional
recommendation for defibrillation sequence has been
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Chien-Hua Huang et al.
REFERENCE
10. Lim HC, Tham KY. Out of hospital cardiac arrests: the experience
of one hospital in Singapore. Resuscitation 2001;51:123-127.
11. Lui JC. Evaluation of the use of automatic external defibrillation
in out-of-hospital cardiac arrest in Hong Kong. Resuscitation
1999;41:113-119.
12. Weaver WD, Hill D, Fahrenbruch CE, Copass MK, Martin JS,
Cobb LA, Hallstrom AP. Use of the automatic external defibrillator in the management of out-of-hospital cardiac arrest. N Engl J
Med 1988;319:661-666.
13. 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.
14. Caffrey SL, Willoughby PJ, Pepe PE, Becker LB. Public use of
automated external defibrillators. N Engl J Med 2002;347:12421247.
15. Ko PC, Lin CH, Lu TC, Ma MH, Chen WJ, Lin FY. Machine and
operator performance analysis of automated external defibrillator
utilization. J Formos Med Assoc 2005;104:476-481.
16. ECG Committee. 2005 American Heart Association Guidelines
for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2005;112(24 Suppl):IV1-203.
17. Ko PC, Chen WJ, Lin CH, Ma MH, Lin FY. Evaluating the quality
of prehospital cardiopulmonary resuscitation by reviewing automated external defibrillator records and survival for out-ofhospital witnessed arrests. Resuscitation 2005;64:163-169.
18. Chiang WC, Chen WJ, Chen SY, Ko PC, Lin CH, Tsai MS, Chang
WT, Chen SC, Tsan CY, Ma MH. Better adherence to the guidelines during cardiopulmonary resuscitation through the provision of audio-prompts. Resuscitation 2005;64:297-301.
19. Chen WJ, Lee YT. Update on cardiopulmonary resuscitation.
Medical Progress 2004;31:401-407.
1. Marenco JP, Wang PJ, Link MS, Homoud MK. Estes Nam Iii.
Improving survival from sudden cardiac arrest: the role of the
automated external defibrillator. JAMA 2001;285:1193-1200.
2. Hu SC, Tsai J, Lu YL, Lan CF. EMS characteristics in an asian
metropolis. Am J Emerg Med 1996;14:82-85.
3. Ko PC, Ma MH, Yen ZS, Shih CL, Chen WJ, Lin FY. Impact of
community-wide deployment of biphasic waveform automated
external defibrillators on out-of-hospital cardiac arrest in Taipei.
Resuscitation 2004;63:167-174.
4. Herlitz J, Engdahl J, Svensson L, Young M, Angquist KA,
Holmberg S. Decrease in the occurrence of ventricular fibrillation
as the initially observed arrhythmia after out-of-hospital cardiac
arrest during 11 years in sweden. Resuscitation 2004;60:283-290.
5. Incidence of ventricular fibrillation in patients with out-ofhospital cardiac arrest in Japan: survey of survivors after outof-hospital cardiac arrest in Kanto area (SOS-KANTO). Circ J
2005;69:1157-1162.
6. Chien KL, Hsu HC, Sung FC, Su TC, Chen MF, Lee YT. Hyperuricemia as a risk factor on cardiovascular events in Taiwan:
the Chin-Shan community cardiovascular cohort study. Atherosclerosis 2005;183:147-155.
7. Huang CH, Chen WJ, Ma MH, Chang WT, Lai CL, Lee YT.
Factors influencing the outcomes after in-hospital resuscitation in
Taiwan. Resuscitation 2002;53:265-270.
8. Macdonald RD, Swanson JM, Mottley JL, Weinstein C. Performance and error analysis of automated external defibrillator
use in the out-of-hospital setting. Ann Emerg Med 2001;38:262267.
9. International Liaison Committee on Resuscitation. Part 3: Defibrillation. Resuscitation 2005;67:203-211.
Acta Cardiol Sin 2006;22:53-7
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Review Article
Acta Cardiol Sin 2006;22:53−7
台北市到院前心跳停止患者之特性與處置之新進展
黃建華 馬惠明 陳文鍾
台灣大學醫學院及附設醫院 急診醫學部及內科部
心臟科
雖然近年來對於冠狀動脈心臟病的治療及心肺急救復甦的實務操作有許多的進展，然而院
外心跳停止的發生還是伴隨著高死亡率及嚴重的後遺症，根據世界各地的報告，發生院外
心跳停止的患者其存活率仍小於百分之五。以台北市內發生院外心跳停止的患者為對象，
近來的研究顯示此類患者以心室纖維顫動為首先被紀錄到心律的比例較西方國家為低，此
現象可能與國人罹患冠狀動脈心臟病比率較西方國家為低有關，不過此類以心室纖維顫動
為首先被紀錄到心律的患者其預後較其他心律者較佳。台北市於西元 2000 年開始全面使
用 150 焦耳固定能量之雙向自動體外電擊器做為院外心跳停止患者的標準治療之一，與過
去的研究相比，此治療方式提高了整體患者存活至出院的機會。由於實證醫學觀念的影響，
治療院外心跳停止患者及急救的概念仍持續進步改變中，足夠的心肺復甦急救，特別是有
效的胸部按壓，是改善急救患者預後最重要的因素之一。而對於心室纖維顫動已持續較久
的患者，優先電擊或優先心肺復甦急救及胸部按壓的觀念也已被重新評估及思考。在復甦
後症候群的治療上，改善患者復甦後的治療及照護，特別是治療性低溫的運用，可使急救
患者的長期預後更佳。
關鍵詞：到院前心跳停止、心室纖維顫動、自動體外電擊器、心肺復甦急救、台北市。
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