Hong Kong Journal of Emergency Medicine Strengthening links in the "chain of survival": a Singapore perspective RA Charles, F Lateef, V Anantharaman Introduction: The concept of the chain of survival is widely accepted. The four links viz. early access, early cardiopulmonary resuscitation (CPR), early defibrillation and early Advanced Cardiac Life Support (ACLS) are related to survival after pre-hospital cardiac arrest. Owing to the dismal survival-to-discharge figures locally, we conducted this study to identify any weaknesses in the chain, looking in particular at bystander CPR rates and times to Basic Cardiac Life Support (BCLS) and ACLS. Methods and materials: A retrospective cohort study was conducted in the Emergency Department of an urban tertiary 1500-bed hospital. Over a 12-month period, all cases of non-trauma out-of-hospital cardiac arrest were evaluated. Results: A total of 142 cases of non-trauma out-of-hospital cardiac arrest were identified; the majority being Chinese (103/ 142, 72.5%) and male (71.8%) with a mean age of 64.3±7.8 years (range 23-89 yrs). Most patients (111/ 142, 78.2%) did not receive any form of life support until arrival of the ambulance crew. Mean time from collapse to arrival of the ambulance crew and initiation of BCLS and defibrillation was 9.2±3.5 minutes. Mean time from collapse to arrival in the Emergency Department (and thus ACLS) was 16.8±7.1 minutes. Three patients (2.11%) survived to discharge. Conclusion: There is a need to (i) facilitate layperson training in bystander CPR, and (ii) enhance paramedic training to include ACLS, in order to improve the current dismal survival outcomes from out-of-hospital cardiac arrest in Singapore. (Hong Kong j.emerg.med. 2002; 9:121-125) Keywords: Bystander CPR, defibrillation, out-of-hospital cardiac arrest Introduction The chance of successful resuscitation of patients with pre-hospital cardiac arrest in any community, is dependent on how efficiently the four links in the chain of survival viz: early access, early cardiopulmonary resuscitation (CPR), early defibrillation and early Advanced Cardiac Life Support (ACLS) are implemented. 1,2 Any interruption of the chain Correspondence to: Rabind Antony Charles, FRCS(Edin) Singapore General Hospital, Department of Emergency Medicine, 1 Hospital Drive, Outram Road, Singapore 169608 Email: rabindcharles@yahoo.com.sg Fatimah Lateef, MBBS, FRCS(Edin) V Anantharaman, FRCS(Edin), FRCP, FAMS precludes a successful outcome. Bystander cardiopulmonary resuscitation (BCPR) has been widely shown to improve the outcome in patients who have sustained pre-hospital cardiac arrest. 3,4 Cardiopulmonary resuscitation (CPR) is most effective when started immediately after the victim's collapse and in the prehospital environment, CPR is the best treatment a cardiac arrest patient can receive until defibrillation and ACLS care is available. 5,6 Of the 2400 persons who sustain a myocardial infarction each year in Singapore, about 57.8% collapse before reaching a hospital. 7 As pre-hospital times are relatively long, time to advanced cardiac life support (ACLS) usually exceeds ten to fifteen minutes after the cardiac arrest. To successfully optimise the survival rates of those who collapse in the pre-hospital setting, it would therefore be important for us to understand the contribution of the individual links in the chain of survival to the overall survival outcomes.
122 Hong Kong j. emerg. med. Vol. 9(3) Jul 2002 Objective To ascertain the rate of BCPR and times to Basic Cardiac Life Support (BCLS), defibrillation and ACLS for patients with pre-hospital cardiac arrest brought to the emergency department (ED) of an urban tertiary teaching hospital in Singapore. Methodology Bystander CPR was defined as the performance of CPR by a layperson not part of the emergency medical service system. If patients were conveyed by ambulance, then the term bystander CPR was taken to refer to that administered before arrival of the ambulance crew and transfer of care to the paramedics. CPR may be in the form of both chest compressions with/without ventilations. The data was obtained from a retrospective, cohort study done during the twelve months from 1st May 1999 to 30th April 2000. It was conducted in the Emergency Department of Singapore's largest acute tertiary-level hospital, which sees a daily average of 320 attendances. A questionnaire was completed for all adult patients (older than 12 years) brought to the ED with out-ofhospital cardiac arrest. Information collected included demographic data, medical history, place and time of collapse, presence and duration of bystander CPR, time to ACLS care, return of spontaneous circulation and disposition from the ED. Pre-hospital records were obtained from the Singapore Civil Defense Force (SCDF) ambulance records completed by the paramedics. ED records were traced electronically for all patients. Where appropriate, further information was obtained from inpatient case records. In accordance with the Utstein recommendations, 8 the following causes of cardiac arrest were excluded: sudden infant deaths, drug overdose, suicide, hypoxia, exsanguination, cerebrovascular accident, subarachnoid haemorrhage, trauma, ruptured aortic aneurysm and pulmonary thromboembolism. Persons who only arrested after arrival in the Emergency Department were also excluded from the analysis. Data entry and statistical analysis were performed with the SPSS (Chicago, Inc) package. Results We were able to document 155 adult patients with out-of-hospital cardiac arrest brought in to the Emergency Department (ED) of Singapore General Hospital during the study period. The 13 trauma cases were excluded from further analysis. The majority of the 142 non-trauma cardiac arrest cases were Chinese (103/142, 72.5%) followed by Indian (19, 13.4%), Malay (13, 9.2%). Males accounted for 71.8% of the cohort. The mean age was 64.3±7.8 years (range 23-89 yrs). Of the 142 patients, 96 (67.6%) had collapsed at home, 40 (28.2%) suffered cardiac arrest in public places/place of work, four collapsed (2.8%) in the taxis in which they were travelling, and two were in private vehicles at the time of arrest. The majority (113/142, 79.6%) were conveyed by ambulance to the ED. The average call-to despatch interval was 58±4 secs. Bystander CPR was documented in 31 patients (21.8%), and of these, 23 were at home and 8 in public places. The most common initial rhythm upon arrival of the ambulance crew was ventricular fibrillation (48/113, 42.5%) followed by asystole (45/113, 39.8%). Of the whole cohort, there were 32 (22.5% of the 142 cases) who had return of spontaneous circulation (ROSC) in the Emergency Department. Three of the patients (2.1%) survived to discharge. The mean time from collapse to basic cardiac life support (BCLS) by the emergency medical services was 9.2±3.5 minutes. Mean time from collapse to arrival in the Emergency Department, and thus initiation of ACLS, was 16.8±7.1 minutes in this study.
Charles et al./strengthening links in the "chain of survival" 123 Discussion and conclusion Survival from pre-hospital cardiac arrest depends on several variables including aetiology of arrest, whether the arrest was witnessed or unwitnessed, presence of ventricular fibrillation, and interval from collapse to CPR, and interval from collapse to first direct-current electrical shock and further Advanced Life Support. The probability of survival from cardiac arrests is said to decrease by a factor of 7-10% for every minute of delay from time of arrest to commencement of resuscitation. 9 At 10 minutes post-collapse, without resuscitative efforts, the survival outcome is only 2-5%. In our study the mean time from collapse to BCLS by ambulance crew was already more than 9 minutes. The dismal survival-to-discharge statistic (2.1%) is thus not unexpected. Early access Early access consists of all the events that are initiated after the collapse of a patient until the arrival of the EMS (paramedic) personnel to institute resuscitation. There are several components to this and they include: (a) early identification of the collapsed individual, (b) early notification of the ambulance services (Singapore Civil Defence Force), (c) early arrival of the SCDF ambulance service at the scene with all the relevant resuscitation requirement. Witnesses to pre-hospital cardiac arrest should quickly activate the emergency response services to improve the survival chances of the victims. Delays may be caused by witnesses attempting ineffective CPR, calling friends/relatives or running off to locate the nearest doctor (usually a general practitioner at the nearest neighbourhood clinic). As such, public awareness programs to educate people on the need for early activation of the Emergency Ambulance Services should be encouraged. The public should also be made aware of the telephone number ('995') for activating our ambulance service. Motorists should also be trained to give way to ambulances on the road to facilitate early access to the patient and shorten delays in pre-hospital transport times. Another major factor which impedes early access of our EMS responders to victims of cardiac arrest is the fact that the majority of our population resides in high-rise apartments. The problems posed by this would include difficulty in locating the patient's particular apartment block and unit among the maze of flats, unavailability of lifts on all floors, narrow passageways and entrances to units. The public can help by providing simple measures such as waiting below their flats to guide ambulance crew to the respective units and freeing lifts to make them available to ambulance crew. Early CPR/BCPR Many studies have confirmed the value of early CPR by lay rescuers, and CPR is most effective when administered immediately after the victim's collapse. The "chain of survival" concept has also been propagated with this in mind. Swor et al 10 ascertained that patients who received bystander CPR had an increased rate of survival to hospital discharge (OR 2.4). This corroborates with a review of 89557 consecutive missions of the Vienna emergency medical system (EMS), where bystander support had an impact on survival to hospital admission. 11 Bystander CPR continues to be the exception rather than the rule. Worldwide, the rates hover at about 20%, 12 similar to the findings in our local study. One reason relates to the lack of training of laypersons in BCLS. Once the knowledge is acquired, it has also to be retained and remembered. It is interesting to note that less than 7% of those attending a public CPR course are competent to perform safe and effective BCLS only six months later. 13 The aversion of laypersons to the act of performing mouth-to-mouth ventilation (MMV) has also been proposed as another reason for bystander inaction. A survey done in Singapore among participants in a mass CPR awareness program in 1999 showed that three factors were largely responsible for BCPR inaction: (i) fear of disease transmission, (ii) fear of litigation, and (iii) lack of confidence in instituting resuscitation. 14 Becker et al 15 have proposed that MMV is not an essential part of bystander CPR in the most common cause of cardiac arrest i.e. sudden myocardial infarction. It is also suggested that MMV has the
124 Hong Kong j. emerg. med. Vol. 9(3) Jul 2002 potential disadvantage of gastric insufflation, and distracting time from chest compressions. Hallstrom et al 16 have shown that survival to hospital discharge after CPR with chest compressions alone is similar to that with MMV. Adequate oxygen exists within the blood during at least the first ten minutes of cardiac arrest. Circulation provided with chest compression-only BLS shows no survival compromise. 17 Therein lies the argument for a simplified sequence of BLS, with the hopeful extrapolation to wider bystander participation. Increasing the frequency of BCPR would obviously require general public education. In addition, CPR training should be targeted at those most likely to be present at the scene of a cardiac arrest. As the majority of cardiac arrests occur at home (67.6% in our study), every household should have at least one family member trained in CPR. This is particularly important in families of patients with ischaemic heart disease or who are elderly. Systematic training has resulted in the equipping of more than 450000 residents of Seattle and King's County with knowledge of CPR, and a resultant bystander CPR rate of 60%. 18 The Singapore National First Aid Council and key community-based organizations have thus set a target of training one person per household in CPR by the year 2020. Dispatcher-directed CPR may represent another option where dispatchers instruct callers on what measures to take, including simple instructions on how to do CPR. These have been shown to be simple and effective to implement in trials internationally. 19,20 Early defibrillation It is well known that early defibrillation is the most important determinant of survival for victims of cardiac arrest due to ventricular fibrillation. The American Heart Association (AHA) recognized the importance of early defibrillation and challenged the medical industry to develop defibrillators that could be widely deployed in public places, and easily used by the layperson. This resulted in the introduction of the automated external defibrillator (AED). The AHA guidelines state that "public access defibrillation, which places AEDs in the hands of trained laypersons, has the potential to be the single greatest advance in the treatment of ventricular defibrillation cardiac arrest since the development of CPR". 21 Defibrillation is more successful in rapid coarse, high amplitude VF than fine VF. The performance of CPR while awaiting defibrillation appears to prolong the duration of coarse VF, before the degeneration into fine VF. 15 To date, field trials have shown that AEDs are both safe and accurate, with sensitivity for detection of ventricular fibrillation from 96%-100%, and specificity (i.e. accurate withholding of defibrillation) approaching 100%. All members of the public are potentially trainable in automated defibrillation. It has been demonstrated that survival-to-discharge rates can be much higher if defibrillation (e.g. with utilization of AEDs) is initiated within the first five minutes of collapse. 22 Widespread availability of AEDs is desirable, but is obviously limited by the current prohibitive cost. Early ACLS Another contributory factor to the overall poor survival rate of pre-hospital cardiac arrest cases in Singapore is the relatively long delay to arrival in the emergency department (16.8±7.1 min in this study). This is significant as ACLS in Singapore is only commenced in the emergency departments, and not by paramedics or ambulance crew. Paramedics in Singapore are currently trained in BCLS and in the use of the automated external defibrillator. As such, widening the scope of the paramedics' capabilities to include ACLS care (e.g. use of laryngeal mask airway, drugs such as adrenaline and vasopressin) may represent another way of improving our overall survival outcomes. One of the main factors contributing to the delay in time-to-acls is the fact that about 80% of Singapore's population reside in high-rise buildings. This results in significant delays in access to patients, and the evacuation of patients to hospital. These delays are largely brought about by physical limitations, such as problems related to use of elevators, and space constraints in passageways and stairways. 23
Charles et al./strengthening links in the "chain of survival" 125 Conclusion In this study, the rate of bystander CPR for prehospital cardiac arrest was 21.8%. The average time from collapse to arrival of the ambulance crew and initiation of BCLS was 9.2±3.5 minutes, while time to arrival in hospital (and thus ACLS) was 16.8±7.1 minutes. There is a need to (1) enhance training of pre-hospital paramedics to include ACLS; and (2) improve public education and training in BCPR and AED utilization; and (3) consider measures to enhance access of pre-hospital paramedics to collapsed patients, particularly in high-rise buildings. References 1. Cummins RO, Ornato JP, Thies WH, et al. Improving survival from sudden cardiac arrest : the "chain of survival" concept. Circulation 1991;83(5):1832-47. 2. Cummins RO. The "chain of survival" concept : how it can save lives. Heart Dis Stroke 1992;1(1):43-5. 3. Cummins RO, Eisenberg M, Hallstrom AP, et al. Survival of out-of-hospital arrest with early initiation of cardiopulmonary resuscitation. Am J Emerg Med 1985;3(2):114-9. 4. Roth R, Stewart RD, Rogers K, et al. Out-of-hospital arrest : factors associated with survival. Ann Emerg Med 1984;13(4):237-43. 5. Jaffe A. Textbook of Advanced Cardiac Life Support. Dallas, Texas: 1987. (American Heart Association). 6. No authors listed. Standards and guidelines for cardiopulmonary resuscitation and emergency cardiac care, part VII : emergency care units in EMS systems. JAMA 1986;255:2974-9. 7. Anantharaman V. Early response to heart attacks. Heartline:Newsletter of the Singapore Heart Association, 1999 July, no. 6. 8. Cummins RO, Chamberlain DA, Abramsons NS, et al. Recommended guidelines for uniform reporting of data from out-of-hospital arrest: the Utstein style. Task Force of the American Heart Association, the European Resuscitation Council, the Heart and Stroke Foundation of Canada, and the Australian Resuscitation Council. Ann Emerg Med 1991;20(8):861-74. 9. Larsen MP, Eisenberg MS, Cummins RO, et al. Predicting survival from out-of-hospital cardiac arrest: a graphical model. Ann Emerg Med 1993;22(11): 1652-8. 10. Swor RA, Jackson RE, Cynar M, et al. Bystander CPR, ventricular fibrillation and survival in witnessed unmonitored out-of-hospital cardiac arrest. Ann Emerg Med 1995;25(6):780-4. 11. Gaul GB, Gruska M, Titscher G, et al. Prediction of survival after out-of-hospital cardiac arrest : results of of a community-based study in Vienna. Resuscitation 1996;32(3):169-76. 12. Ekstrom L, Herlitz J, Wennerblom B, et al. Survival after cardiac arrest outside hospital over a 12-year period in Gothenburg. Resuscitation 1994;27(3):181-7. 13. Morgan CL, Donelly PD, Lester CA, et al. Effectiveness of the BBC's 999 training roadshows on cardiopulmonary resuscitation : video performance of cohort of unforewarned participants at home six months afterwards. BMJ 1996;313(7062):912-6. 14. Fong YT, Anantharaman V, Lim SH, et al. Mass Cardiopulmonary resuscitation 99 survey results of a multi-organisational effort in public education in cardiopulmonary resuscitation. Resuscitation 2001;49: 201-5. 15. Becker LB, Berg RA, Pepe PE, et al. A reappraisal of mouth-to-mouth ventilation during bystander-initiated cardiopulmonary resuscitation. Circulation 1997;96(6): 2102-12. 16. Hallstrom AP, Cobb L, Johnson E, et al. Cardiopulmonary resuscitation by chest compression alone or with mouth-to-mouth ventilation. N Engl J Med 2000; 342(21):1546-53. 17. Kern KB. Cardiopulmonary resuscitation without ventilation. Crit Care Med 2000;28(11 Suppl):N186-9. 18. Eisenberg M. Bystander CPR. J R Coll Physicians Lond 1994;28(5):585-6. 19. Eisenberg MS, Hallstrom AP, Carter WB, et al. Emergency CPR instruction via telephone. Am J Public Health 1985;75(1):47-50. 20. Kellermann AL, Hackman BB, Somes G. Dispatcherassisted cardiopulmonary resuscitation. Validation of efficacy. Circulation 1989;80(5):1231-9. 21. Kerber RE, Becker LB, Bourland JD, et al. Automatic external defibrillators for public access defibrillation: recommendations for specifying and reporting arrhythmia analysis algorithm performance, incorporating new waveforms, and enhancing safety. Circulation 1997;95(6):1677-82. 22. Eisenberg MS, Cummins RO, Damon S, et al. Survival rates from out-of-hospital cardiac arrest: recommendations for uniform definition data and information to report. Ann Emerg Med 1990;9(11): 1249-59. 23. Lateef F, Anantharaman V. Delays in the EMS response to and evacuation of patients in high-rise buildings in Singapore. Prehosp Emerg Care 2000;4(4):327-32.