Outcomes of out-of-hospital cardiac arrest patients in Perth, Western Australia, 1996–1999
Introduction
Since 1966, when Pantridge and Geddes introduced the ‘mobile intensive care unit’ in Belfast, Ireland [1], there have been significant developments in the provision of pre-hospital emergency care throughout the world. Whilst the scope of practice of modern day paramedics extends beyond acute coronary care, the prevention of death due to cardiac arrest remains a key objective. This is especially relevant in locations such as Western Australia, where ischaemic heart disease accounted for 20% of all deaths in 1999, a burden of mortality second only to malignant neoplasms (29%) [2].
There have been many published reports since the 1960s describing the incidence and survival of out-of-hospital cardiac arrests [3], [4], [5], [6], [7], [8], [9]. These descriptive studies have led to the identification of predictive factors that are associated with survival from out-of-hospital cardiac arrest. They include an initial cardiac rhythm of ventricular fibrillation or ventricular tachycardia (VF/VT), the performance of bystander cardiopulmonary resuscitation (CPR), and arrests that occur after the arrival of paramedics (paramedic-witnessed arrests). Nonetheless, there has been a paucity of publications relating to outcomes of out-of-hospital cardiac arrests in Australia. The few published Australian studies have shown wide variations in survival rates (3–22%) [10], [11], [12], [13], [14], [15], [16], explained in part by difference in case definitions, but also highlighting the need for further elucidation of the Australian situation. This report seeks to contribute to this body of knowledge by describing the epidemiology of out-of-hospital cardiac arrests in Perth, Western Australia, over a 4-year-period, 1996–1999. Linkage of the cardiac arrest database of the city's only emergency ambulance provider, the St John Ambulance Australia (WA Ambulance Service Incorporated) to statewide collections of hospital morbidity and mortality data has enabled patient outcomes before and after arrival at the hospital to be included in our evaluation.
Perth is the capital city of the State of Western Australia and together with its surrounding suburbs encompasses over 5500 km2. The 1998 population numbered 1 385 403, of whom 9.6% of males and 12.3% of females were 65 years or older [17]. The 1998 adult population (16 years and over) comprised 531 142 males and 548 239 females.
St John Ambulance Australia (WA Ambulance Service Incorporated) (SJA-WA) is the only provider of emergency ambulance services in Western Australia [18]. It is a single tiered service and receives calls at a central dispatch centre requesting both urgent and non-urgent ambulance responses. Ambulances attending cases of collapse, chest pain, cardiac arrest or trauma are dispatched as a ‘priority one’ response (lights and sirens). Perth, consistent with the rest of Australia, has had a single emergency access phone number, 000, for over 30 years. SJA-WA employs over 300 full-time professional ambulance officers and paramedics to serve the Perth metropolitan area.
Ambulance paramedics are trained in basic and advanced life support procedure; however during the study period their training did not include intravenous cannulation, administration of cardioactive drugs or tracheal incubation. They were authorised to perform external cardiac defibrillation in cases of ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT) using manual defibrillators, according to predetermined clinical protocols. The airway was managed using head position and an oropharyngeal airway with ventilation being undertaken using a demand valve device. In 1998–1999, SJA-WA attended 99 356 calls within the Perth metropolitan area, an increase of 7% from the previous year [18].
Section snippets
Pre-hospital cardiac arrest database
Within the Perth Metropolitan Area the details of all calls to the Ambulance Operations Centre were entered into the computer-aided dispatch system on receipt of the call. Service information, such as the time that the call was received, the time that the ambulance departed, the time that the ambulance arrived at the scene, the time that the ambulance departed the scene and the time that the ambulance arrived at the hospital, were also recorded electronically and on the patient care record
Patient characteristics
From January 1996 to December 1999, the WA Ambulance Service attended 3730 cardiorespiratory arrests occurring in adults, 16 years and older. The crude rate of all cardiorespiratory arrests during this 4-year-period (n=3730), was 89.1 per 100 000 person-years, with an age standardised rate of 94.5 per 100 000 person-years. Resuscitation was attempted in 1531 (41%) of all arrests, including 1293 (84%) presumed to be of cardiac origin. The crude rate of cardiac arrests of cardiac origin, where
Discussion
This study describes the epidemiology of out-of-hospital cardiac arrests occurring on the other side of the world to those most commonly reported. Nevertheless, the trends and outcomes are similar. This is remarkable given the large variability in cardiac events and case-fatality that was demonstrated across the ‘38 populations from 21 countries in four continents’ that were studied in the World Health Organisation's MONICA project [28].
Reported survival from out-of-hospital cardiac arrest is
Conclusions
The results from this study of out-of-hospital cardiac arrests in Perth between 1996 and 1999, reinforce the need to strengthen the out-of-hospital ‘chain of survival’ [38] through several mechanisms. Firstly, it may be possible to reduce the incidence of out-of-hospital cardiac arrests if people with chest pain that persists for more than several minutes were to call for assistance without delay. A prompt response to chest pain would increase the possibility that if an arrest were to occur, it
Acknowledgements
The authors wish to acknowledge the following people and organisations for their contribution to this study. Laraine Salo and Belinda Rowe from the Western Australian Pre-hospital Care Research Unit for data entry and validation, Stuart Fuller from the Health Department of Western Australia for data linkage, the St John Ambulance Australia (WA Ambulance Service Incorporated) for infrastructure support and access to their clinical information and the ambulance paramedics who recorded the initial
Portuguese Abstract and Keywords
Objectivos do estudo: Descrever a epidemiologia e sobrevivência das paragens cardı́acas fora do Hospital. Desenho: Seguimento longitudinal da altura da intervenção dos paramédicos até 12 meses depois. Local: Perth, Western Australia (WA), cidade metropolitana com uma população adulta de aproximadamente um milhão de pessoas. Método: A base de dados de paragens cardı́acas da Ambulância St John Australia (WA Serviço de ambulâncias) foi cruzada com os dados da
References (38)
- et al.
A mobile intensive-care unit in the management of myocardial infarction
Lancet
(1967) - et al.
Out-of-hospital cardiac arrest: factors associated with survival
Ann. Emerg. Med.
(1984) - et al.
Survival of out-of-hospital cardiac arrest with early initiation of cardiopulmonary resuscitation
Am. J. Emerg. Med.
(1985) - et al.
Cardiac arrest and resuscitation: a tale of 29 cities
Ann. Emerg. Med.
(1990) - et al.
Outcome of CPR in a large metropolitan area—where are the survivors?
Ann. Emerg. Med.
(1991) - et al.
The Ontario Prehospital Advanced Life Support (OPALS) Study: rationale and methodology for cardiac arrest patients
Ann. Emerg. Med.
(1998) - et al.
Incidence, duration and survival of ventricular fibrillation in out-of-hospital cardiac arrest patients in Sweden
Resuscitation
(2000) Experience with a mobile coronary care unit in Brisbane
Ann. Emerg. Med.
(1989)- et al.
Population-based linkage of health records in Western Australia: development of a health services research linked database
Aust. New Zealand J. Public Health
(1999) - et al.
Survival after cardiac arrest outside hospital in Sweden. Swedish Cardiac Arrest Registry
Resuscitation
(1998)
A cumulative meta-analysis of the effectiveness of defibrillator-capable emergency medical services for victims of out-of-hospital cardiac arrest
Ann. Emerg. Med.
Cardiac arrest witnessed by emergency medical services personnel: descriptive epidemiology, prodromal symptoms, and predictors of survival
Ann. Emerg. Med.
Quality of bystander cardiopulmonary resuscitation influences outcome after prehospital cardiac arrest
Resuscitation
Circadian variation in sudden cardiac death: effects of age, sex, and initial cardiac rhythm
Ann. Emerg. Med.
Incidence of cardiac arrest during self-transport for chest pain
Ann. Emerg. Med.
Sudden cardiac death. I. A decade's experience with out-of-hospital resuscitation
Mod. Concepts Cardiovasc. Dis.
New South Wales intensive care ambulance system: outcome of patients with ventricular fibrillation
Med. J. Aust.
A review of pre-hospital defibrillation by ambulance officers in Perth, Western Australia
Med. J. Aust.
Cited by (0)
Portuguese Abstract and Keywords
Objectivos do estudo: Descrever a epidemiologia e sobrevivência das paragens cardı́acas fora do Hospital. Desenho: Seguimento longitudinal da altura da intervenção dos paramédicos até 12 meses depois. Local: Perth, Western Australia (WA), cidade metropolitana com uma população adulta de aproximadamente um milhão de pessoas. Método: A base de dados de paragens cardı́acas da Ambulância St John Australia (WA Serviço de ambulâncias) foi cruzada com os dados da morbilidade e mortalidade hospitalar na WA usando a concordância probabilistica. Incidência: das 3730 paragens cardio-respiratórias em 1996-1999, a taxa de paragens, de presumı́vel origem cardı́aca, corrigida para a idade, em que foi tentada a reanimação (n=1293) foi 32.9 por 100 000 pessoas por ano e 7.1 por 100 000 pessoas por ano para as paragens testemunhadas por leigos em FT/TV. Sobrevivência: A sobrevivência aos 28 dias foi de 6.6% após todas as paragens cardı́acas testemunhadas; 10.6% após paragem cardı́aca testemunhada por leigos e em ritmo de FV/TV e de 32% para paragens cardı́acas testemunhadas por paramédicos. Uma análise de regressão logı́stica mostrou uma associação inversa entre o intervalo de tempo de resposta da ambulância e a sobrevivência após todas as paragens cardı́acas testemunhadas (e paragens em FV/TV). Sobrevivência após um ano: 89% dos sobreviventes das paragens cardı́acas testemunhadas e 93% das paragens cardı́acas testemunhadas por paramédicos ainda estavam vivos um ano após a paragem. Conclusão: Os resultados de ocorrência e taxa de sobrevivência após paragem cardı́aca fora do Hospital em Perth, WA, são similares aos encontrados noutros locais. A cadeia de sobrevivência pode ser melhorada, reduzindo o intervalo de tempo de resposta e aumentando o SBV realizada pelas testemunhas. É preciso considerar programas de resposta primária e acesso do público à desfibrilhação, tendo em conta a demografia local, a localização e as caracterı́sticas epidemiológicas da paragem cardı́aca fora do Hospital.
Palavras chave: Paragem cardı́aca súbita; Serviços de Emergência Médica; RCP fora do Hospital; Incidência; Outcome
- 1
Tel.: +61-8-9346-1587; fax: +61-8-9371-6599.
- 2
Tel.: +61-8-9489-7887; fax: +61-8-9489-7700.
- 3
Tel.: +61-8-9334-1222; fax: +61-8-9334-1231.