Elsevier

Resuscitation

Volume 51, Issue 3, December 2001, Pages 247-255
Resuscitation

Outcomes of out-of-hospital cardiac arrest patients in Perth, Western Australia, 1996–1999

https://doi.org/10.1016/S0300-9572(01)00408-7Get rights and content

Abstract

Study objective: To describe the epidemiology and survival from out-of-hospital cardiac arrest. Design: Longitudinal follow-up study from the time of paramedic attendance to 12 months later. Setting: Perth, Western Australia (WA), a metropolitan capital city with an adult population of approximately one million people. Method: The St John Ambulance Australia (WA Ambulance Service Incorporated) cardiac arrest database was linked to the WA hospital morbidity and mortality data using probabilistic matching. Incidence: Of 3730 cardiorespiratory arrests in 1996–1999, the age standardised rate of arrests of presumed cardiac origin, where resuscitation was attempted (n=1293) was 32.9 per 100 000 person-years and 7.1 per 100 000 person-years for bystander-witnessed VF/VT arrests. Survival: Survival to 28 days was 6.8% following all bystander-witnessed cardiac arrests; 10.6% following bystander-witnessed VF/VT arrests and 33% for paramedic-witnessed cardiac arrests. Logistic regression analysis showed an inverse association between ambulance response time interval and survival following all bystander-witnessed cardiac arrests (and VF/VT arrests). One year survival: 89% of bystander-witnessed cardiac arrest survivors and 92% of paramedic-witnessed cardiac arrests were still alive at 1 year post-arrest. Conclusion: The trends in occurrence and survival following out-of-hospital cardiac arrest in Perth, WA, are similar to those found elsewhere. There is an opportunity to strengthen the chain of survival by reducing the response time interval and increasing the use of bystander cardiopulmonary resuscitation (CPR). First-responder programs and public access defibrillation will need to be considered in the light of local demographics, location and the epidemiologic features of out-of-hospital cardiac arrest.

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

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    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

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