The survival of out-of-hospital cardiac arrest (OHCA) victims is highly dependent on receiving immediate cardiopulmonary resuscitation (CPR), which requires bystander involvement. In Singapore, implementing multiple interventions has increased bystander CPR, improving survival rates for OHCA patients.
It is widely known that cardiovascular diseases (CVDs) are the leading cause of death globally. When CVD is discussed, we often think of coronary heart disease and cerebrovascular disease leading to heart attacks and strokes, which are responsible for 85 percent of CVD deaths. However, one form of CVD that should not be overlooked is sudden cardiac arrest, which can easily lead to sudden cardiac death.
Firstly, it is important to note that sudden cardiac arrest is not the same as a heart attack. A heart attack, also known as myocardial infarction, occurs due to a blockage in one or more coronary arteries so the heart does not receive enough oxygenated blood, causing damage and death to heart muscles. In contrast, a sudden cardiac arrest is caused by a malfunction in the electrical system to the heart, causing arrhythmia or irregular heart rhythms. This may progress to ventricular fibrillation, when the heart beats with rapid and erratic electrical impulses. Ventricular fibrillation frequently results in death, and when this occurs due to sudden cardiac arrest, it is known as sudden cardiac death.
Out-of-hospital cardiac arrests (OHCA) are of particular concern, as the majority of victims do not survive to hospital discharge, and even getting the patients to a hospital can be difficult as most cases of OHCA occur at home.
Fortunately, in cases of OHCA, timely administration of cardiopulmonary resuscitation (CPR) performed by bystanders can greatly boost the victims’ chances of survival by up to 50 percent. However, bystanders usually do not administer CPR in such cases, posing a challenge that needs to be overcome.
To investigate how this can be resolved, a collaborative study was conducted by Duke-NUS Medical School in Singapore, Duke University in the USA, Singapore Health Services (SingHealth), the Singapore Civil Defence Force (SCDF) and the Singapore Ministry of Health’s Unit for Prehospital Emergency Care (UPEC).
Their research, published in The Lancet Public Health in August this year, found that the frequency of bystander-administered CPR was significantly increased after implementation of dispatch-assisted CPR, CPR and automated external defibrillator (AED) training, and a first responder mobile application, which alerts CPR- and AED-trained bystanders when they are in close proximity to someone experiencing OHCA.
Unlike other studies which investigated the independent impact of each intervention (either dispatch-assisted CPR, training for CPR and AED, or a first responder mobile application), this study assessed the cumulative impact of each of these measures on the frequency of bystander-administered CPR. Data from Singapore’s national bystander intervention programmes from 2011 to 2016 were included in this study, with analysis of 6,788 patients.
Assistant Professor Audrey L. Blewer, who is this study’s lead and corresponding author, is an epidemiologist and resuscitation scientist in the Department of Family Medicine and Community Health at Duke University School of Medicine. “Our findings clearly showed that a bundled, national, bystander-focused public health intervention increased the chances of laypeople performing bystander CPR,” she says.
As each intervention was introduced, the predicted probability of bystanders administering CPR increased. When all three measures were implemented, the likelihood of bystanders administering CPR to victims greatly increased, and the chances of patient survival to hospital discharge increased over threefold compared to when there was no intervention.
According to Professor Marcus Ong, senior author of the study and Director of the Health Services and Systems Research Programme at Duke-NUS Medical School, and Senior Consultant at the Department of Emergency Medicine in Singapore General Hospital, “Understanding the impact of public health interventions helps inform strategies to increase bystander CPR and targeted initiatives to improve survival from OHCA.” He added that the findings showed that “the increased likelihood of bystander CPR resulting from the bundled interventions was associated with increased survival.”
The insights from this study suggest that other countries could also implement such bundled approaches to encourage more people to take action and administer CPR in cases of OHCA, to enhance public health systems and save more lives.