Review question
To assess the effect of mobilizing community first responders to out-of-hospital cardiac arrest events in adults and children older than four weeks of age, in terms of survival and neurological function.
Background
Out‐of‐hospital cardiac arrest is a major cause of death. It occurs when a person's heart suddenly stops pumping blood around the body, and it is often caused by an abnormal heart rhythm. A person who suffers cardiac arrest will die within minutes unless this rhythm can be reversed.
A safe, portable, and affordable device called a 'defibrillator' can be used to terminate ('defibrillate') the abnormal rhythm causing cardiac arrest, allowing the heart to restart. A defibrillator can be used by almost anyone, even without training. To be effective, a defibrillator must be used within minutes of a cardiac arrest.
Cardiopulmonary resuscitation (CPR) is a technique where a bystander can compress and release the chest of a person who has suffered cardiac arrest, thus artificially pumping blood throughout the body. CPR can keep a cardiac arrest victim alive until a defibrillator arrives, but again it is effective only if started very soon after cardiac arrest occurs.
CPR and defibrillation are the most important interventions following cardiac arrest. Even the most advanced emergency medical systems in the world struggle to reach cardiac arrest victims in time to save life by providing CPR and defibrillation.
To shorten the time from cardiac arrest to CPR and defibrillation, healthcare systems have started to mobilize community first responders to provide these treatments. Community first responders are fellow citizens who are present in the community and have received minimum basic training in CPR/defibrillator use. They are generally alerted to cardiac arrest by the emergency medical services.
Study characteristics
This review searched for high-quality research studies that considered whether mobilizing community first responders could improve survival or neurological outcome, or both, following out-of-hospital cardiac arrest in adults and children. We last searched available databases in January 2019.
Key results
We found two eligible research studies with a total of 1136 participants.
One study conducted in Stockholm, Sweden, and funded by the Swedish Heart-Lung Foundation, Laerdal Foundation, and Stockholm County, found that mobilizing community first responders increased the rate of CPR performed before arrival of emergency medical services (data on 665 participants). The other study was conducted in Amsterdam and surrounding areas (the Netherlands) and was funded by the Netherlands Heart Foundation and Medtronic Physio-Control. Study authors reported that when community first responders were mobilized, more patients received defibrillation before emergency medical services arrived and survived to be admitted to hospital (data on 469 participants).
Neither study found that dispatching community first responders resulted in significantly more overall survivors (data on 612 participants in one study and on 469 participants in the other). Neither study reported on the neurological function of survivors or on their health-related quality of life.
Further research is needed to establish whether mobilizing community first responders can yield more survivors of cardiac arrest. Future research should consider both survival and the neurological function of survivors.
Certainty of the evidence
The certainty of available evidence in terms of overall patient survival was considered low. The certainty of available evidence in terms of performance of CPR and defibrillation before arrival of emergency medical services and in terms of survival to hospital admission was considered moderate. This evidence is current to January 2019.
Moderate-certainty evidence shows that context-specific CFR interventions result in increased rates of CPR or defibrillation performed before EMS arrival. It remains uncertain whether this can translate to significantly increased rates of overall patient survival. When possible, further high-quality RCTs that are adequately powered to measure changes in survival should be conducted.
The included studies did not consider survival with good neurological function. This outcome is likely to be important to patients and should be included routinely wherever survival is measured.
We identified one ongoing study and one planned trial whose results once available may change the results of this review. As this review was limited to randomized and quasi-randomized trials, we may have missed some important data from other study types.
Mobilization of community first responders (CFRs) to the scene of an out-of-hospital cardiac arrest (OHCA) event has been proposed as a means of shortening the interval from occurrence of cardiac arrest to performance of cardiopulmonary resuscitation (CPR) and defibrillation, thereby increasing patient survival.
To assess the effect of mobilizing community first responders (CFRs) to out-of-hospital cardiac arrest events in adults and children older than four weeks of age, in terms of survival and neurological function.
We searched the following databases for relevant trials in January 2019: CENTRAL, MEDLINE (Ovid SP), Embase (Ovid SP), and Web of Science. We also searched the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) and ClinicalTrials.gov, and we scanned the abstracts of conference proceedings of the American Heart Association and the European Resuscitation Council.
We included randomized and quasi-randomized trials (RCTs and q-RCTs) that compared routine emergency medical services (EMS) care versus EMS care plus mobilization of CFRs in instances of OHCA.Trials with randomization by cluster were eligible for inclusion, including cluster-design studies with intervention cross-over.
In some communities, the statutory ambulance service/EMS is routinely provided by the local fire service. For the purposes of this review, this group represents the statutory ambulance service/EMS, as distinct from CFRs, and was not included as an eligible intervention.
We did not include studies primarily focused on opportunistic bystanders. Individuals who were present at the scene of an OHCA event and who performed CPR according to telephone instruction provided by EMS call takers were not considered to be CFRs.
Studies primarily assessing the impact of specific additional interventions such as administration of naloxone in narcotic overdose or adrenaline in anaphylaxis were also excluded.
We included adults and children older than four weeks of age who had experienced an OHCA.
Two review authors independently reviewed all titles and abstracts received to assess potential eligibility, using set inclusion criteria. We obtained and examined in detail full-text copies of all papers considered potentially eligible, and we approached authors of trials for additional information when necessary. We summarized the process of study selection in a PRISMA flowchart.
Three review authors independently extracted relevant data using a standard data extraction form and assessed the validity of each included trial using the Cochrane 'Risk of bias' tool. We resolved disagreements by discussion and consensus.
We synthesized findings in narrative fashion due to the heterogeneity of the included studies. We used the principles of the GRADE system to assess the certainty of the body of evidence associated with specific outcomes and to construct a 'Summary of findings' table.
We found two completed studies involving a total of 1136 participants that ultimately met our inclusion criteria. We also found one ongoing study and one planned study. We noted significant heterogeneity in the characteristics of interventions and outcomes measured or reported across these studies, thus we could not pool study results.
One completed study considered the dispatch of police and fire service CFRs equipped with automatic external defibrillators (AEDs) in an EMS system in Amsterdam and surrounding areas. This study was an RCT with allocation made by cluster according to non-overlapping geographical regions. It was conducted between 5 January 2000 and 5 January 2002. All participants were 18 years of age or older and had experienced witnessed OHCA. The study found no difference in survival at hospital discharge (odds ratio (OR) 1.3, 95% confidence interval (CI) 0.8 to 2.2; 1 RCT; 469 participants; low-certainty evidence), despite the observation that all 72 incidences of defibrillation performed before EMS arrival occurred in the intervention group (OR and 95% CI - not applicable; 1 RCT; 469 participants; moderate-certainty evidence). This study reported increased survival to hospital admission in the intervention group (OR 1.5, 95% CI 1.1 to 2.0; 1 RCT; 469 participants; moderate-certainty evidence).
The second completed study considered the dispatch of nearby lay volunteers in Stockholm, Sweden, who were trained to perform cardiopulmonary resuscitation (CPR). This represented a supplementary CFR intervention in an EMS system where police and fire services were already routinely dispatched to OHCA in addition to EMS ambulances. This study, an RCT, included both witnessed and unwitnessed OHCA and was conducted between 1 April 2012 and 1 December 2013. Participants included adults and children eight years of age and older. Researchers found no difference in 30-day survival (OR 1.34, 95% CI 0.79 to 2.29; 1 RCT; 612 participants; low-certainty evidence), despite a significant increase in CPR performed before EMS arrival (OR 1.49, 95% CI 1.09 to 2.03; 1 RCT; 665 participants; moderate-certainty evidence).
Neither of the included completed studies considered neurological function at hospital discharge or at 30 days, measured by cerebral performance category or by any other means. Neither of the included completed studies considered health-related quality of life. The overall certainty of evidence for the outcomes of included studies was low to moderate.