Automatic external defibrillators: changing the way we manage ventricular fibrillation

Bystander automated external defibrillator use and clinical outcomes after out-of-hospital cardiac arrest: A systematic review and meta-analysis

AIM

To systematically review studies comparing bystander automated external defibrillator (AED) use to no AED use in regard to clinical outcomes in out-of-hospital cardiac arrest (OHCA), and to provide a descriptive summary of studies on the cost-effectiveness of bystander AED use.

METHODS

We searched Medline, Embase, the Web of Science, and the Cochrane Library for randomized trials and observational studies published before June 1, 2017. Meta-analyses were performed for patients with all rhythms, shockable rhythms, and non-shockable rhythms.

RESULTS

Forty-four observational studies, 3 randomized trials, and 13 cost-effectiveness studies were included. Meta-analysis of 6 observational studies without critical risk of bias showed that bystander AED use was associated with survival to hospital discharge (all rhythms OR: 1.73 [95%CI: 1.36, 2.18], shockable rhythms OR: 1.66 [95%CI: 1.54, 1.79]) and favorable neurological outcome (all rhythms OR: 2.12 [95%CI: 1.36, 3.29], shockable rhythms OR: 2.37 [95%CI: 1.58, 3.57]). There was no association between bystander AED use and neurological outcome for non-shockable rhythms (OR: 0.76 [95%CI: 0.10, 5.87]). The Public-Access Defibrillation trial found higher survival rates when volunteers were equipped with AEDs. The other trials found no survival difference, although their study settings differed. The quality of evidence was low for randomized trials and very low for observational studies. AEDs were cost-effective in settings with high cardiac arrest incidence, with most studies reporting ratios < $100,000 per quality-adjusted life years.

CONCLUSIONS

The evidence supports the association between bystander AED use and improved clinical outcomes, although the quality of evidence was low to very low.

Hatzolah emergency medical responder service: to save a life

"First responders" are people trained in advanced first aid who can respond at the same time as, and often more quickly than, ambulance services to suspected medical emergencies. Hatzolah is a volunteer First Responder group, based on halakhic (Jewish legal) principles, in a localised area of metropolitan Melbourne with the highest density of Holocaust survivors outside Israel. Low numbers of "call-outs" to Victoria's Metropolitan Ambulance Service (MAS) from this community suggested that many were reluctant to make contact with a "uniformed" external agency. Hatzolah is an autonomous organisation operating under adapted MAS clinical practice guidelines and clinical governance processes. Hatzolah responders undergo an 18-month MAS training course comprising first aid, cardiopulmonary resuscitation, the use of semiautomated defibrillators, and oxygen therapy. We describe the first 11 years (1995-2005) of the Hatzolah service. The number of patients attended to annually has risen steadily, peaking at 867 in 2005. The most frequent reasons for call-outs were falls (19.4%), chest pain (9.7%), or respiratory distress (7.6%). Hatzolah's median response times were 2 or 3 min for all cases. They attended 35 patients with cardiac arrest (median response time, 2 min), and arrived before the MAS to 29 call-outs (83%). Nineteen patients (54%) with cardiac arrest were resuscitated and transported from the scene alive. Among those transported, significantly more had a shockable cardiac rhythm (50% v 13%, P = 0.03). Five (14%) survived to hospital discharge. Hatzolah has evolved into an organisation providing a complementary service to the MAS. It serves as a model for the establishment of other metropolitan community First Responder groups.

Sudden cardiac death

Sudden cardiac death is a rare but devastating event. The majority of cases in young athletes are caused by congenital cardiac abnormalities that are routinely clinically silent before causing sudden death. An optimal screening practice to help identify underlying asymptomatic cardiac abnormalities has met with much debate. Beyond the American Heart Association's recommendations for cardiovascular screening guidelines for the preparticipation physical examination [47], there are conflicting views regarding the use of more advanced diagnostic screening tests. Athletes in whom a potentially life-threatening cardiovascular abnormality is found face the probability of being restricted from participating in certain types of athletic activity. Participation guidelines for athletes with cardiovascular disease are detailed in the recommendations of the 26th Bethesda Conference [36]. Future goals should continue to focus on the prevention of SCD. The development of a cost-effective screening process that incorporates the use of echocardiography, although having its own set of inherent limitations, may prove to be the most viable option.

Opportunities to prevent sudden out-of-hospital death due to coronary heart disease in a community

BACKGROUND

Intervening successfully to reduce the burden of sudden out-of-hospital death due to coronary heart disease (OHCD) requires knowledge of where these deaths occur and whether they are observed by bystanders.

METHODS

To establish the proportion of OHCDs that were witnessed and where they occurred, we reviewed the coroner's notes and medical records of a previously-described sample of OHCD cases among residents of Olmsted County, Minnesota. This cohort (n=113) consisted of a 10% random sample of all Olmsted County residents who died out-of-hospital between 1981 and 1994 and whose deaths were attributed to coronary heart disease.

RESULTS

Excluding deaths in nursing homes (n=27), 71 (83%) of the deaths occurred in private homes and 15 (17%) occurred in public places. The event was not witnessed in 59% of deaths occurring in private homes and in 20% of deaths occurring in public places. The presence or absence of a bystander could not be established for 10% of deaths in private homes and 7% of deaths in public areas.

CONCLUSIONS

A significant proportion of OHCDs occur in private homes and are not witnessed. Prevention of unwitnessed deaths will require programs that result in primary prevention and/or calls to first responders at the time of impending cardiac arrest.

Cardiac arrests treated by ambulance paramedics and fire fighters

The Emergency Medical Response (EMR) program is a Victorian Government initiative in which fire fighters trained in cardiopulmonary resuscitation and equipped with automatic external defibrillators are dispatched to suspected cardiac arrests simultaneously with ambulance paramedics across metropolitan Melbourne. During the first 12 months (February 2000 to February 2001) of the expanded EMR program, 2942 events involved simultaneous dispatch of ambulance paramedics and fire fighters. In 430 events, patients had suffered a cardiac arrest of presumed cardiac cause, and resuscitation was attempted by the emergency medical services. Fire fighters provided the initial defibrillation to 41 (26.5%) patients presenting in ventricular fibrillation. Survival to hospital discharge for bystander-witnessed ventricular fibrillation cardiac arrests was 21.8%. The mean emergency services (fire and ambulance) response time to cardiac arrest patients was 6.03 (SD, 1.65) minutes. The mean time to defibrillation for ventricular fibrillation patients was 8.75 (SD, 2.07) minutes.

Acceptance of a medical first-responder role by fire fighters

STUDY OBJECTIVE

In July 1998, a pilot trial which used fire fighters as medical first-responders for the first time in Australia, was implemented in Melbourne. We aimed to assess the impact of the introduction of a medical first-responder role to the fire service, on the fire fighters both professionally and personally.

METHODS

Focus groups were conducted at the fire stations located in the study area. Data from the focus groups was collated and examined for themes. The issues identified as important through the focus groups were then incorporated into a questionnaire.

RESULTS

The fire fighters located at the pilot stations involved in the first-responder programme appear to view their new role as first-responders as a positive addition to their emergency profession. Some areas of the programme were identified by this study as in need of improvement. Some aspects of the communication strategies utilised by the Fire Brigade were highly criticised. Some aspects of the support system offered by the Fire Brigade also appear to be regarded as unfavourable.

CONCLUSION

Results from this study provide useful information on professional fire fighter first-responder programmes and their impact on participating personnel. These results can be used to improve training modules, communication strategies and support services.

Results from the first 12 months of a fire first-responder program in Australia

STUDY OBJECTIVE

We aimed to reduce response times and time to defibrillation for out-of-hospital cardiac arrest patients through fire first-responders equipped with automatic external defibrillators (AEDs). The fire first-responders were added as an extra tier to the existing two-tired ambulance response.

METHODS

This prospective controlled trial set in Melbourne, Australia, consisted of a control area (277 km2, population density 2343/km2-ambulance only dispatch) and a pilot area (171 km2, population density 2290/km2-ambulance and fire first-responder dispatch). The main outcome measures were time to emergency medical service (EMS) arrival at scene for all cardiac arrest patients and time to defibrillation for cardiac arrest patients presenting in ventricular fibrillation (VF). The study participants were patients who suffered a cardiac arrest of presumed cardiac aetiology for which a priority 0 emergency response was activated. A total of 268 patients were located in the control area and 161 in the pilot (intervention) area.

RESULTS

The mean response time to arrival at scene was reduced by 1.60 (95% CI 1.21, 1.99) min, P < 0.001. A large reduction in prolonged responses (> or = 10 min) to cardiac arrests was also observed in the pilot area (2%) compared with the control area (18%), chi = 23.19, P < 0.001. Mean time to defibrillation was reduced by 1.43 (95% CI 0.11, 2.98) min, P = 0.068.

CONCLUSION

The results from this study suggest that fire officers can be successfully trained in the use of AEDs and can integrate well into a medical response role. The combined response of ambulance and fire personnel significantly reduced the response interval and reduced time to defibrillation. This suggests that in appropriate situations other agencies could be considered for involvement in co-ordinated first-responder programs.