Survival after Public Access Defibrillation in Stockholm, Sweden – A striking success

doi:10.1016/j.resuscitation.2015.02.032

Resuscitation

Volume 91, June 2015, Pages 1-7

https://doi.org/10.1016/j.resuscitation.2015.02.032 Get rights and content

Abstract

Background

In Stockholm, a first responder system and a Public Access Defibrillation (PAD) program has been implemented. Additionally, the number of “unregulated” public Automated External Defibrillators (AEDs) sold “over-the-counter” has increased. The aim of this study was to evaluate the impact on survival from different defibrillation strategies in cases of out-of-hospital cardiac arrest (OHCA) available for PAD.

Methods and Results

Design: Retrospective study of all OHCAs in Stockholm, 2006–2012. Witnessed OHCAs occurring outside home with cardiac origin and ventricular fibrillation were considered subjects for PAD. The sites within the PAD program increased from 60 to 135 while the number of unregulated AEDs outside the PAD program increased from 178 to 5016.

Of 6532 OHCAs, 7% (n = 474) were defined as subjects for PAD. Of these, 69% (n = 326) were defibrillated by the EMS, 11% (n = 53) by first responders and 16% (n = 74) by public AEDs. Survival to one month was 31% (n = 101) for cases defibrillated by the EMS, 42% (n = 22) when defibrillated by first responders and 70% (n = 52) when defibrillated by a public AED. The AEDs within the PAD program constituted 2.6% of all public AEDs and were used in 28% (n = 21) of cases when a public AED was used.

Conclusions

In OHCAs available for PAD, 70% of patients survived if a public AED was used. Both the structured AED program as well as the spread of unregulated AEDs was associated with very high survival rates, but the structured approach was more efficient in relation to the number of AEDs used.

Introduction

The majority of patients suffering out-of-hospital cardiac arrest (OHCA) have ventricular fibrillation (VF) immediately after collapse occurs and can, within the first few minutes, be treated by means of defibrillation.1, 2 However, as minutes pass without action, survival becomes dismal.³ Low survival rates, on average 5–10%, are mainly due to long time intervals from the arrest to defibrillation.4, 5 To reduce time to defibrillation, first responder systems with dual dispatch of fire/police services in response to OHCAs have been implemented6, 7 in parallel with Public Access Defibrillation (PAD) programs where lay-operated automated external defibrillators (AEDs) are placed in public places.⁸

In Japan, the number of AEDs increased from just below 10,000 to just over 80,000 in 3 years (2007–2009),⁹ however most public AEDs are unused.¹⁰ Dissemination of AEDs throughout society can occur in two different conceptual ways, either as “unregulated” AEDs¹¹ or as part of a structured program with trained responses and strategic selection of sites. Little is known about the effect on survival of these different approaches.

In 2001, survival following OHCA in Stockholm, Sweden was 2.5%.⁵ To increase survival, the Saving Lives in the Stockholm Area (SALSA) project was launched. The main aim of the SALSA project was to decrease time intervals in cases of OHCA by dual dispatch of fire fighters in parallel with standard emergency medical services (EMS).12, 13 An additional aim was to increase public defibrillation via the spread of AEDs within a structured PAD program in Stockholm County.

The aim of the current study was to evaluate the impact on survival of patients available for PAD in relation to three different defibrillation strategies: (a) defibrillation by the EMS, (b) defibrillation by first responders and (c) PAD with AEDs “on site”. An additional aim was to evaluate and compare the impact of a structured PAD program to AEDs purchased “over the counter” by local initiatives (referred to as unregulated AEDs).

Section snippets

Study design, patients

The study was of an open retrospective observational design and included all cases of OHCA within Stockholm County where resuscitation was attempted by the EMS. The study period was the 1st of January 2006 to the 31st of December 2012. The local ethics board approved the study (2005/423-31, 2010/1835-32).

Study area, EMS system and dispatch of first responders

Stockholm County covers 6519 sq. km and holds a population of 2,123,337.¹⁴ The incidence of OHCA is 46/100,000/year. A single EMS dispatch center receives all calls within the county. Ambulances

All OHCA patients

As seen in Fig. 1, there were 6532 EMS treated OHCAs. Of these, 71% (n = 4607) were of presumed cardiac origin, and of these, 54% (n = 2504) were witnessed. In 37% (n = 931) of these OHCA occurred outside home and in 51% (n = 474) of these cases VF or VT was the first recorded rhythm.

Characteristics and location of patients defibrillated at public locations

In 7% (n = 453) out of all 6532 OHCA cases, defibrillation was carried out in public. These subjects were considered as appropriate for PAD and were included in the final analysis (Fig. 1). As seen in Table 1, the median EMS

Discussion

In this paper we report the impact on survival of different defibrillation strategies in cases of OHCA suitable for PAD. To our knowledge, this is the first paper that also describes the effects of two conceptually different strategies for on-site PAD: “over-the-counter” AEDs in comparison with a monitored and audited PAD program with trained responses.¹¹ Our main finding is that defibrillation by public AEDs significantly contributes to lives saved, with a one-month survival rate of 70%. In

Limitations

1.
The exact number of AEDs outside the SALSA–PAD program was not known but based on wholesale numbers.
2.
The number of applied AEDs was not known, only the numbers of AEDs used to deliver shocks.
3.
AED data files were not analyzed in order to gain more objective information about CPR, exact time to defibrillation or first rhythm.
4.
No information regarding CPR quality was available.
5.
Time intervals from cardiac arrest to defibrillation are based upon subjective estimations made by EMS crews.

Conclusions

Among cases of OHCA that are subjects for PAD, defibrillation by public AEDs significantly contributes to survival in terms of lives saved, with one-month survival rates as high as 70%. Both the structured AED program as well as the spread of unregulated AEDs was associated with very high survival rates, but a structured AED program is more efficient in relation to the number of AEDs used.

Disclosure

None.

Author contribution

The present study was designed by the authors Hollenberg and Ringh. The data was gathered by Fredman, Ringh, Riva and Jonsson. The data was analyzed by Jonsson and Ringh. The principal investigators Hollenberg and Ringh vouch for all the data. All co-authors were intellectually and practically involved in analysis and interpretation of data as well as the writing of the article.

Conflict of interest statement

All authors declared that they have no conflict of interest.

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A novel approach to improve bystander defibrillation for out-of-hospital cardiac arrests is to dispatch and deliver an automated external defibrillator (AED) directly to the suspected cardiac arrest location by drone. The aim of this study was to investigate how often a drone could deliver an AED before ambulance arrival and to measure the median time benefit achieved by drone deliveries.
In this prospective observational study, five AED-equipped drones were placed within two separate controlled airspaces in Sweden, covering approximately 200 000 inhabitants. Drones were dispatched in addition to standard emergency medical services for suspected out-of-hospital cardiac arrests and flight was autonomous. Alerts concerning children younger than 8 years, trauma, and emergency medical services-witnessed cases were not included. Exclusion criteria were air traffic control non-approval of flight, unfavourable weather conditions, no-delivery zones, and darkness. Data were collected from the dispatch centres, ambulance organisations, Swedish Registry for Cardiopulmonary Resuscitation, and the drone operator. Core outcomes were the percentage of cases for which an AED was delivered by a drone before ambulance arrival, and the median time difference (minutes and seconds) between AED delivery by drone and ambulance arrival. Explorative outcomes were percentage of attached drone-delivered AEDs before ambulance arrival and the percentage of cases defibrillated by a drone-delivered AED when it was used before ambulance arrival.
During the study period (from April 21, 2021 to May 31, 2022), 211 suspected out-of-hospital cardiac arrest alerts occurred, and in 72 (34%) of those a drone was deployed. Among those, an AED was successfully delivered in 58 (81%) cases, and the major reason for non-delivery was cancellation by dispatch centre because the case was not an out-of-hospital cardiac arrest. In cases for which arrival times for both drone and ambulance were available (n=55), AED delivery by drone occurred before ambulance arrival in 37 cases (67%), with a median time benefit of 3 min and 14 s. Among these cases, 18 (49%) were true out-of-hospital cardiac arrests and a drone-delivered AED was attached in six cases (33%). Two (33%) had a shockable first rhythm and were defibrillated by a drone-delivered AED before ambulance arrival, with one person achieving 30-day survival. No adverse events occurred. AED delivery (not landing) was made within 15 m from the patient or building in 91% of the cases.
AED-equipped drones dispatched in cases of suspected out-of-hospital cardiac arrests delivered AEDs before ambulance arrival in two thirds of cases, with a clinically relevant median time benefit of more than 3 min. This intervention could potentially decrease time to attachment of an AED, before ambulance arrival.
Swedish Heart Lung Foundation.
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Volunteer responder dispatch to nearby out-of-hospital cardiac arrests using a smartphone application can increase the proportion of patients receiving cardiopulmonary resuscitation. It is unknown how population density is related to the efficacy of a volunteer responder system. This study aimed to compare the response time of volunteer responders and EMS dispatched to suspected OHCAs in areas of different population density.
A total of 2630 suspected OHCAs in Stockholm County during 2018–2020 where at least one dispatched volunteer responder reached the patient were identified through the HeartRunner™ application database. Study outcome was the proportion of cases where volunteer responders arrived at the scene before EMS, as well as the difference in time between the arrival of volunteer responders and EMS.
Volunteer responders arrived before EMS in 68% of examined cases (n = 1613). Higher population density was associated with a lower proportion of cases where volunteer responders arrived at the scene before EMS. Time on scene before arrival of EMS was highest in areas of low population density and averaged 4:07 (mm:ss). Response time was significantly shorter for volunteer responders compared to EMS across all population density groups at 4:47 vs 8:11 (mm:ss) (p < 0.001); the largest difference in response time was found in low population density areas.
Volunteer responders have significantly shorter response time than EMS regardless of population density, with the greatest difference in low population density areas. Although their impact on clinical outcome remains unknown, the benefits of dispatching volunteer responders to OHCAs may be greatest in rural areas.
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Observational data from the Swedish Registry for Cardiopulmonary Resuscitation and EMDC.
A total of 9,174,940 medical calls were answered (1-step). The median answer delay was 7.3 s (interquartile range [IQR], 3.6–14.5 s). Furthermore, 594,008 calls (6.1%) were transferred in a 2-step procedure, with a median answer delay of 39 s (IQR, 30–53 s). A total of 45,367 cases (0.5%, 1-step) were registered as OHCA, with a median answer delay of 7.2 s (IQR, 3.6–14.1 s) (AHA high-performance goal, 10 s). For 1-step procedure, no difference in 30-day survival was found regarding answer delay. For OHCA (1-step), an ambulance was dispatched after a median of 111.9 s (IQR, 81.7–159.9 s). Thirty-day survival was 10.8% (n = 664) when an ambulance was dispatched within 70 s (AHA high-performance) versus 9.3% (n = 2174) > 100 s (AHA acceptable) (p = 0.0013). Outcome data in the 2-step procedure was unobtainable.
The majority of calls were answered within the AHA performance goals. When an ambulance was dispatched within the AHA high-performance standard in response to OHCA calls, survival was higher compared with calls when dispatch was delayed.
Dispatch of Volunteer Responders to Out-of-Hospital Cardiac Arrests
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Systems for dispatch of volunteer responders to collect automated external defibrillators and/or to provide cardiopulmonary resuscitation (CPR) in cases of nearby out-of-hospital cardiac arrest (OHCA) are widely implemented.
This study aimed to investigate whether the activation of a volunteer responder system to OHCAs was associated with higher rates of bystander CPR, bystander defibrillation, and 30-day survival vs no system activation.
This was a retrospective observational analysis within the ESCAPE-NET (European Sudden Cardiac Arrest network: Towards Prevention, Education, New Effective Treatment) collaborative research network. Included were cases of OHCA between 2015 and 2019 from 5 European sites with volunteer responder systems. At all sites, systems were activated by dispatchers at the emergency medical communication center in response to suspected OHCA. Exposed cases (system activation) were compared with nonexposed cases (no system activation). Risk ratios (RRs) were calculated for the outcomes of bystander CPR, bystander defibrillation, and 30-day survival after inverse probability treatment weighting. Missing data were handled using multiple imputation.
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^☆: A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2015.02.032.

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Clinical PaperSurvival after Public Access Defibrillation in Stockholm, Sweden – A striking success☆

Abstract

Background

Methods and Results

Conclusions

Introduction

Section snippets

Study design, patients

Study area, EMS system and dispatch of first responders

All OHCA patients

Characteristics and location of patients defibrillated at public locations

Discussion

Limitations

Conclusions

Disclosure

Author contribution

Conflict of interest statement

Resuscitation

Resuscitation

Resuscitation

Resuscitation

Resuscitation

Resuscitation

Resuscitation

Heart Rhythm Off J Heart Rhythm Soc

Resuscitation

Meta-analysis of the implantable cardioverter defibrillator secondary prevention trials. AVID, CASH and CIDS studies. Antiarrhythmics vs implantable defibrillator study. Cardiac arrest study Hamburg. Canadian implantable defibrillator study

Eur Heart J

Outcomes of rapid defibrillation by security officers after cardiac arrest in casinos

N Engl J Med

Difference in survival after out-of-hospital cardiac arrest between the two largest cities in Sweden: a matter of time?

J Intern Med

Clinical Paper
Survival after Public Access Defibrillation in Stockholm, Sweden – A striking success☆