Drone delivery of automated external defibrillators compared with ambulance arrival in real-life suspected out-of-hospital cardiac arrests: a prospective observational study in Sweden

Advancements in automated external and wearable cardiac defibrillators

PURPOSE OF REVIEW

Survival statistics for out-of-hospital cardiac arrests remain unsatisfactory. Prompt defibrillation of shockable rhythms, such as ventricular fibrillation and pulseless ventricular tachycardia, is crucial for improving survival. Automated external defibrillators (AEDs) and wearable cardiac defibrillators (WCDs) seek to improve the survival rates following out-of-hospital cardiac arrests. We aim to review the indications, utility, advancements, and limitations of AEDs and WCDs, as well as their role in contemporary and future clinical practice.

RECENT FINDINGS

Recent advancements in these technologies, such as smartphone applications and drone delivery of AEDs and less inappropriate shocks and decreased size of WCDs, have increased their ubiquity and efficacy. However, implementation of this technology remains limited due to lack of resources and suboptimal patient adherence.

SUMMARY

Out of hospital cardiac arrests continue to pose a significant public health challenge. Advancements in AEDs and WCDs aim to facilitate prompt defibrillation of shockable rhythms with the goal of improving survival rates. However, they remain underutilized due to limited resources and suboptimal patient adherence. As these technologies continue to evolve to become smaller, lighter and more affordable, their utilization and accessibility are expected to improve.

Drones delivering automated external defibrillators for out-of-hospital cardiac arrest: A scoping review

Out-of-hospital cardiac arrest (OHCA) remains a critical health concern, where prompt access to automated external defibrillators (AEDs) significantly improves survival. This scoping review broadly investigates the feasibility and impact of dronedelivered AEDs for OHCA response.

METHODS

PubMed, Cochrane, and Web of Science were searched from inception to August 6, 2024, with eligibility broadly including empirical data. The charting process involved iterative data extraction for thematic analysis.

RESULTS

We identified 306 titles and, after duplicate removal, title/abstract screening, and full text review, included 39 studies. These were divided into three categories: 1) Real-world observational studies (n = 3), 2) Test flights/simulation studies and qualitative analyses (n = 15), and 3) Computer/prediction models (n = 21). Real-world studies demonstrated the feasibility of drone AED delivery, with a time advantage of 01:52 - 03:14 min over ambulances observed in 64-67 % of cases. Test flight/simulation and qualitative studies consistently reported feasibility and positive bystander experiences. Computer/prediction models exhibited considerable heterogeneity, yet all indicated significant time savings for AED delivery compared to traditional EMS methods. Moreover, seven studies estimated improved survival rates, with five assessing cost-effectiveness and favouring drone systems. Regional factors such as EMS response times, volunteer responder programmes, terrain, weather, and budget constraints influenced the system's effectiveness.

CONCLUSION

Across all categories, studies confirmed the feasibility of drone-delivered AED systems, with significant potential for reducing time to AED arrival compared to EMS arrival. Prediction models suggested enhanced survival alongside costeffectiveness. Further research, including more extensive real-world studies and regulatory advancements, is imperative to integrate drones effectively into OHCA response systems.

Survival in relation to number of defibrillation attempts in out-of-hospital cardiac arrest

INTRODUCTION/AIM

Out-of-hospital cardiac arrest (OHCA) with shockable pulseless ventricular tachycardia or fibrillation not responding to defibrillation is a medical challenge. Novel treatment strategies have emerged for so-called refractory ventricular fibrillation not responding to three or more defibrillations but the evidence for optimal timing for these strategies is sparse. The primary aim of this observational study was to assess survival in relation to total numbers of defibrillations in OHCA.

METHODS

This is a registry-based retrospective cohort study based on data reported by the emergency medical services to the Swedish Registry of Cardiopulmonary Resuscitation and the National Patient Registry. All OHCA patients aged 18 years or older with an initial shockable rhythm in Sweden from January 1, 2010 and December 31, 2020 were included. Exposure was total number of defibrillations, and primary outcome was survival to 30 days. Logistic regression was used to adjust for patient and resuscitation characteristics.

RESULTS

Over the study period a total of 10,549 patients were included. Among them, 3,006 (28.5%) received only one shock, 1,665 (15.8%) two shocks, 1,336 (12.9%) three shocks, 1,064 (10.1%) four shocks and 3,478 (33.0%) five or more shocks. In the adjusted analysis an exponential decrease in the 30-day survival was found for each additional defibrillation. For patients receiving one, two, three and four defibrillations, the adjusted probability of survival was 42%, 36%, 30% and 25% respectively.

CONCLUSIONS

In this registry-based retrospective cohort study, additional defibrillations were associated with a lower survival. This association persisted after adjustments for patient and resuscitation characteristics.

Drones can be used to provide dispatch centres with on-site photos before arrival of EMS in time critical incidents

BACKGROUND

Drones are able to deliver automated external defibrillators in cases of out-of-hospital cardiac arrest (OHCA) but can be deployed for other purposes. Our aim was to evaluate the feasibility of sending live photos to dispatch centres before arrival of other units during time-critical incidents.

METHODS

In this retrospective observational study, the regional dispatch centre implemented a new service using five existing AED-drone systems covering an estimated 200000 inhabitants in Sweden. Drones were deployed automatically over a 4-month study period (December 2022-April 2023) in emergency calls involving suspected OHCAs, traffic accidents and fires in buildings. Upon arrival at the scene, an overhead photo was taken and transmitted to the dispatch centre. Feasibility of providing photos in real time, and time delays intervals were examined.

RESULTS

Overall, drones were deployed in 59/440 (13%) of all emergency calls: 26/59 (44%) of suspected OHCAs, 20/59 (34%) of traffic accidents, and 13/59 (22%) of fires in buildings. The main reasons for non-deployment were closed airspace and unfavourable weather conditions (68%). Drones arrived safely at the exact location in 58/59 cases (98%). Their overall median response time was 3:49 min, (IQR 3:18-4:26) vs. emergency medical services (EMS), 05:51 (IQR: 04:29-08:04) p-value for time difference between drone and EMS = 0,05. Drones arrived first on scene in 47/52 cases (90%) and the largest median time difference was found in suspected OHCAs 4:10 min, (IQR: 02:57-05:28). The time difference in the 5/52 (10%) cases when EMS arrived first the time difference was 5:18 min (IQR 2:19-7:38), p = NA. Photos were transmitted correctly in all 59 alerts. No adverse events occurred.

CONCLUSION

In a newly implemented drone dispatch service, drones were dispatched to 13% of relevant EMS calls. When drones were dispatched, they arrived at scene earlier than EMS services in 90% of cases. Drones were able to relay photos to the dispatch centre in all cases. Although severely affected by closed airspace and weather conditions, this novel method may facilitate additional decision-making information during time-critical incidents.

Emerging Evidence in Out-of-Hospital Cardiac Arrest-A Critical Appraisal of the Cardiac Arrest Center

The morbidity and mortality of out-of-hospital cardiac arrest (OHCA) due to presumed cardiac causes have remained unwaveringly high over the last few decades. Less than 10% of patients survive until hospital discharge. Treatment of OHCA patients has traditionally relied on expert opinions. However, there is growing evidence on managing OHCA patients favorably during the prehospital phase, coronary and intensive care, and even beyond hospital discharge. To improve outcomes in OHCA, experts have proposed the establishment of cardiac arrest centers (CACs) as pivotal elements. CACs are expert facilities that pool resources and staff, provide infrastructure, treatment pathways, and networks to deliver comprehensive and guideline-recommended post-cardiac arrest care, as well as promote research. This review aims to address knowledge gaps in the 2020 consensus on CACs of major European medical associations, considering novel evidence on critical issues in both pre- and in-hospital OHCA management, such as the timing of coronary angiography and the use of extracorporeal cardiopulmonary resuscitation (eCPR). The goal is to harmonize new evidence with the concept of CACs.

Combinations of First Responder and Drone Delivery to Achieve 5-Minute AED Deployment in OHCA

Background

Defibrillation in the critical first minutes of out-of-hospital cardiac arrest (OHCA) can significantly improve survival. However, timely access to automated external defibrillators (AEDs) remains a barrier.

Objectives

The authors estimated the impact of a statewide program for drone-delivered AEDs in North Carolina integrated into emergency medical service and first responder (FR) response for OHCA.

Methods

Using Cardiac Arrest Registry to Enhance Survival registry data, we included 28,292 OHCA patients ≥18 years of age between 1 January 2013 and 31 December 2019 in 48 North Carolina counties. We estimated the improvement in response times (time from 9-1-1 call to AED arrival) achieved by 2 sequential interventions: 1) AEDs for all FRs; and 2) optimized placement of drones to maximize 5-minute AED arrival within each county. Interventions were evaluated with logistic regression models to estimate changes in initial shockable rhythm and survival.

Results

Historical county-level median response times were 8.0 minutes (IQR: 7.0-9.0 minutes) with 16.5% of OHCAs having AED arrival times of <5 minutes (IQR: 11.2%-24.3%). Providing all FRs with AEDs improved median response to 7.0 minutes (IQR: 6.2-7.8 minutes) and increased OHCAs with <5-minute AED arrival to 22.3% (IQR: 16.4%-30.9%). Further incorporating optimized drone networks (326 drones across all 48 counties) improved median response to 4.8 minutes (IQR: 4.3-5.2 minutes) and OHCAs with <5-minute AED arrival to 56.3% (IQR: 46.9%-64.2%). Survival rates were estimated to increase by 34% for witnessed OHCAs with estimated drone arrival <5 minutes and ahead of FR and emergency medical service.

Conclusions

Deployment of AEDs by FRs and optimized drone delivery can improve AED arrival times which may lead to improved clinical outcomes. Implementation studies are needed.

Challenges & barriers for real-time integration of drones in emergency cardiac care: Lessons from the United States, Sweden, & Canada

Importance

Out-of-hospital cardiac arrest (OHCA) is a leading cause of morbidity and mortality in the US and Europe (∼600,000 incident events annually) and around the world (∼3.8 million). With every minute that passes without cardiopulmonary resuscitation or defibrillation, the probability of survival decreases by 10%. Preliminary studies suggest that uncrewed aircraft systems, also known as drones, can deliver automated external defibrillators (AEDs) to OHCA victims faster than ground transport and potentially save lives.

Objective

To date, the United States (US), Sweden, and Canada have made significant contributions to the knowledge base regarding AED-equipped drones. The purpose of this Special Communication is to explore the challenges and facilitators impacting the progress of AED-equipped drone integration into emergency medicine research and applications in the US, Sweden, and Canada. We also explore opportunities to propel this innovative and important research forward.

Evidence review

In this narrative review, we summarize the AED-drone research to date from the US, Sweden, and Canada, including the first drone-assisted delivery of an AED to an OHCA. Further, we compare the research environment, emergency medical systems, and aviation regulatory environment in each country as they apply to OHCA, AEDs, and drones. Finally, we provide recommendations for advancing research and implementation of AED-drone technology into emergency care.

Findings

The rates that drone technologies have been integrated into both research and real-life emergency care in each country varies considerably. Based on current research, there is significant potential in incorporating AED-equipped drones into the chain of survival for OHCA emergency response. Comparing the different environments and systems in each country revealed ways that each can serve as a facilitator or barrier to future AED-drone research.

Conclusions and relevance

The US, Sweden, and Canada each offers different challenges and opportunities in this field of research. Together, the international community can learn from one another to optimize integration of AED-equipped drones into emergency systems of care.