Availability and Use of an Automated External Defibrillator at Emergency Medical Dispatch

Strategic placement of volunteer responder system defibrillators

Volunteer responder systems (VRS) alert and guide nearby lay rescuers towards the location of an emergency. An application of such a system is to out-of-hospital cardiac arrests, where early cardiopulmonary resuscitation (CPR) and defibrillation with an automated external defibrillator (AED) are crucial for improving survival rates. However, many AEDs remain underutilized due to poor location choices, while other areas lack adequate AED coverage. In this paper, we present a comprehensive data-driven algorithmic approach to optimize deployment of (additional) public-access AEDs to be used in a VRS. Alongside a binary integer programming (BIP) formulation, we consider two heuristic methods, namely Greedy and Greedy Randomized Adaptive Search Procedure (GRASP), to solve the gradual Maximal Covering Location (MCLP) problem with partial coverage for AED deployment. We develop realistic gradually decreasing coverage functions for volunteers going on foot, by bike, or by car. A spatial probability distribution of cardiac arrest is estimated using kernel density estimation to be used as input for the models and to evaluate the solutions. We apply our approach to 29 real-world instances (municipalities) in the Netherlands. We show that GRASP can obtain near-optimal solutions for large problem instances in significantly less time than the exact method. The results indicate that relocating existing AEDs improves the weighted average coverage from 36% to 49% across all municipalities, with relative improvements ranging from 1% to 175%. For most municipalities, strategically placing 5 to 10 additional AEDs can already provide substantial improvements.

Comparative Analysis of Out-of-Hospital Cardiac Arrest Outcomes in Health Clinics, Nursing Homes, and Public Places: Implications for Optimizing Automated External Defibrillator Strategies

Purpose

Various factors, such as event location and response time, influence the outcomes of out-of-hospital cardiac arrest (OHCA). Very few studies have explored the delivery of basic life support (BLS) to patients having OHCA at health clinics or nursing homes-settings with professional BLS providers. Thus, in this study, we compared prognostic and survival outcomes between health clinics, nursing homes, and other public places (eg, workplaces and sports facilities/recreational areas) to offer insights for optimizing OHCA outcomes.

Patients

This study included adults who had nontraumatic OHCA in Taoyuan City between January 2017 and December 2022.

Methods

We collected data on patient characteristics, emergency medical service parameters, onsite patient management, automated external defibrillator (AED) locations, OHCA prognosis, and survival outcomes. Multivariate analyses were performed to predict survival to discharge (primary outcome) and neurological outcomes at discharge (secondary outcome).

Results

During the study period, the numbers of OHCA events at health clinics, nursing homes, and other public places were 158, 208, and 1986, respectively. The mean age of OHCA in health medical clinics, nursing home and other public places were 63.4, 81.5 and 64.7, respectively (P value<0.001). The proportion of witnessed events, rate of bystander resuscitation, and frequency of AED utilization were the highest for health clinics (53.2% (84/158), 83.4% (132/158), and 13.3% (21/158), respectively, P value<0.001). The average AED-scene distances and response times were the lowest for health clinics (388.8 m and 5.4 min, respectively). In initial shockable rhythm group, the probabilities of survival to discharge at discharge were the highest for health clinics (aOR=1.41, 95% CI=1.04-1.81, P value=0.041)) and lowest for nursing homes (aOR=0.84, 95% CI=0.76-0.93, P value=0.024).

Conclusion

Our research shows that OHCA patients at medical health clinics have higher rates of witnessing and bystander CPR and AED usage than other public places. However, while survival rates for patients with shockable rhythms are slightly better at health clinics, the neurological outcomes are not significantly different. The AED-scene distances are too far to be used effectively.

Pre-Arrival Care of the Out-of-Hospital Cardiac Arrest Victim

Lay rescuers play a pivotal role in the recognition and initial management of out-of-hospital cardiac arrest. The provision of timely pre-arrival care by lay responders, including cardiopulmonary resuscitation and the use of automated external defibrillator before emergency medical service arrival, is important link in the chain of survival and has been shown to improve outcomes from cardiac arrest. Although physicians are not directly involved in bystander response to cardiac arrest, they play a key role in emphasizing the importance of bystander interventions.

Effect of replacing ambulance physicians with paramedics on outcome of resuscitation for prehospital cardiac arrest

INTRODUCTION

Limited evidence suggests that the presence of a prehospital physician improves survival from cardiac arrest. A retrospective study is undertaken to examine this question. In Reykjavik, Iceland, prehospital physicians on ambulances were replaced by emergency medical technicians (EMTs) in 2007. The aim of this study is to compare the outcome of prehospital resuscitation from cardiac arrest during periods of time with and without prehospital physician involvement.

METHODS

All cardiac arrests that underwent prehospital resuscitation by emergency medical systems between 2004 and 2014 were included. The primary outcome was survival to hospital discharge, and the secondary outcome was return of spontaneous circulation (ROSC). Subgroup analyses were performed according to the type of cardiac arrest.

RESULTS

A total of 471 cardiac arrests were included for analysis, 200 treated by prehospital physicians from 2004 to 2007 and 271 treated by EMTs from 2008 to 2014. The overall rate of survival to hospital discharge and ROSC was 23 and 50% during the study period. No significant difference was observed in the rate of survival to hospital discharge [25 vs 22%, difference 3% (95% confidence interval (CI): 11-5%)] or ROSC [53 vs 47%, difference -6% (95% CI: 15-3%)] between these two time periods. In the subgroup of patients with pulseless electrical activity, survival to hospital discharge did not differ between the two periods, but the rate of ROSC was higher in the 'physician period' [50 vs 30%, difference -20% (95% CI: -40 to -1%)].

CONCLUSIONS

The presence of a prehospital physician on the ambulance was not found to result in a significant improvement in survival or ROSC after cardiac arrest compared to care by EMTs. Patients with pulseless electrical activity experienced an increase in ROSC when a physician was present but without improvement in survival to hospital discharge.

Improving bystander defibrillation in out-of-hospital cardiac arrests at home

Aims:

Most out-of-hospital cardiac arrests occur at home with dismal bystander defibrillation rates. We investigated automated external defibrillator coverage of home arrests, and the proportion potentially reachable with an automated external defibrillator before emergency medical service arrival according to different bystander activation strategies.

Methods and results:

Cardiac arrests in homes (private/nursing/senior homes) in Copenhagen, Denmark (2008–2016) and registered automated external defibrillators (2007–2016), were identified. Automated external defibrillator coverage (distance from arrest to automated external defibrillator) and accessibility at the time of arrest were examined according to route distance to nearest automated external defibrillator and emergency medical service response time. The proportion of arrests reachable with an automated external defibrillator by bystander was calculated using two-way (from patient to automated external defibrillator and back) and one-way (from automated external defibrillator to patient) potential activation strategies. Of 1879 home arrests, automated external defibrillator coverage ≤100 m was low (6.3%) and a two-way bystander could potentially only retrieve an accessible automated external defibrillator before emergency medical service in 31.1% (n=37) of cases. If a bystander only needed to travel one-way to bring an automated external defibrillator (≤100 m, ≤250 m and ≤500 m), 45.4% (n=54/119), 37.1% (n=196/529) and 29.8% (n=350/1174) could potentially be reached before the emergency medical service based on current automated external defibrillator accessibility.

Conclusions:

Few home arrests were reachable with an automated external defibrillator before emergency medical service if bystanders needed to travel from patient to automated external defibrillator and back. However, nearly one-third of arrests ≤500 m of an automated external defibrillator could be reached before emergency medical service arrival if the bystander only needed to travel one-way from the automated external defibrillator to the patient.

Effect of New 9-1-1 System on Efficiency of Initial Resource Assignment

Objective: To determine the impact of a new dispatch system on the efficiency of first resource assignment for critical EMS patients. Methods: In December 2014, the Los Angeles Fire Department (LAFD) implemented a new, internally-developed dispatch system. An interrupted time series study compared 9-1-1 incidents processed by LAFD-telecommunicators using either the Medical Priority Dispatch System® (MPDS, January 1 - September 30, 2014), or Los Angeles Tiered Dispatch System (LA-TDS, January 1 - September 30, 2015). All incidents were assigned a Dispatch Level of Service (DLOS), based on whether a basic life support (BLS) or advanced life support (ALS) resource was dispatched, and a Field-Recommended Level of Service (RLOS), a metric based on medical necessity, required scope of practice, number and intensity of interventions, and patient severity. DLOS options included BLS or ALS, whereas RLOS options included BLS, ALS1 and ALS2, with ALS2 cases having the greatest medical need. The primary outcome was critical under-triage rate, and secondary outcomes included rates of over-triage, total resource utilization and test characteristics of each dispatch system. Results: 563,188 incidents met inclusion criteria, including 271,604 using MPDS and 291,584 using LA-TDS. During the MPDS period, 96,561 (35.6%) incidents were initially dispatched with BLS resources (including 194 (0.071% ultimately found in the field to be high-acuity RLOS ALS2), and 175,043 were dispatched with ALS resources. During the LA-TDS period, 127,827 (43.8%) were dispatched as BLS (including 154 RLOS ALS2) and 163,798 were dispatched as ALS. For the primary outcome, the critical under-triage rate was 0.20% using MPDS and 0.12% using LA-TDS (Z 4.7, p < 0.0001, RR 0.61 CI 95% 0.50-0.76), and this improvement was primarily driven by improved triage of cardiac arrest. The over-triage rate using MPDS was 44%, which decreased to 33% using LA-TDS. LA-TDS was associated with significant improvements in specificity, positive predictive value and accuracy of initial resource assignment, and is projected to have saved over 23,000 EMS resource dispatches over the 9-month study period. Conclusion: The new Los Angeles Tiered Dispatch System significantly improved the efficiency of initial 9-1-1 resource assignments by decreasing both over-triage and critical under-triage, thus sending more appropriate resources to each 9-1-1 call.