Optimization of dispatcher-assisted public-access AED retrieval and use: A scoping review (BLS 2120)

Conflict of Interest Declaration

The ILCOR Continuous Evidence Evaluation process is guided by a rigorous ILCOR Conflict of Interest policy. The following Task Force members and other authors were recused from the discussion as they declared a conflict of interest: N/A

The following Task Force members and other authors declared an intellectual conflict of interest and this was acknowledged and managed by the Task Force Chairs and Conflict of Interest committees: Janet Bray – author on Perera et al (2020).

Task Force Synthesis Citation

Smith CM, Snow L, Whiting J, Smyth M, Olasveengen T, Bray J, on behalf of the International Liaison Committee on Resuscitation Basic Life Support Task Force. Dispatcher instructions for public-access AED retrieval and/or use. A scoping review. [Internet] Brussels, Belgium: International Liaison Committee on Resuscitation (ILCOR) Basic Life Support Task Force, 2024 Jan 8. Available from: http://ilcor.org

Methodological Preamble and Link to Published Scoping Review

As part of the continuous evidence evaluation process, the ILCOR Basic Life Support Task Force performed a scoping review of dispatcher instructions for public-access automated external defibrillator (AED) retrieval and use. ILCOR has not previously examined this topic.

This scoping review was conducted with the assistance of two invited members from University of Warwick Medical School.

The search strategy was developed by identifying key search terms and MESH subject headings relevant to dispatcher-assisted AED retrieval with the support of an expert librarian information specialist (Samantha Johnson, University of Warwick).

Scoping Review

Webmaster to insert the Scoping Review citation and link to Pubmed using this format when/if it is available.

PICOST

Search Strategies

We developed the initial search with input of an Information Specialist from the University of Warwick. We updated the search in January 2023, following review from the BLS Task Force.

We did not search grey literature.

We included sixteen articles in the final review.

Inclusion and Exclusion criteria

We included any article that included primary data about the effect of dispatcher instructions for public-access AED retrieval and/or use on any of the outcomes listed in the PICOST above, including simulation studies. As part of this we also considered specific interventions within dispatcher assisted public-access AED interventions that would impact the outcomes listed in the PICOST:

• Video-assisted dispatcher-assisted AED
• Voice-assisted dispatcher-assisted AED
• Use of scripts and specific language
• Use of Artificial Intelligence (AI)
• Use of an AED location registry (with data available to dispatchers)
• Quality improvement processes

During the review, we came across additional outcome measures to those originally recorded in the PICOST that we believed it appropriate to include: time to AED retrieval, distance for AED retrieval, measures of competent AED use; effect on CPR performance; participant-related outcomes.

We did not consider AED use within volunteer first-responder systems. ‘First responder engaged by technology’ is a topic that has been reviewed previously by the Education, Implementation and Teams Task Force.

We did not include information about dispatcher protocols in general where we could not determine the effect / relative contribution of dispatcher instructions for public-access AED retrieval and/or use in particular. (e.g. if an article reported on a dispatcher script for cardiac arrest that might include instruction on AED retrieval, it would not be possible to determine the effect of dispatch AED instructions specifically on patient outcome).

Data tables: BLS 2120 Optimization of DA AED Sc R 2024 data tables

Task Force Insights

1. Why this topic was reviewed.

Bystander use of AEDs is associated with high survival rates from OHCA,^1,2 but use is currently low.³

This topic was selected for review by the BLS Task Force due to the widespread use of dispatch instructions for the retrieval and use of an AED^4,5 and the need to optimize systems to improve the public’s AED use.^6,7 Although there is no existing ILCOR Treatment recommendations related to DA-AED retrieval, the Task Force decided the current evidence required a Scoping Review to fully explore scope of the topic.

2. Narrative summary of evidence identified

Sixteen studies were included in this scoping review. Five were observational studies reviewing real-world OHCAs and 11 were simulation studies (six RCTs, one observational or non-randomised comparisons). Some of the simulation studies provided scripts or instruction to participants that were judged analogous to dispatcher instructions, rather than having been delivered by a trained dispatcher.

There were no studies that addressed the following outcomes: survival with favourable neurological outcome; survival to hospital discharge (or 30 days / one month); ROSC; health-related quality of life. One observational study⁸ did report improvement in survival with favourable neurological outcome in 1132 (of 1606) OHCAs when a dispatcher-assisted CPR script/protocol included instructions to retrieve an AED, but the relative contribution of the dispatcher-assisted AED instruction could not be determined from the data provided.

Real-world studies (n=5)

Five observational studies demonstrate low AED retrieval and use:

• Two observational studies ^9,10 reported on rates of AED retrieval. Callers were directed to an AED ¹⁰ or successfully retrieved one ⁹ in a minority of cases.
• All five observational studies^8-12 reported on rates of bystander AED application. An AED was applied on a minority of cases when one was available. In one study ⁸ the use of a dispatcher-assisted CPR protocol that included instructions to retrieve an AED resulted in a statistically significant improvement in bystander defibrillation.

One observational study reported confusion and delays in the emergency call following the instructions to retrieve an AED.¹¹ Callers often had to ask the dispatcher to repeat the instruction or they asked clarifying questions.

Simulation studies (n=11)

Time to first shock, when measured after AED arrival, was longer when dispatcher assistance was provided than when there was no assistance.^13,14 However, when time to retrieve an AED was factored in, time to first shock was shorter^15,16 because of a reported shorter AED retrieval time¹⁶ or distance travelled for AED retrieval.¹⁵ One study reported shorter AED retrieval times after dispatcher instructions, although each participant had already searched the area without instruction, and the impact of any learning effect was not acknowledged.¹⁷

In simulation studies that evaluated participants’ competence in AED use, performance scores were consistently higher in the group that had received dispatcher-assistance (or an analogous form of instruction).^13,14,18-20 In another study with no comparator group, video dispatcher instruction allowed correction of pad placement, which was initially done incorrectly by bystanders in most cases.²⁰

In one study ¹³ the use of mobile phone video resulted in better performance than verbal instruction alone; a second study demonstrated no difference.¹⁸ The use of pre-recorded video instruction was inferior to real-time (verbal) dispatcher instruction in a third study.¹⁹

Provision of dispatcher instructions on AED use did not affect CPR quality in one study.²¹

In one study, dispatchers facilitated the application of an AED in five out of six cases when the AED had been brought to the (simulated) patient’s side, but the study participant did not attempt to use it (unprompted).²²

Participants reported positive interactions with dispatchers during AED retrieval and use.^18,23

3. Narrative Reporting of the task force discussions

The Task Force discussed the review findings and noted the following:

• There is limited published research in this area, particularly on the impact on patient outcomes, and existing evidence is insufficient to recommend progression to a formal systematic review.
• Given the majority of OHCA occur in the home, public-access AEDs are only likely to be in close proximity in a minority of cases and that far fewer AEDs still are likely able to be located, retrieved and attached to a patient in a meaningful timeframe.
• There is a risk that by implementing dispatcher instructions to retrieve and use public-access other aspects of the community response (e.g. time to CPR, delay to dispatcher CPR instructions, reduced CPR efficacy because of distraction or interruptions) are affected. These risks are likely to be greatest when there is a lone rescuer at the scene.
• Optimization of current systems: What is the optimal way to introduce and implement dispatcher instructions for public-access AED retrieval and use? How and where should AED retrieval integrate into current dispatch protocols/algorithms? What are the optimum phrasing to use? Do the AEDs instructions complement or conflict with DA-CPR instructions? What is the potential role of using live-stream video or similar during dispatcher instruction? How best to use registries and associated technology so that dispatchers can best help bystanders locate and retrieve AEDs?

4. Treatment recommendations

The task force determined that based on the available evidence, the following good practice statements could be suggested:

EMS implementing dispatcher-assisted public-access AED systems should monitor and evaluate the effectiveness of their system (Good Practice Statement).

Once a cardiac arrest is recognized in the emergency call and CPR has been started, dispatchers should ask if there is an AED (or defibrillator) immediately available at the scene and ask the caller to update them when one arrives (Good Practice Statement).

If an AED is not immediately available, and if there is more than one rescuer present, dispatchers should offer instructions to locate and retrieve an AED. Retrieval instructions should be supported, where resources allow, by up-to-date registries about public-access AED locations and accessibility (Good Practice Statement).

Once an AED is available, dispatchers should offer instructions on its use (Good Practice Statement).

Knowledge Gaps

High-quality evidence is needed for:

• The use and effect of dispatch-assisted public-access AED use on critical and important clinical (patient) outcomes.
• The risks associated with dispatcher instructions for public-access AED retrieval and use during an emergency call.
• What contribution does dispatcher instructions for public-access AED retrieval and use have in the overall community and EMS response to OHCA.
• The barriers and facilitators to dispatcher instruction for public-access AED retrieval and use.
• Which specific interventions will increase bystander retrieval and use of a public-access AED following dispatcher instructions.
• Optimization of current systems: What is the optimal way to introduce and implement dispatcher instructions for public-access AED retrieval and use? How and where should we integrate it into current dispatch protocols/algorithms? What are the optimum phrasing to use? What is the potential role of using live-stream video or similar during dispatcher instruction? How best to use registries and associated technology so that dispatchers can best help bystanders locate and retrieve AEDs?

References

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