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: (none applicable)
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: Vaillancourt and Bray co-authored included papers.
Task Force Synthesis Citation
Malta Hansen C, Juul Grabmayr A, Dicker B, Dassanayake V, Vaillancourt C, Dainty K, Olasveengen T, Bray J, on behalf of the International Liaison Committee on Resuscitation (insert) Life Support Task Force(s). Optimization of Dispatcher-Assisted Recognition of Out-of-Hospital Cardiac Arrest: a BLS Task Force Synthesis of a Scoping Review. International Liaison Committee on Resuscitation (ILCOR) Basic Life Support Task Force, 2023 October 30. Available from: http://ilcor.org
Methodological Preamble and Link to Published Scoping Review
In 2011, Vaillancourt et al.1 published a systematic review to determine whether the description of any specific symptoms to the emergency medical dispatcher improved the accuracy of the diagnosis of OHCA. Ten years later, in 2021, a systematic review of dispatcher-assisted (DA) recognition of OHCA focusing on sensitivity and specificity of recognition was published by the BLS Task Force.2 The systematic review focused on reporting efficacy (sensitivity, specificity, positive predictive value) of different telecommunicators’ protocols. The 2020 CoSTR on dispatch recognition of cardiac arrest recommended dispatch centers look for ways to optimize sensitivity.3,4 Since that time a large number of studies using new technology and protocols have been published. A scoping review was conducted to understand factors related to DA recognition and to review the current state of evidence for interventions aiming to optimize recognition to inform the development of a PICOST for a systematic review. Evidence for adult and pediatric literature was sought and considered by the Basic Life Support Adult Task Force.
Scoping Review
Webmaster to insert the Scoping Review citation and link to Pubmed using this format when/if it is available.
PICOST
The PICOST (Population, Intervention, Comparator, Outcome, Study Designs and Timeframe)
Population: Adults and children who are in cardiac arrest outside of a hospital.
Intervention: Factors that improve dispatcher-assisted recognition of cardiac arrest.
Outcomes: Dispatcher recognition of cardiac arrest, defined as initiation of cardiac arrest-specific actions such as initiation of instructions to perform cardiopulmonary resuscitation.
Study Designs: Randomized controlled trials (RCTs) and non-randomized studies (non-randomized controlled trials, interrupted time series, controlled before-and-after studies, cohort studies, qualitative) are eligible for inclusion.
Timeframe: Database inception to June 2nd 2023. All relevant studies with an abstract in English were included.
Search Strategies
The initial search run was based on a recent systematic review of dispatcher recognition of OHCA and edited for the current scoping review with assistance from an information specialist from Copenhagen University. The initial search was carried out in Ovid MEDLINE(R) from 1946 to February 2023. After review from the ILCOR BLS Task Force, the search strategy was edited and re-run June 2, 2023. We did not search grey literature.
Inclusion and Exclusion criteria
Included manuscripts described factors associated with DA-recognition of OHCAs. During the review we came across many manuscripts that described barriers to telecommunicators’ OHCA recognition, which were not described in the original PICOST, but we believe that these were important to be included in this review. Manuscripts that did not describe factors associated with DA-recognition of real OHCAs, including simulation studies, were excluded. We also excluded manuscripts that were not in English.
Data tables: BLS 2102 Optimization of DA recognition Sc R 2024 data tables
Data tables are attached.
Task Force Insights
1. Why this topic was reviewed.
This topic was reviewed by the BLS Task Force as members of the Task Force were familiar with many recent studies reporting new approaches to improve recognition of OHCA.
2. Narrative summary of evidence identified
This scoping review identified 60 papers regarding DA-recognition of OHCA.5-64 The studies ranged in methodology being qualitative, mixed methods, observational, and randomized clinical trials. The data used in the studies originated from Europe (n=35), North America (n=17), Australia (n=3), Japan (n=3), Taiwan (n=3), Singapore (n=1), and South Korea (n=1). The included manuscripts described 4 major categories (18 sub-categories): communication between caller and dispatcher, new technology to improve dispatcher recognition of OHCA, patient characteristics and symptoms, quality improvement (QI)/implementation of new protocols in the emergency dispatch center to improve recognition of OHCA. The main findings within each theme are summarized the attached data tables.
Most of the studies in this review reported retrospective, observational studies assessing the proportion of OHCAs recognized by dispatchers and factors associated with OHCA recognition. Only one study reported dispatcher-assisted recognition in pediatric arrests. There were no studies testing two different protocols in a randomized trial.
The most pertinent challenge to dispatcher-assisted recognition of OHCA seems to be determining whether the patient is breathing normally. Several strategies were studied, including bypassing breathing in the initial assessment and asking the caller to put their hand on the patient’s stomach. No strategy showed better results than the commonly used ‘two-questions’ strategies. Although several strategies were tested, there were no RCTs comparing different strategies.
The only randomized control trial in this review studied the effect of including an AI model to improve recognition of OHCA. Although the model seemed to perform well, the study did not show an effect on telecommunicator recognition of OHCA when using the model in the emergency dispatch center. The main problem appeared to be high false positive rates.
Taken together, the studies reviewed in the present Scoping Review do not provide new evidence prompting changes in current treatment recommendations and there are insufficient studies to perform a systematic review for any intervention at this time.
Knowledge Gaps
Future studies of telecommunicator recognition of OHCA should include both sensitivity and specificity as well positive predictive value. Also, in addition to sensitivity and specificity, time to recognition should be prioritized in future research. Telecommunicator protocols should be tested in randomized controlled trials to test sensitivity/specificity as well as time to recognition of OHCA.
Ascertaining breathing status is still reported as a major issue and future studies should investigate how to improve ascertainment of breathing status and recognition of agonal breathing in a timely fashion. There is little evidence of which specific strategies can be used effectively to address communication barriers.
Another aspect to be studied is when telecommunicators should deviate from the script in the dispatch protocol. There is an expectation or necessity for telecommunicators to follow and not deviate from a script. However, deviation may be necessary in certain cases and continuation of the script in these cases could lead to worse communication, lower rates of recognition of OHCA or longer time to recognition. Studies to identify which cases may benefit from deviation of script are warranted.
Among patients with recognized OHCA, it is unclear whether and how much delay there is in initiating CPR instructions due to a practice of putting callers on hold while vehicles are being dispatched to the scene, including calling fire and police, before coming back on the phone with the 911 caller. This is not often reported and not previously studied well.
Following recognition of OHCA, what happens before the call is transferred over to an "ambulance" call center is not well described. Most calls are first answered by a public safety assessment center to determine if a caller needs fire, police, or an ambulance. Current evidence does not clearly report how well and quickly they perform before transferring the call to a telecommunicator.
There is also currently very limited data on OHCA recognition of pediatric OHCAs. Recognition of pediatric OHCAs has been identified as an important area for future research.
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