Elsevier

Resuscitation

Volume 181, December 2022, Pages 123-131
Resuscitation

Clinical paper
Performance of the medical priority dispatch system in correctly classifying out-of-hospital cardiac arrests as appropriate for resuscitation

https://doi.org/10.1016/j.resuscitation.2022.11.001Get rights and content

Abstract

Background

Emergency dispatch centres receive emergency calls and assign resources. Out-of-hospital cardiac arrests (OHCA) can be classified as appropriate (requiring emergent response) or inappropriate (requiring non-emergent response) for resuscitation. We sought to determine system accuracy in emergency medical services (EMS) OHCA response allocation.

Methods

We analyzed EMS-assessed non-traumatic OHCA records from the British Columbia (BC) Cardiac Arrest registry (January 1, 2019-June 1, 2021), excluding EMS-witnessed cases. In BC the “Medical Priority Dispatch System” is used. We classified EMS dispatch as “emergent” or “non-emergent” and compared to the gold standard of whether EMS personnel decided treatment was appropriate upon scene arrival. We calculated sensitivity, specificity, and positive and negative predictive values (PPV, NPV), with 95% CI’s.

Results

Of 15,371 non-traumatic OHCAs, the median age was 65 (inter quartile range 51–78), and 4834 (31%) were women; 7152 (47%) were EMS-treated, of whom 651 (9.1%) survived). Among EMS-treated cases 6923/7152 had an emergent response (sensitivity = 97%, 95% CI 96–97) and among EMS-untreated cases 3951/8219 had a non-emergent response (specificity = 48%, 95% CI, 47 to 49). Among cases with emergent dispatch, 6923/11191 were EMS-treated (PPV = 62%, 95% CI 61–62), and among those with non-emergent dispatch, 3951/4180 were EMS-untreated (NPV = 95%, 95% CI 94–95); 229/4180 (5.5%) with a non-emergent dispatch were treated by EMS.

Conclusion

The dispatch system in BC has a high sensitivity and moderate specificity in sending the appropriate responses for OHCAs deemed appropriate for treatment by paramedics. Future research may address strategies to increase system specificity, and decrease the incidence of non-emergent dispatch to EMS-treated cases.

Introduction

In North America, the incidence of emergency medical system (EMS)-treated out-of-hospital cardiac arrests (OHCA) is 76.5 individuals per 100 000, with a survival rate of 10.6%.1 The time-sensitive nature of cardiac arrest necessitates rapid interventions to optimize patient outcome, including rapid professional EMS response.2 Emergency Medical Call Takers (EMCT’s) play a significant role in connecting these resources to a cardiac arrest, as they are the first point of contact with bystanders at the scene of an OHCA.3 Many jurisdictions use the Medical Priority Dispatch System (MPDS®, Version 13.3.116, 2020 Release, Priority Dispatch Corp., Salt Lake City Utah, USA), which ranks the priority of 9-1-1 calls and dispatches EMS units with corresponding levels of urgency to the incident location. The MPDS will generate standardized questions to ask the patient or bystander, based upon the nature and severity of the complaint, the answers of which result in an MPDS code assignment.4, 5, 6, 7 Resources and response allocation are locally assigned to each MPDS code for each event.

When EMS crews arrive at a scene where a patient has had a cardiac arrest, they decide whether resuscitative treatments are appropriate, depending on clinical presentation and available advanced care directives. To ensure resource allocation matches patient need, the ideal dispatch system will correctly recommend a fulsome emergent response to all cases later deemed by on-scene paramedics to be appropriate for resuscitation, while sending non-emergent responses for those later deemed to be inappropriate for resuscitation efforts.

For these reasons, we sought to calculate the ability of the MPDS dispatch system to accurately classify OHCA calls as requiring emergent or non-emergent response (our primary aim was not to determine the ability of EMCTs to correctly identify a cardiac arrest occurrence [or would later occur while EMS was en route], but rather the ability to dispatch the correct response type). Second, we wished to identify the proportion of OHCA’s classified as “non-emergent”—presumably due to the dispatch centre impression that the case was futile—who were later considered appropriate for treatment by EMS, given that this error in classification likely has a substantial impact on prognosis. Third, we sought to describe patient characteristics and outcomes of appropriate and inappropriately coded OHCAs.

Section snippets

Study setting and design

This retrospective study analyzed data between January 1, 2019 and June 1, 2021 from the British Columbia (BC) Cardiac Arrest Registry, which prospectively identifies consecutive non-traumatic EMS-assessed OHCAs, defined as cases identified by on-scene EMS personnel to be pulseless.8 Approval was obtained from University of British Columbia-affiliated Providence Health Care Research Ethics Board (H15-03059).

EMS medical care

British Columbia’s population of 5.19 million is under the care of the province-wide EMS

Results

The BC Cardiac Arrest Registry recorded 16 493 non-traumatic OHCA cases between January 1, 2019 and June 1, 2021; we excluded 995 EMS-witnessed cases and 127 missing MPDS codes (Fig. 1). We included 15 371 OHCAs in this analysis, with a median age of 65 years (IQR 51, 78), 4834 (31%) were female, and 11 687 were private-location (82%). Overall, 7152 (47%) were EMS-treated, of whom 651 (9.1%) survived, with 555 (7.8%) having a favourable neurological outcome at hospital discharge. Table 1

Discussion

Using a provincial cardiac arrest registry, we reviewed over 15 000 consecutive non-traumatic OHCAs in BC to examine the performance of the MPDS system to correctly classify cases of out-of-hospital cardiac arrest as appropriate for emergent, vs non-emergent response. Of cases that were deemed appropriate for treatment by paramedics, 97% received an emergent dispatch response. Untreated EMS OHCAs received an emergent response in approximately half of cases. Overall, these findings demonstrate

Conclusion

The MPDS system used in British Columbia demonstrated 97% sensitivity for correctly assigning an emergent response to EMS-treated OHCAs and 48% specificity for assigning a non-emergent response to untreated OHCAs. Future research may address strategies to increase system specificity, and decrease the incidence of non-emergent dispatch to EMS-treated cases.

Funding

This study received funding from BioTalent Canada.

Conflicts of Interest

None.

CRediT authorship contribution statement

Justin Yap: Data curation, Visualization, Formal analysis, Investigation, Methodology, Writing – original draft, Writing – review & editing. Jennie Helmer: Formal analysis, Writing – review & editing, Resources. Marc Gessaroli: Formal analysis, Writing – review & editing, Resources. Jacob Hutton: Formal analysis, Writing – review & editing. Laiba Khan: Formal analysis, Writing – review & editing. Frank Scheuermeyer: Formal analysis, Writing – review & editing. Nechelle Wall: Formal analysis,

Acknowledgments

The BC Resuscitation Research Collaborative acknowledges funding from the Heart and Stroke Foundation of Canada, and Providence Health Care Research Institute, as well as in-kind support from BCEHS. We would like to acknowledge BCEHS, municipal fire departments and emergency first responders’ dedication, and perseverance in providing exceptional patient care across British Columbia, especially during the hardships and obstacles brought about during the COVID-19 pandemic.

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