Emergency medical dispatching : protocols, experiences and priorities

Abstract

Each year, millions of people call the emergency number with a wide variety of symptoms and various levels of illness severity. At its’ core, emergency medical dispatching encompasses the answering of these calls, the assessment of the need for medical assistance, the dispatch of a resource with an appropriate priority level and the provision of instructions assisting the caller. Consequently, emergency medical dispatching is important in ensuring patient safety as well as for ascertaining the best use of limited resources. However, research on different aspects of emergency medical dispatch remains limited. Therefore, this thesis’s overall aim was to provide new knowledge in relation to dispatch protocols and the assessment and prioritization of emergency medical calls. Further, to bring light onto emergency medical dispatchers’ (EMDs) experiences of managing such calls thereby creating an understanding and foundation for further development and strengthening of this first link in the chain of emergency care. The thesis builds upon four studies based on different populations: Study I: a simulation study with the aim to compare the accuracy, in terms of correct dispatch priority, between two dispatch protocols; the Swedish Index and RETTS-A. Expert consensus was used as reference standard. A total of 1,293 calls was included. For priority level, 349 (54%) calls were assessed correctly with Swedish Index and 309 (48%) with RETTS-A (p=0.012). Sensitivity for the highest priority was 82.6% (95% CI: 76.6-87.3) for Swedish Index and 54.0% (95% CI: 44.3-63.4%) for RETTS-A. Overtriage was 37.9% (34.2.-41.7%) in Swedish Index and 28.6% (25.2-32.2) in RETTS-A. The corresponding proportion of undertriage was 6.3% (4.7-8.5) and 23.4% (20,3-26.9) respectively. The results demonstrate that although the Swedish Index had a higher accuracy than RETTS-A, the overall accuracy for both dispatch protocols is low. Study II: a retrospective observational study based on registry data from four Swedish regions in 2015. The aim was to compare calls assessed by an EMD with and without the support of a registered nurse (RN) with respect to priority level, accuracy, and dispatch category. Ambulance personnel’s assessment was used as reference standard. A total of 25,025 calls were included. Dispatch priority was in concordance with the reference standard in 11,319 (50.7%) for EMD and in 481 (41.5%) for EMD+RN, (p<0.01). Overtriage was equal for both groups; 5904 (26,4%) for EMD, and 306 (26.4%) for EMD+RN, (p=0.25). Undertriage was 5122 (22.9%) for EMD and 371 (32.0%) for EMD+RN (p<0.01). Sensitivity for the most urgent priority was 54.6% for EMD, compared to 29.6% for EMD+RN (p<0.01), and specificity was 67.3% and 84.8% (p<0.01) respectively. Dispatch category was in concordance with reference standard in 13,785 (66.4%) EMD and 697 (62.2%) EMD+RN (p=0.01). The results demonstrated that a higher precision was not observed for calls assessed with RN-support. Study III: a qualitative interview study aiming at exploring EMDs experiences of managing emergency medical calls. One main category emerged from the inductive content analysis of 13 interviews: “to attentively manage a multifaceted, interactive task”. The main category was in turn composed of three categories: “to utilize creativity to gather information”, “continuously process and assess complex information” and “engage in the professional role”. Study IV: a retrospective observational registry study on all primary ambulance missions within the Stockholm Region Aug 2019 to Sept 2022. The aim was to identify the proportion of time critical patients, defined as patients receiving time critical interventions in the prehospital setting, having an ambulance dispatched as Priority 1. Further, to describe dispatch categories and emergency department (ED) diagnoses. Of 571 163 included missions, 92 975 (16.3%) were time critical. Of these, 75 504 (81.2%) had an ambulance dispatched as Priority 1, 16 967 (18.2%) as Priority 2, and 504 (0.5%) as Priority 3. When stratified according to dispatch priority, the ranking of the most common dispatch categories differed. ED-diagnosis were mostly symptom-related. The results demonstrate that most patients with time critical conditions receive an ambulance dispatched as Priority 1. Those who are not identified as in need of an ambulance dispatched as Priority 1, differ in regard to their presentation, and often present to the EMCC with unspecific symptoms.

In conclusion, this thesis sheds light on different aspects of emergency medical dispatching in regard to emergency calls with a wide range of symptoms. Specifically, it contributes to the evaluation of dispatch protocols and highlights the need for further investigations in relation to the established, yet understudied, practice of emergency medical dispatching performed predominantly by EMDs with and without the support of RNs. Given their key role in managing this multifaceted interactive task, the results can be used to inform future development of protocols and interview techniques. The results further indicate the need for regular feedback, as part of clinical routine. Finally, the thesis enhances the understanding of the population of patients with time critical conditions and contributes to the understanding and future establishment of a definition of time critical conditions in the pre-hospital setting.