Stroke identification by criteria based dispatch - a register based study

Emergency Medical Services dispatcher recognition of stroke: A systematic review

PURPOSE

Stroke treatments are time-sensitive, and thus early and correct recognition of stroke by Emergency Medical Services is essential for outcomes. This is particularly important with the adaption of mobile stroke units. In this systematic review, we therefore aimed to provide a comprehensive overview of Emergency Medical Services dispatcher recognition of stroke.

METHODS

The review was registered on PROSPERO and the PRISMA guidelines were applied. We searched PubMed, Embase, and Cochrane Review Library. Screening and data extraction were performed by two observers. Risk of bias was assessed using the QUADAS-2 instrument.

FINDINGS

Of 1200 papers screened, 24 fulfilled the inclusion criteria. Data on sensitivity was reported in 22 papers and varied from 17.9% to 83.0%. Positive predictive values were reported in 12 papers and ranged from 24.0% to 87.7%. Seven papers reported specificity, which ranged from 20.0% to 99.1%. Six papers reported negative predictive value, ranging from 28.0% to 99.4%. In general, the risk of bias was low.

DISCUSSION

Stroke recognition by dispatchers varied greatly, but overall many patients with stroke are not recognised, despite the initiatives taken to improve stroke literacy. The available data are of high quality, however Asian, African, and South American populations are underrepresented.

CONCLUSION

While the data are heterogenous, this review can serve as a reference for future research in emergency medical dispatcher stroke recognition and initiatives to improve prehospital stroke recognition.

Telephone triage and dispatch of ambulances to patients with suspected and verified acute stroke - a descriptive study

OBJECTIVES

In this study we aimed to explore EMCC triage of suspected and confirmed stroke patients to gain more knowledge about the initial phase of the acute stroke response chain. Accurate dispatch at the Emergency Medical Communication Center (EMCC) is crucial for optimal resource utilization in the prehospital service, and early identification of acute stroke is known to improve patient outcome.

MATERIALS AND METHODS

We conducted a descriptive retrospective study based on data from the Emergency Department and EMCC records at a comprehensive stroke center in Oslo, Norway, during a six-month period (2019-2020). Patients dispatched with EMCC stroke criteria and/or discharged with a stroke diagnosis were included. We identified EMCC true positive, false positive and false negative stroke patients and estimated EMCC stroke sensitivity and positive predictive value (PPV). Furthermore, we analyzed prehospital time intervals and identified patient destinations to gain knowledge on ambulance services assessments.

RESULTS

We included 1298 patients. EMCC stroke sensitivity was 77% (95% CI: 72 - 82%), and PPV was 16% (95% CI: 14 - 18%). EMCC false negative stroke patients experienced an increased median prehospital delay of 11 min (p < 0.001). Upon arrival at the scene, 68% of the EMCC false negative patients were identified as suspected stroke cases by the ambulance services. Similarly, 68% of the false positive stroke patients were either referred to a GP, out-of-hours GP acute clinic, local hospitals or left at the scene by the ambulance services, indicating that no obvious stroke symptoms were identified by ambulance personnel upon arrival at the scene.

CONCLUSIONS

This study reveals a high EMCC stroke sensitivity and an extensive number of false positive stroke dispatches. By comparing the assessments made by both the EMCC and the ambulance service, we have identified specific patient groups that should be the focus for future research efforts aimed at improving the sensitivity and specificity of stroke recognition in the EMCC.

Differences between the dispatch priority assessments of emergency medical dispatchers and emergency medical services: a prospective register-based study in Finland

BACKGROUND

Responsive and efficient emergency medical services (EMS) require accurate telephone triage. In Finland, such services are provided by Emergency Response Centre Agency (ERC Agency). In 2018, a new Finnish computer-assisted emergency dispatch system was introduced: the Emergency Response Integrated Common Authorities (ERICA). After the introduction of ERICA, the appropriateness of EMS dispatch has not been investigated yet. The study´s objective is to determine the consistency between the priority triage of the emergency medical dispatcher (EMD) and the on-scene priority assessment of the EMS, and whether the priority assessment consistency varied among the dispatch categories.

METHODS

This was a prospective register-based study. All EMS dispatches registered in the Tampere University Hospital area from 1 August 2021 to 31 August 2021 were analysed. The EMD's mission priority triaged during the emergency call was compared with the on-scene EMS's assessment of the priority, derived from the pre-set criteria. The test performance levels were measured from the crosstabulation of true or false positive and negative values of the priority assessment. Statistical significance was analysed using the chi-square test and the Kruskal-Wallis H test, and p-values < 0.05 were considered significant.

RESULTS

Of the 6416 EMS dispatches analysed in this study, 36% (2341) were urgent according to the EMD's dispatch priority, and of these, only 29% (688) were urgent according to the EMS criteria. On the other hand, 64% (4075) of the dispatches were non-urgent according to the EMD's dispatch priority, of which 97% (3949) were non-urgent according to the EMS criteria. Moreover, there were differences between the EMD and EMS priority assessments among the dispatch categories (p < 0.001). The overall efficiency was 72%, sensitivity 85%, specificity 71%, positive predictive value 29%, and negative predictive value 97%.

CONCLUSION

While the EMD recognised the non-urgent dispatches with high consistency with the EMS criteria, most of the EMD's urgent dispatches were not urgent according to the same criteria. This may diminish the availability of the EMS for more urgent missions. Thus, measures are needed to ensure more accurate and therefore, more efficient use of EMS resources in the future.

Symptoms presented during emergency telephone calls for patients with spontaneous subarachnoid haemorrhage

Background

A spontaneous subarachnoid haemorrhage (SAH) is one of the most critical neurological emergencies a dispatcher can face in an emergency telephone call. No study has yet investigated which symptoms are presented in emergency telephone calls for these patients. We aimed to identify symptoms indicative of SAH and to determine the sensitivity of these and their association (odds ratio, OR) with SAH.

Methods

This was a nested case–control study based on all telephone calls to the medical dispatch center of Copenhagen Emergency Medical Services in a 4-year time period. Patients with SAH were identified in the Danish National Patient Register; diagnoses were verified by medical record review and their emergency telephone call audio files were extracted. Audio files were replayed, and symptoms extracted in a standardized manner. Audio files of a control group were replayed and assessed as well.

Results

We included 224 SAH patients and 609 controls. Cardiac arrest and persisting unconsciousness were reported in 5.8% and 14.7% of SAH patients, respectively. The highest sensitivity was found for headache (58.9%), nausea/vomiting (46.9%) and neck pain (32.6%). Among conscious SAH patients these symptoms were found to have the strongest association with SAH (OR 27.0, 8.41 and 34.0, respectively). Inability to stand up, speech difficulty, or sweating were reported in 24.6%, 24.2%, and 22.8%. The most frequent combination of symptoms was headache and nausea/vomiting, which was reported in 41.6% of SAH patients. More than 90% of headaches were severe, but headache was not reported in 29.7% of conscious SAH patients. In these, syncope was described by 49.1% and nausea/vomiting by 37.7%.

Conclusion

Headache, nausea/vomiting, and neck pain had the highest sensitivity and strongest association with SAH in emergency telephone calls. Unspecific symptoms such as inability to stand up, speech difficulty or sweating were reported in 1 out of 5 calls. Interestingly, 1 in 3 conscious SAH patients did not report headache.

Trial registration NCT03980613 (www.clinicaltrials.gov).

Validity and risk factor analysis for helicopter emergency medical services in Japan: a pilot study

Background

Some emergency departments use triage scales, such as the Canadian Triage and Acuity Scale and Japan Urgent Stroke Triage Score, to detect life-threatening situations. However, these protocols have not been used for aeromedical services. Therefore, we investigated the factors predicting these life-threatening situations in aeromedical services as a pilot study for establishing the protocol.

Method

We retrospectively evaluated helicopter emergency medical service cases from 1 April 2015 to 31 March 2020 at Gifu University Hospital using the mission records. We only evaluated cases dealing with suggested internal medicine issues. We excluded cases influenced by external factors such as trauma or cases that included hospital-to-hospital transportation, focusing only on prehospital care. We evaluated the validity of the medical emergencies based on the needs for emergency interventions and hospital admission and of the suggested diagnoses and associated risk factors.

Result

A total of 451 cases were suitable for inclusion in the study. In the analysis for all emergency calls, 235 (52.11%) cases needed emergency intervention and 300 (64.4%) required hospital admission. The suggested diagnosis was valid for 261 (57.87%) cases. After the first assessment by emergency medical technicians, 75 cases were removed. Analysis after this first assessment found that 52.31% cases required emergency intervention, 70.26% needed admission, and the suggested diagnosis was valid for 69.41% of cases. In the analysis of emergency calls, the multivariate analysis of some key variables identified age, playing sports, and gasping as risk factors for emergency intervention. Hospital admission risk factors included being age only. The suggested diagnosis was valid only for sports situations. In the analysis after the first assessment by an emergency medical technician, risk factors for emergency intervention included being age being male, playing sports, and gasping, and those for hospital admission was being age, being male, and experiencing stroke symptoms and/or disturbance of consciousness. The suggested diagnosis was valid only for sports situations.

Conclusion

Some ‘second’ keywords/phrases predict medical emergencies. Therefore, the dispatch commander should gather these keyword/phrases to assess.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12873-021-00471-x.

Which symptoms pose the highest risk in patients calling for an ambulance? A population-based cohort study from Denmark

BACKGROUND

Emergency medical service patients are a vulnerable population and the risk of mortality is considerable. In Denmark, healthcare professionals receive 112-emergency calls and assess the main reason for calling. The main aim was to investigate which of these reasons, i.e. which symptoms or mechanism of injury, contributed to short-term risk of death. Secondary aim was to study 1-30 day-mortality for each symptom/ injury.

METHODS

Historic population-based cohort study of emergency medical service patients calling 112 in the North Denmark Region between 01.01.2016-31.12.2018. We defined 1-day mortality as death on the same or the following day. The frequency of each symptom and cumulative number of deaths on day 1 and 30 together with 1- and 30-day mortality for each symptom/mechanism of injury is presented in proportions. Poisson regression with robust variance estimation was used to estimate incident rates (IR) of mortality with 95% confidence intervals (CI), crude and age and sex adjusted, mortality rates on day 1 per 100,000 person-year in the population.

RESULTS

The five most frequent reasons for calling 112 were "chest pain" (15.9%), "unclear problem" (11.9%), "accidents" (11.2%), "possible stroke" (10.9%), and "breathing difficulties" (8.3%). Four of these contributed to the highest numbers of deaths: "breathing difficulties" (17.2%), "unclear problem" (13.2%), "possible stroke" (8.7%), and "chest pain" (4.7%), all exceeded by "unconscious adult - possible cardiac arrest" (25.3%). Age and sex adjusted IR of mortality per 100,000 person-year was 3.65 (CI 3.01-4.44) for "unconscious adult - possible cardiac arrest" followed by "breathing difficulties" (0.45, CI 0.37-0.54), "unclear problem"(0.30, CI 0.11-0.17), "possible stroke"(0.13, CI 0.11-0.17) and "chest pain"(0.07, CI 0.05-0.09).

CONCLUSION

In terms of risk of death on the same day and the day after the 112-call, "unconscious adult/possible cardiac arrest" was the most deadly symptom, about eight times more deadly than "breathing difficulties", 12 times more deadly than "unclear problem", 28 times more deadly than "possible stroke", and 52 times more deadly than "chest pain". "Breathing difficulties" and "unclear problem" as presented when calling 112 are among the top three contributing to short term deaths when calling 112, exceeding both stroke symptoms and chest pain.

Acute care pathways for patients calling the out-of-hours services

BACKGROUND

In Western countries, patients with acute illness or injury out-of-hours (OOH) can call either emergency medical services (EMS) for emergencies or primary care services (OOH-PC) in less urgent situations. Callers initially choose which service to contact; whether this choice reflect the intended differences in urgency and severity is unknown. Hospital diagnoses and admission rates following an OOH service contact could elucidate this. We aimed to investigate and compare the prevalence of patient contacts, subsequent hospital contacts, and the age-related pattern of hospital diagnoses following an out-of-hours contact to EMS or OOH-PC services in Denmark.

METHODS

Population-based observational cohort study including patients from two Danish regions with contact to EMS or OOH-PC in 2016. Hospital contacts were defined as short (< 24 h) or admissions (≥24 h) on the date of OOH service contact. Both regions have EMS, whereas the North Denmark Region has a general practitioner cooperative (GPC) as OOH-PC service and the Capital Region of Copenhagen the Medical Helpline 1813 (MH-1813), together representing all Danish OOH service types. Calling an OOH service is mandatory prior to a hospital contact outside office hours.

RESULTS

OOH-PC handled 91% (1,107,297) of all contacts (1,219,963). Subsequent hospital contacts were most frequent for EMS contacts (46-54%) followed by MH-1813 (41%) and GPC contacts (9%). EMS had more admissions (52-56%) than OOH-PC. For both EMS and OOH-PC, short hospital contacts often concerned injuries (32-63%) and non-specific diagnoses (20-45%). The proportion of circulatory disease was almost twice as large following EMS (13-17%) compared to OOH-PC (7-9%) in admitted patients, whereas respiratory diseases (11-14%), injuries (15-22%) and non-specific symptoms (22-29%) were more equally distributed. Generally, admitted patients were older.

CONCLUSIONS

EMS contacts were fewer, but with a higher percentage of hospital contacts, admissions and prevalence of circulatory diseases compared to OOH-PC, perhaps indicating that patients more often contact EMS in case of severe disease. However, hospital diagnoses only elucidate severity of diseases to some extent, and other measures of severity could be considered in future studies. Moreover, the socio-demographic pattern of patients calling OOH needs exploration as this may play an important role in choice of entrance.

Stroke identification by criteria based dispatch - a register based study

BACKGROUND

Rapid and precise dispatch of resources is a key element in pre-hospital emergency medicine. Emergency medical communication centres (EMCCs) dispatch resources based on protocols and guidelines, balancing the acute need of the individual and the resource allocation of the pre-hospital emergency medical system. The aim of this study was to determine the validity of stroke identification by the Norwegian dispatch guidelines.

METHOD AND MATERIAL

This was a register-based study where patients suspected for stroke were compared to those with the final diagnosis of stroke as an indicator group for the guideline validation. One EMCC and its three associated hospitals participated with 13 months of data. Four subcodes of the stroke dispatch code were defined as suspicious of stroke and further analysed. Factors associated with stroke identification were explored.

RESULTS

The sensitivity for identifying a stroke patient at initial EMCC contact was 57.9% (51.5, 64.1), specificity was 99.1% (98.9, 99.2), positive predictive value was 45.7% (40.1, 51.4) and negative predictive value was 99.4% (99.3, 99.5). The emergency medical access telephone (113) was initial EMCC contact line in only 48% of the cases. Paralyses and admittance to a smaller hospital were associated with increased probability for stroke (OR 2.6, P = 0.001 and OR 2.7, P = 0.01), respectively.

CONCLUSION

The sensitivity for identification of stroke patients by the dispatch guidelines is modest, while the specificity is high. The 113 telephone line was initial EMCC access point for less than half of the stroke patients.