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Emergency medical service in the stroke chain of survival

Chenaitia, Hichema; Lefevre, Orianea; Ho, Vanessaa; Squarcioni, Christianb; Pradel, Vincentd; Fournier, Marcc; Toesca, Richardc; Michelet, Pierrea; Auffray, Jean Pierrea

European Journal of Emergency Medicine: February 2013 - Volume 20 - Issue 1 - p 39–44
doi: 10.1097/MEJ.0b013e32835015ac
ORIGINAL ARTICLES
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Background The Emergency Medical Services (EMS) play a primordial role in the early management of adults with acute ischaemic stroke (AIS). The aim of this study was to evaluate the role and effectiveness of the EMS in the stroke chain of survival in Marseille.

Methods A retrospective observational study was conducted in patients treated for AIS or transient ischaemic attack in three emergency departments and at the Marseille stroke centre over a period of 12 months.

Results In 2009, of 1034 patients ultimately presenting a diagnosis of AIS or transient ischaemic attack, 74% benefited from EMS activation. Dispatchers correctly diagnosed 57% of stroke patients. The symptoms most frequently reported included limb weakness, speech problems and facial paresis. Elements resulting in misdiagnosis by dispatchers were general discomfort, chest pain, dyspnoea, fall or vertigo. Stroke patients not diagnosed by emergency medical dispatchers but calling within 3 h of symptom onset accounted for 20% of cases.

Conclusion Our study demonstrates that public intervention programmes must stress the urgency of recognizing stroke symptoms and the importance of calling EMS through free telephone numbers. Further efforts are necessary to disseminate guidelines for healthcare providers concerning stroke recognition and the new therapeutic possibilities in order to increase the likelihood of acute stroke patients presenting to a stroke team early enough to be eligible for acute treatment. In addition, EMS dispatchers should receive further training about atypical stroke symptoms, and ‘Face Arm Speech Test’ tests must be included in the routine questionnaires used in emergency medical calls concerning elderly persons.

aDepartment of Emergency Medicine and Intensive Care

bDepartment of Neurological, Stroke Centre

cEmergency Medical Service, Timone University Hospital

dDepartment of Healthcare and Medical Information, Sainte Marguerite Hospital, Marseille, France

Correspondence to Hichem Chenaitia, MD, SAMU 13, CHU La Timone, 264 rue St-Pierre, 13385 Marseille Cedex 5, France Tel: +33 622 074 365; fax: +33 491 386 943; e-mail: chenaitiahichem@gmail.com

Received June 9, 2011

Accepted December 6, 2011

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Introduction

The role of Emergency Medical Services (EMS) is primordial in the early management of adults presenting acute ischaemic stroke (AIS) 1. The first three steps in the stroke chain of survival depend on the efficiency of the EMS 1. The first link in the chain is ‘Detection’: emergency medical dispatchers (EMDs) must be able to recognize the signs and symptoms of stroke on the basis of brief telephone interviews. Once stroke has been identified, the second link is ‘Dispatch’: the role of EMDs is to ensure immediate triage and to quickly dispatch appropriate EMS providers with high priority where there is a suspicion of acute stroke. The third link is ‘Delivery’: this represents transportation of patients to the hospital; EMS involvement is strongly correlated with a shorter time lapse from symptom onset to arrival at hospital 1.

Goals during the prehospital period are rapid identification of patients potentially presenting a stroke, provision of support care for life-threatening symptoms and rapid transportation of these victims to a medical facility properly equipped to manage such patients 1. Thus, immediate recognition of stroke symptoms and activation of the EMS system are crucial factors in improving the outcome of acute stroke patients 1.

Stroke is the leading cause of acquired disability and the third leading cause of death in France 2. Marseille is France’s second largest city, with a population of 852 395 inhabitants within its administrative boundaries on a land area of 240.62 km2. This city is served by an EMS, the SAMU 13 (Service d’Aide Médicale d’Urgence 13), which is organized around basic life support (BLS) and advanced life support (ALS) transport units. Emergency medical technicians belonging to the fire department staff the BLS units whereas emergency physicians staff the ALS units. In France, the free telephone numbers providing access to the nearest EMS are 15, 18 and 112. The EMS (SAMU 13) dispatches all the city’s emergencies among three emergency departments (EDs). These EDs are in three different hospitals, Nord University Hospital, Conception University Hospital and Sainte Marguerite Hospital, situated, respectively, in the north, centre and south of the city. There is also a stroke centre with MRI available 24 h a day at a fourth hospital, the Timone University Hospital, located in the city centre.

The aim of this study was to evaluate the role and effectiveness of EMS in the stroke chain of survival in Marseille. For this purpose, first, we studied the EMS activation by the free telephone system, second, the accuracy of EMS personnel in diagnosing stroke and third which type of EMS system was used for the stroke patients and its influence on prehospital time.

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Methods

Study design

This was a retrospective observational study of stroke patients with a final diagnosis of AIS or transient ischaemic attack made by a physician at one of three EDs or in the Marseille stroke centre, and included patients treated between 1 January 2009 and 31 December 2009.

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Study setting

Stroke is characterized by the sudden loss of blood circulation to an area of the brain, resulting in a corresponding loss of neurologic function. AIS refers to stroke caused by thrombosis or embolism. A transient ischaemic attack (TIA) is an acute episode of temporary neurologic dysfunction resulting from focal cerebral ischaemia not associated with permanent cerebral infarction.

The stroke chain of survival in Marseille is particularly in France; the key feature is the dispatch centre. All emergency calls (to free telephone numbers 15, 18 or 112) are analysed by an emergency physician. When a stroke is suspected, the physician must assess whether the patient is a candidate for thrombolytic therapy, that is, no contraindications, aged less than 80 years, no major disabilities and onset of symptoms within less than 3 h. If the patient is eligible, a telephone conference is organized between the dispatching physician, the patient and the neurologist at the stroke centre; the neurologist decides whether or not to authorize direct admission to the stroke centre; and depending on the MRI results, the neurologist can quickly perform IV thrombolysis at the MRI suite. During dispatch, if the physician dispatcher considers the patients as ineligible for thrombolytic therapy, they are sent to the nearest ED. During dispatch, there is no standardized questionnaire and the most important symptoms are recorded in EMS records.

First, we identified all patients with a final diagnosis of AIS or TIA seen at the three EDs and at the stroke centre in Marseille between 1 January 2009 and 31 December 2009. We reviewed the ED and EMS records of patients dispatched by EMDs and seen by EMS during the prehospital period. This study received ethical approval from Marseille University Hospital’s Emergency committee.

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Population

The inclusion criteria were (a) a final diagnosis of TIA or AIS made by a physician at one of the three EDs or at the stroke centre and (b) availability of EMS and ED records.

The exclusion criteria were: (a) a final diagnosis of haemorrhagic stroke at the ED or stroke centre, (b) transfer from another ED to one of the three EDs or to the stroke centre, (c) death before arrival at hospital, (d) patients not admitted to hospital, (e) stroke occurring during hospitalization and (f) patients aged under 18 years.

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Data collection and evaluation

The following data were extracted from the EMS and ED records: age, sex, time from onset of symptoms to calling the EMS, notifier (patient, witness, caregiver or physician) calling the EMS or addressing the patient directly to the ED, chief complaints or symptoms, and previous medical history noted by the EMD, diagnosis made by EMD, mode of transport to bring the patient to the ED or the stroke centre and time from onset of symptoms to arrival at the ED or the stroke centre. Stroke type was determined using imaging software (Centricity Web Enterprise, Fairfield, Connecticut, USA), which was identical in all the centres included in our study.

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Statistical analysis

Data were collected by two emergency physicians and entered in a database (Open Base). All statistical analyses were performed using statistical software (Statplus, Alexandria, Virginia, USA). All continuous variables are expressed as averages with SD and Student’s t-test was performed. All categorical variables are expressed as numbers with percentages and a χ2-test was used. A P value less than 0.05 was considered statistically significant for all tests.

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Results

Between 1 January 2009 and 31 December 2009, 1034 patients presented a final diagnosis of AIS or TIA at one of the three EDs or at the stroke centre. We excluded 103 stroke patients from the study, out of which 89 were excluded because the EMS record was not available (error in writing the name) and 14 were excluded because they were transferred from another ED. Eight hundred and twenty-nine stroke patients were identified at the Marseille EDs: 298 (36%) at the Conception University Hospital, 290 (35%) at the Nord University Hospital and 241 (29%) at the Sainte Marguerite Hospital, as well as 102 stroke patients at the stroke centre. Of the 931 stroke patients included in the study, 660 (71%) called the EMS using one of the free telephone numbers and received EMS activation. Two hundred and seventy-one (29%) stroke patients did not call the EMS and were admitted directly to one of the three EDs without EMS activation; there were no direct admissions to the stroke centre. The numbers and distribution are shown in Fig. 1.

Fig. 1

Fig. 1

The mean age of the population of stroke patients with EMS activation was 74 years (±15), with an M/F sex ratio of 0.93; there were 560 (85%) AIS and 100 (15%) TIA. The mean age of the population of stroke patients without EMS activation was 71.14 years (±16.16); these patients were younger and TIA was more prevalent (23%) than among stroke patients with EMS activation, and their primary care physician usually acted as the first contact, sometimes addressing them directly to the ED without contacting the EMS. Among the 660 recorded EMS calls, dispatchers correctly diagnosed 375 (57%) stroke patients with a dispatch code of AIS, TIA, stroke or acute cerebrovascular disease and EMDs attributed symptoms to a condition other than stroke for 285 (43%) patients. Age and sex did not affect the diagnosis made by the EMDs, although stroke type (AIS or TIA) did influence the diagnosis by EMDs. The vast majority (79%) of callers or of persons addressing patients directly to an ED were witnesses (i.e. patient’s spouse, family members, neighbours, colleagues, friends or a bystander) or the patients themselves; in some cases (15%), this person was a physician (general practitioner or primary care physician, a physician called to the patient’s home), and in rare cases (6%), a caregiver (home nurse, physiotherapist, laboratory technician). In our study, the type of caller did not influence the diagnosis made by EMDs. The characteristics of the two groups are shown in Table 1.

Table 1

Table 1

The EMS records showed that the majority of this population (52%) had an increased cardiovascular risk and/or a previous medical history of stroke. The symptoms most frequently reported included limb weakness (51%), speech problems (41%) and facial paresis (22%). Other symptoms, such as general discomfort (15%), headache or nausea (11%), chest pain or dyspnoea (9%), confusion (9%), impaired consciousness (8%), fall or vertigo (8%) and blurred vision (4%), were less frequently mentioned and noted in EMS records. Elements helpful for the correct diagnosis of stroke during dispatch are a previous medical history of stroke, presentation of more than two cardiovascular risk factors, positive ‘Face Arm Speech Test’ (FAST) symptoms on questioning by EMDs and impaired consciousness. Elements leading to misdiagnosis by EMDs were general discomfort, chest pain, dyspnoea, fall or vertigo, which were described as the main symptoms. Elements such as headache, nausea, confusion or blurred vision did not influence the diagnosis by EMDs. The characteristics of the two groups are shown in Tables 2 and 3Tables 2 and 3.

Table 2

Table 2

Table 3

Table 3

The most common mode of transportation for stroke patients in Marseille was a BLS unit (56%). A small percentage of patients used their own means of transport (22%) or private ambulances (13%). An ALS unit was less frequently dispatched to the scene (9%).

The group of stroke patients diagnosed by EMDs and dispatched to the stroke centre had a lower average age and shorter time from onset of symptoms to EMS call and arrival at the stroke centre compared with the other group, with the time elapsed from onset of symptoms to a call of less than 2 h for the majority of patients (56%). Thirty per cent of stroke patients diagnosed by EMDs and calling within 3 h of symptom onset were ineligible for thrombolytic therapy for another reason. There was no significant difference in prehospital time for stroke patients sent to an ED whether or not diagnosed in the prehospital period. Twenty per cent of stroke patients were not diagnosed by EMDs and called within 3 h of symptom onset. Prehospital transportation times were similar for all groups. Sex had no influence on prehospital time. The prehospital times for groups of stroke patients with EMS activation are shown in Table 2.

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Discussion

The available data in the literature indicate a serious lack of knowledge about stroke among the population at large 3–53–53–5. Our study also shows the need for public information campaigns in Marseille to inform people about warning signs of stroke and what to do if they experience any of these signs. As for 79% of stroke patients the notifiers or persons addressing victims are witnesses or the patients themselves, 29% of stroke patients are sent to an ED without EMS activation. Increasing the ability to correctly interpret symptoms could reduce the time elapsed from symptom onset to placing a call, thereby helping to reduce the total time from symptom onset to hospital arrival. Such campaigns must emphasize the need to rapidly call EMS free telephone numbers first in order to avoid any delay. Many previous studies have shown the benefit of EMS activation 5–115–115–115–115–115–115–11 and calling an EMS is critical to increasing the chances of an acute stroke patient being seen by the stroke team early enough to qualify for acute treatment.

Our study shows that stroke patients not calling an EMS were younger and more often presenting a TIA. Thus, these patients, who were more independent and less symptomatic, went directly to an ED or consulted their primary care physician. The association of age and sex with EMS use replicates the findings of previous studies: there is no association between patient sex and EMS use, but age was predictive of EMS use, with older patients more likely to use EMS than younger patients 10–1510–1510–1510–1510–1510–15.

Our findings show that primary care physicians send 25% of stroke patients to an ED without EMS activation, and that where the EMS is called by a physician, this does not affect the diagnosis of stroke by EMDs. In Marseille, training and information appears necessary for all physicians working in the city regarding stroke warning signs and what to do if acute stroke is suspected; this information must emphasize the benefits of activating the EMS while stressing the need for rapid action.

Analysis of the mode of transport shows that private ambulance staff in Marseille must also be trained to recognize stroke warnings signs, as they transported 24% of stroke patients without EMS activation and 18% of stroke patients misdiagnosed by EMDs. This training must emphasize the need to call the EMS if they suspect stroke in order to avoid any delay, even if a physician requested transport or if the EMS sent them a different diagnosis, as the EMDs must evaluate the possibility of thrombolysis and the need for direct admission to the stroke centre.

Thus, further efforts to disseminate guidelines and recommendations on stroke recognition and new therapeutic possibilities among healthcare providers, particularly private ambulance staff and primary care physicians, could increase the chances of acute stroke patients being presented to stroke teams early enough to benefit from acute treatment.

There are very few studies investigating emergency calls in cases of AIS. Standard questionnaires used at the dispatch centre mainly concern vital signs such as heart rate, breathing and consciousness 12. Stroke symptoms are not currently included. Nevertheless, most neurological symptoms and signs were reported spontaneously, with the signs most frequently reported for patients presenting AIS being motor deficit, speech problems and facial paresis, because these signs interfere with daily life and are rapidly recognized 12. Our results show that screening of all calls to EMDs using the ‘FAST’ test could allow detection of three of every four strokes (74%), with correction of an erroneous diagnosis in one of every two cases (56%). It therefore appears relevant to systematically carry out the ‘FAST’ test in all emergency medical calls for elderly persons. The feasibility, impact on time to call and the efficiency of such systematic screening require evaluation in a prospective study.

It is also important to inform the dispatcher of any signs that could result in misdiagnosis of AIS. The signs found in our study were generally discomfort, vertigo or fall, which could be a direct consequence of stroke, or chest pain and dyspnoea, which could be a consequence of physiological stress with raised blood pressure, heart rate and anxiety. Knowledge of these pitfalls could help reduce the number of misdiagnosed cases of stroke.

For our EMS, the most appropriate mode of EMS transport for stroke patients is the BLS unit, although an ALS unit must be sent in life-threatening situations. The findings of our study show that in one out of every 10 cases (9%), AISs are severe and life-threatening and a medical team must be dispatched to the scene, underscoring the gravity of this condition.

Our study confirms the findings of previous studies, which show that transport time is not the primary determinant for association of EMS use with reduced prehospital time and travel time to hospital actually represents only a small proportion of the total prehospital period 13,1413,14.

The findings of this report provide a comprehensive overview of prehospital times for stroke patients in Marseille. Our study shows that in 70% of cases of correctly diagnosed patients sent to an ED, calls were made 3 h after the onset of symptoms, rendering patients ineligible for thrombolysis. Only 20% of misdiagnosed patients called within 3 h; this number must be tempered by the fact that these patients more frequently presented a TIA and did not require thrombolysis.

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Limitations

A major limitation of this study is that the study was conducted in only one city. Practices and patient populations vary considerably, and it is necessary to confirm these findings in other settings.

In this study, we were not able to calculate the negative or positive predictive value, the sensitivity or specificity of stroke warning signs or the accuracy of diagnosis by EMDs.

We are not aware of the characteristics of the stroke population travelling to hospital by their own means of transport. Data regarding the hospital phase are limited in this study as the EMS personnel collecting the data had limited access to hospital records.

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Conclusion

Clearly, more work needs to be carried out to educate the general public about the warning signs and symptoms of stroke. The findings of our study demonstrate that the intervention programme aimed at increasing EMS use for stroke patients must emphasize the emergency nature of stroke symptoms, the importance of calling free telephone EMS numbers and the need for broad-based action encompassing not just those at high risk for stroke or family members.

The study identifies the signs and symptoms may result in the misdiagnosis of stroke patients and attribution of their symptoms to a condition other than stroke, and it could thus help improve the ability of EMS personnel to accurately identify stroke patients.

Further efforts to disseminate guidelines and recommendations for healthcare providers regarding stroke recognition and new therapeutic possibilities could reduce the time from stroke onset to hospital arrival, thus increasing the likelihood of acute stroke patients being seen by the stroke team early enough to ensure eligibility for acute treatment.

In addition, increased knowledge by EMS dispatchers of atypical stroke symptoms is required, and a ‘FAST’ test should be included in the routine questionnaires used during emergency medical calls regarding elderly persons.

These results represent an important step in measuring and improving the effectiveness of EMS in the stroke chain of survival in Marseille.

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Acknowledgements

Conflicts of interest

There are no conflicts of interest.

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References

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Keywords:

acute ischaemic stroke; detection; dispatch; emergency medical service; prehospital; stroke centre; transient ischaemic attack

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