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Proceedings of a National Symposium on Rapid Identification and Treatment of Acute Stroke


December 12-13, 1996

Prehospital Identification and Treatment

Michael R. Sayre, M.D.
University of Cincinnati Medical Center

Robert A. Swor, D.O.
William Beaumont Hospital, Royal Oak, Michigan

Linda K. Honeycutt, EMT-P
Providence Hospital and Medical Centers, Southfield, Michigan

Acute stroke is one of the more critical conditions for which patients utilize emergency medical services (EMS). Traditionally, there has not been an emphasis on stroke education for prehospital care providers. Now that proven therapy is available for some stroke patients, it is clear that stroke must be treated as an emergency (1). Since the time window for effective treatment is quite short, early identification of the stroke patient by prehospital personnel should help to mobilize emergency department (ED) and in-hospital services. Therefore, prehospital care providers need enhanced education so that they are prepared to quickly identify and possibly treat acute stroke victims.

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Where Are We Now?

Knowledge Base

At present, most EMT-Basics are taught very little about stroke. One of the commonly used textbooks for the initial training of the EMT-Basic is Emergency Care, 7th edition, by Harvey Grant and colleagues, copyrighted 1995. The primary discussion of stroke is covered in six paragraphs over one column in an 871-page text. The students are advised: "It is not necessary to diagnose the patient's medical problem or to know that a stroke has taken place, although you may suspect it."

This textbook is not alone in its limited discussion about stroke. Table 1 shows the results of a quick survey of other major texts used for the initial training of the EMT-Basic. It is safe to conclude that stroke knowledge among EMT-Basics varies widely.

Paramedics do learn more about stroke than EMT-Basics. One of the major paramedic textbooks is Paramedic Emergency Care, 3rd edition, by Bryan Bledsoe, Robert Porter, and Bruce Shade. The discussion of stroke in that book covers about five pages including line art detailing the etiologies of stroke. The differences between ischemic stroke and brain hemorrhage are explained. A list of risk factors for stroke is included as well as a description of the clinical presentation.

There is a short section on therapy. Students are told to establish and maintain an adequate airway, administer oxygen, and assist ventilation when required. Paramedic students are advised to consider hypoglycemia and to obtain blood for glucose determination. They are further advised to establish an intravenous line with normal saline or lactated Ringer's solution and to monitor the cardiac rhythm. They are instructed to protect paralyzed extremities and provide reassurance to the patient.

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Neurological Assessment Skills

Beyond the limited text information, EMS personnel learn little about neurological disorders. The focus of most EMS curricula is to identify changes in mental status, pupillary size, or major motor deficits. Accordingly, the ability to differentiate nontraumatic causes of neurological disease is limited. As EMS is currently practiced, EMT-Basics and paramedics have little reason to differentiate these entities. They do not learn the importance of identifying the time of onset of the event.

Most EMS providers are trained to identify altered mental status. They often have the basic knowledge to identify obvious deficits such as aphasia or hemiplegia, but their ability to identify the etiology of the deficit is limited. The training to assess toxic-metabolic, infectious, neoplastic, or other causes of neurological deficits, with the exception of hypoglycemia, is minimal. A limited amount of material is presented during initial education regarding other central nervous system events (e.g., subarachnoid hemorrhage, hypertensive crisis). These events are relatively rare, and most EMS providers would be unable to differentiate them from various types of ischemic strokes.

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Patient Evaluation

Data regarding EMS call volumes indicate that strokes place proportionately small demands on EMS. For example, Cincinnati, Houston, and San Diego Fire Department Dispatch records have indicated that stroke accounted for about 2% of EMS dispatches in 1995. A similar proportion of patients was identified by EMTs or paramedics in the suburban city of Reading, Ohio (2).

In the Reading study, the EMT or paramedic assessment of stroke or transient ischemic attack was correct in 72% of cases (95% confidence interval ranged from 61 to 81%). A wide variety of other disorders mimicked stroke. These included infection/sepsis, syncope, cardiac disease, seizure, drug overdose, brain metastasis, hyponatremia, arthritis, global amnestic syndrome, and radial nerve palsy. The study did not identify stroke/TIA patients who were missed by EMS personnel. So one can conclude that the specificity for the prehospital diagnosis of stroke is about 75%, but there is no information from which one can estimate sensitivity.

EMS units in Reading arrived on the scene a mean of about 3 minutes after the 911 call. On-scene evaluation time was 19 minutes for those patients transported by basic life-support (BLS) ambulance and 24 minutes for those transported by paramedic, or advanced life-support (ALS), ambulance. Patients transported by paramedics were seen by the emergency physician in 10 minutes compared with 20 minutes for those patients transported by BLS. The ALS patients also had CT scans performed 30 minutes sooner than those transported by BLS. The patients transported by ALS had larger neurological deficits. The size of the deficits may have motivated quicker action at the receiving hospital.

Existing data indicate that about half of stroke patients in three metropolitan areas used the EMS system to initiate care for stroke (3). The same database shows that 60% of patients presenting within 90 minutes of symptom onset arrived by EMS.

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Mental Status and Hemiparesis

Both EMT-Basics and paramedics learn to assess mental status and are taught to assess the Glasgow-Coma Scale. They also learn to look for findings such as extremity weakness. However, they mainly learn those skills in the setting of assessing the trauma patient.

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Limited Differential Diagnosis

Based on the survey of EMT-Basic textbooks described above, it would appear that EMT-Basics learn little about the differential diagnosis of stroke symptoms. Paramedics are taught to recognize stroke. Most EMS systems encourage paramedics to consider hypoglycemia in the differential diagnosis. However, few paramedics are made aware of conditions such as Todd's paresis that can mimic stroke or subdural hematomas that can manifest themselves late (in a nontrauma setting).

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Identification of Immediate Life Threats

In general, prehospital emergency care providers do a good job identifying and managing immediate life threats such as severe trauma or cardiac arrest (4,5). Paramedic skills include definitive airway management, treatment of cardiac dysrhythmias, and treatment of seizure activity. However, there is no specific education in most training programs about the life threats faced by the stroke patient.

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Therapy

Airway

EMT-Basics learn to manage airways with a variety of minimally invasive tools. They are taught the use of oxygen masks and nasal cannulas. They learn to use nasopharyngeal and oropharyngeal airways and are able to perform suctioning to prevent aspiration. They develop some skill in the use of the bag-valve-mask device to assist ventilations. In a few communities, EMT-Basics are taught endotracheal intubation, although that procedure is usually limited to patients with apnea.

During paramedic training, additional emphasis is placed on endotracheal intubation. Most paramedic training programs emphasize aggressive management of the airway. Paramedics in some areas of North America may utilize nasotracheal intubation. Paramedics in most areas are able to use narcotics or benzodiazapines to facilitate airway management, and in a few areas they may use pharmacologic agents such as succinylcholine to assist intubation.

Hypertension

EMT-Basics are not trained to manage hypertension. Paramedics generally are expected to understand that there are hypertensive emergencies, but they receive limited training in differentiating hypertensive emergencies from acute stroke. In some areas of the country, paramedics carry and administer oral nifedipine for hypertension despite the mounting evidence against the use of this intervention (6). In a very few jurisdictions, paramedics may be able to give sodium nitroprusside or labetalol intravenously. Generally, paramedics are not taught any principles of blood pressure management for the acute stroke patient.

Glucose

Some EMS systems still advocate routine administration of glucose to patients with altered mental status. Although there are no human trials to verify this, evidence from animal trials suggests that administration of glucose to normoglycemic stroke patients may be detrimental (7,8).

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Where Should We Be?

Knowledge Base

EMT-Basics are unlikely to be much better informed about stroke than the general public. Therefore we need to expand training in accurate identification and emergency management of the acute stroke patient.

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What and How Should EMT-Basics be Taught?

EMT-Basics must learn to recognize the key symptoms of an acute stroke. Studies need to measure the impact of such training on the accuracy of stroke diagnosis by EMT-Basics and paramedics. EMT-Basics should be taught about stroke using the following objectives:

  • To gain a better understanding of the etiology of stroke, including the two major types of stroke and the three conditions that cause blockages.
  • To describe the biochemical sequence of events that occurs during a stroke and to gain insight into why stroke must be treated within the first 3 to 6 hours.
  • To identify the signs and symptoms of stroke and list the common dispatch complaints for stroke.
  • To understand the importance of a TIA.
  • To obtain and interpret the key vital signs in the stroke patient.
  • To determine the time of symptom onset, including asking bystanders when the patient was last at baseline neurological function.
  • To perform a simple physical assessment including testing for aphasia ("The sky is blue in Cincinnati"), facial weakness (show teeth), and motor weakness (pronator and arm drift).
  • To encourage bystanders or family members to accompany the patient to the hospital so they can provide historical information to the treating team and provide support to the patient. If bystanders cannot go to the hospital, EMT-Basics should obtain a telephone number where they can be contacted.
  • To notify receiving hospital about the impending arrival of an acute stroke patient.

Students should practice assessments with an instructor. They should then document their assessment on a large number of patients in the field. Utilization of this type of training program may improve prehospital diagnostic accuracy for stroke.

The real challenge is to integrate this stroke training curriculum into the initial training of the EMT-Basic for which limited time is available. For a variety of reasons, EMT-Basic education is limited to about 110 hours. Therefore, addition of new material, such as identification of acute stroke, will necessitate removal of other material. Deciding what to remove will require additional discussions to gain consensus.

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What and How Should Paramedics be Taught?

Paramedics also need to learn skills for the early identification of the stroke patient. Early notification of the receiving ED is an important part of this process. In addition, paramedics need to have a good understanding of the pathophysiology of stroke including the etiology. They need to be aware of the primary risk factors.

Paramedics also need to learn to recognize hypertension in the stroke patient, and literature needs to be developed to support that knowledge. They need to be made aware that thrombolytic therapy is available in hospitals. Paramedics need to understand the mechanism of action of thrombolytic therapy for stroke as well as the indications and contraindications for that treatment so they can accurately advise the receiving hospital of a potentially treatable patient.

They need to be aware of other, still experimental, therapies that may be useful in the early management of the stroke patient. Therapies such as intraarterial thrombolytics might require that some acute stroke patients be transported to hospitals other than the closest available hospital. The development of neuroprotective agents may permit some therapy to be initiated in the prehospital setting (9,10). However, studies still need to be done to demonstrate that such therapy is safe and effective when given before hospital arrival.

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Patient Evaluation

History-Taking Skills

EMS providers need to be able to solicit adequate information to accurately differentiate stroke symptoms from other neurological or systemic illnesses. Although these are fundamental skills used in treating all patients, additional knowledge and experience is needed to enhance diagnostic impressions and increase clinical accuracy. It is especially important to obtain the time of onset of the neurological symptoms.

Physical Exam Skills

All EMS providers need to know how to perform a quick physical assessment for stroke. They should learn to test for aphasia or dysphasia and unilateral weakness. They must also learn to differentiate other common causes of stroke symptoms such as hypoglycemia and drug or alcohol intoxication.

Mobilization of Emergency Department Response

It is important for ED physicians and nurses to develop trust in EMT-Basics and paramedics who deliver patients to their hospitals. If the EMS personnel are well-trained and accurate when they state a stroke is present, then the ED nurses and physicians will be more likely to act and have the CT scanner ready when the patient arrives.

It is also important, however, to maintain sensitivity over specificity in the identification of cases. If EMTs are missing too many cases of acute stroke, then a significant proportion of the patients who would potentially benefit will not do so. It will remain important to cast a wide net when identifying stroke patients.

Critical Role of CT Scan

Prehospital caregivers need to understand that the CT scan is critical for accurate differentiation between ischemic and hemorrhagic stroke. EMS personnel can help stroke patients get CT scans quickly by notifying the receiving hospital of a potential stroke patient. This strategy will only be effective if EMS providers are integrated into ED stroke team development so that field activities are reinforced by an appropriate ED response.

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Therapy

Airway

EMT-Basics and paramedics should be taught proper management of the airway and attention to brain resuscitation. Much of this skill is already taught in training about head injury. It will be necessary to emphasize that the same principles apply when managing the acute stroke patient.

Hypertension

Paramedics have the knowledge and skills to do close vital sign monitoring. At the present time, there are no outcome data to support the prehospital treatment of increased blood pressure. The only clear indication would be for the treatment of hypertensive crisis, which would require careful assessment and probably the concurrence of an on-line medical control physician. Even in this circumstance, there is no literature to guide selection of an ideal agent.

Most experts in acute stroke management suggest that hypertension should not be treated at all in ischemic stroke (11). Some physicians would treat blood pressures higher than 220/120 in hemorrhagic stroke. Of course before the CT scan is obtained, the cause of the stroke is unknown. Therefore it would be prudent to recommend watchful waiting as the preferred prehospital treatment for hypertension in the stroke patient.

Neuroprotective Agents

As additional information is gathered about neuroprotective agents, these drugs may have a role in the prehospital management of stroke. Clinical trials are ongoing to learn whether or not these agents are effective. If effectiveness is demonstrated, then the time window will need to be defined so that appropriate recommendations can be written about the role of these agents.

Measurement of Dial-to-Drug Time Interval

EMS providers need to document events in the assessment and management of the stroke patient. This record should include time of onset of the event, time the call for help was received, time that the first EMS unit arrived on the scene, and time that transport to the hospital began and ended.

EMS programs and hospitals need to cooperate in order to minimize the time interval from the initial 911 call to administration of therapy. Just as in the management of acute myocardial infarction, continuous measurement of process variables will drive improvements in stroke therapy. Including the time the telephone was Dialed is important in terms of the data set along with the other "D's" of Door, Data, Decision, and Drug. Cognizance of the five D’s will help to make sure that the ED staff have a vested interest in helping EMS improve the emergency management of stroke.

Public Education

An often overlooked component of EMS care is public education. This is true for a wide variety of situations. To varying degrees, most EMS providers offer citizen training in first aid, CPR, and fire and injury prevention. The inclusion of educational materials that help patients recognize and respond quickly and appropriately to stroke symptoms may provide additional major benefit to the community.

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Stroke Protocol: EMT-Basic

Historical Findings

  • Patient has altered mental status, loss of speech, decreased sensation, or loss of motor function without suspected trauma.
  • Patient may have past history of stroke.

Physical Findings

  • Altered mental status. May range from dizziness to confusion to complete unresponsiveness.
  • Speech disturbances—slurred, garbled, or incomprehensible speech or complete loss of speech.
  • Weakness or paralysis on one side of the body.
  • Weakness, paralysis, or loss of expression on one side of the face.

Protocol

  • Take body substance isolation precautions.
  • Maintain airway and administer oxygen at 2 liters/minute unless respiratory distress is present. Be prepared to assist ventilations. If inadequate breathing occurs, proceed with intubation.
  • Place patients with an altered level of consciousness in the left lateral recumbent position with the head and chest elevated.
  • Begin transport as quickly as possible.
  • If available, request ALS backup when the patient:

a. is unresponsive, or

b. has airway compromise.

  • Notify the receiving hospital of the projected time of arrival and report the time of onset of the patient's symptoms.
  • Perform an ongoing assessment.

Notes

  • Patients who experience TIA develop most of the same signs and symptoms as those experiencing a stroke. The signs and symptoms of TIAs can last from minutes up to one day. Thus the patient may initially present with typical signs and symptoms of a stroke, but those findings may progressively resolve. The patient needs to be transported to the hospital for further evaluation.
  • Some patients who have had a stroke may be unable to communicate but can understand what is being said around them.
  • Place the patient's affected or paralyzed extremity in a secure and safe position during patient movement and transport.
  • New therapies for stroke are now available. However, successful use is only possible during a short time window after the start of symptoms. Notifying the receiving hospital promptly and minimizing the scene time are important parts of a strategy to treat patients quickly.

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Stroke Protocol: EMT-Paramedic

If paramedics are available, then the following interventions should be considered:

  • Maintain airway and administer oxygen at 2 liters/minute. Be prepared to assist ventilations. If inadequate breathing occurs, proceed with intubation. If pulse oximetry is available, administer oxygen as needed to maintain oxygen saturation at (at least) 95% but consider hypoventilation as a possible complication.
  • Place patient on a cardiac monitor and document the cardiac rhythm.
  • Establish intravenous access with a saline lock or an intravenous line containing normal saline or lactated Ringer’s solution to run at a keep-open rate.
  • Determine the blood glucose.
  • If blood glucose is less than 80 mg/dl, administer 10-25 grams of 50% dextrose slowly (over a minute or two) by intravenous push.
  • In general, hypertension in stroke patients should not be treated in the prehospital setting. Observations show that hypertension in stroke patients tends to improve without drug therapy.

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Conclusion

Implementation of these recommendations should begin to improve care for the brain attack patient. As additional therapy for stroke is developed, optimal and expeditious prehospital care will help to facilitate effective stroke treatment. Appropriate evaluations should be put in place.

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References

1. The National Institute of Neurological Disorders and Stroke rt-PA Stroke Study Group. Tissue plasminogen activator for acute ischemic stroke. N Engl J Med 1995;333:1581-1587.

2. Kothari R, Barsan W, Brott T, et al. Frequency and accuracy of prehospital diagnosis of acute stroke. Stroke 1996;26:937-941.

3. Barsan WG, Brott TG, Olinger CP, et al. Early treatment for acute ischemic stroke [editorial]. Ann Intern Med 1989;111:449-451.

4. Pepe PE, Mattox KL, Fischer RP, et al. Geographic patterns of urban trauma according to mechanism and severity of injury. Trauma 1990;30:1125-1132.

5. Cummins RO, Ornato JP, Thies W, et al. The American Heart Association Emergency Cardiac Care Committee’s Subcommittee on Advanced Cardiac Life Support. Improving survival from sudden cardiac arrest: The "chain of survival" concept. Circulation 1991;83:1832-1847.

6. Grossman E, Messerli FH, Grodzicki T, et al. Should a moratorium be placed on sublingual nifedipine capsules given for hypertensive emergencies and pseudoemergencies? JAMA 1996;276:1328-1331.

7. Kiers L, Davis SM, Larkins R, et al. Stroke topography and outcome in relation to hyperglycaemia and diabetes. J Neurol Neurosurg Psychiatry 1992;55(4):263-270.

8. de Courten-Myers GM, Kleinholz M, Wagner KR, et al. Fatal strokes in hyperglycemic cats. Stroke 1989;20(12):1707-1715.

9. Aronowski J, Strong R, and Grotta JC. Combined neuroprotection and reperfusion therapy for stroke. Effect of lubeluzole and diaspirin cross-linked hemoglobin in experimental focal ischemia. Stroke 1996;27(9):151-157.

10. Diener HC, Hacke W, Hennerici M, et al. Lubeluzole in acute ischemic stroke. A double-blind, placebo-controlled phase II trial. Lubeluzole International Study Group. Stroke 1996;27(1):76-81.

11. Broderick J, Brott T, Barsan W, et al. Blood pressure during the first minutes of focal cerebral ischemia. Ann Emerg Med 1993

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Table 1. Survey of Some of the Major Textbooks for EMT-Basics

 Title Authors/

Editors

Year copyrighted Information about stroke Total pages
AAOS Emergency Care and Transportation of the Sick and Injured, 6th edition Crosby LA, Lewallen DG 1995 2 sentences 766
The Basic EMT: Comprehensive Prehospital Patient Care McSwain NE, White RD, Paturas JL, Metcalf WR 1997 Not mentioned 824
Mosby's EMT-Basic Textbook Stoy WA 1996 Not mentioned 593
Prehospital Emergency Care, 5th edition Hafen BQ, Karren KJ, Mistovich JJ 1996 8 columns 900

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National Institute of Neurological Disorders and Stroke
National Institutes of Health
Bethesda, MD 20892

Last updated May 17, 2011