December 12-13, 1996
Dispatch Life Support and the Acute Stroke Patient: Making the Right Call
Brian S. Zachariah, M.D., F.A.C.E.P.
University of Texas-Southwestern Medical Center, Dallas
James Dunford, M.D.
University of California, San Diego Medical Center
Carl C. Van Cott
North Carolina Office of Emergency Medical Services, Raleigh
Modern emergency medical services (EMS) priority dispatch systems have evolved from rudimentary call-screening programs to much more sophisticated dispatch centers. Staffed by emergency medical dispatchers (EMDs), these centers often include enhanced 911 emergency telephone systems that identify automatically the telephone number and address of the calling party. They also often include medically appropriate protocols and prearrival instructions, computer-assisted dispatch of vehicles, and automatic vehicle locator systems.
Many sophisticated EMS systems are no longer content to send the same kind of equipment, with red lights and sirens (running "hot"), to every call regardless of the nature of the emergency. The goal of the modern dispatch center is "to send the right things to the right people at the right time in the right way and to do the right thing until help arrives" (1).
Such centers are capable of meeting that goal with a high degree of accuracy. Curka et al (2) demonstrated that their computerized dispatch center could correctly identify the prehospital patient requiring advanced life-support interventions 97% of the time. It seems reasonable, therefore, that EMS priority dispatch systems would have much to offer the patient experiencing an acute stroke. Indeed, stroke scales and other instruments do exist that can identify the prehospital patient likely to be having an acute stroke (3). These scales, however, are designed to be used by EMS personnel at the patient's side. Such scales could be converted to dispatch protocols. However, the ease and usefulness of such adaptations remain to be seen.
In fact, while there are some areas of promise, there are also many unresolved issues and there are many questions that must be addressed before dispatch systems can send the right things at the right time to the patient having an acute stroke. Some of these issues are reviewed in this discussion.
For any EMS dispatch system to have a positive impact on the care of the stroke patient, callers must first understand their role and the importance of early recognition of stroke symptoms. Patients and their families or friends may recognize hemiparesis, aphasia, visual problems, or even sensory losses as symptoms of a stroke. However, denial or a lack of understanding or awareness of stroke symptoms may result in a failure to activate 911 or failure to seek care in a timely fashion.
It is even less likely that 911 will be called for the patient with a posterior circulation stroke presenting only as vertigo, nystagmus, or vomiting. Clearly, further public education is needed regarding the signs, symptoms, and new treatment options for acute stroke.
Even well-motivated and well-educated patients may not receive the maximum benefits of 911 dispatch life support if access to care is difficult or delayed. As of March 1996, approximately 15% of the population of the United States was still using a seven-digit telephone number to call for medical assistance (4). Even communities served by a basic 911 emergency telephone system may not have the advantages of an enhanced 911 system. The automatic identification features of these systems can be very useful for the aphasic stroke patient who is unable to communicate with the EMD. Once 911 has been activated, not all EMS agencies utilize trained EMDs or are equipped with medically approved dispatch protocols and prearrival instructions (2).
In some states and regions, managed care initiatives have led to the development of Resource Management Centers and other mechanisms to prevent patients from accessing 911 before they have been screened by a representative of their payor. Cost-effective medical care is a goal for all patients, including those suffering an acute stroke. However, it is neither cost-effective nor medically sound to deny or delay care for the stroke victim. All emergency triage decisions regarding potential stroke victims are best made using written protocols, under medical supervision, by the EMD. Patients found to be at low risk for an acute stroke or other medical emergency can then be referred to their managed care provider.
Even professional, certified EMDs require increased awareness regarding the importance of rapidly recognizing and responding to an acute stroke victim. Standard dispatch texts appear to emphasize that there is no specific prehospital care that will alter the course of a patient's stroke. They do not present stroke as a priority unless the patient presents with an altered level of consciousness or respiratory distress (5). It is logical that the medical and dispatch communities should themselves take stroke more seriously before they can ask the same of the general public.
The evolving designation of a stroke as a brain attack, in terms of its being analogous to a heart attack, has helped both the medical community and the public at large take this entity more seriously. However, the best dispatch protocol and response modes for most EMS systems are unlikely to be the same as those implemented for a myocardial infarction. Instead, prehospital management of the stroke patient ideally should be more similar to the care of the trauma patient.
The challenge and goal is to rapidly and properly identify the patient at risk for an acute stroke and then rapidly transport that patient to an appropriate facility. Proper selection and advanced notification of the receiving facility is also of paramount importance. Unlike the heart attack or cardiac arrest victim, at the present time prehospital interventions have little impact on the stroke victim's course. Similar to the care of the trauma victim, prehospital providers can have a profound influence on the patient's outcome by reducing the time required to deliver the patient to definitive care. Indeed, most of the prehospital benefit comes from the ability of the dispatch center to rapidly identify the stroke victim, to quickly send a transport unit, and to get the patient to a facility capable of performing an emergent CT and delivering appropriate treatment as rapidly as possible.
On-line medical control (overseeing physicians in communication via phone or radio) and/or the dispatch center may also have an important role in identifying and notifying appropriate receiving facilities. In addition, they can relay information for inbound ambulances and quickly notify the receiving facility about important information such as the time of onset of symptoms, medications taken, and estimated arrival time of the stroke patient.
Few of the currently available dispatch algorithms are capable of meeting the goal of rapid and accurate identification of the acute stroke victim. As mentioned, most dispatch algorithms give acute stroke a low priority unless the patient has an altered mental status or is in respiratory distress. The patient with a normal level of consciousness but a new hemiplegia, who may be more likely to benefit from aggressive therapy, is given a low priority. New dispatch algorithms that acknowledge the evolving science of stroke recognition and management must be developed with appropriate medical oversight. Because the recent evidence demonstrates that stroke is a time-critical entity, dispatch protocols should strive for the earliest delivery of the patient to an appropriate facility. Medical control physicians should also guide current decision-making regarding dispatch levels. Nevertheless, it must be qualified that upgrading stroke responses to a higher priority or using warning lights and sirens is intuitive, but not necessarily proved as efficacious. We still need to explore whether such modalities explicitly improve patient outcome or time to definitive care.
Priority dispatch systems are often used with tiered EMS systems to select from among a variety of response modes (2). Many EMS systems can choose to send advanced life-support (ALS) or basic life-support (BLS) ambulances, hot or cold, with or without first responders, supervisors, and even physicians. The exact configuration sent to a stroke victim will depend on the needs and resources of each community as well as the needs of the particular patient. However, the configuration(s) chosen should reflect the current understanding of the importance of rapid transport to a CT scanner and the relative ineffectiveness of prehospital interventions. In many cases, a BLS ambulance with a shorter transport time may be preferable to an ALS ambulance, even though the latter may offer improved assessment and monitoring capabilities en route.
With current training, EMDs are able to identify the stroke victim only 51% of the time (6). A prehospital stroke scale, capable of identifying patients at risk for acute stroke, has been described (3). This scale utilizes information gathered by responding EMS personnel once they arrive at the patient's side, rather than information gathered by the EMD or call-taker. Such a scale potentially could be modified or developed for dispatcher use. There may also be a role for another medic-derived scale, used in conjunction with traditional dispatch information, to facilitate rapid transport and treatment for stroke patients once they have been identified.
Finally, many dispatch centers offer prearrival instructions for such emergencies as childbirth, seizures, and cardiac arrest. Beginning treatment even before the arrival of the field providers is one of the hallmarks of modern dispatch life support. As might be expected, current prearrival instructions for stroke victims are centered around protecting the airway or alleviating respiratory distress. No prearrival instructions are usually available for the majority of stroke patients without such severe symptoms (5). Interventions such as elevating the head of the bed to decrease intracranial pressure or placing the patient in the left lateral decubitus position to minimize aspiration risk may be helpful. Still, it is unclear what interventions, if any, bystanders should be instructed to perform to aid the stroke victim prior to the arrival of EMS. Gathering of medications can be useful as is early identification of certain historical data (such as diabetes, recent head trauma, etc.).
Intuitively, the well-trained and well-equipped EMD certainly can play a valuable role in the care of the stroke patient. However, there still remain many unresolved issues and unanswered questions concerning how best to optimize this role. Summary recommendations regarding these issues can be found in Table 1. While awaiting the necessary further study and implementation of these recommendations, the best way to improve dispatch life support for the stroke patient is to improve public understanding of stroke symptoms and treatment options. In addition, we must ensure access to, availability of, and education for EMDs and EMS providers alike.
1. 9-1-1: Rapid Identification and Treatment of Acute Myocardial Infarction. National Heart Attack Alert Program (NHAAP). US Department of Health and Human Services, National Institutes of Health, Bethesda, MD, NIH Publication No. 94-3302, May 1994.
2. Curka PA, Pepe PE, Ginger VF, et al. Emergency medical services priority dispatch. Ann Emerg Med 1993;22:1688-1695.
3. Kothari R, Hall K, Broderick J, et al. Early stroke identification: A prehospital stroke scale. Stroke 1996;27:171
4. 1996 Addendum to Rapid Identification and Treatment of Acute Myocardial Infarction. National Heart Attack Alert Program (NHAAP). US Department of Health and Human Services, National Institutes of Health, Bethesda, MD.
5. Clawson J, and Dernocoeur K. Principles of Emergency Medical Dispatch. Englewood Cliffs, NJ: Brady (Prentice Hall); 1988.
6. Kothari R. Frequency and accuracy of prehospital diagnosis of acute stroke. Stroke 1995;26:937-941.
Table 1. Summary Recommendations Regarding Dispatch Life Support and Care of the Stroke Patient
|Public education should be provided on early identification of and rapid action for stroke victims. The public should also be educated on when and how to call for assistance.|
|911 should be universally available and access to 911 should not be restricted by payor organizations. Automatic "enhanced" features should be included in emergency telephone reporting systems.|
|EMS dispatchers should be medically supervised and properly trained and equipped. Even for trained and certified EMDs more training on stroke recognition and the importance of early identification and treatment is needed.|
|Further study is required, but if there are prearrival instructions or procedures that the EMD can provide, they should be made widely available.|
|Under proper medical oversight, dispatch protocols should be developed that recognize an acute stroke as a medical emergency. Appropriate EMS resources for the stroke patient must be identified and dispatched in an expeditious fashion.|
|Dispatch and/or medical control should ensure that patients suspected of having an acute stroke are transported to an appropriate facility. They should also ensure that the receiving facility is informed of key information, such as estimated time of patient arrival and the time of symptom onset, so that treatment can be initiated without delay.|
Return to Table of Contents
National Institute of Neurological Disorders and Stroke
National Institutes of Health
Bethesda, MD 20892
Last Modified May 17, 2011