services markedly increases the proportion of patients treated with thrombolytics [40]. It seems clear that the role of medical helicopter transport as part of regional systems of care is expanding [41].
Innovations in prehospital stroke management
Some regions are trialing the concept of mobile stroke units in an effort to improve the time to tPA or other intervention. A mobile stroke unit ambulance allows for the early administration of tPA in a prehospital setting through the ability to perform the neurologic evaluation and obtain CT imaging in a mobile unit. Most exist in urban areas, though the need for timely stroke evaluation and intervention points to significant potential in rural settings as well. Rural areas may use a rendezvous approach, in which EMS clinicians from a rural site bring the patient toward a stroke center, but meet and transfer care of the patient to the mobile stroke unit along the way. The mobile stroke unit crew often has telemedicine capabilities, linking EMS clinicians to additional resources within the affiliated stroke center [42].
One of the earliest such programs on the east coast of the United States was established by New York Presbyterian Hospital in 2016. This particular mobile stroke unit crew consisted of two paramedics, one radiology technologist, and one vascular neurologist. During the 7‐month pilot, 49 patients were transported, with diagnoses of acute ischemic stroke among 49% of those patients; tPA was administered to 32.6% of the patients transported. This program focused on the complete integration of the affiliated stroke centers’ information systems into a mobile unit, the first of its kind known to do so [43].
In February of 2017, the Edmonton Stroke Program in Canada implemented a rural mobile stroke unit, affiliated with the University of Alberta Hospital in Edmonton. The crew consisted of a stroke fellow, a radiology technologist, a registered nurse, a primary care paramedic, and an advance care paramedic. The unit was dispatched to rendezvous with EMS crews arriving from rural scene calls or rural EDs. The patient was then transferred into the mobile stroke unit for neurologic evaluation and CT imaging; the unit had the ability to administer tPA if appropriate. At last published report, 68 patients had been evaluated and 17 (25%) received tPA. An additional 28 patients were transferred to the stroke center for further evaluation [42].
Initial experiences indicate that mobile stroke units, in the settings in which they have been deployed, result in earlier administration of tPA. No increased additional risk of complicating ICH has been noted. It remains difficult to determine the long‐term clinical outcome benefit, primarily due to the small patient numbers in most studies. Interest in broadening the use of mobile stroke units continues, including the introduction of CT angiography and perfusion, as well as the treatment of other neurological emergencies. Additionally, with advancements in telemedicine technologies, the ability to transition mobile stroke unit staffing to paramedics may also exist [42].
Emphasis is growing on endovascular thrombectomy for patients with LVO strokes. Current evaluations are focusing on the direct transport of select patients to thrombectomy‐capable and comprehensive stroke centers. However, although bypassing a closer primary stroke center reduces the time to potential thrombectomy, it may also delay the administration of IV thrombolytics. If there is a paucity of stroke centers capable of performing thrombectomy in a given geographical area, EMS transport times may be prolonged when using a bypass strategy. In addition, the optimal stroke scale for EMS identification of LVO stroke patients who may benefit from direct transport to a thrombectomy‐capable center needs additional research. Recent investigation suggests that patients with suspected LVO stroke may benefit from being redirected to a comprehensive stroke center if additional transport time is <30 minutes in urban areas and <50 min in rural settings. Additional research is needed to define the acceptable time delay in administration of IV thrombolytics for these patients when bypassing closer primary stroke centers [44].
Disparities
Studies have shown disparities related to socioeconomic status and stroke patient outcomes. Varying results have been found regarding the probability of ambulance use, prehospital priority levels, prehospital stroke recognition, and generalized prehospital delays. A study conducted in Sweden attempted to ascertain whether prehospital stroke care differs with respect to socioeconomic status. The study looked at multiple factors, including ambulance use, prioritization, and prehospital recognition of stroke. The study included patients who received stroke care at a larger hospital system over an approximate 2‐year time span and who had been transported by ambulance. A neighborhood‐level socioeconomic status was used, defined by the average income and education level for each postal code number in the hospital system catchment area. This study found those stroke patients with a lower socioeconomic status had prolonged prehospital delays, lower probability of receiving the appropriate highest priority level in the ambulance, and a stroke diagnosis that was less likely to be recognized by prehospital clinicians. The median system delay, defined as time from emergency call by patient or bystander until start time of brain CT, was 30 minutes longer in those patients with lower socioeconomic status. Socioeconomic disparities in health care are well‐documented. This particular study points specifically to inequities concerning prehospital care. A delay of 30 minutes could prove significant for the availability and effectiveness of time‐sensitive treatment options [45].
Summary
Stroke represents a profound public health problem with potentially devastating effects. EMS plays important roles in addressing these. Engagement in public education is vital so that community members recognize stroke signs and symptoms promptly and activate the EMS system. Optimal interrogation of 9‐1‐1 callers leads to identification of potential stroke patients and appropriate prioritization of the EMS response. EMS clinicians should be well indoctrinated in the evaluation of potential stroke patients, including application of screening tools and suspicion for mimics. They must understand the regional stroke system in which they serve so they facilitate optimal definitive care by delivering patients to the most appropriate facility in the most expeditious manner. Stroke was once an illness that prompted a “wait and see” approach but is no more. It demands the attention of EMS leaders and researchers in close collaboration with health care system partners.
Acknowledgments
We acknowledge Todd Crocco, MD, Allison Tadros, MD, and Stephen M. Davis, MPA, MSW for their contributions as authors of this chapter in prior editions of this book.
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