Emergency Medical Services Prehospital Advancements in Stroke Care

Prehospital Advancements in Stroke Care

By Irfan Husain, MD, MPH, Elijah Robinson III, MD, and Reena Underiner, MD, on behalf of the EMS Interest Group

Prehospital stroke care has historically been defined by two goals: early identification and rapid transport to the closest appropriate stroke center. Traditionally, emergency medical services (EMS) agencies would use a validated stroke recognition scale (e.g., CPSS, LAPSS, FAST) to help identify a stroke quickly, limiting time on scene. They would then proceed to transport the patient to the closest stroke center or acute stroke ready hospital (rural setting), while providing prenotification to the receiving hospital. The hospital would then activate the appropriate resources and personnel prior to arrival. However, over the past several years we have seen some interesting new advancements in prehospital stroke management with stroke severity scales for large vessel occlusions and EMS agencies adopting mobile stroke units (MSUs).

LVO Prediction in the Field

Thrombectomy for large vessel occlusion (LVO) has become the standard of care and data has come to support its use up to 24 hours since onset in select patients with LVO. As such, many EMS agencies are now adopting stroke severity scales for LVO to be used in conjunction with the stroke recognition scale to transport

“Regardless of the scale utilized, early identification of large vessel occlusions in the prehospital setting can lead to better clinical outcomes, as transport to either thrombectomy-capable stroke center or comprehensive stroke center can be prioritized, and earlier door-to-balloon times can be achieved.” suspected LVO strokes directly to thrombectomy-capable stroke centers (TSCs) or comprehensive stroke centers (CSC) (both offering thrombectomy). Multiple prehospital stroke severity scales have been developed (e.g., VAN, RACE, C- STAT, FAST-ED, LAMS, NIHSS), with no clear consensus amongst EMS agencies as to which

“To decrease time to tPA administration, EMS agencies are increasingly implementing mobile stroke units (MSUs) — specialized ambulances equipped with the tools and personnel to diagnose and treat acute strokes in the field.”

is best. Several studies have compared the various LVO prediction scales, yet no one scale has been clearly superior. Regardless of the scale utilized, early identification of LVOs in the prehospital setting can lead to better clinical outcomes, as transport to either TSC or CSC can be prioritized, and earlier doorto-balloon times can be achieved.

Mobile Stroke Units

To decrease time to tPA administration, EMS agencies are increasingly implementing mobile stroke units (MSUs) — specialized ambulances equipped with the tools and personnel to diagnose and treat acute strokes in the field. The concept of MSUs originated in Germany in 2008 and has since spread throughout the United States, where there are estimated to be approximately 20 MSU sites. Most MSU sites are in densely populated areas with the exact setup varying agency to agency. For example, in Atlanta, Georgia, Grady EMS has one MSU that contains a CT scanner, thrombolytics, blood pressure medications, anticoagulation reversal agents, and telemedicine capabilities. Its staffing consists of a paramedic, emergency medical technician, registered nurse, and computed tomography technician. Telemedicine capabilities allow access to a neurologist. The BEST-MSU trial has shown MSUs result in faster onset-to-thrombolysis time, particularly in the “golden hour.” The golden hour refers to the first 60 minutes after onset of symptoms in which initiation of thrombolysis is associated with higher rates of excellent early outcome in comparison with later treatment. The trial also demonstrated better functional outcome at 90 days for MSU in comparison to standard EMS care. With MSUs estimated to cost around $1 million U.S. dollars (USD) to purchase and another $1 million USD to operate yearly, cost of MSU programs have been a concern. However, at the 2022 International Stroke Conference, findings using one-year follow-up data from the BEST-MSU trial showed MSU to be cost-effective, in part due to the reduced downstream stroke-related costs.

As we advance in the realm of prehospital care, LVO prediction scales and MSUs are anticipated to become increasingly integrated in prehospital stroke care.

ABOUT THE AUTHORS

Dr. Husain is an assistant professor of emergency medicine at Emory University School of Medicine. He also serves as the associate medical director for Sandy Springs Fire Department and MetroAtlanta Ambulance Service. Dr. Robinson is an assistant professor of emergency medicine at Emory University School of Medicine. Dr. Robinson is the medical director for College Park Fire and Decatur Fire as well as the associate medical director for Grady EMS. Dr. Underiner is a third-year emergency medicine resident at Emory University School of Medicine, Atlanta, Georgia. She is planning to pursue an EMS fellowship. Her career interests include emergency preparedness & disaster response, protocol development, and community violence prevention.