Mobile Stroke Units
Stroke care is extremely time sensitive, hence the quote “time is brain.” This axiom refers to the approximately 2 million neurons that are lost every minute in an ischemic stroke. Over 130,000 deaths in the United States are attributable to strokes, and nearly 87% of yearly strokes in the United States are ischemic strokes. Ischemic strokes occur when a vessel supplying blood to the brain is obstructed. In patients with suspected acute ischemic stroke, immediate brain imaging with computed tomography (CT) is essential to treat and distinguish between a hemorrhage or ischemic lesion. Timely treatment for ischemic stroke patients with intravenous tissue plasminogen activator (rtPA), which is placed through an IV in the arm, dissolving the clot and improving blood flow to the part of the brain that is being deprived, provides substantial clinical improvement. The treatment is very time dependent, there is a 5% decrease in mortality from stroke associated with every 15-minute reduction in door-to-needle times2. A very small proportion of stroke patients receive the early treatment of rtPA in time, as most arrive at the stroke center or hospital too late to receive the therapy.
The incredible imaging capability of CT scanners has truly pushed the medical industry and treatment of stroke patients into staggering heights. Unfortunately, due to the conventionally large size of these scanners, weighing roughly around 4,000 kilograms and requiring high-voltage capacities to function, they have yet to help out in battlefields and ambulance crews rushing to help in emergency situations. Hence the need and great help of mobile stroke units. Further, the standard practice of treating and managing suspected stroke involves transferring the patient via ambulance to a hospital equipped with CT scanners, following with clinical assessment and brain imaging.
A mobile stroke unit, however, brings the hospital to the patient and allows the brain imaging for stroke patients to be completed wherever the patient is located. A mobile stroke unit is an ambulance equipped with a CT scanner, which contains services to diagnose, evaluate and treat symptoms of an acute stroke. It includes standard ambulance medications and equipment, a computed tomography scanner, point-of-care lab equipment, ability for telemedicine and tPA (tissue plasminogen activator.) The telecommunication aspect is crucial to the MSU to obtain valuable guidance from experts in hospitals, it includes real time bidirectional audio and video communication and exchange of videos, CT scans and other important information. In addition to this equipment, there must be the staff of a standard ambulance, a physician in person or through telemedicine and someone that is trained as a CT technologist. It allows doctors to treat these patients with medicine for certain kinds of strokes, for example if appropriate, start the clot-busting treatment tPA in the ambulance while the patient is transferred to the stroke center. It is vital to treat stroke patients as fast as possible to greater their chances of survival and recovering function.
The initial idea of the placement of CT scanners into ambulances was introduced in Germany by Fassbender et al, in 2003 to bring treatment to the patient rather than the patient to the treatment. The first mobile stroke unit implemented in the United States was in 2014, in Houston at the Texas Medical Center complex, and proved to drastically cut down the treatment time for stroke patients. New York’s Presbyterian Hospital became the first on the east coast to field an MSU and had three of them functioning by 2018. As of now, there are approximately 40 MSU units worldwide and the demand continues to grow for this technology3. In urban settings, an MSU is deployed to where the patient is located, and for rural settings an ambulance from the rural area brings the patient toward the closest mobile stroke unit rendezvous site and is transferred to the mobile stroke unit.
The University of Saarland implemented mobile stroke units and found a decrease of 41 minutes from the alert of a stroke to the therapeutic decision made when a mobile stroke unit was used, a following trial found a decrease of 25 minutes to treatment and an increase in the utilization of thrombolysis4. Another study was conducted in Manhattan, New York City between 2016 and 2017, where researchers observed 66 patients with symptoms of stroke who were taken to the hospital by a mobile stroke unit in comparison to 19 suspected stroke patients taken to the hospital in a traditional ambulance. On average, the patients in the mobile stroke unit received care for their stroke half an hour faster. This study was the first to assess the treatments of patients in an area as crowded as New York City.
Before MSU’s were implemented into treatment for stroke patients, only very few patients could be treated within the first hour, known as the “golden hour.” Fewer than 2% of patients were treated with thrombolysis during the golden hour. This term from trauma surgeons, first described the importance of the early period after injury for a patient’s chance of survival. Analysis of American registry showed that treatment of acute stroke within this hour was associated with higher frequencies of discharge to home, and reduced rates of in-hospital complications.
Since the application of mobile stroke units, multiple studies have shown the benefits of the earlier treatment for stroke patients. Stroke care is extremely time sensitive and once a patient arrives at the hospital stroke center, care is streamlined to expedite the stroke treatment, but this doesn’t accelerate the pre-hospital care. Therefore, a mobile stroke unit has the medical expertise and technology to evaluate patients with suspected stroke accurately AND rapidly, it allows to rapidly diagnose the type of stroke that is occurring and what treatment to start with on the way to the hospital care. Although the emphasis for this unit is currently on evaluating and managing strokes, the mobile stroke unit may be used in managing other neurosurgical emergencies in the future. With more and more experience with the mobile stroke units in Europe, North America, Asia and Australia, there is more evidence gathering that the use of mobile stroke units in the care of patients with suspected strokes is remarkably successful.