Mobile Stroke Units Bring the Hospital to the Home

Lucky woman, Maureen Osaka. 

Her stroke was an especially rare and lethal type, a basilar artery occlusion. Those have a mortality rate of more than 85%. Their survivors are often left paralyzed or severely disabled.

But Osaka, born in Nigeria and a world traveler doing philanthropic work, happened to be in Houston when her stroke occurred in 2014. Even better, she was within a few miles of Texas Medical Center, new home to the country’s first mobile stroke unit.

A quick call to 9-1-1 when her symptoms began brought that unit to Osaka, and its crew—a paramedic, neurologist, critical-care nurse and CT technician—initiated a level of care at her home that was previously unknown in America’s prehospital realm.

She got a CT scan in the ambulance courtesy of a CereTom portable scanner. Confirming her stroke was ischemic, the crew performed some quick point-of-care lab testing, then began treating Osaka on scene with intravenous tPA (tissue plasminogen activator), the only treatment for such strokes approved by the FDA. The stuff works, but only within three hours of symptom onset, and the faster, the better. With that accomplished the crew set out for the local comprehensive stroke center.

Once upon a time those critical interventions would have had to wait until a stroke victim reached the hospital, even as two million brain cells a minute died. Bringing them to the patient earlier in the process saves essential time—which means, in stroke, essential brain.

For Osaka it saved both: She received treatment about 78 minutes after symptom onset, faster than 99% of stroke patients. And within days she was moving her affected left side, speaking clearly and walking on her own. “In just one day,” Osaka told media reps from the University of Texas Health Science Center at Houston (UTHealth), which fields the unit, “I went from not being able to speak to speaking but no one could understand me to now speaking and pronouncing things perfectly. Before the end of that same day, I could also move my hand again. It was like a dream! I could even stand up and walk!”¹

A Broad Range of Solutions

Mobile stroke units began in Germany almost a decade ago but have only recently come to the U.S. UTHealth’s was first (see page 33), but others have quickly followed. The Cleveland Clinic rolled its out soon after in 2014.
More started the next year in Toledo and Colorado. Another that debuted this year in Memphis raises the bar with a hospital-grade Siemens SOMATOM Scope scanner and CT angiography imaging of the brain and blood vessels.

These things aren’t cheap, and that systems are investing in them underscores the difficulty we’ve had helping stroke victims in the timely way they need. To that end, mobile stroke units could represent a big advance.

“Historically strokes have had to be identified in the field and brought to the hospital for a CAT scan,” says Andrei Alexandrov, MD, chair of the neurology department at the University of Tennessee Health Science Center and medical director for the Memphis project. “Only recently have the CAT scanners become mobile. So placing one on the ambulance essentially allows the door-to-needle time to become the time from the field to the door of the ambulance. This can shorten the time from symptom onset to treatment and in turn result in more patients recovering from stroke. It’s a very exciting opportunity.”

Indeed it is—the cost of strokes is terrible. They’re the fourth-leading cause of death in the U.S., and a top cause of disability. Around 800,000 Americans a year have them, to a price tag of about $38 billion.

The ischemic variety accounts for 87%, and while ischemic strokes are quite treatable with tPA, that needs to happen within a limited time window. All kind of obstacles work against that, from delays in recognition and calling 9-1-1 to prolonged scene and ED times and times to getting patients scanned and treated.

Mainly because of such delays, just 3%–8.5% of American patients who are eligible for tPA get it. More than 40% should.² So anything we can do to get it to them faster should benefit them—right?

That would seem to be the case with mobile stroke units (MSUs). Because they’re so new, there’s not yet a huge volume of data amassed, but what there is has been positive: 

• A 2014 JAMA writeup of the German PHANTOM-S study reported alarm-to-treatment times averaged 15 minutes faster during weeks when a stroke vehicle (STEMO) was available, and patients for whom it was deployed had a mean alarm-to-treatment time 25 minutes shorter than during control weeks. Thrombolysis rates were 21% during control weeks, 29% during STEMO weeks and 33% after STEMO deployment.³

• A 2012 Lancet report found that prehospital stroke treatment reduced the median alarm-to-therapy-decision time from 76 minutes to 35. A team led by Silke Walter, MD, of Germany’s University Hospital of the Saarland discovered similar gains in intervals from alarm to CT completion, alarm to end of laboratory analysis, and to the overall rate of IV thrombolysis for eligible ischemic stroke patients.⁴ 

• A preliminary 2010 piece by most of the same authors used case studies to show the “feasibility of guideline-adherent, etiology-specific and causal treatment of acute stroke directly at the emergency site.” One of those patients had a hemorrhagic stroke; she received guideline-based differential blood pressure management. Both patients had call-to-therapy-decision times of approximately 35 minutes and good outcomes. 

The cases, Walter and company concluded then, “illustrate the broad range of medical solutions made available by use of the MSU. The MSU…encompasses all major aspects of prehospital stroke medicine, such as prehospital organization of bridging to intra-arterial recanalization, prehospital inquiry regarding the need for surgical or other intervention with hospital experts via telemedicine, guideline-adherent and etiology-specific prehospital management of physiological variables (i.e., blood pressure), and prehospital decision-making about the target hospital (e.g., a more distant hospital with stroke unit, neurosurgery or neuroradiology vs. a closer hospital without those resources).”⁵

Note the second benefit there of getting the patient who may need more than tPA to a destination that can deliver it. Conversely, those with minor strokes can be identified and treated at primary stroke centers, leaving comprehensive stroke centers free for the more severe ones.

The Telemedicine Option

The Cleveland Clinic’s system includes one comprehensive and eight primary stroke/stroke-ready centers. But across that system a few years ago, just 15% of eligible patients were arriving in time for tPA. 

The MSU is an attempt to change that. Clinic staffers traveled to Germany to observe its programs and talk to leaders, local EMS and vehicle manufacturers. “We tried to gather as many ideas as we could,” says Peter Rasmussen, MD, director of the Clinic’s Cerebrovascular Center and its medical director for distance health, “and just hone in on those that worked best for our particular location and facilities.”

Funding, as it did in Houston, came from private sources. Excellance built the unit, which includes a mobile scanner and POC lab testing capabilities. As in Houston, dispatch occurs alongside EMS, which can call the MSU off if a stroke isn’t the case. 

When it came to staffing, though, the Clevelanders changed course: Where the German and Houston projects included neurologists on their MSUs, Cleveland chose telemedicine to link patient to physician.

The reasoning: Vascular neurologists are a scarce resource, and serving on mobile units isn’t the optimal use of their time. 

“We didn’t think that was a very cost-effective model,” says Rasmussen. “We now have good technology that does reliable, HIPAA-compliant telemedicine interactions in a portable fashion, coupled with good availability of 4G broadband wireless connectivity. Germany initially experimented with telemedicine, and the reason it didn’t work is that they didn’t have the broadband capabilities that exist here in the United States.”

Instead the Cleveland MSU is staffed by a paramedic, critical care nurse, CT technologist and EMT driver. CT scans from the unit are obtained in a minute or two and sent to Clinic neuroradiologists, who confirm the stroke and its type. Neurologists can videoconference and monitor symptoms in real time during transport. 

The telemedicine alternative was evaluated by Akron neurologist Ahmed Itrat, MD, and colleagues in a recent JAMA Neurology article; they reported a median duration of telemedicine evaluation of 20 minutes, and found times from the door to CT completion (13 minutes) and door to IV thrombolysis (32 minutes) were significantly shorter in the MSU group versus a control group (18 and 58 minutes, respectively). 

Cleveland’s data thus far is promising. Door-to-drug times are averaging about 20–30 minutes faster for MSU patients, and 9-1-1-activation-to-drug times about 40 minutes faster. And overall, around 40% of MSU patients are getting tPA—many within that first “platinum hour,” when it works best—compared to 12%–18% across the system’s EDs. 

“Roughly what we’ve found,” says Rasmussen, “is that almost any aspect of care that’s delivered in an emergency room in our healthcare system is delivered equally as good if not better on the mobile stroke unit.” 

CT Angiography 

In Memphis stroke incidence beats the national average by 37%. Its MSU is the first in the southeastern “stroke belt” and billed as the most comprehensive in the world. 

That’s largely due the CT angiography of which it’s capable. The SOMATOM scanner has an automated gantry that moves the patient and provides as many slices (pictures) as can be obtained in the hospital. This allows visualization of blood vessels and the ability to identify patients who need endovascular interventions, neurosurgery and neurocritical care from the field. 

These capabilities make the Tennessee unit the mobile equivalent of the ER at any primary stroke center. 

“Imagine if you are able to both give IV tPA, as any primary stroke center does, and quickly identify the patient with emergent large-vessel occlusion,” says Alexandrov. “Then you can bypass the nearest primary stroke center and go directly to the comprehensive stroke center. And then bypass the emergency room and bring the patient directly to the cath lab. The CT angiography images can be sent directly to the endovascular suite, so the interventionist can see what kind of occlusion they will be dealing with when we bring the patient in.” 

The Memphis truck was funded through a public-private collaboration that raised more than $3 million to run it for three years. Built by Medical Coaches, it will be based in the city’s most stroke-heavy area but available throughout the metro region. 

When it came to staffing, UTHSC chose a middle ground between doc and box, using fellowship-trained, doctorally prepared nurses certified as advanced neurovascular practitioners.

“We wanted to explore the presence of a fellowship-trained nurse practitioner just because we want to understand all the nuances of the paramedics’ work and how we can best integrate mobile technologies and treatment capabilities into it,” says Alexandrov. “The United States has the advantage of several hospitals and stroke teams and cities that have fellowship-trained nurse practitioners.”

In anticipation of an eventual switch to teleneurology and teleradiology, project leaders plan to run connectivity tests throughout the city and ensure there are no dead spots. (Cleveland did the same to ensure broadband reliability.)

The main goal of the Memphis project is to treat as many patients as possible in the first 60 minutes after symptom onset; leaders will also track 90-day functional outcomes. That’s something they expect to interest the payers who will, if the MSU is successful, have to sustain it beyond its initial three years. 

“We are looking to address this issue with Medicare,” says Alexandrov. “To make progress here, we need Medicare and third-party payers to recognize that this can be a cost-effective and lifesaving approach.” 

‘Quite a Surprise’

Down in Houston they’re already incorporating lessons from the first two years of their MSU, including switching to the telemedicine option. But as far as data, try this: Forty-two percent of the patients being treated by the UTHealth MSU are being treated within the first hour of their symptoms. In the control group, that number is zero. 

“What we can hopefully say we know,” says David Persse, MD, Houston’s EMS physician director and public health authority, “is that way more patients are being treated within the first hour of their symptoms with a mobile stroke unit than among those who go by ambulance to the hospital.” 

That’s particularly exciting in light of another finding observed in Cleveland and elsewhere: “What we’re seeing is that when patients are given tPA early on, particularly within that platinum hour, even the most severe type of ischemic strokes, like carotid artery occlusions, frequently open up,” says Rasmussen. “That was very surprising to both our neurointerventionalists and stroke neurologists. We really hadn’t seen that before—it was quite a surprise.”

Challenges remain in all these systems. Politics have reared their head in more than one, with stroke centers vying for patients and a playing field they feel equitable. The optimal blend of staffing and technology 
has yet to be worked out. Supporting data still needs built. MSUs may be better turned over to the local EMS or fire department than operated through other entities. 

And of course there’s funding. Operating an MSU with a critical care nurse, CT tech, paramedic and EMT could cost up to a million year.⁷ Units so far generally aren’t operating 24/7 or covering whole cities. Costs 
and benefits have to be balanced. “These vehicles are so specialized; it’s not like we can use it as a regular ambulance while we’re waiting for strokes,” notes Persse.

An early projection in Houston calculated the total fixed and continuing costs for operating their MSU for five years at almost $1.5 million, and concluded it would be cost-neutral if it resulted in seven additional patients completely recovering over five years.⁸

The Cleveland Clinic project is roughly breaking even, Rasmussen says, “but it likely is saving the healthcare system overall in terms of longitudinal care.” Its truck is at about half capacity serving roughly 550,000 people. Fewer than that wouldn’t be profitable.

All that considered, though, the promise held by mobile stroke units seems undeniable. And if and as they’re proven successful, they could even serve as a care model for other time-critical conditions.

“I think one way of looking at this truck,” says Rasmussen, “is perhaps as an entree to the larger concept of treating time-critical diagnoses. Perhaps trucks someday get converted over to be coresponders with traditional EMS to things like an accident or burn or suspected MI. All these things can begin to be treated at the scene. Maybe the mobile stroke unit is really just the beginning of the mobile time-critical diagnosis response unit.” 

References

1. Red Duke Trauma Institute—Memorial Hermann. Nation’s First Mobile Stroke Unit Successfully Transports First Patient, https://trauma.memorialhermann.org/life-flight/nations-first-mobile-stroke-unit-transports-first-patient/. 

2. Cleveland Clinic. Mobile Stroke Unit, https://my.clevelandclinic.org/services/neurological_institute/cerebrovascular-center/treatment-services/mobile-stroke-unit. 

3. Ebinger M, Winter B, Wendt M, et al., for the STEMI Consortium. Effect of the Use of Ambulance-Based Thrombolysis on Time to Thrombolysis in Acute Ischemic Stroke: A Randomized Clinical Trial. JAMA, 2014, Apr 23–30; 311(16): 1,622–31. 

4. Walter S, Kostopoulos P, Haass A, et al. Diagnosis and treatment of patients with stroke in a mobile stroke unit versus in hospital: a randomised controlled trial. Lancet, 2012 May; 11(5): 397–404.

5. Walter S, Kostpopoulos P, Haass A, et al. Bringing the Hospital to the Patient: First Treatment of Stroke Patients at the Emergency Site. PLoS One, 2010 Oct; 5(10): 1–5. 

6. Itrat A, Taqui A, Cerejo R, et al. Telemedicine in Prehospital Stroke Evaluation and Thrombolysis: Taking Stroke Treatment to the Doorstep. JAMA Neurol, 2016; 73(2): 162–8. 

7. Zeltner B. Cleveland Clinic to launch mobile stroke unit, bringing the ER to stroke patients in Cleveland. Cleveland.com, https://www.cleveland.com/healthfit/index.ssf/2014/05/cleveland_clinic_to_launch_mob.html. 

8. Persse D. Delivering Acute Stroke Therapy in the Pre-Hospital Environment in Houston, Texas, U.S.A. Presentation at the 2016 EMS State of the Sciences Conference, https://gatheringofeagles.us/2016/2016presentations/Friday/PerssePrehospitalStrokeTherapy.pdf.