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Mobile Stroke Units Get Their First US Test Drive

Time is brain. It’s a familiar refrain in the stroke care profession. That’s because approximately 1.9 million brain cells die every minute during a stroke. But what if there were a way to save a stroke victim as many as 780 million brain cells just by delivering faster care? Mobile stroke units (MSUs) have the potential to do that, as one German study found. Now, stroke care providers in two US markets get a chance to save time—and brain cells—with mobile stroke units of their own.

Providers Struggle to Get More Patients on tPA
Although the mortality rate for stroke has declined in the last decade, it remains the leading cause of disability in the US, with 40% of stroke survivors suffering major functional deficits at discharge. This ongoing burden contributes to billions of dollars in supportive and ongoing care, not to mention the cost of lost productivity.

Stroke care providers have greatly improved the quality of acute stroke care by focusing on accelerating patients’ access to thrombolytic therapy or tPA (tissue plasminogen activator). tPA is a drug that breaks down the blockage in an ischemic stroke, restoring blood flow, which helps reduce not only mortality and morbidity rates but also the functional impairments caused by stroke.

Stroke centers have driven major reductions in “door-to-needle times” (the key metric measuring time to tPA treatment) by reworking stroke care paths and engaging EMS teams who can initiate stroke team activation. As a result, many stroke centers’ tPA use rates exceed 10%. Nationally, however, we are just approaching 5%. So why the mismatch? Why, with all the research and advances in acute stroke care, can’t we get more patients treated with tPA, save more lives and reduce the rate of disability?

Much of the challenge is due to geography. Strokes don’t always occur in areas with timely access to stroke care and only 35% of Americans live near a designated stroke center.

Mobile Stroke Units Help Break the Geography Barrier
In 2011, researchers with the University of Saarland in Homburg, Germany, placed a mobile CT scanner in an ambulance creating a mobile stroke unit and then initiated clinical trials to evaluate the time to treatment decision making. The program served patients in both urban and rural settings around the university.

The published findings, which appeared in The Lancet Neurology in 2012, were remarkable in demonstrating accelerated access. The time from alarm (911 call) to making a therapy decision was reduced by over half (35 minutes vs 71 minutes in the control group).

In February 2014, the first MSU program to open in the US was at the University of Texas Medical School at Houston (UTHealth) and the Memorial Hermann-Texas Medical Center (TMC), and a second opened shortly thereafter at the Cleveland Clinic.

The Houston program is a clinical trial to determine if the German time savings can be repeated in the US, if a neurologist teleconsult can be as accurate at making treatment decisions as a neurologist on board, and the impact of the program on functional and long-term financial outcomes.

The program is run in collaboration with Houston Fire Department-EMS, Houston Methodist Hospital and St Luke’s Medical Center in Houston. The MSU was designed by a Houston-based company, Frazer Ltd, that builds emergency vehicles. The company started from scratch with a standard 12-foot ambulance, making modifications to include a CereTom CT scanner on a mobile track, a mobile telemedicine system and a slightly larger generator to keep the CT cool in the Houston summer. Total cost of the unit was around $600,000. Equipment and operating costs for the first two years have been covered by philanthropic support.

Currently the unit, along with a neurologist, nurse, CT tech and paramedic who make up the team, is being deployed two to four times daily in conjunction with a standard EMS unit. The MSU is activated by a 911 call. The noncontrast CT performed on the scene is quickly read by the neurologist and a treatment decision is made. tPA treatment is initiated in the field for appropriate patients.

While originally designed to cover a 3-mile radius, the trial geography has already expanded. Early on they found they could easily cover more geography. Officially, the trial covers patients within a 15-minute radius, but patients outside the geographic perimeter are not excluded. The MSU can meet other ambulances on their way into the medical center to get the assessment team and technology to the patient sooner. James C Grotta, MD, director of stroke research in the Clinical Institute for Research and Innovation at Memorial Hermann-TMC and director of the mobile stroke unit consortium, estimates that in the Houston metropolitan area, four to five MSUs, strategically stationed throughout the market, would be needed to cover the population fully.

Only patients eligible for tPA are being transported by the unit, about four per week. Although still early in the trial, about half of transported patients are being treated with tPA in the unit and over 60% are being treated within the first 80 minutes of their stroke compared to less than 1% with standard management. The trial is expected to take nearly four years to complete.

MSUs Create Shift in Stroke Care Paradigm
While there are still many questions about the best way to operate mobile stroke units in urban and rural markets, their entry into the stroke care pathway could create some major changes in local market dynamics and how we think about stroke care overall.
New time points in the care continuum. Door-to-needle time will take a backseat to “alarm-to-needle time” and “onset-to-needle time” as key metrics in evaluating efficient and effective processes for stroke care. Stroke care providers should begin planning for capturing additional time points along the stroke care continuum such as time the patient was last known to be well, time of the 911 call and time of EMS response.
New care paths. Length of stay in the ED will significantly decline as more stroke patients transfer directly from the MSU to the stroke unit or neuro-ICU upon arrival. Developing care paths that specifically cover patients arriving via a mobile stroke unit will be an essential component of planning for adoption.
Elevated role of EMS teams. EMS providers will increasingly become a full part of the stroke response team, elevating their role in many markets. In anticipation of MSU adoption, organizations should work to strengthen relationships with EMS leadership across their market.
Stronger EMS partnerships. EMS controls most ambulance routing. Where delivery of stroke patients to designated stroke centers is not dictated by state regulations, organizations will need to effectively partner with EMS teams and demonstrate superior quality to be the preferred destination for stroke patients.

Taking stroke care to the patient doesn’t solve all the access issues we have in stroke care today, but it is well positioned to be a major solution to the geography barrier. Stroke care providers and the communities they serve will still need to focus on public education, increasing the community’s knowledge about stroke signs and symptoms, and the importance of calling 911.

The time to focus on all aspects of stroke care is now: Sg2’s Impact of Change® forecast projects that ischemic stroke admissions will increase by 13% over the next 10 years. Sg2 can help your organization evaluate its stroke care pathway, beginning with our door-to-needle performance guide, case studies, and neurosciences analytics and forecasts. Contact us for more details.

Sources: Sg2 Interview With UTHealth and Memorial Hermann-Texas Medical Center, October 2014; Miller D. Stroke: Time is brain in delivering EMS care. EMS1.com. March 22, 2012; Phend C. EMS triage to stroke centers doubles tPA use. MedPageToday. July 2, 2013; Walter S et al. Lancet Neurol. 2012;11:397–404; Hughes S. PHANTOM-S: Mobile stroke unit reduces time to tPA. Medscape. May 30, 2013; Zeltner B. Cleveland Clinic to launch mobile stroke unit, bringing the ER to stroke patients in Cleveland. Cleveland.com. May 31, 2014; Sg2 Analysis, 2014. All websites accessed October 2014.

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