EXECUTIVE SUMMARY

Now well-established throughout Europe, mobile stroke unit (MSU) programs are in the early stages of development in the United States. The concept aims to improve outcomes by bringing diagnostic capabilities and clot-busting care to the patients experiencing stroke, thereby reducing the time to treatment. In October, New York Presbyterian/Weill Cornell Medical Center in New York became the first medical center on the East Coast to deploy an MSU, and in July, the University of Tennessee College of Medicine in Memphis deployed a first-of-its-kind MSU that is larger and more robust than other MSUs currently in use.

  • In the first month of operation, the MSU in New York responded to 29 calls and brought 12 patients to the hospital with suspected strokes. Two of these patients received tissue plasminogen activator in the field and both made full recoveries by the next day.
  • The MSU deployed in Memphis is larger and carries more sophisticated diagnostic equipment than other MSUs. The program also relies on doctorally prepared, vascular neurology fellowship-trained nurse practitioners, instead of relying on telemedicine connections to external experts.
  • Now operating with the assistance of grant funding, leaders of both programs hope that strong outcomes will prove convincing to hospitals and payers, although the U.S. healthcare model complicates the establishment of a reimbursement structure for MSUs.

Everyone knows that shortening the time to treatment is key to improving outcomes in stroke patients. However, some experts believe that continued progress in this area requires a bold approach and new thinking on how care can be delivered optimally. For example, a number of medical centers are experimenting with the use of mobile stroke units (MSU), ambulance-like vehicles that are equipped with the necessary technology and expertise to bring brain-saving treatment to the patient.

Although the units are deployed in several states, including Texas, Ohio, Colorado, Tennessee, and New York, investigators at these pioneering sites are experimenting with all the different parameters, everything from how, when, and where the units should be deployed to how the MSUs should interface ideally with hospitals and EDs. Further, some sites are experimenting with larger, more robust units equipped with the technology to perform more sophisticated diagnostics and potentially more care delivery in the prehospital environment.

Cut Through Red Tape

In October 2016, New York Presbyterian/Weill Cornell Medical Center in New York became the first medical center on the East Coast to deploy an MSU. It’s a project that Matthew Fink, MD, the neurologist-in-chief of the Division of Stroke and Critical Care Neurology at the hospital, has been championing since 2013.

“The very first ambulance like this was developed in Hamburg, Germany, in 2003,” Fink explains. “I heard about it on my trips there and was very intrigued because the European model of emergency medical service is different than the American model. In Europe, doctors often go out on the ambulances and they do more treatment in the field than we do.”

With good results observed in Europe from use of the MSUs, Fink concluded that his center should offer this capability.

“We have worked very hard to initiate treatment of stroke as fast as possible, and we have done very well, but we have come to the point where we have done it as fast as we possibly can when patients [are brought] to the ED,” he says. “The only way we can do it even faster is to do it in the field.”

Initially, stakeholders were hesitant to approve the project because of all the rules, regulations, and bureaucracy, but Fink persisted in pushing the concept.

“I was convinced that this was really the next phase in treating patients with acute stroke because if we could cut down the time to treatment, it was going to result in saving lives and increasing the number of people making a full recovery,” Fink notes. “To me, that was a really important goal.”

The turning point came in 2015 when a hospital board member bought into the MSU approach, convinced others on the merits of the idea, and offered to underwrite the project. “Then we were off and running,” Fink adds.

However, Fink notes that building the MSU and getting all the physicians on board with the innovation was the easy part. Much more difficult was the process of working through all the regulatory agencies and receiving appropriate approvals from both the state and the city.

“We had to integrate [the MSU approach] with the 911 EMS fire department system, which runs all of the ambulances in New York City,” Fink explains. “We have the largest EMS system in the country.”

Integrate with EMS

With all the approvals finally in hand, the MSU began deploying on Oct. 3, 2016, in what is phase one of the project. During this period, a neurologist is on board the MSU along with two paramedics and a CT technologist. Also on board is a portable CT scanner that can image a patient’s brain to determine if the patient is suffering a stroke.

When someone calls 911, the dispatcher will ask a few questions based on the Cincinnati Prehospital Stroke Scale. If the answers suggest that the probability of stroke is high, then the dispatcher will send both a basic life support unit and the MSU to the scene.

“We also monitor all the radio chatter on the EMS radio channel so if we hear of a case that we are not called for but we think it sounds like a stroke, then we will dispatch the stroke unit ourselves,” Fink explains. “We have what is called a roaming license, which means that we can really go to any call that we think is appropriate.”

If the patient on the scene is suffering a stroke, and is an appropriate candidate for clot-busting medication, he or she can receive this treatment before transport to the hospital, potentially restoring blood flow to the brain quickly. The MSU will take the patient to the closest appropriate hospital.

If it is determined that the patient is not experiencing a stroke, then the traditional ambulance will take over the care and transport of the patient. (See also in this issue: “The Puzzle of Financing Effective Stroke Care")

Prepare Receiving Hospitals

Although there is only one MSU, it serves two different geographic areas on a rotating basis: two weeks on the Upper East Side of Manhattan, which generally is served by New York Presbyterian’s Cornell campus, and two weeks in the Washington Heights and Inwood areas of upper Manhattan, which are served primarily by the hospital’s Columbia campus.

“We are actually going to be able to look at two different demographic groups: a higher-income, white, elderly population, and a lower-income, younger, Dominican population,” Fink explains. “During the times when the ambulance is not operating in a particular area, we are collecting data from regular ambulance arrivals to compare.”

There is only one hospital in upper Manhattan neighborhoods, so all patients in that region treated in the MSU will be taken to New York Presbyterian’s Columbia campus. However, there are three hospitals on the Upper East Side of Manhattan, all of which are capable of providing advanced care, so the MSU will take patients to the closest appropriate facility, according to Fink.

“We have talked with the emergency physicians at all the hospitals and geared them up,” he says. “I have given a number of talks to them, so they are ready to accept patients.”

In the first month of operation, the MSU made 29 calls, and brought 12 patients back to the hospital with suspected strokes.

“Two of these patients were given tPA [tissue plasminogen activator] in the field ... and both of these patients made full recoveries by the next day,” Fink observes. “One patient was treated within 55 minutes of the onset of symptoms, which is the fastest time we have on record in our hospital.”

Fink also notes that one patient was diagnosed with a primary brain hemorrhage.

“That is diagnosed on the CT scan,” he says. “That patient had an extremely high blood pressure [BP] of 250/150, and we brought that BP down immediately in the field with very strong medicines, which are almost never given to a patient until he or she gets to hospital.”

Fink adds that treating high BP in the field has the potential to improve outcomes in patients with a brain hemorrhage because it will reduce the growth and expansion of the hemorrhage. Further, he notes that while the CT scanner on board the MSU is capable of conducting CT angiography in the ambulance, the team has decided not to take that step because it would delay transport to the hospital.

“While you are doing the scan, the [MSU] cannot be moving. It has to be stationary, so you have to stop and do the scan,” he explains. “To do angiography would probably add 15 minutes before we could get back to the hospital, so we don’t want to delay that.”

Other neuroprotective agents in development also can reduce damage from strokes.

“The hope is that as these agents become available for clinical trials, we will use them in the field and not wait for the patient to get to the hospital,” Fink says. “Opportunities arise and new discoveries are made that we never even anticipate, but we think we are ready to apply those treatments as they become available.”

Beginning in March or April 2017, when phase two of the project kicks in, the MSU approach will shift to a telemedicine-based model whereby the neurologist will not travel with the MSU but rather will view the assessment of the patient in real time through a wireless broadband cell network.

“We are building a command center in the hospital, which will have big screen video monitors and a monitoring system so that a nurse or a physician assistant [PA] who is out on the MSU will examine the patient while we observe through a high-resolution televideo system,” Fink explains. “We will be able to ask questions, and we can actually do the exam ourselves remotely. We can look at the CT brain images and then make decisions about what to treat and how to treat, so that is going to be the next step.”

Consider Size, Staffing

The MSU deployed by the University of Tennessee College of Medicine in Memphis is different than all the other units currently in use in terms of its size and capabilities. For instance, this MSU weighs 14 tons and occupies a larger footprint to accommodate trainees and researchers working in the field of stroke management. Additionally, this MSU is equipped with a more powerful CT scanner that can provide very high-resolution brain and vascular imaging in less than four minutes, explains Anne Alexandrov, PhD, RN, CCRN, ANVP-BC, NVRN-BC, FAAN, a professor of nursing at UT Memphis and the chief nurse practitioner on the MSU.

“We do a non-contrast CT scan and CT angiography of the head and neck blood vessels using a scanner that is better than most that are traditionally used in hospitals,” she says, noting that most other MSUs rely on portable CT scanners that do not image the entire brain or blood vessels. “They have to repeat imaging once they get to the hospital, whereas we do not.”

Another innovation, according to Alexandrov, involves how the MSU is staffed.

“The big manpower difference is our use of doctorally prepared, vascular neurology fellowship-trained nurse practitioners, instead of having to rely on telemedicine connections to external experts,” she says. “This results in faster treatment decision-making. Our median scene arrival to tPA bolus time is 16 minutes — about 10 minutes faster than other programs.”

The MSU, which began responding to calls in the Memphis region in mid-July 2016, is staffed by an EMT (who also is the driver of the unit), a paramedic, an advanced practice provider, and a CT technician. The unit can be deployed in two different ways: via a 911 dispatcher or another first-responding unit that has determined a patient may be exhibiting symptoms of a stroke, explains Wendy Dusenbury, DNP, APRN, FNP-BC, CNRN, ANVP-BC, one of the nurse practitioners working on the MSU and an assistant professor of nursing at Wichita State University in Wichita, KS.

“That EMS unit could then call us out,” she says. “We don’t usually show up on the scene by ourselves. There is generally another EMS unit involved, and most of the time we are not the first to arrive because of geographic location. Usually, the 911 dispatcher will send an EMS unit that is closer to the patient first.”

Fine-tune Connections, Transitions

For cases in which it appears that a patient is experiencing a stroke, the MSU team will put the patient on a gurney, bring him or her to the MSU, and prepare for imaging studies.

“From there, it will be determined whether the patient is having an ischemic stroke, and whether the patient is a candidate for tPA,” Dusenbury explains. “If it is a [hemorrhagic stroke], then we do what we can to help decrease the risk of devastation by controlling the patient’s BP and then take him or her to the hospital.”

A neurologist always makes the decision to treat. The neurologist makes his or her decision in consultation with the nurse practitioners who have assessed the patient on board the MSU. The MSU is not equipped with telestroke capabilities yet, although Dusenbury anticipates that it will at some point, enabling the CT pictures to be transmitted to the remote neurologist, if needed.

The MSU will take patients to one of three stroke centers in the region, depending on which hospital is the shortest distance away.

“Many times, we have the stroke team at the hospital there waiting for us because we call ahead,” Dusenbury explains. “If it looks like the patient has a large vessel occlusion, many times the interventionists are right there so they can see the scans. We take the scans inside the hospital with us and put them into their system so they can see them.”

Dusenbury adds that these are early days, so the MSU team is working with the hospitals in the region to figure out the best way of integrating with the emergency staff so that patient transitions are smooth and effective.

“We are working to develop really good relationships with everyone,” she says. “When the patients get to the ED, the scans have already been done, and if the patients are appropriate candidates for tPA, they are already treated and are ready for the next level of care.”

For example, patients who need no interventional therapy might be directed to a stroke unit or an ICU, Dusenbury observes.

“The MSU helps the ED as far as time and resources because a big majority of the workload is done,” she says.

Further, Dusenbury anticipates that there will be additional streamlining of the process in the days ahead.

“What I have noticed is that every time I have gone to work on the unit, it has gotten better,” she says. “You can see that everyone involved is getting with the flow and can see what the capabilities are. At first, people didn’t realize what those capabilities were.”

Educate First Responders

In cases in which the MSU has been dispatched but providers quickly determine that the patient is not experiencing a stroke, the EMS unit that has been dispatched along with the MSU typically will take over care of that patient.

“Our general rule is if we put the patient into our MSU and we scan them, then we will take them to the hospital, but if it is obviously not a stroke ... then we will send those patients with the other EMS teams,” Dusenbury notes. “There is only one MSU and we don’t want to put ourselves out of service for someone who really needs it.”

Even in these cases, the MSU team tries to educate the other first responding teams about what the MSU can do to help stroke patients, Dusenbury says. In fact, she notes that one case in particular that was handled by Alexandrov has attracted attention in the local media.

“A lady suddenly started to experience symptoms of stroke, and her daughter called 911,” she says. “The woman had visual deficits, she was completely flaccid on one side of her body, and she couldn’t speak.”

The MSU responded, recognized it was a stroke, and the door-to-drug time in that case was just eight minutes, Dusenbury recalls.

“She got tPA, we got her to the hospital, and the outcome was total recovery,” she says. “The woman left the hospital with an NIH stroke score of zero or no deficit, which is miraculous.”

It is no secret why UT Memphis was interested in pioneering the MSU. The region’s stroke rate is 37% higher than the national average. The MSU team hopes to demonstrate that this new approach can reduce morbidity and mortality to stroke over the next three years. Investigators believe they will have the evidence they need to prove the metrics of the approach once the MSU has evaluated and treated 300 patients.

Initially, the unit is operating every other week, but Dusenbury anticipates that it will be running every week before long, with investigators capturing data and tracking outcomes. Further, the different MSU teams operating around the country are comparing notes as well.

“This is going to evolve over time until we all figure out what are the best protocols and procedures to use,” Fink observes. “We all share this information. It is a very collaborative group that is working together on this.”

SOURCES

  • Anne Alexandrov, PhD, RN, CCRN, ANVP-BC, NVRN-BC, FAAN, Professor of Nursing, University of Tennessee; Chief Nurse Practitioner, Mobile Stroke Unit, Memphis, TN. Email: aalexa33@uthsc.edu.
  • Wendy Dusenbury, DNP, APRN, FNP-BC, CNRN, ANVP-BC, Nurse Practitioner, Mobile Stroke Unit, University of Tennessee College of Medicine, Memphis, TN; Assistant Professor of Nursing, Wichita State University, Wichita, KS. Email: wendy.dusenbury@wichita.edu.
  • Matthew Fink, MD, Neurologist-in-Chief, Division of Stroke and Critical Care Neurology, New York Presbyterian/Weill Cornell Medical Center, New York. Email: mfink@med.cornell.edu.