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A Mobile Stroke CT Unit Cuts tPA Administration Times By One-Third: Would It Work in the US?

Samson, Kurt

doi: 10.1097/
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THE MOBILE STROKE UNIT, used in Berlin, includes (from left to right) neurologist and emergency physician Dr

THE MOBILE STROKE UNIT, used in Berlin, includes (from left to right) neurologist and emergency physician Dr

The potential benefits and challenges of using a mobile stroke unit, staffed by a neurologist and including a point-of-care laboratory and a telemedicine infrastructure that allows remote image reading, is discussed by stroke experts in the US.

A special ambulance equipped with a CT scanner and manned by a neurologist and a trained CT technician provided tissue plasminogen activator (tPA) to patients with acute ischemic stroke more than 30 minutes earlier than the standard model for transporting patients to the nearest hospital, according to a pilot study conducted in Berlin, Germany.

The Stroke Emergency Mobile Unit (STEMO) provided tPA in a mean time of 62 minutes versus 98 minutes in patients rushed to a hospital in 2010, researchers at the University of Berlin School of Medicine's Charité Center for Stroke Research reported in the Dec. 5 online edition of Neurology.

According to the International Stroke Thrombolysis Registry, only 11 percent of patients treated from 2002 to 2010 received tPA within the first 90 minutes, compared with 48 percent in the study, said lead author Heinrich J. Audebert, MD, professor of neurology.

The Pre-Hospital Acute Neurological Treatment and Optimization of Medical Care in Stroke pilot tested the feasibility of STEMO in a metropolitan area of one million persons. A mobile neurological intensive care vehicle, the ambulance also has a point-of-care laboratory and a telemedicine infrastructure that allows remote image reading, together with a video-conferencing support network.





During the three-month pilot study, 152 patients were treated; 77 were able to give informed consent and 58 percent of them had suffered acute ischemic stroke. Of these, half received tPA, Dr. Audebert said.

The team is recruiting patients for a controlled trial, the results of which should be available next May or June. A smaller German study, published this year in Lancet Neurology, found similar benefits.

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Diagnostic set-up and thrombolytic treatment is feasible in the pre-hospital setting, said Dr. Audebert, and the new approach promises a relevant time saving in call-to-needle times.

In addition to a neurologist and radiology technician with at least 2.5 years of clinical experience and special CT training, the ambulance is also staffed by an emergency paramedic/driver.

Non-contrast brain CT was performed in 83 percent of patients, with 12 percent showing motion artifacts and moderately impaired reading quality in 8 percent. However no technical failures occurred in the vehicle itself, the mobile laboratory, or in any of the other medical instruments except for a single instance of CT dysfunction.

During conventional care in 2010, the mean call-to-door time was 44±13 minutes, while door-to-needle time was 54±22 minutes, resulting in a call-to-needle time of 98±27 minutes and an onset-to-needle time of 146±67 minutes.

In the study, a neurologist established a pre-hospital stroke diagnosis in 56 patients, with 45 confirmed by final in-hospital diagnosis. The mean onset-to-call time was 55 (median 34) minutes, and the mean call-to-needle time was 58 (median 58) minutes.

“It may be time to rethink the way we organize stroke management in general,” Dr. Audebert said.

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While stroke experts interviewed by Neurology Today said that such a service is interesting, they expressed some concerns about its applicability in the United States.

From an equipment standpoint alone, the cost would be prohibitive in most EMS systems, and neurologists are unlikely to be available to staff such an ambulance, said Larry B. Goldstein, MD, professor of neurology and director of the Duke Stroke Center at Duke University Medical Center in Durham, NC. “It would not be possible in rural areas, and the transit time to a close-by hospital in urban areas is generally not excessive,” he added.

Sean I. Savitz, MD, associate professor of neurology, University of Texas Medical School at Houston, said however the ambulance shows how quickly stroke care technology is evolving. “The biggest issue, I think, is the cost of trying to do something similar here,” he told Neurology Today in a telephone interview. “There is a lot of interest in finding philanthropic support for the idea, but remember, this is just one ambulance and we would need many more units. It is hard to envision how something like this could be implemented on a large scale.”

“We are looking more at telemedicine, creating a system so that ambulance personnel could be in contact with a stroke neurologist who would be able to see the patient and guide paramedics through the triage process and determine which patients are actually having a stroke,” Dr. Savitz said. “Once they reached the stroke center, we would then just have to do a CT and start treatment when indicated.”

He also observed that the STEMO ambulance team was unable to get consent from a number of patients, which is also problematic.

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“I think this is a marvelous achievement in feasibility that changes the stroke response paradigm by bringing the hospital to the patient,” said Lee Schwamm, MD, professor and vice-chairman of neurology at Harvard Medical School, and director of acute stroke services and telestroke at Massachusetts General Hospital, who dubbed the procedure “ambulysis.”

But he, too, questioned whether the costs would justify the benefits.

“Is this ready to shift to prime time? This is an open question that will have to wait until the final study results are published. It is not exactly clear yet what added value the approach would offer the public in terms of quicker tPA delivery,” he said.

Without neurologists trained in emergency medicine, telemedicine is more likely to be the approach that will be taken in the US, Dr. Schwamm, who wrote an accompanying editorial, told Neurology Today in a telephone interview.

“Having telemedical capacity in an ambulance could be used anywhere without having to have a neurologist on board. In Berlin, one agency controls location and distribution of ambulances, unlike here, where we have multiple competing ambulance services,” he noted.



“I think it is more likely that telemedicine will enter the ambulance before CT scanners. Telemedicine for stroke is here to stay, and every day we are seeing more hospitals using telemedicine for acute and subacute stroke as well as for consultations with both in- and outpatients. In five years or so we will have videoconferencing so that physicians can be present to guide decisions in ambulances.”

It is also likely that at some time in the future there will be a less complex diagnostic track for stroke patients, with blood tests to help diagnose acute ischemic stroke and more advanced ultrasound technology, he said. The only barrier is a lack of reliable bandwidth, something that will eventually be resolved, he noted.

“Once these happen this is going to take off like a rocket. Bringing advanced diagnostics to the patient will be a reality one day, and we will look back and wonder what took so long.”

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• Weber JE, Audebert HJ, Ebinger M, et al. Pre-hospital thrombolysis in acute stroke: Results of the PHANTOM-S pilot study. Neurology 2012; E-pub Dec. 5.
    • Hacke W, Donnan G, Fieschi C, et al. Association of outcome with early stroke treatment: Pooled analysis of ATLANTIS, ECASS, and NINDS rt-PA stroke trials. Lancet 2004;363:768–774.
      • Walter S, Kostopoulos P, Fassbinder K, et al. Diagnosis and treatment of patients with stroke in a mobile stroke unit versus in hospital: a randomised controlled trial. Lancet Neurol 2012;11:397–404.
        © 2012 American Academy of Neurology