Meta menu:

From here, you can access the Emergencies page, Contact Us page, Accessibility Settings, Language Selection, and Search page.

Open Menu

Stroke Einsatz Mobil (STEMO) and STEMO research: Phantom-S and B_PROUD

You are here:

The Stroke-Einsatz-Mobil (STEMO) was designed specifically for the care of stroke patients. To identify possible strokes, the staff of the fire brigade uses a query algorithm developed for this purpose. If a stroke is suspected and a STEMO is available, they send one of these specialized ambulances to the patient. Thanks to the CT and laboratory diagnostics in the vehicle, the team can rule out a cerebral hemorrhage directly on site and treat an ischemic stroke using systemic thrombolysis. In a STEMO patients can thus receive prehospital care. This increases their chances of suffering little or no permanent damage from the stroke. The crew of a STEMO includes a neurologist qualified as an emergency physician, a radiology assistant and a paramedic. A neuroradiologist can be called in via telemedicine to evaluate the CT images.

The Berlin STEMOs

Interior of a STEMO
Interior of a STEMO

The Stroke-Einsatz-Mobil, "STEMO" for short, was developed together with the Berlin Fire Brigade and the company MEYTEC and was dispatched for the first time in February 2011. The development is based on a concept by Professor Klaus Faßbender, head of the Department of Neurology at Saarland University Hospital, who established the first Stroke Mobile in Homburg in 2008.

After successful testing of the Berlin STEMO, the second STEMO generation followed in 2017 with four new vehicles. In addition to the Charité – Universitätsmedizin Berlin, Unfallkrankenhaus Berlin and Vivantes Klinikum Neukölln each operate another STEMO today. The fourth ambulance is available as a replacement if one of the regular vehicles is out of order due to maintenance, technical inspection, or repair. The STEMOs are in operation seven days a week from 07:00 a.m. to 11:00 p.m. in almost the entire urban area of Berlin.

Mobile Stroke Units (MSUs for short) are now in operation or in the planning stages at almost 30 locations worldwide. In Norway and Australia, helicopters are also used to rescue stroke patients. An overview of the projects is provided by the international consortium of MSU operators PRESTO.

Scientific evaluations of STEMO care

PHANTOM-S: The Pre-Hospital Acute Neurological Therapy and Optimization of Medical Care in Stroke Patients - Study

From 2011 to 2013, the Phantom-S study investigated the extent to which STEMO care is safe and effective for patients. Among other things, the focus was on evaluating process times, for example, the time interval from emergency call receipt to lysis treatment. In addition, it was analyzed whether patients who were eligible for lysis could be treated more frequently with lysis therapy due to the use of the STEMO.

During the Phantom-S study, STEMOs were alternately used for one week and not used for one week for organizational reasons. During the weeks when it was not available, patients were cared for by the conventional ambulance service despite the "STEMO alert". These patients served as the control group in PHANTOM-S. A total of 6,182 patients were included in the study.

B_PROUD - Berlin PRehospital Or Usual Delivery of Acute Stroke Care

In the first evaluation phase of B_PROUD, the study team examined the effects of STEMO care on long-term treatment outcomes from February 2017 to May 2019. A standardized query using the "modified Rankin Scale" (mRS) and the use of the EQ-5D questionnaire to assess quality of life determined the extent to which patients were still suffering from limitations three months after stroke.  

During the study period, initially one, later two and three STEMOs were used. The division into treatment and control groups was based on the availability of STEMOs: If the fire department was able to dispatch a STEMO to patients with suspected stroke, they were assigned to the treatment group. If no STEMO was available - for example, because they were already in use - patients were cared for by conventional means and assigned to the control group. A total of 1,543 patients participated in the B_PROUD study.

B_PROUD provided direct evidence for the first time that patients sustainably benefit from the care provided by a Mobile Stroke Unit. The BEST-MSU study, for which scientists led by James Grotta from the University of Texas investigated the effects of various MSUs deployed in US cities, came to a very similar conclusion.

B_PROUD 2.0 - Berlin PRehospital Or Usual Delivery of Acute Stroke Care 2.0

B_PROUD 2.0 currently looks at patients who met study criteria from May 2019 to January 2021 and were cared for either by the three Berlin STEMOs or (if the STEMOs were unavailable) by the regular ambulance service. This allows the effects of care to be considered on an even broader data base and the effects of changes in deployment strategies and process flows to be examined. Analysis of the results is currently pending due to the need for blinded adjudication.

Summary of previous research findings from the B_PROUD and Phantom-S studies

Effects of STEMO care versus conventional care were demonstrated by Phantom-S and B_PROUD 1.0:

  1. Less time lost until lysis: Time from emergency call to start of treatment can be reduced by 20 (B_PROUD) to 25 (Phantom-S) minutes.
  2. More patients receive lysis therapy, many already within the first hour after symptom onset: In B_PROUD, a good 60 percent of patients in the STEMO group received lysis, and almost 13 percent could be treated within the first hour, the "golden" first hour, after symptom onset. In the control group, 48 percent of patients received lysis at the hospital, and 4 percent received lysis in the first 60 minutes.
  3. Better prognosis for patients with STEMO care: B_PROUD 1.0 showed that patients with STEMO care had less overall impairment at three months than patients who received conventional care. If a STEMO was dispatched, about 7 percent of patients died, compared to about 9 percent with conventional ambulance care. At the same time, around 51 percent of patients in the STEMO group reported that they had not suffered any restrictions in their daily lives as a result of their stroke. In the control group, this figure was around 42 percent. The STEMO group also performed significantly better in the quality of life survey.
  4. No gain of treatment time for thrombectomies: Owing to early diagnosis and the ability to transport patients to the appropriate hospital with pinpoint accuracy, STEMO use has the potential to accelerate the time to endovascular intervention. If CT and CTA examinations are performed in STEMO, the images can be sent directly to the hospital's neurosurgical team and the procedure can be prepared. However, the results of B_PROUD 1.0 show that this could not yet be implemented frequently in practice. Thrombectomies even occurred with a slight delay compared to conventional care. Without STEMO use, the endovascular procedure was performed after a mean of 125 minutes, with STEMO after 136 minutes.

STEMO as a research platform: Further studies on the STEMO

Neurologists on the STEMO see stroke patients much earlier than colleagues in the clinic. This makes STEMO an ideal research platform when it comes to developing innovative diagnostic procedures or therapies for acute, very early strokes.

Four projects at the Center for Stroke Research Berlin (CSB) Berlin are currently aiming in this direction:

  • "ProGrEss-Bio": Can strokes be diagnosed and differentiated using biomarkers?
  • "ULTRAFAST": Can CT be replaced by a much smaller automated diagnostic tool?
  • "FASTEST": Can patients with hemorrhagic stroke be helped by administration of Recombinant Activated Factor VII within the first two hours after symptom onset?
  • "LVOCheck": Is it possible to detect a large vessel occlusion via blood test?


Emergency physicians and neurologists

  • Dr. med. Joachim Weber, Head of STEMO Headquarters)
  • Dr. med. Martina Zuber
  • Marc Schehadat
  • PD Dr. med. Dorothee Kübler-Weller
  • Fulvio Bondi

Operators and paramedics

  • Olaf Müller
  • Jan Hildebrandt
  • Team of the Berlin Fire Brigade

Radiography assistants

  • Louisa Fiona Schröter
  • Maren Lorenz
  • Lisa Haacke
  • Cay-Robin Hasse
  • Jenny Sulejmanov

Cooperations and research partners

Steering Committee B_PROUD 2.0

  • Prof. Heinrich A. Audebert, MD (Project Manager)
  • Prof. Martin Ebinger, MD, PhD (Deputy Project Manager)
  • Prof. Matthias Endres, MD (Scientific Advisor)
  • Prof. Christian Nolte, MD (Scientific Advisor)
  • Ira Napierkowski, PhD (Study Monitor)
  • Irina Lorenz-Meyer (Study Monitor)

Further Members B_PROUD 2.0

  • Annegret Hille, PhD (Study Assistant, Data Manager)