Mobile stroke units: improved outcomes for ischemic stroke

If someone is having a stroke, you call an ambulance. But getting to the hospital can be time-consuming. To prevent long-term disabilities and death, patients need to be treated as quickly as possible. According to a recent study by the Charité - Universitätsmedizin Berlin, mobile stroke units play a key role in this setting.

In an interview with MEDICA.de, Prof. Heinrich Audebert talks about reason, approach and aim of the study on mobile stroke units, the advantages of these special ambulances and gives recommendations of acute stroke care for physicians, emergency services and hospitals.

Prof. Audebert, you carried out a study on acute care in mobile stroke units and presented the research findings at the International Stroke Conference (ISC) in Los Angeles. What prompted this study?

Prof. Heinrich Audebert: The sooner you can start thrombolysis, also known as thrombolytic therapy, to treat and dissolve dangerous clots in blood vessels, the more effective the outcome will be for the stroke patient. Mobile stroke units are specialized ambulances equipped with a built-in CT scanner to obtain on-the-spot imaging to check for cerebral hemorrhage and diagnose stroke. Patients can then be immediately started on thrombolytic therapy long before they arrive at the hospital. Previous studies have shown that treatment in mobile stroke units is safe and saves between 20 to 30 minutes. Although stroke registry comparisons have already suggested that this also results in an improvement in patient outcomes in terms of preventing long-term disability, there had been insufficient evidence up to this point. The study we presented in Los Angeles is the first to research this clinical question in a controlled study.

What was your approach?

Audebert: Right now, Berlin has three mobile stroke units, also called STroke Emergency MObile (STEMO). In the study, the availability of STEMO units determined the assignment to the treatment and control group, respectively. This included patients with abrupt interruption of constant blood flow to the brain, ischemic stroke, who were suspected of having had a stroke at the time of the emergency call and who exhibited loss of neurological function when the emergency medical services arrived. Patients with contraindications in which thrombolytic therapy and mechanical thrombectomy should not be used because it may be harmful to the person were excluded from the study. The so-called modified Rankin Scale (mRS) was used as the primary clinical outcome measure after three months as a scale for measuring the degree of disability. The scale has possible scores ranging from 0 indicating "no neurological symptoms at all" to 6 meaning "dead".

What was the objective of the study?

Audebert: The study investigated whether the use of STEMO units in Berlin results in an improved functional outcome after acute cerebral ischemia.

What equipment is on board the mobile stroke units and which medical personnel ride along in these specialized ambulances?

Audebert: Besides the computer tomograph and a CT scan to reveal the structure of the vascular system, called CT angiogram, the STEMO units are also equipped with a mini-laboratory and the typical equipment found in an ambulance vehicle. In addition to a neurologist trained in emergency medicine, the unit is always accompanied by a specially trained medical care assistant. A neuroradiologist is included via teleradiology to assist with stroke patients.

How do mobile stroke units provide acute care for stroke patients?

Audebert: The emergency communications center dispatches a STEMO unit to the patient’s location if the responder suspects acute stroke was indicated during the call. Apart from the routine emergency examination, patients also undergo a neurological examination, a head CT and a coagulation panel to test for blood clots on site. With massive strokes, CT angiography is added to detect large-artery occlusion in the head area. The patient’s arrival is announced to the hospital for preparation, while the patient is already receiving ongoing thrombolytic treatment in the ambulance. The hospital performs a thrombectomy, a catheter-based procedure to remove blood clots.

What are some remaining challenges of stroke management?

Audebert: The latest study provides clear evidence that prehospital initiation of thrombolytic therapy improves clinical outcomes in treated patients. Future challenges include: improved emergency dispatcher identification of acute stroke and development of more compact and cost-effective stroke diagnostic devices.

What are the guidelines and recommendations the German Stroke Association issues for physicians, emergency services and hospitals?

Audebert: The German Stroke Association suggests increasing the use of these specialized ambulances in dense urban areas as the incidence of stroke is very high in these settings, thus warranting the frequent use of STEMO units. The Association also recommends an evaluation of mobile stroke unit deployment in suburban and rural areas and housing developments because when stroke strikes, every minute’s delay of treatment counts.