“Mobile Stroke Unit” for Hyperacute Stroke Treatment
To the Editor:
Ischemic stroke is a major cause of death and of permanent severe functional deficits in the developed countries. In most cases this disease is caused by obstruction of the cerebral blood vessels, ie, by emboli originating from the heart or large brain-supplying blood vessels. Experimental studies show that within minutes after vascular obstruction, cell death occurs in the core of the focal ischemic brain tissue. In the region around this core (penumbra), cells exhibit a compromised metabolism but might be rescued by adequate therapies.1
At present, the only acute treatment for acute stroke that has been shown to be effective and that has been approved in most Western countries is thrombolysis of the obstructing emboli by recombinant tissue plasminogen activator (rtPA).2 However, even in centers specialized for stroke <5% of the stroke patients are treated by thrombolysis. One explanation for this may be that most patients arrive at the hospital after the temporal window of 3 hours for the use of rtPA.3–5⇓⇓ Even this arbitrarily set temporal window might still be too large as indicated by pathophysiological knowledge1 and clinical observations.6–8⇓⇓ Much better outcomes can be expected if treatment would start within 1 hour. Thus, the major problem of acute stroke treatment is the unacceptable delay between onset of cerebral ischemia and therapeutic restoration of the cerebral blood flow.
Since thrombolysis for ischemic stroke can only be performed after exclusion of possible hemorrhage, computed tomography (CT) is the major time-determining factor in stroke management. Usually only larger centers can provide this service (24 hours a day), and important time is lost by carrying patients to the CT at such centers. In order to reduce time to therapeutic intervention, we propose a hypothetical “mobile stroke unit” for hyperacute stroke treatment complementary to a stationary stroke unit already in use in many countries. Such a mobile stroke unit Figurea) would be a vehicle (eg, a Mercedes Vario) carrying both conventional emergency equipment and all relevant diagnostic tools necessary for a decision for or against thrombolysis directly at the place where the patient is found. Such a device implies several technical innovations, such as an integrated small CT scanner (Figure 1a) with an operation console (Figure 1b) and an energy supply. The vehicle has to be shielded by a 2-mm lead layer against radiation produced by the CT (Figure 1c). On the other side this vehicle has to be within normal limits of dimension in order not to compromise mobility. Although relatively small, lightweight (<650 kg), cooling system-independent, and accumulator-driven CTs are already available to be used in this mobile stroke unit (eg, Tomoscan M, Figure 1a), it can be expected that much smaller CT specialized for brain imaging can be developed in future. As shown in Figure 1b, we suggest that the console for operation is placed at the front part of the car, well isolated from the radiation. To save space, a metal-free stretcher should be used as a CT table (Figure 1d). Optionally, a small laboratory unit for basal blood analysis (ie, coagulation parameters) and a system to transmit CT data to radiologists at the hospital could be included, according to currently discussed concepts of point-of-care laboratory medicine or telemedicine, respectively.
Bringing treatment to the patient rather than the patient to the treatment, enabled by the mobile stroke unit, could save precious time lost by transport to and within the hospital. Thrombolysis in <1 hour could become a reality for many patients. The effectiveness of such a mobile stroke unit, however, depends on the presence of well-trained professionals and on the location of its use. It is likely to be more effective in rural areas than in large cities with a high density of hospitals with a 24-hour CT service.
According to the “time is brain” concept, the mobile stroke unit proposed here might offer a novel solution. By reducing the delay between the onset of cerebral ischemia and therapeutic decision, use of the mobile stroke unit can rescue brain tissue from ischemic damage, thereby reducing individual suffering and life-long cost. The additional costs incurred by the use of a mobile stroke during the few first few hours of disease will be outweighed by cost savings in care of these patients for years or decades.
Please direct correspondence to Prof Fassbender.
- ↵Jorgensen HS, Nakayama H, Reith J, Raaschou HO, Olsen TS. Factors delaying hospital admission in acute stroke: the Copenhagen stroke study. Neurology. 1996; 47: 383–387.
- ↵Wester P, Radberg J, Lundgren B, Peltonen M. Factors associated with delayed admission to hospital and in-hospital delays in acute stroke and TIA. Stroke. 1999; 30: 40–48.
- ↵Donnan G, Davis SM, Chambers BR, Gates PC, Hankey GJ, McNeill JJ, et al. Streptokinase in acute ischaemic stroke: does time of therapy administration affect outcome? JAMA. 1996; 271: 961–966.
- ↵Marler JR, Tilley BC, Lu M, Brott TG, Lyden PC, Grotta JC, et al. Early stroke treatment associated with better outcome: the NINDS rt-PA Stroke Study. Neurology. 2000; 55: 1649–1655.