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Stroke management and the impact of mobile stroke treatment units

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ABSTRACTStroke remains the fifth leading cause of death in the United States, despite declining morbidity and mortality rates. Patients who receive timely care provided by mobile stroke treatment unit staffs have dramatically improved outcomes compared with patients who receive initial treatment in an emergency department. Portable imaging technology and wireless communication devices have contributed significantly to shorter time to treatment, which is a key factor in improved outcomes.

KEY POINTS

  • Therapeutic use of tissue plasminogen activators (tPA) has had a major impact on morbidity and mortality rates in patients with acute ischemic strokes.
  • Even a 1-minute delay in time-to-tPA treatment affects morbidity and mortality rates.
  • The major reason patients do not receive tPA is that they do not reach the hospital quickly enough to be assessed and treated within the treatment window.
  • Portable computed tomography and high-speed wireless data transmission are fundamental to the success of mobile stroke treatment units.


 

References

Stroke is the fifth leading cause of death in the United States. Approximately 795,000 strokes occur every year and about 130,000 patients die.1 The impact of stroke-related medical costs and disability is significant, making it a key target for treatment and prevention strategies.

Stroke is defined as an acute loss of neurologic function caused by damaged brain tissue. There are two primary types: ischemic and hemorrhagic. Ischemic strokes are by far the most common, accounting for 87% of all strokes.2 An ischemic stroke is caused by an arterial occlusion that restricts cerebral blood flow; a hemorrhagic stroke is caused by a rupture or leak in the cerebrovasculature. Treatment of an ischemic stroke focuses on thrombolysis and revascularization strategies to restore blood flow, whereas with hemorrhagic stroke, treatment focuses on controlling intracerebral bleeding, elevated intracranial pressure, and secondary brain injury. This article addresses a key factor in improved stroke outcomes—time to treatment—and the impact that a mobile stroke treatment unit (MSTU) can have on this factor.

DECLINING MORBIDITY AND MORTALITY RATES

Although the morbidity and mortality associated with stroke are high, the rates have been declining. From 2001 o 2011, the stroke mortality rate declined by 35%.2 The American Heart Association attributes the reduction to improvements in both prevention and treatment.

A significant portion of the decline has come from population-wide stroke prevention efforts. These include community efforts to control the major cardiovascular risk factors for stroke, including hypertension and hypercholesterolemia. Treating hypertension can reduce the incidence of stroke by up to 40%.3 In addition, community education efforts aimed at improving awareness of stroke symptoms and early detection have contributed to the declining rates, although, by some estimates, only about one-third of the population knows the major signs and symptoms of stroke.

Improved stroke treatments have also contributed to better outcomes, primarily through the more widespread use of thrombolytics. When first approved by the US Food and Drug Administration (FDA), thrombolytics were primarily the purview of cardiologists. However, as outcomes data accumulated, neurologists recognized the utility of thrombolytics in treating ischemic cerebrovascular disease and began investigating their use in clinical trials. Positive outcomes from those trials led to their FDA approval for stroke treatment and universal recognition as the primary therapy for acute stroke. More recent efforts have concentrated on early treatment by bringing the therapy to the patient as opposed to the traditional treatment algorithm of providing care in the emergency department. If therapy is instituted quickly enough, ischemic stroke symptoms can be reversed.

TIME TO TREATMENT

Therapeutic use of tissue plasminogen activators (tPA) has had a major impact on morbidity and mortality in patients with acute ischemic strokes. The efficacy of tPA as thrombolytic therapy in this patient population is well documented.4

Reprinted from The Lancet (Lees KR, et al. The Lancet 2010; 375:1695-1703). Copyright 2010 with permission from Elsevier.

Figure 1. Odds ratio (OR) for favorable outcomes at 3 months in tPA-treated patients versus control. This pooled analysis of three stroke trials shows that the more quickly tPA is administered (stroke onset to time to treatment [OTT]), the better the outcome. CI = confidence interval.

Also well documented is the significant impact of time-to-tPA treatment on outcomes. If therapy is started within 3 to 4.5 hours of ischemic stroke onset, patients have improved functional outcomes 3 to 6 months after the incident (Figure 1). Between 31% and 50% of patients treated with tPA within 3 hours experienced improved recovery at 3 months compared with 20% to 38% of patients treated with placebo.5–9 Faster onset to treatment, measured in 15-minute increments, has been shown to significantly reduce in-hospital mortality, reduce intracranial hemorrhage, increase ability to walk at discharge, and increase number discharged to home.6 Even a 1-minute delay in time-to-tPA treatment has a substantial impact on rates of morbidity and mortality (Table 1).10 National and international guidelines recommend starting intravenous tPA within 1 hour of patient arrival in the emergency department and not longer than 4.5 hours since symptom onset, although some evidence indicates a 3-hour window.5,11,12

Although the evidence supports the benefit of rapid therapy for acute ischemic stroke, the national percentage of patients who actually receive tPA within the therapeutic window is small, by some estimates as low as 3% to 5%.13 For optimal stroke care, the rate should be 30% to 50%.

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