Prevention and Treatment of Stroke

Prehospital and emergency department management of ischemic stroke

Prehospital management is critically important to increasing the survival rates of stroke patients. This phase starts with the emergency medical services (EMS) call and continues in the hospital emergency department (ED) ( Table 30.1 ). Many ischemic stroke patients do not reach the hospital soon enough, owing to lack of local services and facilities, and for social reasons. When a stroke is first suspected, the patient should be rapidly transported to an appropriate facility for diagnostic evaluation and treatment initiation. Stroke patients who present within 3 to 4.5 hours or less of symptom onset are eligible for IV thrombolysis. EMS use is strongly associated with a decreased time to initial physician examination, initial CT imaging, and neurological evaluation. The benefits of EMS contact are superior to contacting the family physician or hospital directly, and were confirmed with several studies. Stroke should be given a priority dispatch like myocardial infarction (MI) and trauma. Patients who show signs and symptoms of hyperacute stroke must be treated as time- sensitive emergency cases and transported without delay to the closest institution that provides emergency stroke care. With the demonstration that thrombectomy is a highly effective treatment for patients with proximal, large vessel, intracranial occlusion, patients should be transported to hospitals that perform thrombectomy, as long as bypassing primary stroke centers that only give tissue plasminogen activator (tPA) does not result in an excessive delay. The precise paradigm for primary stroke center bypass remains to be elucidated. One approximation would approve the bypass of a primary stroke center if the delay to reaching a thrombectomy-capable center is 30 minutes or less.

To facilitate this process, medical authorities and media sources should encourage the recognition of stroke signs by providing public education about this condition. All members of the public should be able to recognize and identify the signs and symptoms of stroke. These include sudden localized weakness, difficulty speaking, loss of vision, headache, and dizziness. Patient, family, and caregiver education is an integral part of stroke care that should be addressed at all stages across the continuum of stroke care for both adult and pediatric patients. Currently, thrombolytic treatment with tPA and thrombectomy are the only approved treatment options for AIS. The National Institute of Neurological Disorders and Stroke (NINDS) and Advanced Cardiac Life Support Resources (ACLSR) recommend the possible timing sequences shown in Table 30.2 for the potential recanalization candidate.

Data from the Thomas Lewis Latané (TLL) Temple Foundation Stroke Project controlled trial showed the benefits of educational interventions on stroke identification and management targeting patients, EMS, hospitals, and community physicians. This approach increased thrombolytic use in patients with ischemic stroke from 2.21% to 8.65% compared with communities that did not have such programs, which saw only a 0.06% increase. For patients with ischemic stroke who were eligible for thrombolytic therapy, rates of tPA usage increased from 14% to 52% in intervention communities. Prehospital delays continue to contribute the largest proportion of time to late initiation of therapy.

EMS arrival starts the diagnostic and management process. The EMS crew transfers the patient to a medical center able to provide appropriate diagnostic and treatment modalities to stroke patients. After the ambulance arrives on the scene, EMS providers should obtain a brief history and patient examination, stabilize vital signs, and rapidly transport the patient to the closest, most appropriate facility for either IV thrombolysis or thrombectomy in appropriate patients ( Table 30.3 ). Several prehospital assessment scales have been developed with varying degrees of accuracy to identify acute stroke patients with a likely large vessel occlusion (LVO) because patients with a likely LVO should be transported to a thrombectomy ready center, if the transport time is not unreasonable compared to transport to a primary stroke center. Prehospital evaluation is helpful for ED physicians and the inpatient care team for planning treatment options. Critical medical interventions in the ED should focus on the need for intubation, BP control, and determining risk/benefit for thrombolysis or thrombectomy. General ED stroke care issues are outlined in Table 30.4 .

Acute stroke patients urgently need IV access and cardiac monitoring in the ED, preferably initiated in the transporting ambulance. These patients also are at risk for acute cardiac diseases such as arrhythmias and MI. In addition, atrial fibrillation may be associated with acute stroke as either the etiology (embolic disease) or as a result. Acute stroke patient evaluation in the ED should include a rapid assessment by obtaining a relevant history, physical examination, neurological examination, stroke scale scores (National Institutes of Health Stroke Scale [NIHSS]), and appropriate diagnostic tests ( Box 30.2 ).

Patients presenting with compromised ventilation require emergent airway control via nasal oxygenation or rapid sequence intubation. Adequate tissue oxygenation is important in the management of acute cerebral ischemia to prevent hypoxia and further brain damage. The most common causes of hypoxia in the patient with acute stroke are partial airway obstruction, hypoventilation, atelectasis, or aspiration pneumonia. Oxygen requirements should be monitored with pulse oximetry, with a target oxygen saturation level ≥ 92%. Endotracheal intubation and supplemental nasal oxygen may be used as needed. If brain herniation is present, hyperventilation using mechanical ventilation (to decrease intracranial pressure [ICP]) by decreasing CBF) is recommended. An arterial partial pressure of carbon dioxide (P co ₂ ) of 32 to 36 mm Hg should be targeted. IV mannitol may be considered to reduce increased ICP. Oxygen supplementation should be guided by a pulse oximeter.

Acute stroke therapy

The only AIS pharmacotherapy currently approved by the US Food and Drug Administration (FDA) is IV tPA initiated within 3 hours after symptom onset. Approval of this treatment is based on the results of the NINDS tPA trial in 1995. The NINDS tPA trial used two primary outcome measures: improvement over 24 hours after tPA and improvement at 90 days. The trial demonstrated a significant improvement in 90-day outcome on multiple outcome measures (mRS, Barthel Index, and NIHSS), with a number needed to treat of 8. However, the trial did not show a statistically significant early improvement with tPA (within 24 hours), which is a point worth noting when discussing this treatment with patients.

The benefit in functional status was observed in different stroke subtypes and in patients with various ranges of baseline stroke severity, ranging from mild to severe. Despite a 6.4% risk of symptomatic intracranial hemorrhage, the overall treatment benefit remained significant. Following the NINDS trial, several other trials attempted to extend the therapeutic time window of tPA to 6 hours after stroke onset. None of these trials demonstrated a significant benefit on the pre-specified primary outcome measures. However, a combined analysis of the European Cooperative Acute Stroke Studies (ECASS) I & II and ATLANTIS trials demonstrated a significant treatment effect with IV tPA out to 4.5 hours after stroke onset. The ECASS III trial evaluated AIS patients between 3 and 4.5 hours after onset of stroke and reflected the European license for tPA: excluding patients over 80, those with very severe strokes with an NIHSS score > 25, history of prior stroke, diabetes, and use of anticoagulants prior to stroke. The ECASS III study demonstrated that 52.4% of tPA-treated patients achieved a favorable outcome of 0 to 1 on the mRS, compared to 45.2% with placebo treatment (odds ratio [OR], 1.34; 95% confidence interval [CI], 1.02–1.76; P = .04). The results of ECASS III led to recommendations from the American Heart Association (AHA) and others that the use of IV tPA be extended to 4.5 hours in selected AIS patients. A subgroup analysis of the ECASS III data suggested that patients older than 65 and those with more severe strokes had less benefit than younger patients or those with milder deficits ( Box 30.3 ).