Summary of knowledge points: early recognition and management of acute ischemic stroke

In the past 60 years, stroke has dropped from the second leading cause of death in the United States to the fifth leading cause of death
.

This trend may be accompanied by the latest advances in stroke management, highlighting the importance of early recognition and early revascularization
.

Recent studies have shown that early recognition of acute ischemic stroke (AIS), emergency interventional therapy, and treatment in specialized stroke centers can significantly reduce stroke-related morbidity and mortality
.

However, stroke is still the second leading cause of death in the world and the number one cause of acquired long-term disability
.

Yimaitong compiles and organizes, please do not reprint without authorization
.

Early identification of AIS AIS can occur both in the community and in the hospital, so early identification of stroke is of great significance (see Table 1)
.

Stroke is a clinical diagnosis, and several characteristics of the patient's clinical manifestations can be used to identify stroke patients (see Table 2)
.

The medical emergency system is the key to detection, triage, and transportation of stroke patients to receiving institutions
.

Table 1 8 Ds of stroke management Table 2 BEFAST, prehospital management of stroke recognition AIS Organized workflow and management system can effectively reduce the delay in the treatment time of stroke patients (see Figure 1)
.

With the provision of CT and mobile stroke unit (MSU), the identification and treatment management of stroke patients will be more precise and efficient
.

Recent studies have shown that, compared with conventional ambulances to transport patients to the emergency department (ED), MSU can effectively reduce the time for IV-tPA administration and the time for patients to be admitted to the hospital
.

Figure 1 Neuroimaging of AIS in the Stroke Center.
Traditional non-enhanced CT can be performed at the prehospital level of a dedicated MSU
.

Non-enhanced CT has sufficient sensitivity to rule out hemorrhagic stroke, such as subarachnoid hemorrhage or cerebral hemorrhage
.

The Alberta Stroke Program Early CT Score (ASPECTS) is designed to use non-enhanced head CT to determine the severity of middle cerebral artery (MCA) infarction
.

In 10 predefined areas (range 0-10), any signs of early ischemia are subtracted from the highest score of 10 by 1 point (see Figure 2)
.

Patients with a high NIHSS score and a normal brain appearance or an ASPECTS score greater than 6 (Figure 2A) means that there may be no infarction and revascularization strategies can be implemented
.

Early signs of infarction on CT or lower ASPECTS are usually associated with poor prognosis and hemorrhage transformation (Figure 2B)
.

According to current guidelines, the time for CT and preliminary data reporting should be completed within 20 minutes
.

Figure 2 Early CT score (ASPECTS) of the Alberta Stroke Program
.

Score 10 areas, each area is graded 1 (normal) or 0 (abnormal)
.

The sum of all areas is ASPECTS
.

A: ASPECTS=10, a brain with a normal appearance
.

B: Brain with ischemic changes and ASPECTS<6
.

C = caudate nucleus, Ic = internal capsule, In = insular cortex, M = middle cerebral artery, P = putamen
.

CT angiography (CT-A) can effectively detect LVO and provide useful information about the patient's vascular anatomy and the cause of stroke (Figure 3)
.

Based on its characteristics of rapid acquisition, CT perfusion (CT-P) technology can be used to assess cerebral blood flow (CBF) by quantitatively analyzing the threshold of the maximum time (T-max) transmission and cerebral blood volume
.

Figure 3 CT angiography shows that the patient’s left middle cerebral artery suddenly occludes the ischemic “core” (CBF<30%) and the “penumbra” or risk tissue estimates (T-max>6s) can provide immediate information for treatment decisions
.

Clinical trials have shown that a core/penumbra perfusion mismatch ratio greater than 1.
8 may indicate EVT compliance (Figure 4)
.

The CT-P threshold for predicting infarction depends on the time from the onset of stroke symptoms to imaging, the time from imaging to reperfusion, and the quality of reperfusion
.

For this reason, procedures including CT-A/CT-P or MRI advanced imaging should not delay IV thrombolysis or EVT
.

Figure 4 Through the quantitative analysis of the maximum transit time (T-max) threshold of patients with right middle cerebral artery occlusion, the cerebral blood flow (CBF) mismatch ratio analysis was performed
.

Dark gray CBF and light gray T-max
.

Ratios greater than 1.
8 usually indicate suitability for endovascular treatment
.

Reconstruction of AIS The main goal of advanced stroke management is the limitation of revascularization and secondary neuronal damage
.

Intravenous thrombolysis and EVT can be used for suitable patients
.

1.
Intravenous thrombolysis The first landmark clinical trial that confirmed the safety and efficacy of IV-tPA in 1995 changed the treatment of AIS from a purely symptomatic treatment to a highly time-sensitive issue
.

Studies have shown that if IV-tPA is given within the first 3 hours of the onset of symptoms, the likelihood of a patient with only minor or no disability at 90 days increases by at least 30%
.

Although symptomatic bleeding increased in the treatment group, the difference in mortality between the IV-tPA and placebo groups was not significant
.

Although until recently, IV-tPA was the only treatment for AIS, the use rate of IV-tPA among all AIS patients in the United States was as low as 3.
2-5.
2%
.

One of the main reasons for the low treatment rate is the limited time window of IV-tPA
.

According to the European study of Alteplase thrombolysis treatment of AIS after 3-4.
5 hours (ECASS-3), the American Heart Association/American Stroke Association (AHA/ASA) extended the IV-tPA window from 3 hours to 4.
5 hours in 2009, And added other exclusion criteria
.

The extension of the time window increases the utilization rate of IV-tPA by up to 20%
.

Tenecteplase is a new type of thrombolytic agent with high fibrinogen specificity and long half-life.
It can be administered as a single bolus injection and has achieved promising results in clinical trials
.

The trial of tenecteplase versus alteplase in thrombectomy treatment of ischemic stroke (EXTENT-IA-TNK) showed that in patients with AIS who meet EVT, tenecteplase administration is better than alteplase administration Has a higher reperfusion rate and better functional results
.

When used in patients without LVO, tenecteplase is as effective as alteplase and has similar side effects
.

2.
The FDA's approval of IV-tPA for intravascular treatment has revolutionized the entire field of emergency neurology
.

However, up to 69% of stroke patients are not eligible for IV-tPA due to delayed hospitalization
.

Due to the development of EVT, the time window for AIS treatment has expanded
.

The success of EVT depends on the degree or quality of revascularization
.

Since 2015, many trials have shown that when EVT is performed within 6 hours, 8 hours or 12 hours after the onset of symptoms, the addition of EVT to standard medical care can effectively improve the proximal MCA or internal carotid artery (ICA ) The overall outcome of occluded AIS patients
.

A pooled meta-analysis showed that EVT treatment more than doubled the chance of achieving better functional outcomes compared to standard treatment alone, without any significant difference in mortality or the risk of parenchymal hemorrhage at 90 days
.

Two recent clinical trials have shown that if the clinical defect does not match the infarct size or imaging perfusion, the time window can be further extended to 24 hours after the onset of symptoms
.

ICU management of AIS 1.
Oxygenation and ventilation If the patient's blood oxygen saturation is lower than 94%, supplemental oxygen is required
.

The rapid deterioration of nerve function and subsequent loss of consciousness and impaired reflexes to maintain the airway require immediate airway control
.

Failure to recognize impending airway damage can lead to serious complications, such as aspiration, hypoxemia, and hypercapnia, which can cause secondary neuronal damage
.

Hyperbaric oxygen is ineffective or harmful to patients with AIS and should be avoided
.

For severe AIS patients with respiratory failure and unable to escape the ventilator, long-term tracheotomy is required
.

2.
Blood pressure is part of the brain's automatic regulation.
Blood pressure usually rises during the acute phase of AIS, thereby maximizing the perfusion of the ischemic area
.

However, severe hypertension can lead to hemorrhagic transformation of infarcts, hypertensive encephalopathy, and cardiopulmonary and renal complications
.

The current AHA/ASA guidelines recommend permissible hypertension, with a blood pressure target of ≤220/120mmHg in the first 24-48 hours
.

However, these blood pressure variables are only applicable when the patient has not received any acute intervention (such as IV-tPA or EVT)
.

If the patient receives IV-tPA treatment, the risk of hemorrhagic transformation increases, and blood pressure should be lowered to ≤185/110mmHg before IV-tPA administration
.

Once IV-tPA is administered, blood pressure should drop to ≤180/105mmHg
.

In the case of EVT, reperfusion injury and hemorrhagic transformation are of concern; therefore, blood pressure must be closely monitored during and after EVT
.

3.
Evidence of blood glucose shows that due to a variety of potential mechanisms, such as endothelial dysfunction, increased oxidative stress, and impaired fibrinolysis, compared with normal blood sugar, persistent high blood sugar in the hospital during the first 24 hours after AIS is associated with worse The prognostic outcome is related
.

Intensive insulin regimens are associated with significant hypoglycemic events and higher levels of care
.

For this reason, it is reasonable to treat hyperglycemia to achieve blood glucose levels in the range of 140-180mg/dL, and to monitor closely to prevent hypoglycemia in AIS patients
.

4.
Fever observational studies have shown that fever has an adverse effect on every outcome after stroke
.

Fever (core temperature [Tc]>37.
5°C) seems to be related to patients with severe brain injury in the intensive care unit
.

Clinical studies have shown that therapeutic hypothermia (Tc, 34-35°C) has a potential role in the treatment of cerebral edema and intracranial hypertension
.

A study evaluated the impact of targeted thermoregulation on the mortality and neurological outcomes of patients with cerebral hemispheric infarction, but failed to show a difference in trends with better functional outcomes
.

Although there are few high-quality data to support fever control after ischemic stroke, it is recommended that fever patients with severe brain injury and drug therapy fail to receive a certain degree of fever prevention in the ICU
.

5.
Rehabilitation In order to maximize the recovery of function and independence after AIS, early activities are very important
.

The data shows that even in ICU patients, early rehabilitation and rehabilitation training intensity are associated with better functional outcomes
.

However, the optimal intensity and timing of early activities are still uncertain
.

6.
Nutrition is the same as that of all neurosurgery patients.
Enteral feeding should be started within 48 hours to avoid protein catabolism and malnutrition
.

Small-caliber nasal and duodenal feeding tubes can reduce the risk of aspiration events
.

Evaluating the speech and swallowing function of patients with AIS is essential to determine the long-term enteral nutrition requirements for percutaneous gastroenterostomy
.

Summary In the past few decades, a number of new innovations have opened up a new era of vascular neurology and allowed more patients to receive acute treatment, thereby improving the final outcome
.

Despite these breakthrough changes, the continued decline in stroke mortality is slowing or even reversing
.

One of the reasons for this trend is the increasing number of patients with risk factors for stroke (such as diabetes, hypertension, and hyperlipidemia)
.

In the future, the focus should shift more to patient education and prevention to reduce the incidence of strokes that cause severe disability or death
.

Yimaitong compiled from: Herpich F, Rincon F.
Management of Acute Ischemic Stroke.
Crit Care Med.
2020;48(11):1654-1663.
doi:10.
1097/CCM.
0000000000004597