Immediate Laboratory Studies in the Acute Stroke Patient

Management of the Acute Stroke Patient

Immediate Laboratory Studies in the Acute Stroke Patient

·  Noncontrast CT or MRI of the brain

·  Electrocardiogram

·  CBC including platelets

·  Cardiac enzymes including troponin levels

·  Electrolytes, BUN, creatinine and glucose

·  Prothrombin time and international normalized ratio (INR)

·  Oxygen saturation

·  Lipid Profile

Other studies may be appropriate in select patients and include:

·  Liver function tests

·  Toxicology screen

·  Blood alcohol level

·  Pregnancy test (in women of child bearing age)

·  Arterial Blood Gas (if hypoxia is present)

·  Lumbar Puncture (if subarachnoid pressure is suspected and CT is negative for blood)

·  Electroencephalogram (if seizures are suspected).

Use of Intravenous Fibrinolytic (Thrombolytic) therapy in Acute Ischemic Stroke

Treatment timeline — "Time is brain": the sooner intravenous rTPA (altepase) treatment is initiated after ischemic stroke, the more likely it is to be beneficial. Eligible patients should be treated as quickly as possible within the appropriate 3 or 4.5 hour time limit. To achieve the earliest treatment, current guidelines recommend that the elapsed time to the start of alteplase infusion should be ≤60 minutes from the time of patient arrival in the emergency department. The following in-hospital timeline is suggested as a goal for all patients with acute ischemic stroke who are eligible for treatment with intravenous altepase:

§  Evaluation by physician - 10 minutes

§  Stroke or neurologic expertise contacted, ie, stroke team - 15 minutes

§  Head CT or MRI scan - 25 minutes

§  Interpretation of neuroimaging scan - 45 minutes

§  Start of treatment - 60 minutes from arrival

In-hospital treatment delay can occur with any of these steps. Other items that can lead to inordinate delay include initial telephone triage by the stroke physician, obtaining and waiting for results of blood and laboratory tests, obtaining consent, and delivery of Altepase (rTPA) from the pharmacy to the bedside.

Informed consent

Whether to proceed to thrombolysis in an individual patient should be based upon a discussion of the risks and benefits with the patient and family if possible. However, neurologic deficits caused by acute stroke often preclude obtaining informed consent from the patient. Altepase is an approved therapy for acute stroke; consent is not required to administer alteplase as an emergent therapy for eligible patients if surrogate consent is not possible.

Indications and Contraindications for rTPA use in acute stroke

Intravenous administration of rTPA is the only FDA-approved medical therapy for treatment of patients with acute ischemic stroke. Its use is associated with improved outcomes for a broad spectrum of patients who can be treated within 3 hours of stroke onset. Earlier treatment (ie, within 90 minutes) may be more likely to result in a favorable outcome. Later treatment, at 90 to 180 minutes, also is beneficial. Patients with major strokes (NIHSS score >22) have a very poor prognosis, but some positive treatment effect with rTPA has been documented. Because the risk of hemorrhage is considerable among patients with severe deficits, the decision to treat with rTPA should be made with caution. Treatment with rTPA is associated with symptomatic intracranial hemorrhage, which may be fatal. In the original NINDS trials, the risk of symptomatic bleeding was ≈6%. Recent community-based studies and registries report lower rates of hemorrhage. Expand+Strokestroke.ahajournals.org*(Guidelines for the Early Management of Adults with Ischemic Stroke. Stroke. 2007; 38: 1655-1711) Published online before print April 12, 2007, doi: 10.1161/​STROKEAHA.107.181486

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The American Heart Association/American Stroke Association (AHA/ASA) inclusion guidelines for the administration of rTPA in under 3 hours are as follows :

·  Diagnosis of ischemic stroke causing measurable neurologic deficit

·  Neurologic signs not clearing spontaneously

·  Neurologic signs not minor and isolated

·  Symptoms not suggestive of subarachnoid hemorrhage

·  Onset of symptoms less than 3 hours before beginning treatment

·  No head trauma or prior stroke in past 3 months

·  No MI in prior 3 months

·  No GI/GU hemorrhage in previous 21 days

·  No arterial puncture in noncompressible site during prior 7 days

·  No major surgery in prior 14 days

·  No history of prior intracranial bleed

·  Systolic blood pressure under 185 mm Hg, diastolic blood pressure under 110 mm Hg

·  No evidence of acute trauma or bleeding

·  Not taking an oral anticoagulant, or if so, INR under 1.7

·  If taking heparin within 48 hours, a normal activated prothrombin time (aPT)

·  Platelet count of more than 100,000/μL

·  Blood glucose greater than 50 mg/dL (2.7 mmol)

·  No seizure with residual postictal impairments

·  CT scan does not show evidence of multilobar infarction (hypodensity over one-third hemisphere)

·  The patient and family understand the potential risks and benefits of therapy

In May 2009, the AHA/ASA guidelines for the administration of rTPA following acute stroke were revised to expand the window of treatment from 3 hours to 4.5 hours to provide more patients with an opportunity to receive benefit from this effective therapy.

Eligibility criteria for treatment in the 3 to 4.5 hours after acute stroke are similar to those for treatment at earlier time periods, with any 1 of the following additional exclusion criteria:

·  Patients older than 80 years

·  All patients taking oral anticoagulants are excluded regardless of the international normalized ratio (INR)

·  Patients with baseline NIHSS score > 25

·  Patients with a history of stroke and diabetes

Thrombolytic therapy should be withheld for patients with extensive multilobar infarction with hypodensity involving more than one-third of the cerebral hemisphere on head CT. Minor ischemic changes (ie, early signs of infarction) on CT are not a contraindication to treatment.

How to give rTPA

Infuse 0.9 mg/kg (maximum dose 90 mg) over 60 minutes with 10% of the dose given as a bolus over 1 minute.
Admit the patient to an intensive care or stroke unit for monitoring.
Perform neurological assessments every 15 minutes during the infusion and every 30 minutes thereafter for the next 6 hours, then hourly until 24 hours after treatment.
If the patient develops severe headache, acute hypertension, nausea, or vomiting, discontinue the infusion (if rTPA is being administered) and obtain emergency CT scan.
Measure blood pressure every 15 minutes for the first 2 hours and subsequently every 30 minutes for the next 6 hours, then hourly until 24 hours after treatment.
Increase the frequency of blood pressure measurements if a systolic blood pressure is ≥180 mm Hg or if a diastolic blood pressure is ≥105 mm Hg; administer antihypertensive medications to maintain blood pressure at or below these levels (see Table 10).
Delay placement of nasogastric tubes, indwelling bladder catheters, or intra-arterial pressure catheters.
Obtain a follow-up CT scan at 24 h before starting anticoagulants or antiplatelet agents

Treatment options for acute ischemic stroke patients who are not candidates for rTPA*

Aspirin reduces the risk of early recurrent ischemic stroke when given within 48 hours of the onset of stroke but increases the risk of hemorrhagic stroke (absolute risk reduction = 0.7%; number needed to treat = 143). Overall, for aspirin, there is a slight, but statistically significant benefit in reducing recurrent stroke. Conversely, unfractionated heparin and LMW heparin/heparinoids, when used within 48 hours of onset in patients with acute ischemic stroke, have not been shown to reduce the rate of stroke recurrence.

Recommendations

1. Patients with acute ischemic stroke presenting within 48 hours of symptom onset should be given aspirin (160 to 325 mg/day) to reduce stroke mortality and decrease morbidity, provided contraindications such as allergy and gastrointestinal bleeding are absent, and the patient has or will not be treated with recombinant tissue type plasminogen activator (Grade A). The data are insufficient at this time to recommend the use of any other platelet antiaggregant in the setting of acute ischemic stroke.

Other agents

2. Subcutaneous unfractionated heparin, LMW heparins,and heparinoids may be considered for DVT prophylaxis in at-risk patients with acute ischemic stroke, recognizing that non pharmacologic treatments for DVT prevention also exist (Grade A). A benefit in reducing the incidence of PE has not been demonstrated. The relative benefits of these agents must be weighed against the risk of systemic and intracerebral hemorrhage.

3. Although there is some evidence that fixed-dose, subcutaneous, unfractionated heparin reduces early recurrent ischemic stroke, this benefit is negated by a concomitant increase in the occurrence of hemorrhage. Therefore, use of subcutaneous unfractionated heparin is not recommended for decreasing the risk of death or stroke-related morbidity or for preventing early stroke recurrence (Grade A).

4. a. Dose-adjusted, unfractionated heparin is not recommended for reducing morbidity, mortality, or early recurrent stroke in patients with acute stroke (i.e., in the first 48 hours) because the evidence indicates it is not efficacious and may be associated with increased bleeding complications (Grade B).

b. High-dose LMW heparin/heparinoids have not been associated with either benefit or harm in reducing morbidity, mortality, or early recurrent stroke in patients with acute stroke and are, therefore, not recommended for these goals (Grade A).

*( Anticoagulants and Antiplatelet Agents in Acute Ischemic Stroke

Report of the Joint Stroke Guideline Development Committee of the American Academy of Neurology and the American Stroke Association (a Division of the American Heart Association))