急性卒中 (Acute Stroke)

 

Introduction

A stroke, or cerebrovascular accident (CVA), is the rapid loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia (lack of blood flow) caused by blockage (thrombosis, arterial embolism), or a hemorrhage;

 

Acute stroke is a leading cause of death in the United States. Rapid response is critical for treating the acute stroke patient. Both out-of-hospital and in-hospital treatment is critical when treating stroke victims. Stroke is a generic term that refers to neurological damage resulting from disrupted blood supply to part of the brain.

·  Ischemic stroke (85% of stroke cases) is caused by the blockage of an artery in the brain.

· Hemorrhagic stroke (15% of stroke cases) is caused by the rupture of a blood vessel in the brain.

Speed of response is crucial to patient survival. The American Heart Association and American Stroke Association suggest the following steps to ensure a prompt response:

· Recognize and react to the signs of a stroke

· Prompt EMS response

· Rapid EMS transport to a hospital or emergency department

· Prompt diagnosis and treatment of the patient in the hospital

 

Approach to Stroke Care

1. Stroke Chain of Survival

Stroke Chain of Survival is similar to the Chain of Survival for sudden cardiac arrest. The links are as follows:

· Fast recognition and reaction to the warning signs of stroke

· Fast EMS dispatch

· Fast EMS transportation and pre-arrival notice to the receiving hospital

· Fast diagnosis and treatment as soon as the patient arrives in the hospital

Figure A: Stroke Chain of Survival

 

2. The 7 D’s of Stroke Care

The 7 D’s of stroke care are the major steps for diagnosing and treating stroke cases. They describe the major points in which delays often occur:

· Detection of the onset of symptoms and signs of stroke

· Dispatch of EMS through calling 911 or an emergency response number

· Delivery with pre-arrival notification to a hospital that has the proper facilities for stroke treatment

· Door of the emergency department which includes the arrival of the patient and fast triage in the emergency room

· Data which includes CT scan information along with interpretation of the scan

· Drug administration for appropriate drug treatments including post-administration monitoring

 

3. Warning Signs and Symptoms of Stroke

It is important to know the signs of stroke:

· Weakness and numbness of the face, arm, or leg -- this may occur on only one side of the body

· Mental confusion

· The patient may have trouble speaking or understanding when spoken to

· Visual impairment

· Difficulty walking

· Dizziness or balance and coordination problems

· Sudden onset of a severe headache

These signs will occur suddenly in response to a stroke.

 

4. Suspected Stroke

Figure B: Adult Suspected Stroke

Treatment of the Stroke Patient

The rescuer will use the Suspected Stroke Algorithm to treat any suspected stroke case. Remember prompt response, treatment and transport to a hospital is critical to the survival of a stroke patient. The goal is to get the patient to the emergency room within 10 minutes of presentation! The first responders are responsible for the first 2 steps of the algorithm: identifying the signs of a stroke and applying initial EMS treatments.

1. Apply the assessments and actions of the BLS

2. Administer oxygen if needed

3. Perform pre-hospital stroke assessment

4. If possible, determine onset of symptoms

5. Plan to transport patient to a stroke center (if one is available nearby)

6. Alert hospital

7. Check glucose

8. The goal is to arrive at the emergency room within 10 minutes

When treating stroke victims, the following time limits are critical:

· Immediate general assessment within 10 minutes

· Neurological assessment within 25 minutes

· Head CT within 25 minutes

· Interpret CT within 45 minutes

· Fibrinolytic therapy within 60 minutes of ED arrival

· Fibrinolytic therapy within 3 hours of onset

· Admission to a monitored bed within 3 hours of onset

Both initial EMS care and prompt hospital treatment are critical to saving a stroke victim. Remember, time is of the essence, and every responder is critical to saving the patient!

 

5. Cincinnati Prehospital Stroke Scale:

The CPSS is involved in the identification of stroke using 3 physical observations:

· Facial droop (the patient is asked to smile or show their teeth)

· Abnormal speech (the patient is asked to repeat a sentence)

· Arm weakness (the patient closes his or her eyes and puts his or her arms out)

The CPSS evaluates for facial droop, motor weakness, and speech abnormalities. Items are scored as either normal or abnormal. If any of these signs are abnormal, the probability for stroke is 72%.

Facial Weakness Ask the patient to show his or her teeth or smile. Normal: Both sides of the face move equally. Abnormal: One side of the face does not move at all.

Motor Weakness (arm drift) Ask the patient to extend his or her arms out at 90 degrees if the patient is sitting or at 45 degrees if the patient is supine. Drift is scored if the arm falls before 10 seconds. Normal: Both arms move the same, or both arms do not move at all. Abnormal: Or one arm drifts down compared to the other or one arm does not move at all.

Alphasia (speech) Ask the patient to say “The sky is blue in Cincinnati” or “You can’t teach an old dog new tricks.” Normal: The phrase is repeated correctly with no slurring of words. Abnormal: The patient slurs the words or says the incorrect words or is unable to talk.

6. EMS Assessments

EMS providers must be capable of reducing the time between the onset of symptoms and arrival at the hospital. Since stroke therapy can only be provided at a hospital with stroke care facilities, the fast identification and transportation of stroke patients by EMS officials can greatly improve their treatment outcome.

7. Immediate General Assessment

Once a patient arrives in the emergency department, he or she must be quickly assessed and managed by ED providers. Protocols should be used to reduce delays and improve the efficiency of treatment and diagnosis.

8. Immediate Neurological Assessment

The stroke team must then assess the patient. Neurological assessment by a stroke team should occur within 25 minutes of the patient’s arrival in the emergency department. Assessment may also be performed by a neurologist or another qualified medical professional. The stroke team or neurologist may do the following:

· Review patient history, perform a physical examination, and create a timeline of symptom onset

· Neurologic examination

 

9.  CT scan

An important point in the process of stroke assessment is the CT scan and its interpretation. A major purpose of the scan is to differentiate between ischemic and hemorrhagic stroke. It is also used to identify structural abnormalities that could be contributing to patient symptoms or present contraindication to fibrinolytic therapy. The non-contrast CT scan is considered to be the most important test for the assessment and management of an acute stroke patient.

The differentiation between hemorrhagic and ischemic stroke determines the next step in the treatment process:

· Non-hemorrhagic stroke patients that have no other signs of abnormality may be candidates for fibrinolytic therapy.

· Hemorrhagic stroke patients are not candidates for fibrinolytics and a neurologist or neurosurgeon should be consulted.

· If the patient remains a candidate for fibrinolytic therapy , he or she will proceed to be assessed for fibrinolytic therapy

· If the patient shows no hemorrhaging on the CT scan but for some reason is not a candidate for fibrinolytic therapy, aspirin administration may be considered

10. Fibrinolytic Therapy

There are numerous studies that show a good to excellent outcomes for stroke patients when tPA is used as a treatment for acute ischemic stroke within 3 hours of the onset of symptoms. These results only come from strict adherence to stroke protocols that are themselves in strict accordance to the criteria and therapeutic regimen of the NINDS protocol.

The AHA guidelines recommend IV tPA administration to patients that have acute ischemic stroke. The evaluation for fibrinolytic therapy is a multi-step process that involves eligibility evaluation in accordance to NINDS eligibility criteria. The process also includes a discussion with the patient’s family on the benefits and risks of the therapy. As with all drugs, fibrinolytics have potentially adverse effects.