Sub-Arachnoid Hemorrhage - 2 Nursing CEs

Course Objectives

Upon completion of this course, the student will be able to:

• Describe the pathophysiology involved with a sub-arachnoid hemorrhage
• List 3 signs and symptoms of sub-arachnoid hemorrhage
• Have a better understanding of how the Hunt-Hess Grading scale is used
• Discuss 3 risk factors for vasospasm
• Describe 3 signs and symptoms of vasospasm
• Explain methods used to diagnose vasospasm
• Discuss the benefits of daily Transcranial Doppler studies to rule out vasospasm
• Explain the risk vs. benefit of using Nimodipine for treatment of vasospasm

What is a Sub-Arachnoid Hemmorhage?

Subarachnoid hemorrhage occurs when there is bleeding into the space between the brain and the arachnoid membrane (the middle membrane covering the brain). This may occur either by a spontaneous or traumatic rupture of a cerebral aneurysm, an arteriovenous malformation, or from other unidentified causes. Risks include: disorders associated with aneurysm or weakened blood vessels, including a history of polycystic kidney disease, fibromuscular dysplasia (FMD), other connective tissue disorders, aneurysms in other blood vessels, high blood pressure and smoking.

Signs and Symptoms:

•  Headache: sudden onset and very severe
• Meningeal Signs
• A warning leak may occur in 50% of the cases several days or weeks prior to the onset of hemorrhage (Headache, Dizziness, Nausea and/or Vomiting). 

Hunt-Hess Grading System

The Hunt-Hess classification is used to help guide the physician in diagnosing the severity of a Sub-Arachnoid Hemorrhage secondary to aneurysmal bleeding, as well as assist in the timing surgical intervention. It can also be used to judge the risk of vasospasm. The patient is assigned to a category on admission to the hospital. Changes in the patient’s condition are then monitored according to the baseline.

Signs and Symptoms (Depending on Location of Vasospasm)

Middle Cerebral Artery: 

• Hemiparesis affecting the arm more than the leg
• Facial weakness
• Dysphagia (difficulty swallowing)
• Aphasia (difficulty speaking) if the brain's left hemisphere is involved
• Anosognosia (denial of paralysis) if the right hemisphere is affected

Anterior Cerebral Artery:

• Hemiparesis (one sided weakness affecting the leg more than the arm)
• Flat affect

Posterior Cerebral Artery:

• Visual deficits

Vertebrobasilar Arteries:

• Cranial nerve palsies
• Ataxia (difficulty walking

Diagnosis of Vasospasm

Frequent Neuro assessment because vasospasm is often seen as a gradual neurologic deterioration. 50% of patients can remain asymptomatic during vasospasm and approximately 20% to 30% will have some delayed neurological ischemia. Decreased LOC or confusion is often the first signs of vasospasm. 

Transcranial Doppler Study (TCD) is a non-invasive ultrasound technology used to assess blood flow velocity in the major basal intracranial arteries on a real time, beat-to-beat basis.  Blood flow velocity is calculated and used to make determinations about intracranial hemodynamics. Transcranial Doppler Studies are used in early (sub-angiographic) bedside detection of vasospasm in Subarachnoid hemorrhage patients, evaluation of stroke and transient ischemic attack, as an adjunct in the assessment of cerebral circulatory arrest, and as a monitoring tool for patients undergoing intracranial interventional procedures. 

Blood Flow Velocity (BFV) increases as flow volume increases or the diameter of the vessel decreases. Velocity readings are as follows:

• 80cm/sec = no vasospasm
• 80 – 120 cm/sec = non-critical spasm
• 120 cm/sec = critical vasospasm 

Note: Initial CT scans that show blood clots that 3x5mm or a 1mm layer of blood in the basal cisterns can be an early predictor that the patient will later vasospasm. 

Nursing Assessment for Vasospasm

Clinically, vasospasm can be recognized when nurses doing frequent neuro exams report subtle changes. It is important to make sure a well-documented base line neuro exam is present so it can be used for comparison. Some of the more subtle or gradual changes that can occur and should be frequently assessed include:

• Level of consciousness
• Complaints of headache
• Periods of disorientation
• Inappropriate behavior
• Language impairment
• Hemiparesis 

Note: Nurses must quickly detect and report changes as these deficits if undetected, can cause permanent disability. 

Treatment of Vasospasm

The cause of vasospasm is a decreased blood flow to the clinically affected arterial territory. Therefore treatment for symptomatic vasospasm is directed at increasing Cerebral Perfusion Pressure using “Triple H” therapy, which is comprised of Hypertension, Hypervolemia and Hemodilution. 

Hypertension – Therapy is aimed at keeping the heart rate greater than 70 beats per minute and maintaining a 30% increase in the patients mean arterial blood pressure for the duration of the vasospasm. This can be induced with vasopressors such as Dopamine, Neosynephrine, Levophed or Dobutamine. 

Hypervolemia – Central venous pressure (CVP) should be maintained at approximately 8 to 10mmHg and Pulmonary Artery Wedge Pressure should be maintained at approximately 14 to 18 mmHg. This is done with fluid resuscitation on a regular schedule, often a colloid (5% albumin) to allow for the expansion of the intravascular space. 

Hemodilution – The balance of oxygen-carrying capacity and viscosity is optimized with lower then normal Hematocrit (around 25%). In order to attain this decreased concentration of cells and solids in the blood, volume expanders again can be used, or in critical situations removing blood and replacing it with plasma can achieve a decreasing blood volume. 

Note: Careful assessment for pulmonary edema, electrolyte imbalances (especially hyponatremia and hypokalemia) and cerebral edema must be done frequently when using Triple H therapy. 

Other Treatment Options for Vasospasm

Fibrinolytics – The most common used drug is recombinant tissue plasminogen activator (rt-PA) or streptokinase.  These and other Fibrinolytic agents act by lysing the clot in the subarachnoid space. 

Angioplasty – Spastic intracerebral vessels can be dilated to improve cerebral perfusion. This is done by passing a balloon through the carotid artery, and inflating and deflating it into the vessels that are in spasm. 

Medications for the Treatment of Vasospasm:

Mannitol – Which is an osmotic diuretic, has been shown to increase cerebral blood flow in the setting of vasospasm, with improvement in neurological function. 

Nimodipine – Is a calcium channel blocker that that has been a standard treatment for nearly a decade and has been shown to have a beneficial effect on stroke and cerebral blood flow after Sub-Arachnoid Hemorrhage. It dilates collateral arteries around the vasospasm. This therapy seems reasonable as long as the hypertension treatment of “Triple H” therapy is not compromised. If hypotension results from the use of Nimodipine, the dose can be divided in two and given twice as often. If hypotension continues after this, the practitioner should consider discontinuing its use. 

References