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27 Cards in this Set
- Front
- Back
Monro-Kellie doctrine (DEFINE)
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if the volume of any one of the three components increases within the cranial vault and the volume from another component is displaced, the total intracranial volume will not change
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Normal intracranial ICP ranges
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0-15 mm Hg
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Autoregulation (DEFINE/PROVIDE RANGE)
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automatic adjustment in diameter of cerebral blood vessels by the brain to maintain a constant blood flow during changes in arterial blood pressure; functions between mean arterial pressure values of 50-150 mmHg
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CPP formula & Normal values
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CPP = Flow x Resistance – Normal values lie between 70-100 mHg
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Compliance (DEFINE & FORMULA)
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expandability of the brain = Volume/Pressure
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Cushing’s triad
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systolic hypertension with widening pulse pressure, bradycardia with bounding pulse, altered respirations, altered temperature
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PaCO2 is a potent vasoactive agent acting by...
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...relaxing smooth muscle, dilating cerebral vessels, decreasing cerebrovascular resistance, increasing CBF
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Vasogenic cerebral edema (DEFINE)
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MOST COMMON, occurs in the white matter d/t changes in endothelial lining of cerebral capillaries allowing leakage of macromolecules from capillaries into surrounding extracellular space -->osmotic gradient that favors flow of fluids from intravascular to extravascular
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Cytotoxic cerebral edema (DEFINE)
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local disruption of functional or morphologic integrity of cell membranes most often in the gray matter d/t destructive lesions or trauma to brain tissue --> cerebral hypoxia or anoxia
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Interestitial cerebral edema (DEFINE)
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result of pervientricular diffusion of ventricular CSF in patient with uncontrolled hydrocephalus d/t systemic water excess (water intoxication, hyponatremia) --> fluid moves into cells to equilibrate with hypoosmotic interstitial fluid
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Reticular activating system (RAS) DEFINE
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located in the brainstem, it may maintain a state of wakefulness even in the absence of a functioning cerebral cortex, once interrupted --> unconsciousness
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Compression of cranial nerve III Manifestations
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dilation of the pupil on the same side as the mass lesion (ipsilateral), sluggishness to light, inability to move the eye upward and ptosis of the eyelid are also common (indicates herniation of the brain)
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Hemiparesis/Hemiplagia Manifestations
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occurs contralateral (opposite side) to the mass lesion
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Tentorial herniation (DEFINE)
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a mass lesion in the cerebrum forces the brain to herniated downward through the opening created by the brainstem
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Uncal herniation (DEFINE)
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occurs when there is lateral and downward herniation
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Cingulate herniation
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occurs when there is lateral displacement of brain tissue beneath the falx cerebri
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Diagnostic tests to assess ICP
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gold standards include CT and MRI to differentiate the conditions causing ICP, lumbar puncture is NOT performed for fear of cerebral herniation from sudden release
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Monitoring ICP
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gold standard is ventriculostomy in which catheter is inserted into right lateral ventricle and coupled to external transducer; alternative is fiberoptic catheter using a sensor transducer within the catheter tip to provide a direct measurement of brain pressure (USE ANTIBIOTICS)
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CSF drainage
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foramen of Monroe is selected 15 cm above the ear canal and the system is raised to diminish drainage or lowered to increase volume – watch for ventricular collapse, infection or herniation
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Mannitol (classification and action)
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osmotic diuretic given IV which acts through plasma expansion and osmotic effect – monitor electrolyte levels
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Corticosteroids and their use in treating ICP
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Dexamethasone, may control vasogenic edema surrounding tumors and abscesses – watch for hyperglycemia, increased infections, GI bleeding and hyponatremia
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Barbiturates and their use in treating ICP
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reduce the metabolic rate to decrease CBF and therefore the ICP (pentobarbital, thiopental) and to reduce cerebral edema and production of more uniform blood supply to the brain
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Controversial/Unproven treatments for decreasing ICP
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hyperventilation to lower PaCO2 and lead to constriction of cerebral blood vessles to decrease ICP, early feeding to meet higher glucose needs and to fuel the metabolism of the injured brain, dehydration to reduce cerebral edema
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Glascow Coma Scale (DEFINE)
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assesses degree of impaired consciousness by assessing inability of patient to speak, obey commands or open eyes when verbal/painful stimulus is applied
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ICP Nursing goal: Maintain patient airway - Nursing measures to take
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lay patient on one side with frequent changes, removed secretions by suctioning as needed (O2 provided before AND after), elevate HOB to 30 degrees, insert NG tube to aspirate stomach contents and prevent distention, provided sedatives/paralytics to reduce pain/anxiety/fear
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Diabetes insipidus (DEFINE)
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increased urinary output related to a decrease in ADH secretion, may result in severe dehydration with treatment being fluid replacement, vasopressin or decompression acetate
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SIADH (DEFINE)
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syndrome of inappropriate antidiuretic hormone secretion decreased urinary output
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