Neurologic Trauma

8/7/2019 Neurologic Trauma

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Management of Neurologic

Trauma

bryiane pascua medina, rn, man 1


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Is the pressure exerted in the cranium by itscontents: The brain The blood The Cerebrospinal Fluid

Is measured with a monitor in either a ventricle,

the brain parenchyma, or a subarachnoid space Normal = 5-15 mm Hg Pressures over 20 increased ICP that impairs

cerebral perfusion


Increased Intracranial Pressure


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Cerebral Perfusion Pressure (CPP) Is the amount of blood flow from the systemic

circulation that is required to provide adequateoxygenation and glucose for brain metabolism

CPP = MAP - ICP

Mean Arterial Press

ure (MAP) Represents the average pressure during the cardiac

cycle

Calculated by: (systole + 2 diastole) /3




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ETIOLOGY Space occupying lesion

Cerebral infarction

Obstruction of outflow of CSF

Abscess

Ingested or accumulation of toxins Impaired blood flow to or from the brain

Vasodilation from increased paCO2 or decreased PaO2

Increased intrathoracic pressure




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Risk factors

Head injury

Brain tumors

Cerebral bleeding

Hydrocephalus

Edema from surgery or injury




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MUNRO Theory

States that because the bony skull cannot expand, whenone of the three components expands, the other twomust compensate by decreasing in volume in order forthe total brain volume and pressure to remain constant




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Munro theory As an intracranial mass enlargesCompensatory:

1st: displacement of CSF into the spinal canal COMPLIANCE = ability of the brain to adapt to an increasing

pressure without increasing ICP When exceeded = ICP rises

2nd: reduction of blood volume in the brain When reduced by 40%, brain tissues become acidotic. When 60%,

alters cerebral metabolism leading to brain tissue hypoxia andareas of brain tissue ischemia 3rd: Displacement of Brain tissue

Across the tentorium, under the falx cerebri, or through foramenmagnum into the spinal canal

HERNIATION = may result to DEATH




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HERNIATION SYNDROMES

Supratentorial Herniation Syndromes Transcalvarial Herniation Occurs with open head injuries when brain tissue is extruded through an

unstable skull fractures Central Transtentorial Herniation

Is the end result of the downward displacement of diencephalon throughthe tentorial notch

Caused by injuries or masses in the cerebral cortex or on the outwardperimeter of the cerebrum

RAPID CHANGE on LOC = early indication As pressure increases, 1st: cheyne stokes; then centra neurogenichyperventilation; later, apneustic and ataxic breathing (Biots); finally,

apnea Pupils become small with progression to a dilated and fixed state Babinski sign followed by abnormal flexion extension posturing Dolls eye reflex




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HERNIATION SYNDROMES Supratentorial Herniation Syndromes

Lateral Transtentorial Herniation (Uncal herniation) Displacement of masses in or along temporal lobe

Pupils become sluggish first, then become unresponsiveipsilaterally, then contralateral 2o to third cranial nerve

compression at the midbrain Cingulate Herniation

Occurs when frontal lobes of the cerebrum are compressed

Cerebral artery compression = ischemia, congestion, edema,increased ICP




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INFRATENTORIAL (Tonsilar) Herniation

a.k.a Cerebellar herniation occurs when the cerebellartonsil shifts throught the foramen magnum,compressing the medulla and upper portion of thespinal cord.

Increasing pressure in the posterior fossa 2 tocerebellar bleeding underlying problem

Erratic changes on BP, PR, breathing, dec LOC, anarched stiff neck and quadriparesis


Increased intracranial Pressure


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OUTCOME MANAGEMENT

Decrease Intracranial Pressure

ABC

Hyperventilation CO2 causes cerebral blood vessel todilate. Hyperventilate to cause hypocarbic blood level

creation. PaCO2 30-35 results in vasoconstriction of thecerebral blood vessels, leading to decrease blood flow andthus decreasing ICP. PaO2 must be kept at 90-100 mm Hg




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OUTCOME MANAGEMENT

Decreased ICP

MANNITOL hyperosmotic agent, does not cross an intactblood-brain barrier. Increases intravascular pressure bydrawing fluid from the interstitial spaces and from braincells. If the blood-brain barrier is damaged, the medicationenters the brain and increasesswelling. DIURESIS isexpected, risk for dehydration




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OUTCOME MNGT Decrease ICP

Cerebral Perfusion Give vasoactive medication to maintain CPP at a normal level.

CPP at more than 70 mm Hg

Prevention of Complications

Antibiotics Infection increases metabolism, thus increased ICP Anti-seizure phenytoin, barbiturates, diazepam) Seizures

increase metabolism

Hypertonic IV solutions are avoided because of the risk ofpromoting cerebral edema




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Neurologic Trauma

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