4 nervous system alterations Flashcards by Brendon Allen

glucose for the brain:

-its the only what for the brain
-can the brain store it?

only source of energy

cant store it in brain

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glucose for the brain:

—decreased cerebral glucose
Under 70
Under 20

<70
—lead to mental status changes and seizures

<20
—brain damage

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Brain and CO2:

-its a good measure of what in brain?
-CO2 >45
-CO2<35

—good measurement of blood flow in brain

> 45:
—vasodilation

<35:
—constriction

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PaO2

<50 leads to what?

If it stays that low it can lead to what else?

<50
compensation occurs:
—cerebral vessel dilation
—attempt to increase blood flor and O2 delivery

If remains low:
—anaerobic metabolism begins
—leads to lactic acid accumulation and vasodilation

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In the brain constant pressure is required

Monroe-kellie doctrine:
-3 volumes
+ what if present

Normal ICP (intracranial pressure)

Brain volume
Blood volume
CSF volume
+lesion volume (if present)

Normal ICP = 5-15

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ICP over 20 for 30min lead to what?

CPP normal range
—what we want CPP if ICP is increased

ICP over 20:
—Increase risk of herniation

CPP: 60-100
—if ICP is elevated need to keep CPP at least 70

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ICP 15-30

Brain has a auto-regulation system:
-3 distinct mechanisms:

—displacing cerebral blood flow
—altering CSF production and reabsorption
—movement of brain parenchyma

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ICP >30

Auto-regulation mechanisms begin to fail

—small changes = significant increased pressure
—brain herniation is imminent

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Causes of increased ICP:
-increased brain volume

Cerebral edema:
—hypoxia
—hypo-osmolality
—increased capillary permeability
(tumor, meningitis, abscesses)

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Causes of increased ICP:
Increased CSF

Hydrocephalus r/t:
—meningitis
—SAH
—excess production of CSF

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Causes of increased ICP:
Increased cerebral blood volume

Ineffective ventilation:
—hypoxia
—hypercapnia
—hypocapnia

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Glasgow coma scale: 3 main levels
Mild
Moderate
Severe

Mild:
GCS 13-15
-periods of change LOC

Moderate:
GCS 9-12

Severe:
GCS 3-8
Motor score of GCS <5 =
= potential abnormal finding with CT scan

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Glasgow coma scale:

Eye opening
Motor response
Verbal response

Eye opening: 1-4

Motor response: 1-6

Verbal response: 1-5

Possible: 3-15

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Assessment for possible increased ICP:

Pupillary function

Dilated:
—brainstem compression “blown” pupil

Nonreactive (fixed) dilated pupil:
—CN III damage/brain herniation
-unilateral fixed dilated pupil
-indicated side of injury (same side)

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Assessment for possible increased ICP:

Motor assessment (GCS)

Follows commands
Withdraw stimulus

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Assessment for possible increased ICP:

Posturing

Decorticate
—flexion

Decerebrate (worse)
—extension

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Assessment for possible increased ICP:

Cranial nerve assessment
(Number and what to check)

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II (optic):
—check pupils

III (oculomotor)
—pupils with consensual response

V (trigeminal) & VII (facial)
—corneal reflex

VIII (acoustic)
—hearing, dizziness, tinnitus

IX (glossopharyngeal) & X (vagus)
—gag reflex

Assessment for possible increased ICP:

Brainstem functioning:
—dolls eyes (oculocephalic reflex)
Contraindications

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Must rule out spinal injury before testing
—bc you cant turn head with SCI

Eyes move with head = doll eyes absent
=possible brainstem involvement

Assessment for possible increased ICP:

Brainstem functioning:
—Oculovestibular reflex (cold caloric testing)

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Inject cold water in ear

—patient will look toward involved ear with intact brainstem (bad if they dont)

Early signs of increased intracranial pressure

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HA
Visual disturbances
N/V
Tachycarda/tachypnea
Seizures

Restlessness/agitation (first sign)

ICP over 30 could be a sign of what?

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Impending brain stem herniation

Late sign of increased ICP

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Cushings triad:

—systolic HTN (widened pulse pressure)
-SBP-DBP

—bradycardia

—respiratory abnormalities (cheyne-stokes)

TBI (traumatic brain injury)

-most common cause of what?

-usually what

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Increased ICP

Usually external insult to the brain

Types of TBI

-what is happeneing

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Object striking the head

Coup-contrecoup

Human body moving at a high rate of speed and suddenly stopped by impact

2 types of TBI Primary vs secondary

Primary: Damage incurred at impact S/s: change LOC, decreased HR/RR, dilated pupils, respiratory arrest Secondary: More global (the entire brain) Injury after the initial injury

Primary injury (TBI) examples

Injury from initial impact: Scalp lac Skull fx Concussion Contusion Hematoma Subarachnoid hemorrhage Diffuse axonal injury

Scalp laceration: -usually causes what Tx Assess what

Profuse bleeding -avulsion (tearing away) =may need sx Assess underlying tissue (fx, protrusion)

Skull fx What happens Compound/displaced/linear

Excessive bleeding d/t vasculature Compound: open wound Displaced: closed wound-edges do not meet Linear: edges are approximated

Skull fracture s/s —risk for what if what is injured (tx?) —places of csf leaks and what fx it means —raccon eyes and what its a sign of —what is battle signs

—Injury to dura places at risk for meningitis Tx: (Prophylactic abx) —CSF leak: -otorrhea (ear) = fx in middle fossa -rhinorrhea (nose) = anterior fossa -csf w/ bleeding = wipe with gauze look for “halo” —Raccoon eyes (late sign of basilar fracture) —Battle signs (behind ear bruising)

Basilar fractures —what is not allowed —assess what —csf heals how? We do what for csf leaks if what?

No NG tube or naso-tracheal intubation Assess extra-ocular movements to determine cranial nerves that are involves CSF: —heal on their own —drains put in if ICP is noted —DONT blow nose

Concussion -what is it S/s Tx What can last up to a year

Any change of LOC following brain injury S/s: short-term memory loss/HA Tx w/ rest Change in memory can last 1 year (educate pts)

Cerebral contuson Results from what? S/s Injury peaks when post injury (may lead to what?)

Truama: —laceration of microvessels starting on the surface and moving to deeper layers S/s: Move from focal defects to significant changes in LOC/ abnormal posturing to death Peaks at 24-72 hours —may lead to worsening brain pressure and death

Epidural hematoma Where is the bleeding -usual cause S/s Tx

Blood located between dura and inner table of the skull Laceration of extradural artery S/s: —Lose consciousness/regain consciousness and deteriorate rapidly —posturing —unilateral dilation of pupil late sign of cerebral herniation Tx: neurosurgical emergency (evacuation of clots)

Subdural hematoma: Where is blood located S/s Tx

Blood below dura and above arachnoid S/s: within 24-48hrs —HA —unilateral pupil involvement —decreased LOC —herniation if increased ICP Tx: —craniotomy to remove clot and place drain —HOB flat to decrease tension

Intracerebral hematoma Where is blood located Primary cause Tx

Blood within brain tissue Penetrating brain injury = primary cause Tx: —sx only if lesion continues to expand —manage edema and cerebral perfusion

Diffuse axonal injury What is it 3 classifications How to diagnose

Shearing of axons from white to gray matter 3 class: MILD: coma <24hrs Moderate: coma >24hrs w/ decorticate/decerebrate posturing Severe: prolonged coma, fever, diaphoresis, severe decerebrate posturing Tx: MRI to diagnose after 24hrs (only if bleeding occurs)

Secondary TBI What is it Key difference

Multi-faceted biochemical and cellular response to primary injury Key difference: Global and harms tissue that may not have been involved in the primary injury

CCP (cerebral perfusion pressure) What is it How to measure Normal range What is high causes What are low causes

Blood pressure gradient across the brain CPP = MAP - ICP Normal = 60-100 >100 = potential hypoperfusion and increased ICP <50/60 =decreased blood supply to brain leads to hypoxia/brain death

CPP (cerebral perfusion pressure) If MAP = ICP then what is CPP? What are we measureing

CPP would be 0 meaning no Cerebral perfusion Difference between systemic inflow pressure from the LV and the amount of pressure that the heart must overcome to produce a constant forward CBF

CPP At MAP <40 what happens Acutely injured brains require what? What is the min CPP for this type of patient

At MAP <40 the: —autoregulation systems will not function right Acutely injured brains require: —high than normal CPP —min of 70 d/t inability of blood to flow across TBI brain

4 nervous system alterations Flashcards

(41 cards)