Week 5: Cerebral dysfunction Flashcards
Brain uses what for metabolism?
glucose and oxygen
Autoregulation is the brains ability to? When does it shut down
- maintain constant cerebral blood flow
- less than 60, greater than 160 systolic, or cerebral perfusion suboptimal
Arterial is the ? system in the brain
High Pressure System
Thinner & more fragile
Carotid & Vertebral arteries supply blood to the brain
Circle of Willis: where blood flows up and is able to flow over to the oppposite side
Venous is the ? Pressure System
Low pressure system
- Lack valves
- Compress easily with Increase Pressure
Cerebral Perfusion Pressure
- CPP= MAP –ICP
- Normally greater than 50
- Less than 50 indicates loss of autoregulation
Monro Kellie Hypothesis
Changes in the brain volume result in
Increased ICP
(or) decrease in one of the other volumes
VIC
Volume brain + Volume of Blood + Volume of CSF + Volume of Lesion
Compliance is the attempt to ?
- Compliance is the attempt to maintain the ICP between 5-15 mm/hg
- CSF displacement
- CSF reabsorption
- Venous compression and blood shunting
Cerebral Autoregulation helps?
ensure optimal CBF
Decrease in CBF leads to?
- Ischemia
- Build-up Lactate (does not cross blood brain Barrier)
- Ultimately cerebral acidosis
Hyperemia
- Is increased blood flow to brain. Causes arterial congestion
- Luxury Perfusion
- Progressive vasodilation
- Increased CBF
- Loss of Autoregulation: Increased ICP
Conditions That Affect CBF & CBV
Increase CBF/CBV
- Hypertension
- Fever
- Pain
- Hypercapnia
- Ischemia
- Cerebral vasodilation
Decrease CBF/CVP
- Hypotension
- Sedation
- Paralysis
- Hypocapnia
- Cerebral edema
- Decrease CO
- Cerebral vasoconstriction
Cerebral Spinal Fluid
What percent of volume?
How much volume
Pressure?
functions?
- Approximately 10% of Cerebral Volume
- Volume = 150 ml
- Pressure = 3-13 mm/Hg
- Functions: Cushion brain & spinal Cord, Stable chemical milieu, Assist in the excretion of toxic waste
Confusion
Disorientation differences?
disorientations: agitation and anxiety plus the confusion
obtunded
responses are slower
stupor
only respond with painful stimuli
coma
don’t respond to painful stimuli
Vowel- TIPPS
Common Reasons for altered LOC
Vowel-Tipps
- Alcohol
- Epilepsy
- Insulin
- Opiates/drugs
- Uremia
- Trauma
- Temperature
- Infection
- Psychogenic
- Poisin
- Shock-Stroke
Glascow coma scale
- Looks at eye opening, verbal response, motor response.
- Higher the score the higher the function
- Score less than 9=concern
Neuro Checks how often and what?
- Vital Signs Q15 minutes
- Glasgow Coma Score Q15 minutes
Reasons for pupil abnormalities
- hypoxia
- hypothermia
- orbital trauma
- pharmacological treatement (atropine)
- cataract surgery
- seizures
- hypotension
- illegal drug use
- toxic exposure
- artificial eye
- cerebral edema
- congenital abnormality
- severe TBI
decerebate
decorticate
as intercranial pressure increases what happens to pupils?
- 1st decrease in one sided response
- then fixed pupils that are not bilateral or responsive to light. Usually dilated
What is a positive Dolls Eyes?
turn the patient and the eyes stay fixed straight. Head goes sideways and eyes go sideways too
Caloric Ice Test negative and positive findings?
- insert 20 ml of cold water into the ear. You expect to see the eyes start moving, and then they fix over to the side you put the ice water in. This would be a normal response and a negative eyes test
- abnormal response is the eyes staying fixed
Cranial Nerve Assessment
- Corneal: stick something on cornea, they blink (normal)
- Gag
- Swallow
- Cough
Type of breathing assoc with problem:
- Cheyne-Stokes
- Cheyne-Stokes variant
- Central neurogenic hyperventilation
- Apneustic
- Ataxic
- Cheyne-Stokes: large bilateral supratentorial
- Cheyne-Stokes variant:large unilateral
- Central neurogenic hyperventilation: large bilateral partial
- Apneustic: large bilateral midpontine
- Ataxic: large bilateral posterior fossa
S/S of Increased ICP infants, children
Infants
- Bulging fontanel
- Separated cranial sutures
- Cracked-pot sign: bang on head, sounds like a hollow pot (extra fluid)
- Setting-sun sign: eyes are low set and whites are showing above it
- Positive transillumination
Children
- c/o headaches, projectile vomiting, and new seizure onset activity
Late signs for infants and children of increased ICP
- Bradycardia
- Decreased sensory/motor response
- Alterations in PERRLA
- Cheyne –stokes respirations
- Papilledema
- Decreased LOC/ Coma
Early Signs of ↑ ICP
- Slight LOC changes ***MOST IMPORTANT****
- Pupils sluggish / Impaired eye movement
- Limb strength changes
- Headache
ICP Peaks?
48 – 72 hours after injury