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s
· Brain metabolism o
Soul source of energy for the brain is glucose. Brain needs glucose to function. Brain cannot
store it, but needs a constant supply. If glucose levels start to fall you will some changed.
o Cerebral glucose < 70 mg/dL = confusion
o Cerebral glucose < 20 mg/dL = damage
· Cerebral blood flow
· Autoregulation o Changes
in pressure o Changes
in CO2
▪ Alters cerebral blood volume with change in blood vessel size
, o Ability of the blood vessel in the brain to either constrict or dilate in response to pressure or
CO2 levels
▪ Hypotension or hypoventilating causing hypercapnia BV in brain will dilate and vice versa
try to send more blood and oxygen to brain.
▪ If hypertension or hypocapnia blood vessels in the brain will constrict.
▪ Systolic less than 50 or greater than 160 BV in brain lose the ability to autoregulate.
o GCS, LOC, Memory, speech, Reflexes (babinski with brain injury) which only babies should have
if adult has it this is not good, motor response, sensation , look for aphasia, motor strength
▪ Concerned with GAS or 8 or lower o
Posturing
▪ Decorticate
· Extremities go toward the body ▪
Decerebrate
· Extremities pull away from the body, more severe, damage to brainstem – this is
the worse
posturing
· Cranial nerves o 1 –
Olfactory - Smell
o 2 – Optic - vison, pupil response, visual fields – PERRLA - need flashlight or pen light dim the
lights in room
o 3, 4, 6 - Oculomotor, Trochlear, Abducens - eye movement – 6 fields of gaze “EOM’S”
o 5,7 – Trigeminal, Facial - corneal reflex touch patients eyeball, on unresponsive patients- corneal
reflex, use gauze or cotton. Touch the eyeball – you want the person to blink as a response. Only
do the corneal reflex on someone who is unresponsive.
o 8 – Acoustic – hearing - whisper test or just ask the patient questions Just talk to the patient
o 9,10 – Glossopharygeal, Vagus – swallow and gag reflex cough and gag – assess gag take a
tongue depressor. If patient is intubated use suction to assess gag reflex.
o 11 – Accessory – shoulder and neck movement o 12 – Hypoglossal – tongue movement
· Oculocephalic Reflex (Doll’s Eyes Reflex) o
Usually absent or negative
o Only done on unconscious patients when trying to asses brainstem functioning
,NR 340 CHAMBERLAIN WEEK 3 EXAM
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o Not done on if spinal cord injury is present or suspected
o Look forward and then move head side to side,
▪ Normal (negative) - eyes will move contralateral (opposite) to the direction the head
moves
▪ Irregular (positive) – eyes do not move, stay fixed. (Sign of brain death)
· Oculovestibular Reflex (Cold Caloric)
o Done on unresponsive patients trying to Asses brainstem functioning. We say its normal or
abnormal.
o Must have intact tympanic membrane o You need a 50 ml syringe and cool saline
▪ Instill 50ml of cool saline into patients ear
▪ Normal – Eyes will turn toward side you are putting water and go back to center
▪ Abnormal – Eyes do not move (brain death)
, o Components of ICP: brain tissue, blood, CSF fluid
▪ Monro-Kellie doctrine
· Increase in any one component requires a reduction in one or both of other
components to sustain normal ICP.
o Normal ICP: 0-15 mm Hg
o Cerebral Perfusion Pressure (CPP)
▪ How well brain is being profuse
▪ Dependent upon ICP and MAP (CPP = MAP – ICP) Systolic + 2(Diastolic) / 3 = ·
Optimal is 70-100 mmHg
· If less then 70 you can develop ischemia to brain tissue.
· If under decrease BP or increase ICP
▪ If CPP is inadequate, ischemia or infarction can occur ·
Increased Intracranial Pressure
Increased metabolic
o Associated with many neurological problems demands, fevers,
seizures can also
o ICP 20mm Hg or greater for 5 minutes or longer increase intracranial
pressure.
o Results from an increase in any one of the three components:
▪ Increased Blood Volume
· Loss of Autoregulation
· Decreased Oxygenation
· Hypercapnia – cause blood vessels in brain to dilate sending more blood to brain
which can increase pressure
· Obstruction – Ex: Tumor
▪ Increased Brain Volume
· Cerebral Edema
▪ Increased Cerebrospinal Fluid