Page 1
Critical Care Exam 3 Study Guide 2025 Full
Paper
Neuro Basics
· 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
Page 1 of 57
, Page 2
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.
Neuro Assessment
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
Page 2 of 57
, Page 3
o 3, 4, 6 - Oculomotor, Trochlear, Abducens - eye
movement – 6 fields of gaze “EOM’S”
Page 3 of 57
, Page 4
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 re- sponse. 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
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
Page 4 of 57
Critical Care Exam 3 Study Guide 2025 Full
Paper
Neuro Basics
· 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
Page 1 of 57
, Page 2
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.
Neuro Assessment
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
Page 2 of 57
, Page 3
o 3, 4, 6 - Oculomotor, Trochlear, Abducens - eye
movement – 6 fields of gaze “EOM’S”
Page 3 of 57
, Page 4
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 re- sponse. 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
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
Page 4 of 57
