NSG 533 Exam 4: Questions & Answers
describe brain compliance
(Ans- the ability of cranial content to tolerate changes in volume
as brain volume increases, ICP initially does not increase due to
____________
(Ans- brain compliance
how to monitor CSF in ICP
(Ans- ICP waveform
a healthy brain will have peak 1 higher than peak 2, which is higher than
peak 3
an unhealthy brain will have peak 2 higher than peak 1 (going up)
explain impaired brain autoregulation
(Ans- as blood flow to the brain drops, vasodilation will occur to increase
blood flow to the brain to increase ICP
if ICP is too high, vasoconstriction will occur to limit the amount of blood
reaching the brain
formula for calculating Cerebral Perfusion Pressure (CPP)
(Ans- CPP = MAP - ICP
what is normal CPP?
(Ans- 50-150mmHg
how can you reduce CPP?
(Ans- increase ICP
,do you want a higher or lower MAP in an injured brain?
(Ans- higher MAP
normal Intracranial Pressure (ICP)
(Ans- 0-10mmHg
what is a major cause of ICP hypotension?
(Ans- loss of CSF volume
when does ICP Hypertension warrant treatment?
(Ans- sustained ICP > 15-20mmHg
severe ICP Hypertension
(Ans- sustained ICP >40mmHg
causes of increased ICP
(Ans-
1. disordered CSF hydrodynamics
2. too much blood inside the brain
3. Increased volume of brain tissue
three causes of disordered CSF hydrodynamics
(Ans-
1. CSF overproduction (rare)
2. impaired absorption (blood in CSF clogs outflow)
3. impaired drainage (tumor blocks duct for draining CSF)
two causes of increased volume of brain tissue
(Ans-
1. abnormal growth/tumor
2. cerebral edema
what is the function of the Blood Brain Barrier?
(Ans- Regulates the movement of substances from the blood to the brain
tissue; protects the brain from infection and toxins
, what happens to the Blood Brain Barrier and brain autoregulation when
there is increased ICP?
(Ans- they break down
three types of cerebral edema
(Ans-
1. osmotic
2. vasogenic
3. cytotoxic
osmotic edema
(Ans- cerebral edema d/t fluid shifting into the brain tissue (hyponatremia)
vasogenic edema
(Ans- cerebral edema d/t altered capillary permeability (tumor)
cytotoxic edema
(Ans- cerebral edema d/t death of brain tissue (ischemia)
basics of how brain herniation occurs
(Ans- as ICP continues to increase, the brain begins to push on the skull
and has nowhere to go, which can result in herniation
four types of brain herniation
(Ans-
1. central
2. subfalcine
3. uncal
4. tonsillar
central herniation
(Ans- Downward shift of the diencephalon that compresses the midbrain --
> impedes blood flow to the brain
describe brain compliance
(Ans- the ability of cranial content to tolerate changes in volume
as brain volume increases, ICP initially does not increase due to
____________
(Ans- brain compliance
how to monitor CSF in ICP
(Ans- ICP waveform
a healthy brain will have peak 1 higher than peak 2, which is higher than
peak 3
an unhealthy brain will have peak 2 higher than peak 1 (going up)
explain impaired brain autoregulation
(Ans- as blood flow to the brain drops, vasodilation will occur to increase
blood flow to the brain to increase ICP
if ICP is too high, vasoconstriction will occur to limit the amount of blood
reaching the brain
formula for calculating Cerebral Perfusion Pressure (CPP)
(Ans- CPP = MAP - ICP
what is normal CPP?
(Ans- 50-150mmHg
how can you reduce CPP?
(Ans- increase ICP
,do you want a higher or lower MAP in an injured brain?
(Ans- higher MAP
normal Intracranial Pressure (ICP)
(Ans- 0-10mmHg
what is a major cause of ICP hypotension?
(Ans- loss of CSF volume
when does ICP Hypertension warrant treatment?
(Ans- sustained ICP > 15-20mmHg
severe ICP Hypertension
(Ans- sustained ICP >40mmHg
causes of increased ICP
(Ans-
1. disordered CSF hydrodynamics
2. too much blood inside the brain
3. Increased volume of brain tissue
three causes of disordered CSF hydrodynamics
(Ans-
1. CSF overproduction (rare)
2. impaired absorption (blood in CSF clogs outflow)
3. impaired drainage (tumor blocks duct for draining CSF)
two causes of increased volume of brain tissue
(Ans-
1. abnormal growth/tumor
2. cerebral edema
what is the function of the Blood Brain Barrier?
(Ans- Regulates the movement of substances from the blood to the brain
tissue; protects the brain from infection and toxins
, what happens to the Blood Brain Barrier and brain autoregulation when
there is increased ICP?
(Ans- they break down
three types of cerebral edema
(Ans-
1. osmotic
2. vasogenic
3. cytotoxic
osmotic edema
(Ans- cerebral edema d/t fluid shifting into the brain tissue (hyponatremia)
vasogenic edema
(Ans- cerebral edema d/t altered capillary permeability (tumor)
cytotoxic edema
(Ans- cerebral edema d/t death of brain tissue (ischemia)
basics of how brain herniation occurs
(Ans- as ICP continues to increase, the brain begins to push on the skull
and has nowhere to go, which can result in herniation
four types of brain herniation
(Ans-
1. central
2. subfalcine
3. uncal
4. tonsillar
central herniation
(Ans- Downward shift of the diencephalon that compresses the midbrain --
> impedes blood flow to the brain
