Neuroanesthesia Pt. 2 (Exam I) Flashcards
How much CSF do we typically have at any given moment?
150mls
Where does CSF typically “pool”?
Cisterns
Areas where arachnoid membrane and pia mater are further apart.
Don’t need to know specific cisterns.
What is normal CSF pressure for a horizontal patient?
10 mmHg
What type of tissue lines the cerebral ventricles?
What does this tissue do?
Choroid Plexus (produces CSF)
Which cells excrete CSF?
Ependymal (E = Excrete)
What absorbs CSF?
Arachnoid Villi (A = Absorb)
What is the path of CSF?
In which ventricles is the majority of CSF produced?
Lateral Ventricles
CSF Diagram (Flip)
What is idiopathic Intracranial HTN?
CSF Buildup causing ↑ICP with no obvious reason.
Who is idiopathic intracranial HTN common in?
- Obese women of reproductive age.
What is another name for idiopathic Intracranial HTN?
Pseudotumor Cerebri
What is normal ICP?
7 - 15 mmHg
When is ICP considered pathologic?
> 20 mmHg
Whats a normal CPP?
60 - 80 mmHg
What is the critical ischemic threshold for CPP?
30 - 40 mmhg
What would the following do to CBF?
- Hypoxia
- Hypercarbia
- ↑ CMRO₂
↑CBF
Where does aqueductal stenosis occur?
Aqueduct of Sylvius (between 3ʳᵈ & 4th ventricles)
What are the three components of Cushing’s Triad?
- Irregular Respirations
- Bradycardia
- Widened pulse pressure
How long might the effects of hyperventilation on PaCO₂ last?
6 - 12 hours
What dose of Mannitol is typical in neurosurgery?
0.5 - 1 mg/kg
What are the benefits of corticosteroids in neurosurgery?
What are the negatives?
- Pros: Lowers local cerebral swelling (around tumors typically)
- Cons: May ↑BG and ↓ elasticity of blood vessels
What is parenchyma?
Functional Brain Tissue (grey & white matter)
What are potential concerns associated with utilizing hyperventilation to induce brain relaxation?
- Potential ischemia in some areas
- Brain relaxation temporary (6 - 12 hours)
What dose of decadron is typical for cerebral edema reduction?
10mg Q6 hours
What drug is typically paired with mannitol? Why?
Furosemide
Prevents rebound effect of cellular swelling from mannitol by inhibiting chloride osmoles.
What is the MOA of levetiracetam?
Binds to synaptic vesicle protein 2A (SV2A)
Inhibits release of Ca⁺⁺ by inhibiting this vesicles release.
What is a typical dose of Keppra?
500mg BID over 15 min
Which factors are associated with ION?
- Prone position
- ↓BP
- ↓ H/H
- Long surgery
- Large volume administration
Between LR & NS, which should be used in neurosurgery? Why?
NS > LR
NS = 308 mOsm/L
LR = 274 mOsm/L
NS will reduce cerebral edema.
What can occur with Dextran?
Dilutional coagulopathy
Does Hypothermia provide brain protection? Is it used?
Yes
But, no demonstrated benefits, and can cause arrhythmias & coagulopathy.
What is the recommended BG level for neurosurgery?
150 - 200 mg/dL
What is a pressure transducer placed into the subdural space or the brain parenchyma?
Subdural bolt
What is a catheter placed in the ventricle allowing for the drainage of CSF?
Ventriculostomy
What catheter allows for drainage of CSF but can be inaccurate for measurement of ICP due to the area of its placement?
Lumbar subarachnoid catheter
What is normal ScO₂ (cerebral oximetry)?
70% (+/- 20 - 30%)
What are SSEPs?
Cutaneous electric stimulation peripherally resulting in EEG changes
Are latency readings more reliable with SSEP or MEPs?
SSEPs
What are MEPs?
Stimuli elicited via electrodes in the head that cause a muscle reaction peripherally.
A __% decrease of amplitude in SSEPs and MEPs is significant.
50%