Intro to Neuro anesthesia PPt-josh Flashcards
The adult brain weighs about ______or 2% of tbw
1350gm
CBF is how much
(not a single number but _-_/__/__)
45-55 mL/100g/min
Avg is 50mL/100g/min
What is the avg CBF ml/min
750mL/min
What is the equation for CBF
CBF= CPP/CVR
the brain receives what % of CO
12-15%
CMRO2 is what % of O2 consumption
20%
What is avg CMRO2
(__/__/__)
3.5mL/100g/min
what is equation for CPP
CPP= MAP-ICP (or CVP which ever is more)
what happens to CMRO2 during sleep
decreases
CBF decreases ___% for every __C decrease in body temp below 37C
7%
1C
what do VAA do to CMRO2?
decrease it
what is autoregulation
MAP 60-160mmHg
(or her slide says 70-150 mmHg)
Autoregulation of CBF is know as what type of regulation?
Myogenic regulation
Rapid changes in MAP can result in transient periods of Altered _____ (probally no more than 3-4 min)
CBF
what are the 2 types of regulation for CBF?
- Myogenic
- Neurogenic
Myogenic regulation on CBF is thought to occur why?
b/c of the autoregulation and rapid changes in MAP in transiet periods of altered CBF, probaly occurs d/t direct muscle changes in the tone of vascular smooth muscle
the Neurogenic regulation of CBF has its greatest neurogenic effect on the larger cerebral arteries. what is the most important determinant?
viscosity (HCT)
the CNS is derived form what 2 primary cells?
- Neurons
- Neuroglial cells
what are the 5 neuroglial cells?
- astrocytes
- Ependymal cells
- Microglia
- Olgodendrocytes
- Schwann cells
(All Ethipoians Munch On Snails)
Neuroglial cells: Functions
Astrocytes
- Support
- metobolic
- nutritive functions
Neuroglial cells: Functions
Ependymal Cells
- lines cavities in teh CNS and make up walls of ventricles
Neuroglial cells: Functions
Microglia
Phagocytosis
Neuroglial cells: Functions
Oligodendrocytes
insulation for axons in teh CNS (myelin sheath in brain and spinal cord)
Neuroglial cells: Functions
Schwann Cells
- Insulation-myelin sheath in peripheral nervous system
(Schwann in your arms)
Blood Brain Barrier: BBB
it is for effective _______ of the brain and spinal cord
Insolation
Blood Brain Barrier: BBB
________ Cells of the CNS form tight junctions b/t cells.
Endothelial cells
Blood Brain Barrier: BBB
what is the function of the endothelial cells of the CNS that form tight junctions b/t cells?
to prevent intracellular transfer
Blood Brain Barrier: BBB
Midline structures receive neurosecretory products from blood and exist OUTSIDE the BBB (AKA not protected by BB) what are the 5 parts of the brain not protected by teh BBB?
- Area of Postrema
- Pituitary gland
- Pineal gland
- Choroid plexus
- portions of the hypothalamus
VAA’s effect on CBF:
VAA’s during normocapnia @ > 0.5 MAC do what 3 things? and all this results in what?
- Dose related suppression on Cerebral Metabolism
- Vasodilation d/t direct effects on vascular smooth muscle
- CBF/CMRO2 ratio altered
** results in*** increases in CBF
VAA’s effect on CBF:
in recap all VAAs greater than 0.5 MAC cause what?
increases in CBF
VAA’s effect on CBF:
list which ones increase CBF In order from least to greatest?
Halothane
enflurane
Des=ISO
Sevo
(found that des and iso are equal is very interesting)
N2O effect on CBF:
what 3 things does N2O increase
- CBF
- ICP
- CMRO2 (is questionable)
Ketamine:
w/o controlled ventilation what 3 things are increased?
- PaCO2
- CBF
- ICP
Ketamine:
if given w/ controlled ventilation or another sedative what happens to the SE?
they are negligible
Ketamine:
what do most providers do with it? (use it/avoid it)
Avoid it
Benzo, barbs, and prop reduce _____ and _____ in a dose dependent fashion
- CMRO2
- CBF
Narcs likely have little effect on ____ and ____
- CMRO2
- CBF
NDMR:
do they effect CBF, ICP, or CMRO2?
- no
- only effects are from histamine release!!
- Atracurium and Mivacurium should only be used in doses not associated w/ hypotension
SCh:
does what to ICP
increases it
SCh:
does what to CBF?
- Increases it
- D/t cerebral activation from muscle spindle apparatus
SCh:
is it contraindicated when RSI is required?
nope (u can give a defasiculate dose)
ICP:
what are the 3 determinants of ICP not including the brain?
IC water (78%)
CSF (75mL)
Blood 50 mL
ICP:
what is normal ICP?
5-15 mmHg
(miller says 8-12mmHg)
**miller also said the world was flat so maybe we shuould just agree with everything he says even if everything else says something else fucking jackass***
ICP:
what is the total fluid volume in the brain? Including the 3 determininats of ICP IC water, CSF, and Blood
1200-1500mL
ICP:
elevated ICP is above what #
15mmHg
ICP:
what can cause and increase in ICP?
any of the 3 determinants of ICP
Blood/ IC water/ CSF
ICP:
Intracranial HTN is a sustained increase in ICP above what?
15-20mmHg
ICP:
when ICP rises above 30mmHg what ensues?
- CBF decreases
- Ischemia
- Cerebral edema
- Increased ICP
- CBF decreases more
- More ischemia
- More edema
- Repeat!!!
ICP:
S/S of Increased ICP
- Nausea/vomiting
- HTN
- Bradycardia
- Personality changes
- Altered level of consciousness
- Altered breathing pattern
- Papilledema
ICP:
what are ways to decrease ICP
- Elevate head (improves venous outflow)
- Hyperventilation
- Surgical Decompression
- CSF drainage
- Osmotic Diuretics/Loop diuretics
ICP:
what are 2 main drugs that decrease ICP
- Barbs
- Prop
ICP:
one way to decrease ICP is to the avoidance of cerebral vasodilating drugs. what is a cerebral vasodilating drug that we use everyday that can be avoided or used in decreasd amounts to help in this?
VAAs
ICP and HYPERventilation:
is it a clear fix?
Nope controversial and efficacy and duration of effect are unclear
ICP and HYPERventilation:
the effects of hyperventilation decrease over time, there is usually no benefit after ___ hours
6 hrs
ICP and HYPERventilation:
what is a concern w/ hyperventilation
- Decreasing CBF will increase likelihood of ischemia and more edema