Neuraxial Anesthesia Flashcards
what are the different names for a spinal
subarachnoid
intrathecal
How many of each kind of vertebrae are there?
7 cervical
12 thoracic
5 lumbar
5 sacral
4 coccygeal
what structure is different on the 7th cervical vertebrae when compared to the others
7th does not have a bifid spinous process
what direction do thoracic vertebrae spinous processes point
downward
what direction do spinous process point on lumbar verebrae
straight out
where do lumbar vertebrae connect
facet joint
the meeting of the inferior and superior articular processes
what does redicular mean
nerve root
what two ligaments bind the vertebrae
anterior longitudinal
posterior longitudinal
what are the three layers covering the spinal cord
pia mater
arachnoid mater
dura mater
Where is the conus medullaris?
L1-L2
What is the conus medullaris?
end of spinal cord
where do we not do epidurals and spinals above
conus medularis/ L1-L2
how many cervicle nerve roots are there
16 total (8 pairs)
how many total nerve roots are there
31 pairs
anterior roots are __________ nerves
motor
posterior roots are __________ nerves
sensory
what structure differentiatres anterior and posterior nerve roots
posterior root ganglion
What is the filum terminale?
A pia mater extension that tethers the tip of the conus medullaris to the end of the sacrum, around S2
what is the filum terminale made from
pia mater
what are the layers you go through for an epidural
skin
sub q tissue
muscle
supraspinous ligament
interspinious ligament
ligamentum flavum
epidural space
what are the layers you go through for a spinal
skin
sub q tissue
muscle
supraspinous ligament
interspinious ligament
ligamentum flavum
epidural space
dura mater
subdural space
arachnoid mater
subarachnoid space
where is CSF found
subarachnoid space
what is the total volume of CSF
120-150 ccs
how much CSF is in the spinal subarachnoid space
20-30 ccs
how much CSF is produced in a day
500ccs
what makes CSF
choroid plexus
how does lasix affect CSF production
decrease production
what is the specific gravity of CSF
1.002-1.009
what is the blood supply for the posterior spinal cord
posterior spinal arteries
paired arteries fed by many radicular arteries
what is the blood supply for the anterior spinal cord
anterior spinal artery
single artery, midline that has many circumfrential vessels
what can happen when anterior spinal arteryis damaged
bilateral lower extremity motor loss 2/2 damage to this artery during aorta sx or by a stray epidural needle
what is the the name of the anterior spinal artery
artery of adamkiewicz
where is the artery of adamkiewicz located on
78% on the left side of vertebral column
between T8-L3
what is a high take off artery of adamkiewicz
artery comes through at T5
what are epidural veins called
Batson’s Plexus
how do you make sure you are not in the epidural vein
test dose
the top of the scapula correlates with what vertebrae
T3
the botton of the scapula correlates with what vertebrae
T7 or T7-T8 interface
thoracic epidural insertion
what is Tuffiers line
A line drawn between the highest points of both iliac crests will yield either the body of L4 or the L4-L5 interspace.
What does S2 correlate with?
the caudal limit of the dural sac in most adults
what is the most prominent spinous process in the cervicle area
C7
how do you find the sacral haitus
felt as a depression just above or between the gluteal cleft and above the coccyx
where is conus medullaris located
L1
where is Tuffiers line located
L4-L5 interface, L4 body, correlates with the iliac crest
where does the Dural sac end
S2
correlates with superior iliac spine
where is the sacral hiatus and sacrococcygeal ligament
S5
how does obesity affect epidural space
increased epidural fat
how does advanced age affect epidural space
decreased epidural fat, decrease dose
what are the borders of the ligamentum flavum
ligamentum magna to sacral hiatus
what is the cranial border of the epidural space
foramen magnum
what is the caudal border of the epidural space
sacrococcygeal ligament
what is the anterior border of the epidural space
posterior longitudinal ligament
what is the lateral border of the epidural space
vertebral pedicles
what is the posterior border of the epidural space
ligamentum flavum
vertebral lamina
what causes a patchy block
epidural space is discontinous
lacks uniformity
what can cause an epidural to have a one sided block
possible midline band in epidural space called plica mediana dorsalis
what is the most narrow portion of the epidural space
anterior
what is the widest/deepest part of the epidural space
posterior space in midlumbar region
T/F there is free fluid in the epidural space
F, if there is free fluid you are in subarachnoid space
what is the pressure of the epidural space
subatmospheric (negative)
once you inject fluid in epidural space where does it go
superior- foramen magnum
inferior- sacral haitus, caudal canal
lateral- intervetebral foramen to spinal nerve roots AND to dural cuff into CSF
anterior-to anterior epidural space
what is the area that spinal nerve roots pass through
intervertebral foramen
what is the sight of action of epidurals
spinal nerve roots
what are the advantages of an epidural
delay in response
gradual onset
fewer episodes of hypotension
more time to manage
how long does a spinal last
3 hrs
what kind of neuraxial block do you use for a procedure lasting 4-6 hours
epidural
what is sympathectomy
decrease SNS decreased HR, BP and vasodilation
which has a greater control of the level of sensory and motor blockade (spinal or epidural)
epidural
an increase in LA concentration causes an increase in (motor/sensory) block
motor
a decrease in LA concentration and increase in volume causes an increase in (motor/sensory) block
sensory
T/F epidurals are good for postoperative pain relief
true
do epidurals or spinal have a lower incidence of systemic hypotension
epidurals
what are disadvantages of epidurals
delay response
longer procedure
patchy block
greater tissue trauma
greater risk for local anesthetic toxicity
paralysis
epidural hematoma
spinal HA
what is the name of the needle used in epidurals
Touhy needle
what size is a Touhy needle
16-18 g
what is the shape of a Touhy needle
curved tip
what is the angle of the Touhy needle
30*
what is the angle of the Hustead needle
15 degrees
what is the angle of the crawford needle
0 degrees
what are indications for epidurals
surgery
post op pain control
labor and delivery
chronic pain
sympathetic blockade
what are contra indications of epidural
increased ICP
Coagulopathy
aortic stenosis
infection at insertion site
watch for tattoo
what is the platelet cutoff for epidural
80,000-100,000
why are epidurals contraindicated in aortic stenosis
decreased SNS, decreases SVR, code
when do you use an epidural for a single shot injection
steroid
post op pain
what layers do you pass through with midline epidural
skin and SubQ
supraspinous ligament
interspinous ligament
ligamentum flavum
epidural space
how does the supraspinous ligament feel
small pop
how does the interspinous ligament feel
gravel
how does the ligamentum flavum feel
wall
how do you place needle in Paramediaum approach
needle is inserted 1.5-2 cm lateral to spinous process
at transverse process below selected level
angle upwards
what layers do you go through in paramedian approach
skin and SubQ
ligamentum flavum
epidural space
what is the first ligament you hit in paramedian approach
ligamentum flavum
what nerve root are you at if you get thumb (first digit) numbness
C6
what nerve root are you at if you get 2nd and 3rd digit numbness
C7
what nerve root are you at if you get numbness in the 4th and 5th digits
C8
what nerve root are you at if you get numbness at the nipple line
T4
what nerve root are you at if you get numbness at the xiphoid process
T6
what nerve root are you at if you get numbness at the umbilicus
T10
what nerve root are you at if you get numbness at the pubic symphysis
T12
what nerve root are you at if you get numbness at the anterior knee
L4
what dermatome do you want to be at for upper abdominal surgery/C section
T4-T5 (nipple)
what dermatome do you have to be at for intestinal sx, gynecologic pelvic exam, ureter and pelvic surgery
T6-T8 (xiphoid)
what dermatome do you have to be at for TURP, vaginal delivery, hip surgery
T10 (umbilicus)
what dermatome do you have to be at for thigh surgery, lower limb amputations
L1
what dermatome do you want to be at for foot surgery
L2-L3
what dermatome do you want to be at for perineal surgery, hemorrhoidectomy and dilation
S2-S5 (saddle block, sit up for spinal to settle)
where is the cardioaccelerator blockade
T1-T4
what nerve roots control the diphragm
C3, C4, C5
what happens with a block at level t1-t4
cardioaccelerator blockade
(central sympathetic blockade)
venous pooling
Bradycardia
what nerve roots make up the peripheral sympathetic blockade?
T1-L2
what happens in the peripheral sympathetic blockade
venous pooling
CO maintained by an increase in HR and vasoconstriction above the level of the block
how do you determine if you are in the epidural space
tough insertion through ligamentum flavum
loss of resistance entering epidural space
hanging drop
test dose
what can happen if you put too much air in epidural space
pneumocephalus
the hanging drop helps you know you are in the
epidural space
if you hit a bone early when inserting the needle what did you hit
spinous process
if you hit a bone early how do you adjust your needle
up or down
if you hit a bone deep what did you hit
transverse process
if you hit a bone deep how do you adjust your needle
left or right
how far should epidural catheter be inside epidural space
3-5 cm into epidural space
if your needle is in 8 cm in epidural space, how far should your catheter be in
11-13
what can happen if epidural catheter is too deep in epidural space
increase chance of hitting vessel, pull catheter back
what do you inject for a test dose
3 ml of 1.5% lidocaine (45 mg)
5 mcg/ml of epi (15 mcg)
what happens with test dose if epidural catheter is in subQ/tissue
nothing will happen
what will happen with test dose if epidural catheter is in epidural space
nothing will happen
what will happen with test dose if epidural catheter is in subarachnoid space
spinal anesthesia will occur within 3 minutes
you do a test dose to confirm your epidrual and your patient has numbness in sacrum and legs, where is your epidural
subarachnoid (spinal)
what will happen with test dose if epidural catheter is in a vessel
20% raise in HR and BP within 30 sec
local anesthetic for epidurals must be _____________ free
preservative
what can be added to epidurals to lenthen the duration of the block
epi/steroids (dexamethasone)
what is the provided concentration of chloroprocaine
2-3%
what is the time of onset of chloroprocaine (epidural)
5-10 min
what is the provided concentration of lidocaine
1-2%
what is the onset of lidocaine (epidural)
10-15min
what is the provided concentration of Bupivicaine
0.25-0.5 %
what is the onset of Bupivicaine (epidural)
15-20 min
what is the provided concentration of Ropivicaine
0.25-1%
what is the time of onset of ropivicaine
10-20 min
what is Duramorph
preservative free morphine
what is the least lipid soluble narcotic you can give in epidurals
duramorph
low lipid solubility means that it has a __________ spread in CSF
higher
what is the most lipid soluble epidural narcotics
fentanyl/sufentanil
being lipid soluble means that it is taken up by
epidural fat
what opioids can you give with epidurals
Duramorph
Fentanyl
sufentanil
Meperidine
Hydromorphone
what is the general lipid solubility of Morphine
1
what is the onset of epidural Morphine
30-60min
what is the general lipid solubility of Hydromorphone
10
what is the onset of epidural Hydromorphone
15-30min
what is the general lipid solubility of Meperidine
30
what is the onset of epidural Meperidine
5-10 min
what is the general lipid solubility of Fentanyl
800