Spinal and epidural part II Flashcards
Incidence of PDPH appears to be related to?
size of needle and maybe type of needle
What avoid tracking of skin in to SA space?
stylet
What is the cut and injection of Quinke point?
standard cutting, end injection
What is the cut and injection of Sprotte needle?
rounded point, side injection
What’s the point and injection of Whitacre?
pencil port, side injection
Needle size for spinal/epidural?
22-27
Smaller needles may require?
introducer needle
How do you want to turn towards the dural fibers?
parallel
What do blunt needles do when entering dura?
pop
2 advantages of blunt needles?
less coring, decreased incidence of PDPH
After inserting needle you check for CSF where?
in all 4 quadrants
When you aspirate, what do you look for?
swirl
A block at what level will produce loss of perception of intercostal and abdominal wall muscle movement-dyspnea?
T2-T4
Landmark to block the inguinal ligament?
T12-L1
Landmark for umbilicus?
T10
What do you need to be prepared for for block from C8-T2?
support resp and circulatory
What is it called when medication injected rapidly creates vortex effect and spreads more cephalad?
barbotage
This is defined as the resting position of 2 fluids with different specific gravities when mixed in the same container?
baracity
Specific gravity of CSF?
1.004-1.009
Why is baricity not an issue in the epidural space?
there is no liquid interface
Epidural space is mostly?
fat
How is epidural anesthesia different from SAB?
slower onset and not as dense
Epidural anesthesia is variable based on what 4 things?
drug, dosage, level of injection, concentration
How do you get a walking labor epidural?
sensory block w/out motor block; dilute LA with opioid
What is a segmental epidural block?
blockade around injection site
Is HTN a contraindication to a block?
relative contraindiction
The skin to the epidural space is how many cm in 80% of population?
4-6 cm
Most prominent vertebrae in the neck?
C7
Anatomic landmark for root of spine in scapula?
T3
Anatomic landmark for inferior angle of scapula?
T7
The groove just above or between gluteal clefts above coccyx?
sacral hiatus
Any procedure below the diaphragm can have what type of epidural?
lumbar
This type of epidural is most commonly used for postop analgesia?
thoracic
How is a pt positioned for cervical epidural?
sitting with neck flexed
Where is the LA placed in caudal epidural?
sacral epidural space found at sacral hiatus
With a block from T5-L1 what CV effects occur?
venous pooling, arterial vasodilation, decreased SVR
A block above T4 is a high sympathetic blockade and what 3 symptoms occur?
hypotension, bradycardia, poor contractility
Above T4 block, what happens to CVP and SV?
increased CVP, no increase in SV
What happens to the upper body in a block above T4?
vasoconstriction
A block above T4 creates a splanchic sympathetic blockade, which means what?
adrenal medullary catecholamine secretion is gone
What happens to the capacitance vessels in the LEs in block above T4?
blockade
Always assume nausea is caused by what?
hypotension
Tx of nausea/hypotension?
phenyl, ephedrine, small dose epi (0.1 mcg)
Nausea occurs secondary to? Tx with?
unopposed vagal activity; atropine
What happens to renal blood flow with epidural/spinal?
RBF is well maintained
Blockage of this will cause paralysis of urinary sphincters?
S2 and S4
Adequate epidural anesthesia does what to the neurohumoral response to surgical insults?
blocks
The epidural inhibitory effect to the neurohumoral response is greatest in what types of surgery?
lower abdominal and lower extremity surgery
The most critical effect of neuroendocrine activation in the perioperative period is?
the increase in plasma norepinephrine
The increase in plasma norepinephrine is associated with activation of nitric oxide in the endothelium of patients with atherosclerotic disease, producing?
paradoxic vasospasm
In patients with significant atherosclerotic disease, what may be the reason underlying the cardioprotective effects of thoracic epidural anesthesia and analgesia in patients with cardiac disease?
combination of paradoxic vasospasm and the hypercoagulable state in response to surgical stress
3 suspected sites of action of spinal/epidural?
spinal nerve roots, brain, spinal cord
How do LA work?
bind to Na channels, primarily in inactivated state, effectively preventing Na influx and development of AP
For the loss of resistance technique, you attach a fluid or air filled syringe to the needle after entering what?
interspinous ligament
What type of needle and size is commonly used for epidural?
18 g Touhy
Does the direction of the needle tip guarantee catheter direction?
no
Common epidural catheter sizes?
19 or 20 g
If the catheter is longer than the usual 4-6 cm to the epidural space, what may occur?
it may exit the epidural space via the foramen
Why should you not pull the epidural catheter back thru needle?
it may shear off the tip
What types of solutions are better for surgical epidurals?
more concentrated
What types of solutions are better for pain management/labor?
less concentrated- 0.0625%
Size of the epidural space does what as we go down the cord?
increases
Advantage of using epidural opioids?
produces analgesia without motor or sensory blockade, therefore avoiding hypotension and other affects of sympathetic blockade
Why can you give smaller doses of the opioid with an epidural than with parenteral/oral admin?
opioid travels directly to receptors in dorsal horn
How are opioid epidurals distributed?
diffuse thru the meninges into the CSF from which they reach their site of action in the dorsal horn directly, they enter systemic circulation after being absorbed by the vasculature in the epidural space, or absorbed by fat in the epidural space, creating reservoir by which drug can reach systemic circulation
The #1 factor in block height?
volume
For the adult, you give ___-___ mL/ segment you want blocked?
1-2
Therefore, you give what type of dose for a shorter patient versus a taller patient?
less
When two segment regression occurs, redose with what?
half the original dose
Pregnant ppl and elderly require what type of dose to achieve the same block height as someone young and healthy?
less
We should position all of our patients how when first starting?
sitting
If a well trained assistant is not available, what position requires less help from an assistant?
lateral
For the obese patient, which approach is easier?
midline
If you are having trouble you are almost always?
off midline
You can use the skin wheel to?
identify midline structures
In the lumbar area you should insert the needle in a slightly what direction?
cephalad
If the needle is not sitting firmly once thru the supraspinous ligament, then it is likely that the needle is where?
off midline
The catheter should not be inserted > __cm in to epidural space?
5
Patients who cannot be positioned easily or cannot flex teh spine should have what approach?
paramedian
5 types of patients who may need paramedian approach?
trauma, arthritic, calcified interspinous ligament, kyphoscoliosis, prior lumbar surgery
Why is entry level at T3-T7/midthoracic approach almost impossible to use for midline approach?
angle of spinous processes is more oblique, space between spinous processes is narrower, ligaments are less dense –> false loss of resistance is much more common
First resistance felt with paramedian approach?
ligamentum flavum
How do you advance the needle with paramedian approach?
perpendicular to skin until bone encountered
How do you “walk off” the bone with paramedian approach?
advance needle at 10-25 degree angle toward midline
Caudal approach is usually used for what 4 needs?
pediatrics, adults in procedures requiring blockade of sacral and lumbar nerves, epidurography, lysis of adhesions for pts with low back pain after spinal surgery
With caudal approach, the use of what is recommended since the sacral hiatus is ossified in some patients?
fluoro
What creates the sacral hiatus?
nonfusion of fifth sacral vertebral arch
The sacral hiatus is covered by which ligament, which is an extension of the ligamentum flavum?
sacrococcygeal ligament
The point of access to the sacral epidural space?
sacral hiatus
How can you identify the sacral hiatus?
palpate the groove above the coccyx
If fluoroscopy is not used, there are two methods for identifying the hiatus. What are they?
(1)Locate the posterior superior iliac spines. A line drawn between them becomes one side of a equilateral triangle. At the apex of the triangle is the sacral hiatus. (2)With firm pressure, identify the coccyx with the index finger. As the finger moves cephalad, the first pair of bony protuberances are the cornu, which surrounds the hiatus.
