Neuraxial Blocks Flashcards
3 names for spinal?
spinal, subarachnoid block, SAB
4 names for epidural?
epidural, extradural, caudal, central neuroaxial blockade
How many cervical, thoracic, lumbar, sacral, and coccygeal vertebrae are there and are they anterior or posterior?
cervical: 7 and anterior; thoracic: 12 and posterior; lumbar: 5 and anterior; sacral: 5 and posterior; coccygeal: 4
Which parts of the spine are fused in adults?
sacral and coccygeal
Landmark for T7?
line drawn on the lower borders of the scapula
Landmark for L4 is also known as?
Tuffier’s line
Landmark for S2?
line between posterior superior iliac spines (distal extend of dural sac)
Spinal cord stops at the level of? And what emerges from there?
L1; cauda equina
6 characteristics all vertebrae have?
vertebra body, 2 pedicles (notched for nerve roots), 2 transverse processes (notched for muscle attachment), 2 laminae (one left and one right), 1 spinous process (allows us to tell what level we’re at), 4 articular processes (2 project upward and 2 downward)
What part of the vertebra serves as synovial joints and allow us to bend, twist, and move spinal column?
articular processes
What part of vertebra do we palpate from the outside?
spinous process
These 2 kinds of vertebrae in the spine are more horizontal?
lumbar and cervical
From cephalad to caudad what happens to the vertebral laminae?
they become more vertical
Lumbar spinous processes have what shape characteristic?
they’re shorter and broader
The spinous process angle of cervical, thoracic, and lumbar?
cervical: more horizontal but small; thoracic: angular; lumbar: almost horizontal and bone is very thick
A way to get the sacral region anesthetized?
Have pt lie on side and flat, place small pillow under knees and flatten out lumbar curve which promotes more even distribution of hyperbaric LA in spine
Hyperbaric solution has a viscosity that compares how to the CSF?
hyperbaric solution has > varicity than CSF
What holds together the anterior vertebral bodies?
anterior longitudinal ligament
This ligament is on the far side of the dura and holds together the posterior part of the vertebral bodies?
posterior longitudinal ligament
This ligament joins the vertebral spines?
supraspinous
Where does the supraspinous ligament extend from?
occipital protuberance to coccyx
This ligament runs between the spinous processes?
interspinous
Where does this ligament extend to?
foramen magnum to sacral hiatus
Where does the epidural space extend to?
base of skull to sacrococcygeal membrane
5 things in epidural space?
epidural veins, fat, lymphatics, arteries, nerve roots
Skin to epidural space is how many cm?
2.5-8
In adults the spinal cord extends to what vertebra? In children it extends to where?
L1; L3
What is the tapered end of the spinal cord called?
conus medullaris
What anchors the spinal cord to the coccyx?
filum terminale
What is significant about the cauda equina and an epidural?
the nerve roots in the cauda equina are pushed away from the needle
3 layers of meninges?
dura, arachnoid, pia
Which space contains the CSF?
subarachnoid space
At what level does the anterior spinal artery arise? And from what artery does it arise?
level of foramen magnum; vertebral artery
At what level does the posterior spinal artery arise? And what artery does it arise from?
foramen magnum; posterior inferior cerebellar artery
How many pairs of segmental radicular arteries supply the nerve roots and spinal arteries?
21
This artery supplies the lower thoracic and upper lumbar parts of the cord?
anterior radicular artery of Adamkiewicz/radicularis magna
In the cervical region, spinal arteries receive from from what 2 arteries?
vertebral arteries from posterior inferior cerebellar arteries and segmental branches from cervical radicular artery
In the thorax and lumbar region, spinal arteries receive blood from what arteries?
radicular
The artery of Adamkiewica is also known as?
radicularis magna
The principal arteries for the spinal cord are?
thoracic radicular artery and arterioradiculus magna/major anterior radicular artery
The blood supply of the lower 2/3 of the spinal cord is typically found between what levels?
T11 and L3
CSF is between what 2 layers of spinal cord?
pia mater and arachnoid mater
Where is CSF produced?
ependymal cells in choroid plexus
Where is CSF absorbed?
arachnoid villi
How many mL of CSF is produced per day?
500
Total volume of CSF in body and in spinal cord?
120-150 mL; 25-35 mL in spinal cord
Specific gravity of CSF?
1.004-1.009
Pressure in CSF?
6-8
4 functions of CSF?
immunity, shock absorber, chemical stability prevention of brain ischemia
This supplies the posterior 1/3 of cord?
paired posterior spinal arteries
The single anterior spinal artery arises from?
vertebral artery
The paired posterior spinal arteries arise from?
cerebellar arteries
This artery arises from the aorta?
artery of adamkiewicza
What does artery of adamkiewicz supply?
anterior lower 2/3 of cord
6 blood supply arteries/veins to cord?
single anterior/spinal artery; paired posterior spinal arteries, intercostal and lumbar arteries, artery of adamkiewicz, epidural veins
In the upright position what is the fullness of the epidural veins?
they’re enlarged d/t venous pressure
3 areas on spinal cord that are most vulnerable to deprivation of blood supply?
T1-T3; T5; L1
3 signs from ischemia of anterior central part of cord?
flaccid paralysis, loss of pain and temp sensation
Thrombosis of great radicular artery of Adamkiewicz may cause?
paraplegia
The spinal nerve that comes across the L4 area after you’ve punctured the skin, SQ fat, supraspinous, intraspinous, ligamentum flavum, epidural space, intrathecal space, filum terminale, cauda equina?
ventral and dorsal ramus
Motor fibers are?
A-a
These fibers are responsible for touch and pressure?
A-B
These fibers are responsible for proprioception?
A-y
These fibers are responsible for pain and temp and are lightly myelinated?
A-g
These fibers are preganglionic and autonomic?
B
These fibers are responsible for pain and temp and are not myelinated?
C
Biggest fibers?
A-a
Smallest fibers?
C
Most mylenated fibers?
A-a
2 types of lightly myelinated fibers?
A-g; B
2 types of moderately myelinated fibers?
A-a; A-B
Some indications for spinal and epidurals?
lower abdominal, inguinal, urogenital, rectal, lower extremity surgery, obstetric procedures, acute and chronic pain, diagnostic procedures
7 advantages to lumbar/epidurals?
less N/V, less urinary retention, reduced narc requirement, increased return to mental alertness, quicker to eat, void, ambulate, preemptive analgesia, pt safety (TURP), post op analgesia
6 debatable advantages to epidural/spinals?
safer; decreased blood loss, decreased thromboembolic events, decreased post op ileus, increased cardiac stability, increased respiratory stability
7 absolute contraindications to epidural/spinal?
pt refuses; increased ICP, severe hypovolemia, severe aortic or mitral stenosis, significant coagulopathy (prolonged INR, hepatic dysfunction, plt
Why is an epidural/spinal contraindicated in pt with increased ICP?
risk of brain herniation d/t increased CSF volumes
Some relative contraindications to epidural/spinal?
pt uncooperative; mild or mod stenotic valve, sepsis/elevated WBC/fever, progressive or unstable neuro disease, demyelinating lesions, chronic back pain or HA, multiple back surgeries, severe spinal deformity, heart blocks, age, HIV, difficult to discern effects of complications of block, don’t know length of surgery
6 controversial contraindications?
prolonged operation, major blood loss, maneuvers that compromise respiration, acute URI, full stomach, difficult airway
Use what 3 lab values as thromboprophylaxis and regional anesthesia guidelines?
PT, PTT, INR
3 herbs w the potential to affect coagulation?
garlic, ginko, ginseng
When you do a block, autonomic nerves are blocked where in response to sensory level?
2 levels above where sensory level is
When you do a block, motor neurons are blocked where in response to sensory level?
2 below
Onset of motor, autonomic, and sensory block?
autonomic, sensory, motor
Recover from motor, autonomic, and sensory block?
motor, sensory, autonomic
Autonomic neurons are what type of fibers and how are they myelinated?
B; light myelenation
Sensory neurons are what kind and how myelinated?
C; nonmyelinated
Sympathetic fibers arise from what level?
T5-L1
The sympathetic cardio accelerator fibers are at what level?
T1-T4
5 CV affects from block?
arterial vasodilation, decreased SVR, increased venous pooling, decreased venous return, slow of HR
Do not place the pt in T burg how long after receiving hyperbaric spinal?
30 min
The phrenic nerve is at what level of the spine?
C3-C5
5 pulmonary effects of spinal anesthesia?
loss of accessory muscles, intercostal nerve paralysis, loss of perception of breathing, small decrease in VC, impaired cough
GI effects from spinal?
increased peristalsis, relaxed sphincter
What happens to thermoregulation with spinal?
decreased thermoregulation
2 neuro effects from spinal?
CNS depression, decreased stress response
5 immediate complications from spinal?
total spinal, cardiac arrest, failed spinal, GI complications, IV injection/local toxicity
If you inject the dura, what will result?
total spinal
Symptoms of total spinal?
agitation, nausea, severe hypotension, bradycardia, resp insufficiency, unconsciousness, apnea
Early symptom of cardiac arrest bc of spinal?
profound bradycardia
Person most at risk for cardiac arrest after spinal?
young and healthy
Response to decreased preload?
bradycardia
Immediate GI complications from spinal/epidural?
N/V 25%
Good antiemetic for spinal/epidural?
atropine
Cerebral ischemia in spinal is d/t?
hypotension
3 things you can do to decrease incidence of IV injection?
aspirate prior to injection, use test dose with epidurals, WAIT for result
CNS toxicity common with which LA?
lido
3 signs of CNS toxicity?
tingling, strange taste, visual disturbances
LA that produces cardiac toxicity?
marcaine
6 delayed complications from spinal and epidural anesthesia?
PDPH, urinary retention, backache, transient neuro symptoms, infection, major neuro injuries
Cauda equina syndrome symptoms?
weakness of lower extremities, urinary incontinence, sexual dysfunction, fecal incontinence, post void incontinence
Name a couple characteristics of saddle anesthesia.
lack of ankle reflexes, is not cure, either goes away or does not
Solution implicated in saddle anesthesia?
high dextrose containing solutions; 10% lido very hyperbaric and concentrated
Most common complication of SAB?
PDPH
Cause of PDPH?
leakage of CSF thru dural hole. CSF pressure falls. brain stem drops in to foramen magnum
Needle gauge size which is a risk factor for PDPH ?
17 g Touhy; 20 g Sprotte
What’s something you can do with the needle to reduce risk of PDPH?
keep parallel to fibers to avoid cutting
PDPH is highest in what population? And lowest in?
pregnant young female; elderly male
Do multiple attempts place the pt at risk for PDPH?
yes
Why does marcaine produce ventricular arrhythmias?
it is highly lipid soluble and gets in to the heart quickly
Onset of PDPH?
12-72 hours
Symptoms of PDPH?
POSITIONAL HEADACHE, HA behind eyes moving posteriorly to occiput and extending to neck and shoulders, throbbing, constant, associated with photophobia and nausea
Treatment of PDPH?
recumbent positioning, analgesia, fluids, caffeine, autologous epidural blood patch, 15-20 mL blood, at or one level below leak, conservative for 12-24 hours
What type of relief do you get from administering 15-20 mL of blood one level below leak in response to a PDPH?
immediate
GI contraindication for spinal/epidural?
bowel obstruction
What is the cause of backache from an epidural/spinal?
profound skeletal muscle relaxations, positioning (lithotomy) may cause ligament strain
Treatment for backache after epidural/spinal?
reassurance, rest, heat, mild analgesics, resume ADLs
7 causes of paralysis from epidural or spinal?
direct needle trauma, positioning, surgical, viral, bacterial, chemical, hematoma/ischemia
What are transient neurological symptoms?
pain or dysthesia in the buttocks, thighs, or lower limbs
What is the etiology of transient neurological symptoms?
radicular irritation
Transient neurological symptoms usually resolve when?
in 1 week
3 risk factors for transient neurological symptoms?
lidocaine implicated, lithotomy, obesity
4 symptoms of cauda equina syndrome?
bowel and bladder dysfunction, paresis of the legs, patchy sensory deficits
What causes cauda equina syndrome?
neurotoxicity
4 possible factors for cauda equina syndrome?
multiple attempts, paresthesia, microcatheters, 5% lidocaine
Symptoms of epidural hematoma?
sharp back pain and leg pain with progression to numbness and motor weakness +/- sphincter dysfunction
What do you do if an epidural hematoma is expected and how quickly does it have to be evacuated?
STAT CT or MRI; 6 hours
Symptoms of epidural abscess?
backpain with fever
Treatment for epidural abscess?
antibiotics and surgical decompression
If you’re doing an epidural on a person with a fractured hip, how do you position that person?
fracture side down
Why would you use a paramedian approach?
enlarged target area, avoids the intraspinous ligament
How do you find the paramedian approach?
one fingerbreadth lateral and caudad to interspace
What 2 types of patients is the paramedian approach often used on?
elderly and arthritic patients
How do you direct the needle in paramedian approach?
10-15 degrees toward midline and cephalaud
How many mL/kg should you pretreat a spinal/epidural pt w?
10-15 mL/kg
How long does betadine have to be left on skin?
at least 1 minute
What size needle should you use to make the skin wheal?
25-30 g
If bone is encountered early what should you do?
withdraw and redirect needle upward
If bone is encountered later what do you do?
withdraw and redirect downward
If angling > 10-15 degrees in midline technique then redirect how?
more parallel to spinous processes
If dead parallel to spinous processes how should you redirect?
more cephalaud
Landmarks for upper extremities?
C5-T1
Landmarks for not on chest, underside of arms?
C6-C8
Landmarks for nipple line?
T4
Landmarks for umbilicus?
T10
Landmarks for inguinal ligament?
T12-L1
2 factors which give higher level of anesthesia?
higher dose and higher site of injection
Patient positioning when effects epidural anesthesia?
during and after injection
10 things which effect epidural/spinal?
position of pt during and after injection, baricity of solution, drug dosage, site of injection, age, curvature of the spine, drug volume, intraabdominal pressure (pregnancy, obesity, ascites), needle direction, barbatoge
Why does increased intraabodminal pressure effect spinal/epidural?
decreased CSF
Where does hyperbaric solution move?
dependent areas of spine
Hypobaric solution has addition of what and hyperbaric has addition of what?
sterile water; glucose
Where does hypobaric solution go?
floats upwards in spine
What happens in T burg and reverse T burg to spinals and epidural?
greater variability and less predictability
Most commonly used anesthetics for spinals and epidurals?
hyperbaric bupivacaine and tetracaine
12 mg ropivacaine= ___ mg bupivacaine
8
4 factors affecting duration of the spinal?
type of drug used-protein binding, amt of drug used, use of vasoconstrictors, use of opioids
What is the dose of epi usually added to spinal?
0.1-0.2
1:1000; 1:100,000; 1:200,000 what do those mean?
1 g: 1000 mL; 0.01mg/mL; 0.005 mg/mL
