NEURAXIAL Flashcards
What are the 5 divisions of the spinal column and how many vertebrae are present in each?
33 vertebrae
C5 - T12 - L5 - S5 - C4
What are the anatomic borders of the facet joint?
Formed by the superior articular process of one vertebra and the inferior articular process of the vertebrae directly above.
Injury to the facet joint can compress the spinal nerve that exits the respective intervertebral foramina causing pain and muscle spasm along the associated dermatome
Order the 5 ligaments of the spinal column from posterior to anterior
Supraspinous - interspinous - ligamentum flavum - PLL - ALL
List all of the structures and spaces between the skin and spinal cord as they would be encountered during a subarachnoid block
skin - SQ - supraspinous - interspinous - ligamentum flavum - epidural - dura - subdural - arachnoid - subarachnoid - pia mater - spinal cord
What are the boundaries of the epidural space?
Cranial border = foramen magnum
Caudal border = Sacrococcygeal ligament
Anterior = PLL
Lateral = vertebral pedicles
Posterior = ligamentum flavum, vertebral lamina
What happens when you inject LA into subdural space during SAB? vs epidural
Epidural = high spinal w/delayed onset (15 - 20m)
Spinal = failed spinal
What is the plica mediana dorsalis, and what is its significance?
Controversial existence
Band of CT that courses between the ligamentum flavum and the dura mater. Conceivably creates a barrier that impacts the spread of meds in epidural space. Possible etiology for difficult epidural placement as well as unilateral epidural block
Important dermatome levels
C6 = thumb
C7 = pointer, middle
C8 = ring, pinky
T4 = nipple
T6 = xiphoid process
T10 = umbilicus
T12 = pubic symphysis
L4 = anterior knee
Site of action for spinal vs. epidural
Spinal = myelinated preganglionic fibers of the spinal nerve roots
Epidural = infuse thru the dural cuff before they can block the nerve roots. They also leak through the intervertebral foramen to enter the paravertebral area.
What contributes to the spread of LA in subarachnoid space?
Patient position
Baricity
Dosing
Site of Injection
Volume of CSF
Density of CSF
What is the primary determinant for spread of epidural anesthesia
Volume
Differential blockade for spinal anesthesia
1st = autonomic (+2 - 6 levels above motor)
2nd = sensory (+ 2 levels above motor)
3rd = motor
Differential blockade for epidural anesthesia
Only sensory & motor differential
Sensory is 2 - 4 dermatomes higher than motor block
A-Alpha
Skeletal muscle motor & proprioception
Blocked last
Heavily myelinated
12 - 20 um
B-Beta Fibers
Touch, Pressure
Blocked last
Heavy myelination
5 - 12 um
Gamma Fibers
Skeletal muscle tone
Blocked third
Medium myelination
3 - 6 um
Delta
Fast pain, temperature, touch
Blocked third
medium myelination
2-5 um
B Fibers
Preganglionic Fibers
Blocked 1st
Light myelination
3
C Fiber Sympathetic
Sympathetic = postganglionic ANS
Blocked 2nd
No myelination
0.3 - 1.3
C Fiber
Slow pain, temperature, touch
Blocked 2nd
No myelinaiton
0.4 - 1.2
Respiratory effects of neuraxial
Impaired intercostal muscles (inspiration and expiration)
Abdominal muscle (ability to cough and clear secretions)
If there is apnea, it’s d/t hypoperfusion
GI function & neuraxial
The gut receives PSNS from CN10 and SNS from sympathetic chain T5 - L2. Neuraxial increases PSNS = sphincters relaxed, peristalsis increased
What is the risk of neuraxial anesthesia with the patient with a coagulopathy? What labs?
Plt < 100
PT, aPTT, bleeding time 2x normal
Cardiac pathologies that are a c/i
AS
MS
HCM
CSF s/g
1.002 - 1.009
Lordosis
T7
Kyphosis
L3, C5
Cutting point spinal needles
Quinke, Pitkin
Pencil point needles
Sprotte, whitacre ( has a whiittle hole)
Rounded bevel spinal needle
Green
Name the three epidural needles
Tuohy 30 degrees
Hustead 15 degrees
Crawford 0 degrees
Caudal dosing in children
Sacral = 0.5 mL/kg
T10 = 1 mL/kg
Mid Thoracic = 1.25 mL/kg
Caudal dosing in adults
Sacral = 12 - 15 mL
Low Thoracic (T10) = 20 - 30
Absolute c/i to caudal
spina bifida, meningitis, meningomyelocele of sacrum
MOA of neuraxial opioids
-afferent pain tx inhibition in rexed lamina 2
-decreased camp
-decreased ca
-increased k
sufentanil intrathecal & epidural dose
5 - 10 mcg
25 - 50 mcg
fentanyl dosing
10 - 20 mcg
50 - 100 mcg
hydromorphone
0.5 - 1 mg (e only)
meperidine
10 mg
25 - 50 mg
morphine
0.25 - 0.3 mg
2 - 5 mg
lipophilicity
sufent > fent > meperidine > dilaudid > morphine
Glycoprotein IIb/IIIa Antagonists - How long do you wait before neuraxial
Ex = tirofiban, eptifibatide, abciximab (TEA)
Tirofiban & Eptifabatide = 4 - 8 horus
Abciximab = 24 - 48 hours
Thienopyridine - how long do you wait
Clopidogrel - 5- 7 days
Prasurgrel - 7- 10 days
Ticlopidine - 10 days
restart in 24 hours
Unfractionated heparin
Low dosing (< 5k) = 4 - 6hours
High dosing < 20,000 = 12 hours
> 20, 000 = 24 hours
restart in 1 hour
hold 4 - 6 hours before removal
Warfaarin
5 days and verify INR
10a anti-factor (oral)
apixaban
betrixabaan
edoxaban
rivoraxaban
WAIT 72 hours prior to placing
removing = 6 hours before 1st dose
Thrombolytic agents
i.e., tpa, streptokinase, alteplase, urokinase
ABSOLUTE C/I
Conus medullaris in adult
L1 L2 vs L3 in kids
Subarachnoid space ends @ S2, vs S3 (kids)
Cauda equina cause
Neurotoxicity
5% lido & microcatheters = RF
TNS
Cause = positioning, muscle spasm
RF = lido, lithotomy, ASC, knee arthro
s/s = back/butt pain that radiates to both legs
develops in 6 - 36 hours, persists for 7 days
Most common organism for post-spinal meningitis
STREPTOCOCCUS VIRIDANS FROM THE MOUTH
