Neuraxial Review Part 1 Flashcards
The anatomic landmark for spinal insertion is
Tuffier’s line
A spinal is based on
dosage
baricity
patient position influences block level
An epidural is a _____ block
volume block (volume determines level)
Absolute contraindications to neuraxial technique include:
patient refusal increased ICP coagulopathy or bleeding diathesis severe hypovolemia infection at the injection site severe aortic or mitral valve stenosis
Describe the jet velocity, mean gradient, and valve area for mild aortic valve stenosis.
jet velocity: <3.0
mean gradient: <25
Valve area: >1.5
Describe the jet velocity, mean gradient, and valve area for moderate aortic valve stenosis.
jet velocity: 3.0-4.0
mean gradient: 25-50
valve area: 1.0-1.5
Describe the jet velocity, mean gradient, and valve area for severe aortic stenosis.
jet velocity: >4.0
mean gradient: >50
valve area: <1.0
Describe the jet velocity, mean gradient, and valve area for critical aortic valve stenosis.
jet velocity: >5.0
mean gradient: >80
Valve area: <0.7
Relative contraindications for neuraxial technique include
uncooperative patient- inability to communicate/obtained informed consent or unable to assist
local anesthetic allergy
patient on anticoagulant or thrombolytic therapy
preexisting neurologic deficit
chronic headache or backache
severe spinal deformity
valvular stenosis
The relative contraindication of anticoagulant and thrombolytic therapy is inclusive of patients with comorbidities such as
atrial fibrillation
previous DVT
or postsurgical administration for initiation of DVT prophylaxis
Pre-procedure considerations for neuraxial include
versed
NPO status
consider fluid bolus administration
Pre-procedure monitoring includes:
patent peripheral IV suction airway supplies ECG, BP, pulse ox, possibly oxygen supportive meds: induction agent, paralytic, atropine, vasoactive meds
The following landmarks should be palpated for neuraxial technique
iliac crests
spinous processes of lumbar vertebrae
L2-L3 interspace is most common (examine one level above & below target)
Describe the Tuohy needle
pronounced curve
easier for novices
directional placement of catheter
Describe the Crawford needle.
is not curved
easier to insert
higher rate of dural punctures
The standard depth of insertion at the lumbar level for an epidural is
4-6 cm
The ligaments that are transversed include
supraspinous ligament
interspinous ligament
ligamentum flavum
The two type of techniques to discern that you are in the epidural space include
loss of resistance hanging drop (more pronounced at thoracic levels)
Describe the following markings on the epidural catheter:
dashed lines
two-dashed lines
thick line
dashed lines= 1 cm
two-dashed lines= 10 cm
thick line= 12 cm
Multiport epidural catheter considerations include
lower incidence of inadequate analgesia
higher incidence of accidental vein cannula
The epidural catheter should be advanced _________ past the needle hub
3-5 cm past the needle hub
Shallow displacement of the epidural catheter may result in
dislodgement from epidural space
Too deep placement of the epidural catheter may result in
puncture of dura
passage into epidural vein
migration through intervertebral foramen
When placing an epidural, you should NEVER attempt to
withdrawal the catheter through the needle- sheering will be created
An appropriate test dose of an epidural catheter is
3 mL of 1.5% lidocaine with epinephrine 1:200,000
45 mg of lidocaine
15 mcg of epinephrine
If the needle is placed in the intravascular space,
20% increase in HR & BP
The first spinal was placed in
1899
The specific gravity describes the
density of a substance compared to the density of water
SG water= 1.0
SG CSF= 1.003-1.009
Baricity is the
resting position of two fluids with different specific gravity when mixed in a single container- this helps determine the potential spread of LA in the SAH
The types of baricity include
isobaric- same, NS or CSF
hyperbaric- heavier (more dense than CSF), dextrose
hypobaric- LA is lighter than CSF, sterile water
Factors that influence local anesthetic level include
Most important: baricity, position of the patient drug dosage, site of injection
other: patient height, pregnancy, age, CSF volume, curvature of the spine, drug volume, intra-abdominal pressure, needle direction
Hyperbaric solutions mitigate to the
most dependent areas of the spine
T4-T8
When using a _____ spinal needle or smaller, first place an introducer
25 gauge
The following are examples of pencil point needles:
Gertie Marx
Sprotte
Whitacre
The following are examples of cutting needles
Quincke
A continuous spinal can be considered when
a “wet tap” occurs during epidural placement
-small incremental doses of LA are given until desired level achieved
A combined spinal epidural can be placed
two-level- spinal placed first, epidural catheter placed 1-2 levels above
one-level- placement of epidural needle, spinal needle passed through, small intrathecal dose injected, epidural catheter placed
Concerns of a combined spinal epidural include
intrathecal opioid effects on fetus
inability to ambulate after receiving narcotics
maternal hypotension and itching
Potential complications of combined spinal epidurals include
failure to obtain either intrathecal or epidural block catheter migration increased spinal level metallic particles PDPH neurologic injury
The paramedian approach can be used when
patient cannot flex spine- hx of previous spine surgery, RRA or hip or upper leg trauma
will not pass through supraspinous or interspinous ligaments
When the needle touches the superior crest of spinous process below the interspace or you have early contact
redirect cephalad
When the needle touches the inferior surface of the spinous process above the interspace or you have late contact,
redirect caudad
Describe what to do if the patient experiences a parasthesia.
stop- if it resolves, continue
if it does not, remove and reposition
If there is blood in the catheter,
withdrawal the catheter and replace
If you have absence of CSF, no paresthesia, and no bone then it is possible that
the dura was transversed- remove stylet and attach syringe
gently aspirate as you slowly withdrawal needle
may get CSF as needle tip is withdrawn in to subarachnoid space
If you have blood-tinged CSF
frank blood- withdrawal and reposition
blood-tinged CSF- allows CSF to flow for several seconds and if it clears aspirate & inject
Adding _______ to LA will slow absorption and prolong block
vasoconstrictors
Describe the onset of nerve blockade.
B A delta & C pain fibers A gamma A beta A alpha
The cardioaccelerator fibers are located at
T4
A delta & C fibers are responsible for
light touch, temperature, sensory loss
A alpha, a beta, and a gamma are responsible for
touch and proprioception
surgical muscle relaxation
may feel pressure
The ______ blockade is two dermatome levels higher than level of ____ block
autonomic
sensory
motor block is two levels below sensory block
Complications of neuraxial technique include
hypotension intercostal muscle paralysis apnea/phrenic nerve paralysis paresthesia subarachnoid or epidural hematoma meningitis/epidural abscess chemical meningitis nausea & vomiting post dural puncture headache
Risk factors for PDPH include
needle size & type patient population (younger, female & pregnancy)
Signs & symptoms of PDPH include
headache
photophobia
nausea
can be positional
Treatment for PDPH includes
recumbent position analgesics fluid administration caffeine stool softeners and soft diet epidural blood patch
