Regional/Neuraxial Flashcards
What forms the anterior portion of the vertebral arch
Vertebral body.
What part of the vertebrae is palpated during spinal assessment
Spinous process
Which type of cartilage covers the articular surface of the facet joints and permits a gliding motion between cartilage
Hyaline cartilage
The cervical and thoracic spinous process project in which direction to provide stabilization and protection to the spinal column
Caudal
The lumbar spinous process project in which direction allowing for easier access for needle placement
Posterior
Caudal anesthetics are accomplished through the palpation of what
Sacral cornua
What three ligaments aid in the placement of spinal and epidural anesthetics
Spinous ligament, intraspinous ligament, ligamentum flavum
Which spinal ligament connects the apices of the spinous process. It is thick and serves as the major ligament in the cervical and upper thoracic regions
Supraspinous ligament
Which spinal ligament runs between spinous processes
Intraspinous ligament
Which ligaments are the strongest, they join the vertebral arches through vertical extensions of adjacent lamina. They run caudad from the inferior border of one lamina to the upper border of the lower lamina
Ligamentum flavum
Which ligament is responsible for upright posture
Ligamentum flavum
What are the support tissues that provide a protective covering for the cord and nerve roots from the foramen magnum to the base of the cauda equina
Meninges
What are the layers of the meninges called from internal to most external
Pia, arachnoid, dura mater
Spinal cord nerve roots exit through what
Intervertebral foramen
Which meningeal space is filled with CSF
Subarachnoid
Which meningeal layer is in contact with the outer layer of the spinal cord
Pia
What is the potential space outside the dural sac but inside the vertebral canal and is continuous from the base of the cranium to the base of the sacrum at the sacrococcygeal membrane
Epidural space
Which space contains fat that acts as a pad and lubricant for movement of neural structures
Epidural space
What is the average distance from skin to lumbar epidural space using a midline approach
5cm (2.5-8cm)
Where is the epidural space the largest
Midline of the midlumbar region at 5-6cm
The epidural space in what region is only 1.5-2mm
Cervical
The epidural veins are most prominent in the _____ portion, making ____ needle approach more safe
Lateral, midline
The potential for injury or accidental cannulation of epidural veins is more common in obese and pregnant women due to what physiological alterations
Engorged and swollen epidural veins from increased abdominal pressure
Which segments of the vertebral column have posterior (concave) curvatures
Thoracic and sacral
Which segments of the vertebral column have anterior (convex) curvatures
Cervical and lumbar
In the supine position, the apex of the lumbar curve occurs where
L3-L4
Lateral curvature of the spine
Scoliosis
Excessive posterior curvature or hump
Kyphosis
Hollowing of the back in obesity and pregnancy
Lordosis
Level of dermatomal sensory block can be determined by what methods
Scratch or temperature sensation
What is the primary site of action of local anesthetics
Nerve roots within the spinal cord
LA’s affect nerve transmission by inhibiting what type of ion channel
Sodium
Do LA’s inhibit neural transmission to the brain
No, there is neuronal transmission but no sensory perception
What is a differential block
Blockade of autonomic transmission, but not sensory or motor.
How does LA injected into the epidural space travel to get to the site of action
Bulk flow, NOT DIFFUSION, noncircumferential spread
What is considered the more dense neuraxial anesthetic
SAB
How can we make epidural a more dense block
Allow time, increase volume, increase concentration
What is selective anesthesia
Injecting small amount of LA into the subarachnoid space that directly supply nerve roots to the surgical site.
Which LA can produce single lower limb anesthesia
Hyperbaric bupivicaine
What level block is required for TURP
T10
Spinal anesthesia for TURP decreases the risk of what
Bladder overdistension and rupture
What type of LA should be used for patients in the jackknife or prone position for perianal procedures
hypobaric (LA will rise to the upright sacrum and coccyx
What two adjuncts can be added to spinal anesthesia to increase the duration
Opioids, A-2 agonists like clonidine
What preoperative findings are contraindications to spinals
Increased ICP, coagulopathy skin infection at the site, hypovolemia, spinal cord disease, hypertropic cardiomyopathy, aortic stenosis, long surgical time.
Epidural placement in a patient with increased inter cranial pressure increases the risk of what
Herniation
What are some spinal anatomy relative contraindications to spinal anesthesia
Kyposcoliosis, arthritis, osteoporosis, fusion and scaring of the vertebrae.
What is the most prevalent cause of peripheral polyneuropathy
DM
What are potential causes of the double crush phenomenon
Epi in the LA, needle trauma, toxic reaction from the LA
If the patient has a normal coagulation profile preop this medication is safe to give as a continuous infusion intraop after receiving a spinal anesthetic
Heparin
What is the median time to onset of neurologic dysfunction after initiation of LMWH
3 days
What is the most common causative organism in epidural abscess
staph. Aureus
Irritation to the meninges by foreign substances causes what two complications
Arachnoiditis and aseptic meningitis
What are the names of the cutting needles
Quincke, Greene, and Pitkin
What are the names of the non-cutting needles
Sprottle, Whitacre, and Pencan
What is the size range of spinal needles
22-29 gauge
What is the most popular spinal needle gauge and length
25-27G gauge, 3.5 inch long
To minimize the risk of PDPH, the bevel of the needle should be inserted _____ to the longitudinal dural tissue fibers to minimize risk of PDPH
Parallel
The line formed between the tops of the iliac crests
Tuffiers or intercristal line
Spinal anesthetic skin prep should be in contact with the skin for at least how long before dried residue can be wiped off
1 minute
Wiping excess skin prep off the patients skin reduces the risk of what
Chemical arachnoiditis
Removing excess iodine with what solution reduces the iodines antiseptic effect
Alcohol
An introducer should not be inserted to the depth of what spinal tissue layer
Subarachnoid
The average depth to the epidural space and dura is typically how much
4-5cm, rarely up to 9cm
If an introducer is inserted into the subarachnoid space it is likely to cause what
PDPH
After breaching the subarachnoid space, and return of CSF, the needle can be rotated how much to confirm the needle is in the subarachnoid space
360 degrees in 90 degree increments
Bracing the spinal needle against the patient back with the non dominant hand is called what
Bromage grip
Which approach to neuraxial anesthetic is often easier in arthritic and elderly patients
Paramedian, to avoid calcified interspinous ligaments
Which interspace has the largest interlaminar space
L5
Which approach to neuraxial is best for pelvic and perineal surgical procedures
Taylor approach
The specific gravity of CSF is affected by what two things
Protein level, glucose levels, uremia, temperature,
What decreases CSF specific gravity
Liver disease and jaundice (due to bilirubin in the CSF), warm temperature,
An increase of 1 degree Celsius, changes the specific gravity of CSF by how much
0.001 decrease
What is the resting position of two fluids with different specific gravities called
baracity
When the ratio of specific gravity to local anesthetic to patient CSF equals 1, the Local anesthetic is considered
Isobaric
When the ratio of specific gravity to local anesthetic to patient CSF is less than 1, the Local anesthetic is considered
Hypobaric
When the ratio of specific gravity to local anesthetic to patient CSF is more than 1, the Local anesthetic is considered
Hyperbaric
What direction to hypobaric and hyperbaric LA’s travel in the CSF
Hyperbaric sinks, Hypobaric rises
What solution are hypobaric and hyperbaric solutions mixed in
Hyperbaric dextrose, Hypobaric water, Isobaric saline
What factors related to spread of LA in the CSF can we control (4)
Dose, injection site, baracity, position of the patient
What determines the duration of the spinal anesthetic
LA chosen, and total dose
Highly ___ bound LA’s have a long duration of action
Protein bound
Which LA’s are highly protein bound leading to long duration of action
Tetracaine, bupivicaine, ropivicaine
Which LA’s are less protein bound, leading to a shorter duration of action
Lidocaine and mepivicaine
What medication increase the duration of action of LAs
Epi, 0.1-0.2mL of 1:1000 (1mg/mL)
How does epi increase the duration of action of LA’s
Causing vasoconstriction and preventing washout or uptake into the circulation
The addition of epinephrine is most appreciated with which LA
Tetracaine, less with lidocaine, and minimal with bupivicaine
What is the dose of fentanyl added to LA
25-50mcg
What is the dose of sufentanil added to LA
2.5-10mcg
What is the dose of morphine added to LA
250mcg
What is the dose of clonidine added to LA
150mcg
Fentanyl, sufentanil, morphine and clonidine act at which receptors
Opioid and a-2 adrenergic receptors
Increasing the dose of hyperbaric bupivicaine from 10mg to 15mg prolongs the duration of the sensory block by how much
50%
Hyperbaric solution injected while in the sitting position during and after block will cause what
Saddle block
Continuous spinal anesthetic catheters should be inserted to what depth into the subarachnoid space
2-3cm
What are symptoms of cauda equina syndrome
LE weakness, bowel and bladder dysfunction, persistent paralysis
Which LA is the most common culprit of cauda equina syndrome and transient neurologic syndrome
5% lidocaine
Pain the radiates to both legs originating in the gluteal region is called what
Transient neurologic syndrome
What is the onset and duration of transient neurologic syndrome
Onset within 24 hours, duration of 10 days
What is the treatment of transient neurologic syndrome
NSAID’s and sometimes opioids
What explains differential blockage of spinal anesthetics
Neurons having different levels of susceptibility to LAs.
Order proprioception, pinprick, and temperature in the correct differential blockage
Proprioception, light touch, cold sensation, pinprick
Describe differential blockage height for autonomic, sensory and motor block
Autonomic is 2-7 dermatomes higher then sensory, and sensory is 2 dermatomes higher than motor block.
Somnolence from neuraxial anesthesia is caused by decreased sensory input to which area of the brain
Reticular activating system
What are the effects of sympathetic blockade
Arterial vasodilation, decreased SVR, venous pooling, reduced venous return
What is the fluid bolus dose, pre-neuraxial anesthetic to prevent hypotension
15mL/kg, 15 minutes before neuraxial placement
Which medication can block the reflexive decrease in heart rate caused by sympathetectomy, blocking bradycardia and hypotension
5-HT3 antagonist ondansetron 4-8mg
What medication should be used to treat symptomatic bradycardia caused by neuraxial anesthesia
Ephedrine 5-10mg
Which respiratory dynamics are not affected by neuraxial (4)
Tidal volume, rate, minute ventilation, ABG tensions
Neuraxial anesthesia affects which muscles of respiration
Intercostals and abdominal muscles
How does neuraxial affect the GI system
Increased peristalsis, decreased sphincter tone, increased intraluminal pressure, increased GI blood flow, increase PNS tone
GI hyperperistalsis and parasympathetic dominance causes what
Increased risk of Nausea and vomiting
What causes PDPH
Leak in the CSF from neuraxial catheter placement, there is loss f hydraulic pressure causing the brain to drop into the foramen magnum and create tension on the meninges and tentorium.
What vasconstrictor drugs help treat PDPH
Caffeine and theophylline
What type of spinal needle has the highest risk of PDPH
16 Touhy
Contributing factors for PDPH include
Anxiety, lack of sleep, hypoglycemia, lack of morning caffeine
Pain severity scores are not improved in PDPH with which of the following medications: Gabapentin, theophylline, hydrocortisone, sumatriptan
Sumatriptan
What is the definitive treatment for PDPH
Blood patch
Blood injected for a epidural blood patch will spread in which direction
Cephalad
What are some triggers for identifying when enough blood has been injected for a epidural blood patch
Pressure ***, back or legs, about 12-15mL
Nausea during neuraxial anesthesia can be attributed to cerebral ischemia which activates which area of the brain
Medulla
Which medication added to spinal anesthetics increases the risk of PONV
Epinephrine, intrathecal morphine
Urinary retention after neuraxial is increased in patient who received what
Long acting LAs, adding epi, epidural analgesia
