REGIONAL-neuraxial block Flashcards
(276 cards)
1
Q
What are the 4 points of spinal curvature
A
- Cervical and lumbar lordosis
2. Thoracic and sacral kyphosis
2
Q
Which portion of the vertebrae project laterally
A
The 2 transverse processes
3
Q
Which portion of the vertebrae project posteriorly
A
The spinous process
4
Q
Which vertebral landmark helps determine midline
A
Spinous process
5
Q
What distinction differentiates lumbar vertebrae from thoracic and cervical vertebra
A
The orientation of the spinous process
- Lumbar SP project posteriorly
- C and T-spine SP angle in caudal direction
6
Q
How does the difference in spinous process angle of the lumbar vs thoracic vertebra affect epidural access
A
The thoracic SP angle caudally requiring a more cephalad approach with the needle
7
Q
How does the altered anatomy of C1 and C2 affect function
A
Allows for head rotation at the AO joint
8
Q
Which vertebra doesn’t have a vertebral body
A
C1 atlas
C2 has a very small vertebral body
9
Q
Which vertebra has the odontoid process
A
C2 Axis
Also called the dens
10
Q
Where do spinal nerves exit the vertebral column
A
the intervertebral foramina
11
Q
What portion of the vertebrae form the posterior border of the intervertebral foramina
A
Facet joints
12
Q
What alterations reduces the size of the intervertebral foramina
How does this impact the spine
A
Disc degeneration reduces intervertebral foramina size
This can cause nerve compression
13
Q
What processes form the facet joints
A
Inferior articular process of the top vertebra
Superior articular process of the bottom vertebra
14
Q
Name the corresponding posterior surface landmarks for each vertebra C7 T3 T7 L1 L4 S2
A
C7 = vertebra prominens T3 = Spine of scapula (top) T7 = Inferior angle of scapula L1 = Rib 12 margin L4 = Superior aspect of iliac crest S2 = Posterior superior iliac spine
15
Q
Name the corresponding vertebra for each surface landmark Vertebra prominens= Spine of scapula= Inferior angle scapula= Rib 12 margin= Superior iliac crest= PSIS=
A
Vertebra prominens= C7 Spine of scapula= T3 Inferior angle scapula= T7 Rib 12 margin= L1 Superior iliac crest= L4 PSIS= S2
16
Q
What is the landmark called that corresponds to the superior aspect of the iliac crest
Correlates with which vertebra
A
Intercristal line aka Tuffier’s line
L4
17
Q
What do the interspaces above and below the intercristal line correlate with
A
Above = L3-L4 space Below = L4-L5 space
18
Q
In infants up to 1 year, what interspace level does the intercristal line correlate
A
L5 - S1 interspace
19
Q
4 facts about the sacral hiatus
A
- Coincides with S5
- Results from incomplete fusion of laminae at S5 (or S4)
- Covered by the sacrococcygeal ligament
- Entry point to epidural space
20
Q
2 facts about the sacral cornua
A
- Bony nodules that flank the sacral hiatus
2. Result from incomplete development of facets
21
Q
Where does the spinal cord end in adults vs infant
What is this anatomy called
A
Conus medullaris
Adults = L1-L2
Infant=L3
22
Q
What is the cauda equina
A
Bundle of spinal nerves extending FROM the conus medullaris to the dural sac
23
Q
What spinal levels make up the cauda equina
A
Nerves and nerves roots from L2 - S5, coccygeal nerve
24
Q
Where does the dural sac terminate in adults vs infants
A
Adult = S2 Infant = S3
25
What space terminates at the dural sac
The subarachnoid space
26
What is the filum terminale
A continuation of pia mater from the conus medullar that extends to the coccyx
27
What is the function of the filum terminale
Anchors the spinal cord to the coccyx
28
What is the bundle of spinal nerves that extend from the conus medullaris to the dural sac
Cauda equina
29
The filum terminale is fixated at which two points
Conus medullaris and coccyx
30
List the 5 ligaments of the spinal column in order from superficial to deep
1. Supraspinous
2. Interspinous
3. Ligamentum flavum
4. Posterior longitudinal
5. Anterior longitudinal
31
List the ligaments the needle passes through when performing a spinal, from superficial to deep
1. Supraspinous ligament
2. Interspinous ligament
3. Ligamentum flavum
32
Which spinal ligaments are not traversed when performing a spinal
Posterior longitudinal ligament
| Anterior longitudinal ligament
33
Describe the anatomy of the supraspinous ligament
Runs the length of the spin and joins the tips of the spinous processes
34
4 facts of the ligamentum flavum
1. Two flava run the length of the spinal canal
2. Form the dorsolateral margin of epidural space
3. Thickest in the lumbar region
4. Piercing them contributes to LOR when needle enters the epidural space
35
What ligament forms the dorsolateral margin of the epidural space
Ligamentum flavum
36
When using the paramedian approach to perform a spinal, which ligaments are traversed
Which ligaments are not traversed
Traversed = ligamentum flavum
NOT traversed = supraspinous and interspinous ligaments
37
When is the paramedian approach for performing a spinal useful
1. Calcified interspinous ligament
| 2. Pt cannot flex their spine
38
How is the paramedian approach different from the midline approach
1. 15 degrees off midline
OR
2. 1 cm lateral and 1 cm inferior to interspace
Doesn't traverse supraspinous or interspinous ligaments
39
What is the order of meningeal layers of the spinal cord from the outside in
Dura
Arachnoid
Pia
40
What are the layers traversed when doing a spinal
1. Skin
2. SQ tissue
3. Supraspinous ligament
4. Interspinous ligament
5. Ligamentum flavum
6. Epidural space
7. Dura mater
8. Subdural space
9. Arachnoid mater
10. Subarachnoid space
41
What is another name for epidural veins
Batson's plexus
42
From where do epidural veins drain blood
From the spinal cord
43
What happens to epidural veins with pregnancy and obesity
Increased intra-abdominal pressure causes engorgement of epidural veins
44
What risks are increased when performing an epidural during pregnancy
Increased risk of cannulation or injury
45
What occurs if medication is inadvertently injected into the subdural space when performing a spinal or epidural
Spinal dosing = failed spinal
| Epidural dosing = high spinal
46
What space is the target when performing a spinal
subarachnoid space
47
What structures are contained in the subarachnoid space
CSF
Nerve roots
Rootlets
Spinal cord
48
Which meninge is never punctured during spinal anesthesia
Pia mater
49
How many paired spinal nerves are there
31
50
What is the anatomy of each spinal nerve
They each have a posterior (dorsal) nerve root or anterior (ventral) nerve root
51
What information is carried via posterior vs anterior nerve roots
```
Posterior = sensory
Anterior = motor, autonomic
```
52
What is a dermatome
An area of skin that's innervated by a dorsal spinal nerve
53
```
What is the corresponding cutaneous landmark for each nerve root
C6
C7
C8
T4
T6
T10
T12
L4
```
```
C6 = thumb
C7 = 2nd/3rd digits
C8 = 4th/5th digits
T4 = Nipple line
T6 = Xiphoid process
T10 = umbilicus
T12 = Pubic symphysis
L4 = Anterior knee
```
54
What nerve serves as sensory innervation of the face
The 3 branches of cranial nerve V (trigeminal nerve)
55
What are the 3 branches of cranial nerve V
```
V1 = ophthalmic
V2 = Maxillary
V3 = Mandibular
```
56
```
What spinal nerve roots correspond to the following landmarks
Anterior knee =
Thumb =
Umbilicus =
Nipple line =
2nd/3rd digit =
Pubic symphysis =
4th/5th digits =
Xiphoid process =
```
```
Anterior knee = L4
Thumb = C6
Umbilicus = T10
Nipple line = T4
2nd/3rd digit = C7
Pubic symphysis = T12
4th/5th digits = C8
Xiphoid process = T6
```
57
What 3 surgical procedures require sensory level at T4
| Landmark
1. Upper abd surgery
2. C-section
3. Cystectomy
Landmark = nipple line
58
What 2 surgical procedures require sensory level block at T6-T7
Landmark
1. Lower abd surgery
2. Appendectomy
Landmark = xiphoid process
59
What 3 surgical procedures require sensory level block at T10
Landmark
1. Total hip arthroplasty
2. Vaginal delivery
3. TURP
Landmark = umbilicus
60
What surgery requires sensory level block at L1 - L3
| Landmark
LE surgery
Landmark = inguinal ligament
61
What surgery requires sensory block at L2-L3
Foot surgery
62
What surgery requires sensory block at S2-S5
Hemorrhoidectomy
63
Where is catheter insertion location for thoracic surgeries like thoracotomy or thoracic aneurysm repair
How much local
T2 - T6
Local = 5-10 mL
64
Where is catheter insertion location for upper abdominal surgeries
How much local
T6 - L1
Local = 10 - 20 mL
65
Where is catheter insertion location for LE surgeries like THA or TKA
How much local =
L2 - L5
Local = 20 mL
66
What are 4 key benefits of thoracic epidural vs lumbar epidural
1. Superior analgesia
2. Minimizes surgical stress response
3. Reduces incidence of postop pulmonary complications
4. Can spare LE nerves, allowing for postop ambulation
67
What are 2 reasona thoracic epidural may be more challenging than a lumbar epidural
1. Spinous processes are more angles in the T-spine
| 2. The epidural space is small
68
When an epidural is combined with GA, there can be an increased risk of what 3 cardiopulmonary issues
1. bradycardia
2. HoTN
3. Altered airway resistance
69
Why is bradycardia possible when epidural anesthesia is used with GA
The cardioaccelerator nerves are blocked at T1 - T4
70
Why is HoTN possible when epidural anesthesia is used with GA
There's a decrease in CO and increased vasodilation
71
What airway changes occur d/t epidural anesthesia in conjunction with GA
Epidural anesthesia can increase vagal influence on airways (increased resistance and constriction)
72
What is the primary site of spinal anesthesia action in the subarachnoid space
Myelinated preganglionic fibers of spinal nerve roots
73
what is the site of action for epidural anesthesia
- Diffusion through the dural cuff to the nerve root
| - Leaking into the intervertebral foramen to enter the paravertebral area
74
How is the spread of local anesthetic controlled with spinal anesthesia (4)
1. Baracity
2. Pt position during and after block placement
3. Dose
4. Site of injection
75
What are 2 non-controllable factors that affect spread of spinal anesthesia
1. Volume of CSF
| 2. Density of CSF
76
List 7 factors that do not affect spread of spinal anesthesia
1. Barbotage
2. Increased intra-abdominal pressure (i.e. cough)
3. Speed of injection
4. Orientation of bevel
5. Addition of vasoconstrictor
6. Weight
7. Gender
77
What is the most reliable factor of intrathecal spread when using hypo- or isobaric solution
Dose
78
What is the most reliable factor of intrathecal spread when using hyperbaric solution
Baracity
79
What are the 2 most reliable determinants of intrathecal spread
1. Dose when hypo- or isobaric
| 2. Baracity when hyperbaric
80
What 3 factors significantly affect spread of epidural anesthesia
1. LA volume
2. Level of injection
3. LA dose
81
What are 2 non-controllable factors that significantly affect spread of epidural anesthesia
1. Pregnancy
| 2. Old age
82
What are 2 factors that have a small effect on epidural anesthesia spread
1. LA concentration
| 2. Patient position
83
What are 3 factors that have a SMALL effect on epidural anesthesia spread
1. Height
2. Body weight
3. Pressure in nearby body cavities
84
What are 3 factors that do NOT affect epidural anesthesia spread
1. Additives
2. Direction of bevel
3. Speed of injection
85
How does the level of injection affect epidural anesthesia spread
Lumbar
Midthoracic
Cervical
1. Spread is mostly cephalad
2. Spread is equally cephalad and caudad
3. Spread is mostly caudad
86
What is the order of blocking fibers with local anesthetic
1. Autonomic fibers
2. Sensory fibers
3. Motor neurons
87
How does neurologic function return as local anesthetic decreases
1. motor neuron
2. sensory fibers
3. Autonomic fibers
88
How are the levels of blockade for autonomic, sensory, and motor fibers distributed with spinal anesthesia
Autonomic block is 2-6 levels above sensory
| Sensory is 2 levels above motor
89
How are the levels of blockade for autonomic, sensory, and motor fibers distributed with epidural anesthesia
Sensory and SNS block are 2-4 levels above motor
90
Why are the level of autonomic and sensory blocks higher than motor
Because the LA concentration required to block sensory fibers is less than motor
The concentration to block SNS fibers is less then sensory
As the LA anesthetic spreads upward, the concentration is less but still effective as SNS or sensory block
91
What is the first sensory modality blocked
Sense of temperature
92
How can you test the first portion of differential blockade
With an alcohol pad, they won't feel cold
93
What is the second sensory modality blocked
Pain
94
How can you test the second portion of differential blockade
Pinprick
95
What is the last sensory modality blocked
Sense of light touch or pressure
96
What is the method of monitoring motor block
Modified Bromage Scale to assess the degree of motor block
97
What does the modified bromage scale assess
Motor block of the lumbosacral nerves
98
What are the levels of the modified bromage scale
0=no motor block
1=Cannot raise an extended leg; moves knees/feet
2=Cannot raise an extended leg or move knee; moves feet
3=Complete motor block; no leg, knee, or feet movement
99
Peripheral nerve fiber velocity greatest to least
A alpha = A beta > A gamma = A delta > B > C sympathetic = C dorsal root
100
Peripheral nerve fiber block onset from first to last
```
1st = B
2nd = C sympathetic, C dorsal root
3rd = A gamma, A delta
4th = A alpha, A beta
```
101
Peripheral nerve fiber myelination from most to least
Heavy: A alpha = A beta Medium: A gamma = A delta
Light: B
C fibers = NO myelination
102
Why are B and C fibers blocked first and second
B fibers = preganglionic ANS fibers
| C fibers = Postganglionic ANS fibers (then pain/temp/touch)
103
What structure must be traversed by epidural LAs and what is their primary target?
First diffuse through the dural cuff before they can anesthetize the nerve root (target)
104
What is the primary drug-related determinant of local anesthetic spread in the epidural space
The volume of LA
105
What type of nerve fiber is blocked first after a spinal anesthetic
Type B - preganglionic ANS fibers
106
Function of A alpha fibers
Skeletal muscle = motor
Proprioception
(preserved with anterior spinal artery ischemia)
107
Function of A beta fibers
Touch
| Pressure
108
Function of A gamma fibers
Skeletal muscle tone
109
Function of A delta fibers
1. Fast pain
2. Temperature
3. Touch
110
Function of B fiber
preganglionic ANS fibers
111
Function of C sympathetic fibers
Postganglionic ANS fibers
112
Function of C dorsal root
1. Slow temp
2. Temperature
3. Touch
113
The addition of what solution leads to a hyperbaric solution in spinal anesthetic
Dextrose
114
```
Spinal dose Bupivacaine 0.5 - 0.75%
Dose T10=
Dose T4=
Onset=
Duration plain=
Duration epi=
```
```
Level T10= 10-15 mg
Level T4= 12-20 mg
Onset= 4-8 min
Duration plain= 130-220 min
Duration epi= +20-50%
```
115
```
Spinal dose Levobupivacaine 0.5%
Level T10=
Level T4=
Onset=
Duration plain=
```
Level T10= 10-15 mg
Level T4= 12-20 mg
Onset= 4-8 min
Duration plain= 140-230 min
116
```
Spinal dose Ropivacaine 0.5-1%
Level T10=
Level T4=
Onset=
Duration plain=
```
Level T10= 12-18 mg
Level T4= 18-25 mg
Onset= 3-8 min
Duration plain= 80-210 min
117
```
Spinal dose 2-Chloroprocaine 3% (w/wo dextrose)
Level T10=
Level T4=
Onset=
Duration plain=
```
Level T10= 30-40 mg
Level T4= 40-60 mg
Onset= 2-4 min
Duration plain= 40-90 min
118
```
Spinal dose Tetracaine 0.5-1% (with dextrose)
Level T10=
Level T4=
Onset=
Duration plain=
Duration epi=
```
```
Level T10= 6-10 mg
Level T4= 12-16 mg
Onset= 3-5 min
Duration plain= 90-120 min
Duration epi= +20-50%
```
119
```
List the following meds from quickest onset to slowest
Tetracaine
Chloroprocaine
Bupivacaine
Ropivacaine
Levobupivacaine
```
2-Chloroprocaine, Tetracaine, ropivacaine, bupivacaine = levobupivacaine
120
```
Duration of the following meds from longest to shortest
Tetracaine
Chloroprocaine
Bupivacaine
Ropivacaine
Levobupivacaine
```
Levobupivacaine > Bupivacaine > Ropivacaine > Tetracaine > 2-Chloroprocaine
121
Which LA requires the largest dose for spinal anesthesia
Chloroprocaine (30-60 mg)
122
Which LA requires the smallest dose for spinal anesthesia
Tetracaine (6-16 mg)
123
What is the initial dose for epidural anesthetic
1-2 mL per segment to be blocked
124
What is the "top-up" dose for epidural anesthesia
50-75% of initial dose
125
When is a "top-up" dose administered
Before the block recedes more than 2 dermatomes
126
Why is LA spread greater in the thoracic region vs the lumbar with an epidural
The thoracic epidural space is smaller than lumbar
127
What is the primary determinant of epidural block height
Volume
128
What is the primary determinant of epidural block density
Concentration
129
How is a "walking epidural" achieved
Low concentration that provides analgesia but preserves motor function
130
Epidural with 2-Chloroprocaine
Concentration=
Onset=
Duration=
```
Concentration= 3%
Onset= 5-15 min
Duration= 30-90 min
```
131
Epidural with Lidocaine
Concentration=
Onset=
Duration=
```
Concentration= 2%
Onset= 10-20 min
Duration= 60-120 min
```
132
Epidural with Ropivacaine
Concentration=
Onset=
Duration=
```
Concentration= 0.1-0.75%
Onset= 15-20 min
Duration= 140-220 min
```
133
Epidural with Bupivacaine
Concentration=
Onset=
Duration=
```
Concentration= 0.0625-0.5%
Onset= 15-20 min
Duration= 160-220 min
```
134
Epidural with levobupivacaine
Concentration=
Onset=
Duration=
Concentration= 0.0625-0.5%
Onset= 15-20 min
Duration=150-225 min
135
```
What is the onset for the following drugs from fastest to slowest when dosing an epidural
Chloroprocaine
Bupivacaine
Ropivacaine
Levobupivacaine
```
2-Chloroprocaine
Lidocaine
Ropivacaine = Bupivacaine = Levobupivacaine
136
```
What is the duration for the following drugs from shortest to longest when dosing an epidural
Chloroprocaine
Bupivacaine
Ropivacaine
Levobupivacaine
```
2-Chloroprocaine
Lidocaine
Ropivacaine, Levobupivacaine, Bupivacaine
137
Define baricity
The density of a LA relative to the CSF
138
Compare the following
Isobaric
Hyperbaric
Hypobaric
LA solution compared to CSF
Isobaric = 1 (remain)
Hyperbaric = >1 (sinks)
Hypobaric = <1 (rise)
139
What solutes are added to make the following mixture baracities
Isobaric
Hyperbaric
Hypobaric
```
Isobaric = sline
Hyperbaric = dextrose
Hypobaric = water
```
140
Why is procaine 10% in water hyperbaric
because a 10% solution contains a lot of molecules
141
Where do hyperbaric solutions accumulate (i.e. sitting vs supine)
The lowest point of spinal canal
Sitting = sinks, causing saddle block
Supine = in the thoracic kyphotic portions (T5-T7, S2)
142
Where do hypobaric solutions accumulate (i.e. sitting vs supine)
The highest point of the spinal canal
Sitting = rise towards brain
Supine = Lordotic lumbar region (L3)
143
What physical body alterations can affect spinal LA spread
Obesity = excessive lumbar lordosis
| Ankylosing spondylosis = spinal fixation w/ lac of normal curve
144
What is the highest point of lordosis in the supine position
C5 and L3
145
What are the highest points of kyphosis in the supine position
T5-T7 and S2
146
When is bradycardia a concern with neuraxial anesthesia
When fibers at T1-T4 are inhibited (cardioaccelerator nerves)
147
What effects does neuraxial anesthesia have on the respiratory system
Negligible effect on Vm, Vt, RR, Vds, & ABG
148
How are respiratory muscles affected by neuraxial anesthesia
- Accessory muscle function is reduced
| - Impaired intercostal and abd muscles decrease pulm reserve
149
What 2 effects does neuraxial anesthesia have on the GI tract
1. relaxation of sphincters
| 2. Increased peristalsis
150
What is the primary mechanism of HoTN during neuraxial anesthesia
Block of pre-ganglionic B fibers in the sympathetic chain
151
What are 4 additional reasons HoTN occurs with neuraxial anesthesia
1. Decreased catecholamine output from adrenals
2. Skeletal muscle paralysis
3. Direct effects of LA on systemic circulation
4. Decreased preload d/t venous dilation
152
```
What effect does neuraxial anesthesia have on the following:
Preload
Afterload
Cardiac output
HR
```
Preload = decreased
Afterload = decreased
Cardiac output = variable
HR = variable
153
Why is neuraxial anesthetic effect on cardiac output variable
d/t 2 competeing changes
1. decreased VR => decreased SV => decreased CO
2. decreased SVR => INC CO
154
Why is neuraxial anesthetic effect on HR variable
Competing HR effects
1. HoTN => baroreceptor reflex activation => increased HR
2. Preganglionic block of cardioaccelerator fibers => relative INC PNS tone
155
What pts can have pulmonary problems with neuraxial anesthesia
COPD pts
156
Rationale for apnea in the following neuraxial aneshtesia
Result of brainstem hypoperfusion
157
What mechanism can cause drowsiness with neuraxial anesthesia
Reduced sensory input to reticular activating system
158
How does neuraxial anesthesia decreased surgical stress response
1. Inhibits afferent traffic from surgical site
| 2. Reduces circulating catecholamines, renin, angiotensin, glucose, TSH, growth hormone
159
Which spinal nerves provide sympathetic innervation to the GI tract
T5 - L2
160
Which nerve provides parasympathetic innervation to the GI tract
CN 10 (vagus nerve)
161
What reflex contributes to asystole that occurs with spinal anesthesia
Bezold-Jarisch reflex
| -The heart slows to allow it adequate time to fill
162
Where do neuraxial opioids inhibit afferent pain transmissions
Substantia gelatinosa (lamina 2 of dorsal horn)
163
What 3 mechanisms reduce neurotransmission with neuraxial opioids
1. Decreased cAMP
2. Decreased Ca++ conductance
3. Increased K+ conductance
164
What effect do neuraxial opioids have when combined with local anesthetics
They create a denser block
165
Describe the CSF spread of hydrophilic neuraxial opioids (3)
1. Extensive spread
2. Wide band of analgesia
3. Most rostral spread toward brain
166
Describe the CSF spread of lipophilic neuraxial opioids (3)
1. Minimal
2. Narrow band of analgesia
3. Less rostral spread
167
Where is the site of action of hydrophilic neuraxial opioids
Rexed laminae 2 and 3
168
What is the onset of hydrophilic vs lipophilic neuraxial opioids
```
Hydrophilic = 30 - 60 min (DELAYED)
Lipophilic = 5 - 10 min (FAST)
```
169
What is the duration of hydrophilic vs lipophilic neuraxial opioids
```
Hydrophilic = 6-24 hrs (LONGER)
Lipophilic = 2-4 hrs (SHORTER)
```
170
How does systemic absorption of hydrophilic vs lipophilic neuraxial opioids differ
```
Hydrophilic = less systemic absorption
Lipophilic = more absorption
```
171
Describe the effect of hydrophilic neuraxial opioids on respirations
Biphasic respiratory depression
Early <6 hrs (from minimal systemic absorption)
Late >6 hours (from action on the brainstem)
172
Compare the incidence of N/V and pruritis with hydrophilic vs lipophilic neuraxial opioids
The incidence of N/V and pruritis is much higher with hydrophilic opioids
173
How do opioids injected in the epidural space exert their action
1. Diffuses in the epidural tissue
| 2. Diffuses across the dural cuff into the CSF to the spinal cord
174
Sufentanil dosing:
Intrathecal =
Epidural =
Infusion =
```
Intrathecal = 5-10 mcg
Epidural = 25 - 50 mcg
Infusion = 10-20 mcg/hr
```
175
Fentanyl dosing:
Intrathecal =
Epidural =
Infusion =
```
Intrathecal = 10-20 mcg
Epidural = 50-100 mcg
Infusion = 25-100 mcg/hr
```
176
Hydromorphone dosing:
Intrathecal =
Epidural =
Infusion =
```
Intrathecal = NONE
Epidural = 0.5-1 mg
Infusion = 0.1-0.2 mg/hr
```
177
Meperidine dosing:
Intrathecal =
Epidural =
Infusion =
```
Intrathecal = 10 mg
Epidural = 25-50 mg
Infusion = 10-60 mg/hr
```
178
Morphine dosing:
Intrathecal =
Epidural =
Infusion =
```
Intrathecal = 0.25-0.30 mg
Epidural = 2-5 mg
Infusion = 0.1-1 mg/hr
```
179
What are 4 common side effects of neuraxial opioid administration. Which is the most common
1. Pruritis (most common)
2. Respiratory depression
3. Urinary retention
4. N/V
180
What is the mechanism of neuraxial opioid induced pruritis
Stimulation of opioid receptors in the trigeminal nucleus
| NOT by mast cell degranulation (it is NOT a histamine reaction)
181
How is neuraxial opioid induced pruritis treated
Opioid antagonist i.e. naloxone
182
What medication does not treat neuraxial opioid induced pruritis
Diphenhydramine
183
What 6 factors increase respiratory depression with neuraxial opioids
1. High opioid dosing
2. Co-administration of sedatives
3. Low lipid solubility
4. Advanced age
5. Opioid naivety
6. Increased intrathoracic pressure
184
What are 3 facts of urinary retention r/t neuraxial opioid administration
1. Most common in young males
2. More common wit neuraxial opioids vs IV/IM injection
3. Can be reversed with naloxone
185
What is the mechanism of neuraxial opioid induced urinary retention
Inhibition of sacral parasympathetic tone
Causes bladder detrusor muscle relaxation and urinary sphincter contraction
186
Activation at which 2 areas causes neuraxial opioid induced N/V
Activation of opioid receptors in the:
1. Area postrema of medulla
2. Vestibular apparatus
187
Which LA can reduces the efficacy of epidural opioids
2-Chloroprocaine
188
Which neuraxial opioid most commonly causes sedation
Sufentanil
189
Why do neuraxial opioids have an antidiuretic effect
By increasing vasopressin release
190
What is an absolute contraindication to neuraxial anesthesia
Patient refusal
191
What are 11 relative contraindications of neuraxial anesthesia
1. Coagulopathy
2. Increased ICP
3. Sepsis
4. Infection at puncture site
5. Severe hypovolemia
6. Valve lesions with fixed stroke volumes (AS)
7. Scoliosis, spinal fusions
8. Difficult airway
9. Full stomach
10. Peripheral neuropathy
11. MS
192
Why is coagulopathy a relative contraindication for neuraxial anesthesia
d/t risk of spinal or epidural hematoma
193
At what lab levels are neuraxial blocks contraindicated
Plt < 100,000 mm3
| PT, aPTT, bleeding time > 2x normal
194
Why is increased ICP a relative contraindication for neuraxial anesthesia
It can increase the chance of brain herniation with sudden change in CSF pressure
195
Why is sepsis a relative contraindication for neuraxial anesthesia
1. Can introduce contaminated blood beyond BBB
| 2. Worsening of HoTN
196
Why is hypovolemia a relative contraindication for neuraxial anesthesia
Hypovolemia can worsen HoTN d/t sympathectomy
197
Which valve lesions can be considered a relative contraindication for neuraxial anesthesia
Severe aortic and mitral stenosis
| Hypertrophic cardiomyopathy
198
Why is a h/o scoliosis, arthritis, or spinal fusion a relative contraindication to neuraxial anesthesia
These conditions make neuraxial techniques more technically difficult and less reliable
199
Why is MS a relative contraindication for spinal anesthesia
There is a small risk of possible symptom exacerbation
Demyelination could increase susceptibility to LA-induced neurotoxicity so use lower dose
200
Which spina bifida defects are at greatest risk for complications d/t neuraxial anesthesia
Severe neural tube defects
| Tethered cord
201
What are the categories of spinal needles
1. Cutting Type
2. Non-cutting type
- pencil point
- rounded bevel
202
Which needles are pencil point
Sprotte
Whitacre
Pencan
203
Which needle is a cutting point
Quincke
| Pitkin
204
What are 4 benefits of using a non-cutting tip spinal needle
1. Lower risk of PDPH
2. More tactile feel
3. Needle less likely to deflect
4. Less likely to injure the cauda equina
205
What are 4 drawbacks of using a cutting tip spinal needle
1. Higher risk of PDPH
2. Less tactile feel
3. Needle more easily deflected
4. More likely to injure cauda equina
206
What is a benefit of using a cutting tip spinal needle
Requires less force
207
What is a drawback of the non-cutting tip spinal needles
Requires more force
208
How is the risk of needle deflection minimized when using a spinal needle <22g
By placing an introducer in the interspinous ligament
209
What are 3 types of epidural needles
Crawford
Hustead
Tuohy
210
How does the needle angle compare between epidural needles
```
Crawford = 0 degree
Hustead = 15 degree
Tuohy = 30 degree
```
211
What are the benefits of the increased needle of an epidural needle
Minimizes the risk of dural puncture
212
What are the benefits of using a Tuohy needle
The 30-degree curvature and blunt tip minimizes dural puncture risk
213
What is the distance of the epidural space from skin
Adults =
Pregnant/obese=
```
Adults = 3-5 cm
Pregnant/obese= >5 cm up to 9 cm
```
214
What is the approximate distance from the ligamentum flavum to the dura
~7 mm
| Range = 2 mm - 2.5 cm
215
What is the optimal depth of catheter inside the epidural space
3 - 5 cm
216
What are the risks of not advancing the epidural catheter enough OR too much
Too shallow = higher incidence of inadequate analgesia (epidural failure)
Too deep = Cath may enter an epidural vein or exit an intervertebral foramen
217
Where should the epidural catheter be secured at the skin (length) if LOR is at 4 cm
7 - 9 cm at skin
218
What are the areas blocked by a caudal approach to the epidural space
Sacral, lumbar, and lower thoracic dermatomes
219
What procedural level is a caudal block useful
Sensory block up to T10
220
Why are caudal blocks infrequently used in adolescence or adults
1. Sacral anatomy is more difficult to identify
| 2. Lumbar approach to epidural space is easier to perform
221
What are 3 absolute contraindications for caudal anesthesia
1. Spina bifida
2. Meningomyelocele of the sacrum
3. Meningitis
222
What are 5 relative contraindications for caudal anesthesia
1. Pilonidal cyst
2. Abnormal superficial landmarks
3. Hydrocephalus
4. Intracranial tumor
5. Progress degenerative neuropathy
223
What are the landmarks for performing a caudal block
Posterior superior iliac spines
| Sacral hiatus
224
At what angle is a caudal block approached
45* angle aiming cephalad
225
Technique for preforming a caudal block
1. Position laterally or prone
2. Identify landmarks (PSIS - sacral hiatus)
3. Sterilize injection site
4. Using 22 or 25 g needle, bevel up through sacral hiatus at 45* aiming cephalad
5. Once pop felt, drop angle and advance further into the epidural space
226
When performing a caudal block, what does the "pop" signifiy
Getting into the epidural space after passing through the sacrococcygeal ligament
227
How is the risk for dural puncture with a caudal block increased
Passing the needle tip beyond S2-S3
228
What are 3 assessments that should be done while performing a caudal block
1. Aspirate for blood or CSF
2. Palpate skin during injection to r/o SQ infiltration
3. Resistance = tip in subperiosteal area
229
Is air used for LOR when performing a caudal block
No, d/t the risk of air embolism
230
What adjunct can increase caudal block duration. Mechanism of action
Epinephrine 1:200,000 (5 mcg/mL)
| MOA: reduced vascular uptake of LA
231
What adjunctive medication can be used in place of an opioid in a caudal block
Clonidine 1 mcg/kg provides analgesia equal to epidural opioid
232
How is the height of a caudal block determined
By the volume of LA (similar to epidural)
233
Pediatric caudal block dosing level
Sacral=
Sacral to low thoracic (T10)=
Sacral to mid thoracic=
Sacral= 0.5 mL/kg
Sacral to low thoracic (T10)= 1 mL/kg
Sacral to mid thoracic= 1.25 mL/kg
234
Adult caudal block dosing level:
Sacral=
Sacral to low thoracic (T10)=
Sacral to mid thoracic=
Sacral= 12-15 mL
Sacral to low thoracic (T10)= 20-30 mL
Sacral to mid thoracic= N/A
235
What is the max dose of LA for pediatric caudal block
2.5 - 3.0 mg/kg of any concentration of bupivacaine, levobupivacaine, or ropivacaine
236
5 Procedural Indications for caudal block in children
1. Circumcision
2. Hypospadias repair
3. Anal surgery
4. Inguinal herniorrhaphy
5. Low thoracic surgery
237
Why is there a risk for epidural hematoma with concurrent use of anticoagulant medication and neuraxial anesthesia
Epidural blood can accumulate between the dura and the bone
The accumulation of blood in the epidural space can compress the spinal cord, causing ischemia and permanent neurological dysfunction
238
What are 4 presenting symptoms of epidural hematoma
1. LE weakness
2. LE numbness
3. Low back pain
4. Bowel and bladder dysfunction
239
What intervention must be performed within what timeframe if an epidural hematoma occurs following neuraxial anesthesia
Surgical decompression
Within 8 hours
240
Neuraxial management when patient takes NSAIDs or ASA
Assess coagulation status appears normal
| No added risk, proceed
241
Neuraxial management when patient takes glycoprotein IIb/IIIa antagonist
Drug examples
Hold time
Restart time
Examples: Tirofiban, Eptifibatide, Abciximab
Avoid neuraxial until plt function is recovered:
Hold = 4-8 hrs (tirofiban, eptifibatide)
Hold = 24-48 hrs (abciximab)
Do NOT restart within 4 weeks of neuraxial
242
Neuraxial management when patient takes thienopyridine derivative
Drug examples
Hold times
Restart time
Ex: clopidogrel, prasugrel, ticlopidine
Pre block
Hold 5-7 d (clopidogrel)
Hold 7-10 d (prasugrel)
Hold 10 d (Ticlopidine)
Restart = 24 hrs postop
243
```
Neuraxial management when patient takes unfractionated heparin
Drug examples
Hold times
Restart time
Cath removal
```
Ex: Heparin
Clinical assessment of coag status normal?
PreBlock
Hold 4-6 hrs = low dose
Hold 12 hrs = Up to 20,000 U/day
Hold 24 hrs = high-dose >20,000 U/d
Restart heparin:
1 hr post block placement
1 hr post cath removal
Cath removal:
Hold 4-6 hr post SQ dose or IV infusion dc'd
244
```
Neuraxial management when patient takes low molecular weight heparin:
Drug examples
Hold times
Restart time
Cath removal
```
Ex: enoxaparin, dalteparin, tinzaparin
Clinical assessment of coag status normal? Get plt count
Preblock:
Prophylactic dose = Hold for 12 hrs then block
Therapeutic dose = hold 24 hrs then block
Restart LMWH
12 hrs post cath insertion
24 hrs post cath removal
Cath removal:
Remove before initiating preferably
12 hrs post last dose
245
How long should LMWH be held after epidural catheter removal
4 hrs
246
Neuraxial management when patient takes anti-vitamin K drugs
Drug examples
Hold times
Cath removal
Ex: warfarin
Preblock hold
5 days
Verify INR normal
Cath removal:
Verify INR <1.5
247
What should the INR be prior to epidural catheter removal
<1.5
248
Neuraxial management when patient takes oral anti-factor 10a agents
Drug examples
Hold times
Restart time
Ex: apixaban, betrixaban, edoxaban, rivaroxaban
Preblock:
D/c 3 d prior to block
Check anti-factor 10a activity if <73 hrs
Cath removal:
6 hrs before 1st postop dose
249
Neuraxial management when patient takes thrombolytic agents
| Drug examples
Ex: T-Pa, streptokinase, alteplase, urokinase
ABSOLUTE contraindication to neuraxial anesthesia
250
Neuraxial management when patient takes herbal therapies that inhibit plt aggregation
Drug examples
Ex: garlic, ginkgo, ginseng
Proceed with neuraxial if pt isn't taking other blood thinners
251
What 3 etiologies explain a post-dural puncture headache
1. CSF leaks from the subarachnoid space via the dural puncture
2. As CSF pressure is lost, the cerebral vessels dilate
3. Meninges are stretched, pulling on tentorium, d/t brainstem sagging into foramen magnum
252
What are 6 classic symptoms of a post-dural puncture headache
1. Fronto-occipital HA
2. N/V
3. Photophobia
4. Diplopia
5. Tinnitus
6. Worse when upright
253
What position relieve PDPH
supine
254
What 3 patient factors increase risk of PDPH
1. Younger age
2. Female
3. Pregnancy
255
What are 4 practitioner factors that increase the risk of PDPH
1. Use of cutting tip needle
2. Using large diameter needle
3. Use of air for LOR with epidural
4. Needle perpendicular to long-axis of neuraxis
256
What are 5 practitioner factors that lower risk of PDPH
1. non-cutting tip needle use
2. Smaller diameter needle
3. Using fluid for LOR
4. Needle parallel to long-axis of neuraxis
5. Continuous spinal catheter after wet tap
257
What are the 5 indicated treatments for PDPH
1. Bed rest
2. NSAIDs
3. Caffeine (cerebral vasoconstriction)
4. Epidural blood patch)
5. Sphenopalatine ganglion block
258
What is the definitive treatment for PDPH
Epidural blood patch
259
How is a blood patch performed
Using sterile technique, 10-20 mL of venous blood is drawn then reintroduced into the epidural space
When pressure is sensed in her legs, buttocks, or back the injection is complete
260
What are 2 useful reasons to employ blood patch following PDPH
1. Compresses the epidural and SA space, increasing CSF pressure
2. Acts as a plug, preventing further leaks
261
How is a sphenopalatine ganglion block performed
1. LA soaked cotton-tipped applicator
2. Sniff position
3. Insert applicator in each nare until nasopharynx is encountered
4. Leave applicator for 5-10 minutes
262
Why does a 5-HT3 antagonist minimize spinal-induced HoTN
The Bezold-Jarisch reflex is likely mediated by 5-HT3 receptors in the vagus nerve and ventricular myocardium
263
What is the most effective method of hydrating with spinal blocks
Co-load with 15 ml/kg just after performing the block
264
What causes cauda equina syndrome
Neurotoxicity is the result of exposure to high concentration of LA
265
What factors increase the risk of cauda equina syndrome
1. 5% lidocaine
| 2. spinal microcatheters (focus LA on a small area of the SC)
266
What are 4 s/sx of cauda equina syndrome
1. Bowel/bladder dysfunction
2. Sensory deficits
3. Weakness
4. Paralysis
267
Treatment for cauda equina syndrome
Supportive
268
What is the cause of transient neurologic symptoms
Patient positioning, stretching of the sciatic nerve, myofascial strain, and muscle spasm
269
What are 4 factors that increase the risk of TNS
1. Lidocaine
2. Lithotomy position
3. Ambulator surgery
4. Knee arthroscopy
270
4 factors that do NOT increase risk of TNS
1. Early ambulation
2. LA concentration
3. Baricity
4. Glucose concentration
271
What are the s/sx of transient neurologic symptoms
1. Severe back and butt pain radiating to both legs
| 2. Develops w/in 6-36 hrs and persists 1-7 days
272
Treatment for transient neurologic symptoms
NSAIDs
Opioid analgesics
Trigger point injections
273
What is the reason blood is in an epidural needle
Needle was inserted to laterally
| Redirect the needle towards midline
274
What to do is blood is aspirated in an epidural catheter
Pull back catheter a little and flush with saline
| Repeat until no blood is aspirated or not enough cath is in epidural space
275
How is the risk of venous cannulation with epidural catheter reduced
Injecting fluid in the epidural space before threating the catheter
Use of wire reinforced catheter
276
What are 5 risks of epidural vein cannulation with catheter
1. Multiple insertion attempts
2. Pregnancy (venous engorgement)
3. Sitting position
4. Using stiff catheter
5. Trauma to epidural vein during block placement
