Neuraxial Flashcards
1
Q
cardiac accelerator nerves
A
T1-T4
2
Q
Phrenic nerves
A
C345
3
Q
Spinal anesthesia definition
A
injection of LA into Subarachnoid space
4
Q
Dose of prop for induction
A
1.5 - 2.5 mg/kg
5
Q
onset spinal vs epidural
A
spinal = rapid
epidural = slow
6
Q
spread spinal vs epidural
A
spinal; higher than expected; may extend extracranially
epidural; as expected can be controlled with volume of LA
7
Q
nature of block spinal vs epidural
A
spinal; dense
epidural; segmental
8
Q
motor block spinal vs epidural
A
spinal; dense
epidural; minimal
9
Q
hypotension spinal vs epidural
A
spinal; likely
epidural; less than spinal
10
Q
walking epidural
A
Ropivicain; not very dense, segmental
11
Q
onset epidural vs spinal
A
spinal; 5 min
epidural; 10-15 min
12
Q
duration epidural vs spinal
A
spinal; limited and fixed
epidural; unlimited
13
Q
placement level for spinal
A
L3-L4, L4-L5, L5-S1
14
Q
Dosage of LA for spinal vs epidural
A
spinal; dose - based (mg)
epidural; volume- based
15
Q
Largest dose that can be given for spinal
A
3 ml
16
Q
LA toxicity
A
IV admin of LA ( bupivacaine = most sensitive to the heart)
high risk with epidurals because of veins and volume given
17
Q
Gravity influence on spinal
A
spinal = big effect
epidural; no gravity effect
18
Q
Coag levels that are absolute contraindications for neuraxial
A
INR > 1.5 (ASRA), some texts > 1.2
Platelets < 100,000; 50,000 Miller; consider trends*
Nagelhout x 2 (PT, aPTT, bleeding time)
Known coagulation disorder or taking anticoagulants
increase risk of hematoma
19
Q
Valvular disease absolute contraindications for neuraxial
A
AS < 1.0 cm2 or MS < 1.0 cm2
IHSS (Idiopathic hypertrophic subaortic stenosis)
20
Q
relative contraindications for neuraxial anesthesia
A
Deformities of spinal column
Preexisting disease of the spinal cord
Chronic headache/backache
Inability to perform SAB after 3 attempts
21
Q
Total number of vertebra and how much for each area
A
33 total
7 cervical
12 thoracic
5 lumbar
5 sacral
4 coccyx
22
Q
Total spinal nerves and number/ location
A
31 nerves pairs
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccyx
23
Q
Distance from skin to ligamentum flavum
A
4 cm in 50% of pts and 4-6 cm in 80% of pts
24
Q
The spinal cord ends at…
A
30% end at T12
60% end in L1
10% end in L3
board answer; L1
25
Spinal cord ends at....for peds
L3
26
High and low points while supine
high = C3 and L3
Low = T6 and S2
27
End of dural sac
S2
end of subarachnoid space
28
Orientation of lumbar spinous processes
straight/ horizontal
needle = straight
29
Orientation of Thoracic spinous process
caudally/ oblique
needle = point cephalad / up.
30
dura matter start and end points
Starts at the foramen magnum, ends in S2 (fuses with filum terminale)
31
Spinal cord blood vessels
one anterior spinal artery - vertebral artery
2 posterior spinal arteries- inferior cerebellar artery
segmental spinal arteries - intercostal and lumbar arteries
32
CSF volume
100 to 160 ml
20 -25 ml/hr
entire csf volume replaced q6h
33
dermatome looks at...
sensory levels
34
Umbilicus dermatome
T10
35
Nipple dermatome
T4 (csection height)
36
Thumb dermatome
C6
37
Hand dermatome
C6 - thumb
C7- pointer and middle
C8- ring and pinky
38
Tuffier’s (Intercristal) Line
Line between L3 and L4 interspace and is at or above the level or the superior iliac crest
39
LA for spinal spreads to the.....
cauda equina and spreads to the nerve roots
40
Even with epi, whats the longest a spinal will last?
150 min = 2.5 hr
41
Spinal nerves in subarachnoid space is covered by thin.....
pia layer
42
factors that influence the decision on which LA to use for Neuraxial anesthesia
Type of sx
Length of sx
Surgeon
43
shortest acting LA
lidocaine
good for outpt sx
44
LA structure and difference between Ester and amide
aromatic ring, intermediate link (ester or amide), tertiary amine
45
opioid adjuncts does what to a blockade
Make “denser”
It intensifies the blockade/ sensation
46
Alpha 2 agonist adjunct with neuraxial blockade
Improves Density, duration, and analgesia
47
Vasopressor effect as an adjunct with neuraxial blocks
Extends duration only; No effect on density or analgesia
Epinephrine (good IV marker epidurals: initial bolusing)
Causes vasoconstriction
48
Epidural morphine dose
3-5 mg (24 hr duration)
49
epidural fent dose
50 -100 mcg
50
sufent epidural dose
10-25 mcg
51
morphine spinal dose
100-400 mcg (24 hrs)
52
fent spinal dose
10-25 mcg
53
sufent spinal dose
2.5-10 mcg
54
opioids spread...
cephalad
55
hydrophilic and lipophilic opioids
Hydrophilic drugs (morphine)
lipophilic drugs (Fentanyl/Sufentanil)
Hydrophilic drugs slow cephalad spread than lipophilic drugs
56
side effect of sufent
muscle rigidity
57
Opioid to use in out pt setting
sufent
58
incidence of pruritis with opioid use
30-100%
59
Treatment for Pruritis
benedryl 25-50 mg IV
Nalxone 0.1 mg IV - best
Buprenex (mixed agonist/antagonist)
60
Prophylaxis for Pruritis
minimize the dose of morphine < 300 mcg (100 mcg)
Ondansetron 4 mg IV
Nubain 2.5-5 mg IV (partial agonist/antagonist)
61
treatment for nausea
ondansetron (8mg)
Naloxone (0.1 mg)
Phenergan (12.5-25 mg IM)
62
Epi wash dose
0.2-0.3 mg
63
Spinal with epi is most profound increase in effect with what med?
Tetracaine
64
Epi with epidural has the greatest effect in the duration of anesthesia in what meds?
lidocaine, mepivacaine and 2 chloroprocaine
65
Where is clonidines site of action when given spinal or epidural
substantia gelatinosa
66
Neo wash dose
2- 5 mcg
67
tetracaine with epi/ neo effect
profound increase in effect
68
Spinal dose for Dexmedetomidine
3 mcg
69
clonidine dose for spinal
15-45 mcg
70
Factors affecting uptake of LA into neural space
concentration of LA in CSF
Surface are of the nerual tissue
lipid content of the nerve
Blood flow of the nerve
71
A alpha fiber
propioception and motor
large
heavy mylinated
last to get blocked
72
A beta fibers
touch, pressure
heavily mylinated
intermediate block onset
73
A gamma fibers
muscle tone
small
heavily mylinated
intermediate block onset
74
A delta fibers
pain, cold temperature, touch
small
heavily mylinated
intermediate block onset
75
B fibers
preganglionic autonomic vasomotor
pretty small
lightly myelinated
early block onset
76
C sympathetic fibers
Post ganglionic vasomotor
really small
no myelin
early block onset
77
C Dorsal root fibers
pain, warm and cold temp, touch
really small
no myelin
early block onset
78
Progression to differential block
B fibers
C fibers
A delta
A gamma
A beta
A alpha
79
Progression from differential block
A alpha
A beta
A gamma
A delta
C fibers
B fibers
80
Sympathetic level is ....
2-6 levels higher than sensory level - B fibers
81
sensory level is.....
2 levels higher than motor block
82
which block is segmental?
epidural
83
Elimination of LA from SAB...
all LAs are eliminated by reuptake
vasular reabsorption
84
What drugs have a high affinity for epidural fat?
lipophilic drugs = slow reuptake because of the fat affinity
85
Most important factors affecting LA distribution and block height for spinal
Dose
Baracity
CSF volume
Advanced age
pregnancy
Pt position
Epidural injection post spinal (EVE- epidural volume extension)
86
Water specific gravity
1.000
87
CSF specific gravity
1.00033 (pregnant)
1.00067 (men)
88
what is the most reliable determinant of LA spread for spinal
dose
89
what LA are primarily influenced by baracity
hyperbaric LA
90
How to make hypobaric solution
water 3x vol SAB LA
91
baracity for upper abd surgeries
hyperbaric
c-section
92
Baracity for hemerrhoidectomy
hypobaric
pt is prone
93
Dose of hyperbaric SAB in nonOB for T4
2ml
94
Dose of hyperbaric SAB in nonOB for T10
1.5 ml
95
Dose of hyperbaric SAB in nonOB for Sacral level
1 mL
96
swirl is present in....
hyperbaric solution
97
ED 50 for bupivacaine
4.7 mg - 9.8 mg
98
ED 95 for bupivacaine
8-15 mg
99
balanced anesthesia
muscle relaxation
analgesia
amnesia
hemodynamic stability
100
CSF volume
100-160 ml
101
small CSF volume correlates with....
extensive spread of LA in intrathecal space= more effect
102
Bain bridge reflex
reflex thats mediated via sensors from the ns that feedback onto the nodal tissue through reductions in vagal tone
Involves some sensory neurons and when they see increase stretch they feed back to the vagal nerves and tell the vagal nerves to slow firing = increase hr.
Amount of hr increasing- full initiation of the bainbridge reflex by itself with nothing else = increase hr by 50%.
103
LA on the heart
inhibition of bainbridge reflex,
block T1-T4
Bezold Jarisch reflex
block T1-L3/4 (SNS output)
104
The Bezold-Jarisch reflex
Seratonin -> chemo and mechano receptors on LV -> inc parasympathetic, decreased sympathetic output
105
zofran on hypotension
inhibits Bezold-Jarisch reflex
106
Fluids to give for preloading/coloading
isotonic; NS, LR, Osmolyte A
107
GI sympathetic outflow originates
T6-L1
108
what respiratory capacity changes with SAB
vital capacity decreases because of loss of abd muscle contribution to forced expiration
109
What sympathetic blockade affects bladder control
T10
urinary sphincter tone relaxed
110
Why is there shivering with SAB
Blockade impairs central thermoregulation center of the brain
vasodilation -> redistribution of blood flow and heat to periphery
111
Prevention of shivering
ondansetron
bare hugger
112
High thoracic blockade can result in the blockade of respiratory ....
accessory muscle (intercostal and abdominal muslces)
113
Ester metabolite
paba =allergies
114
3 common reasons for neuraxial failure
wrong dose, wrong location, wrong position
115
Saddle block
S2 -S5
116
Interlipid dose
20%; 1.5 ml/kg (bolus)
gtt 0.25ml/kg
117
C section dermatome level
T4
118
quincke type of spinal needle
cutting
119
sprotte type of spinal needle
non cutting
120
Whitacre type of spinal needle
non cutting
121
Another name for non cutting needles
pencil-point
122
Lateral position is good for neuraxial procedures for what surgeries?
Hip surgeries (can use hypobaric solution)
123
Benefit of non-cutting spinal needle
feel more of pop when through Dura
reduced incidence of post-dural puncture HA
124
Layers transverse during median approach
skin
subq fat
supraspinous ligament
interspinous ligament
ligamentum flavum
dura mater
subdural space
arachnoid mater
subarachnoid space
125
Layers transversed during paramedian approach
skin
subq fat
ligamentum flavum
dura mater
subdural space
arachnoid mater
subarachnoid space
126
succinylcholine brand name
anectine
127
bupivicaine brand name
marcaine
128
needle hits bone early in spinal
hitting spinous process
point the needle caudad
129
needle hits bone late in spinal
hitting lamina
point the needle cephalad
130
spinal anesthesia needle size
25 guage
131
epidural needle size
18-19 guarge
132
Low csf from post-dural puncture headache leads to
cranial nerve traction
traction causes
diplopia (CN VI)
tinnitus (CNVIII)
133
Name for end of the spinal cord
conus medularis
134
what relieves PDPHA
supine
nsaids and narcotics (fent)
(caffeine)
blood patch
135
amount of blood used for blood patch
20 mL
136
transient neurologic symtoms
develops immediately
resolves within a week in 90% of cases
11.9% incidence rate (5% lido)
severe radicular back pain
positional correlation (hip or knee flexion) -> stretched spinal roots
137
cauda equina sydrome
permanant-> can lead to paraplegia
pooling of lido (5%) in cauda equina = dense blockade
138
Cauda equina sydrome s/s
bowel/bladder dysfucntion
paraplegia (late sign)
back pain
saddle anesthesia
sexual dysfunction
139
cauda equina location
L1 -S4 + coccygeal nerves
140
causa equina sydrome treatment
if compression is a factor, then immediate laminectomy > 6hrs
141
horners syndrome
ptosis
anyhydrosis
miosis
high sympathetic spred
142
trigeminal nerve branches
CN5
V1 = opthalmic
V2 = Maxillary
V3 = Mandibular
143
Trigeminal nerve palsy
ganglion bathed in CSF
144
Nerves to block for awake intubation
Glosspharyngeal - 9- suck on tongue depressor and 4x4
Vagus - 10-
Trigeminal nerve - 5 (V2) - cotton q tip in nose
145
Vagus nerve branches
recurrent layrngeal nerve
superior laryngeal branch - internal and external branches
146
Superior laryngeal nerve
internal = sensory innervation for larynx
external = motor function for cricothyroid muscle
147
Inflammation of meninges
Arachnoiditis
Leads to extensive sclerosis of arachnoid membranes and constriction of vascular supply
148
Symptom of numbness/weakness confusing by the use of local anesthetics; Pain is a major symptom
Epidural/Spinal Hematoma
Cord ischemia reversible if laminectomy is performed in < 8 hours
149
Can maintain the ability to ambulate and void if epidural is placed
above T10
150
Epidural space extends...
Extends from the base of the skull to the sacral hiatus
151
Epidural space is filled with....
filled with the fat, areolar tissue, lymphatics, veins, nerve roots and blood vessels
152
onset of LA is based on....
closer PKA is to physiologic Ph = faster onset
exception to the rule = 2-chloroprocaine 3%
153
Uptake of LA based on regional anesthetic technique
IV
Tracheal
Intercostal
Caudal
Paracervical
Epidural
Brachial
Sciatic
SubQ
154
Epidural injection diffuses...
diffuses through the dural sheath of spinal nerves, roots, rootlets, and CSF where nerve transmission is altered
155
Determinants of block spread for epidural
Volume and dose of LA
156
increased epidural pressure can _______ spread in epidurals
increase spread
pregnancy, coughing,Valsalva, obesity
157
Lumbar epidural injection produces a preferential ______spread
cephalad
due to the narrowing of the epidural space at the lumbosacral junction
The larger diameter of the L5-S1 nerve roots may delay the onset or result in patchy anesthesia.
158
Thoracic epidural injection produces _____ spread of anesthetic solution
symmetrical
A reduced volume of local anesthetic solution should be used at this level because of the potential for higher block and resultant hemodynamic instability
159
Caudal injection predominantly results in.....
sacral and low lumbar anesthesia
160
what determines epidural dermatome spread?
volume
A larger volume will block a greater number of segments
161
incremental dosage = _______
5 mL at a time
162
Epinephrine increases the ________ of useful epidural anesthesia with all the agents
duration
Greatest with lidocaine, mepivacaine, and 2-chloroprocaine
163
Dose of bicarb and what it does to the LA
Alkalinization - Adding NaHCO3 (1 mEq/10 mL of local anesthetic)
Increases the pH of LA
Increase the concentration of nonionized free base
164
2- chloroprocaine can only be used in....
epidural
metabolized by plasma cholinesterase
165
medication with greatest motor function depression for epidural
Lidocaine
ropivacaine is the least
166
Fastest to slowest onset and shortest to longest duration
2 - chloroprocaine 3%
lidocaine 2%
mepivacaine 2%
ropivicaine 0.7%
bupivacaine 0.5%
167
Test dose dose
3 ml of lidocaine 1.5% with epidural (1:200,000)
168
Epidural needle with the most curvature (30 degrees) blunt tip is less likely to puncture subarachnoid space
Tuohy
169
Epidural needle with 15 degree curve
Hustead
170
Medication that decreases efficacy of subsequent epidural opioids?
2 chloroprocaine
171
Epidural needle preferred when catheter placement is difficult or the angel is steep (thoracic epidural)
Crawford
172
Epidural needle markings
Each mark = 1 cm
9 cm length - hub
10 cm - window
12.5 cm = hub
173
Epidural cath placed _____ within the epidural space
placed 3-5 cm
174
Epidural catheter markings
thicker marking = 11 cm
small marking = 5 cm increments
175
Distance from Skin to Epidural Space
Average adult is 4-6 cm (80% of patients)
176
Reason for test dose
Identify unintentional IV or SAB
177
A change of ______ or greater in heart rate after the test dose indicates a probable intravascular injection
20%
178
S/S of IV injection of LA = Positive test dose
Tinnitus
Metallic taste
Circumoral numbness
179
The intrathecal injection of lidocaine will produce a significant______ block consistent with_______ anesthesia in _____ mins
The intrathecal injection of lidocaine will produce a significant motor block consistent with spinal anesthesia in 3 mins
A dense motor block within 5 min of a test dose should prompt a suspicion of a spinal block
180
Spinal nerves in subarachnoid space is covered by thin.....
pia layer
181
Saddle block
S2 -S5
182
Spinal hematoma treatment
cord ischemia is reversible if laminectomy is performed in 8 hrs.
183
Major symptom of spinal hematoma
pain
184
res ipsa loquitur
the principle that the occurrence of an accident implies negligence.
