spinals & epidurals Flashcards
1
Q
from superficial to deep, what are the ligaments
A
interspinous ligament, ligamentum flavus, posterior longitudinal ligament, anterior longitudinal ligament
2
Q
piercing the ___ contributes to the loss of resistance when the needle enters the epidural space
A
ligamentum flavum
3
Q
midline approach passes thru which 3 ligaments
A
surpaspinous, interspinous, ligamentum flavum
4
Q
paramedian approach passes thru
A
ligamentum flavum
5
Q
an epidural hematoma accumulates between the ___ and the ___
A
dura bone
6
Q
epidural space is located between?
A
ligamentum flavum and dura mater
7
Q
subdural space is located between?
A
dura mater and arachnoid mater
8
Q
subarachnoid space is located between?
A
arachnoid mater and pia mater
9
Q
how many cervical vertebra
A
7 (c1-c7)
10
Q
how many thoracic vertebra?
A
12
11
Q
how many lumbar vertebra
A
5
12
Q
how many sacral vertebra
A
5
13
Q
how many coccygeal vertebra
A
4
14
Q
LA’s are bases or acids?
A
weak bases
15
Q
esters have __ structure
A
c-o-c
16
Q
amides have __ structure
A
N-h
17
Q
agents with a ___ pka value will have a ___ onset
A
lower , faster. because a greater fraction of molecules will exist in the uncharged form, this will more easily diffuse across nerve membranes
18
Q
the ___ form of an LA is most lipid soluble and is able to gain access to the axon
A
uncharged
19
Q
mechanism of LA’s
A
block nerve conduction by impairing propagation of the action potential in axons
20
Q
LA’s ___ the rate of rise of the action potential such that threshold potential is not reached
A
decrease
21
Q
does the unionized form of the drug work while inside the cell?
A
no! it becomes ionized once inside
22
Q
LA’s work ___cellularly
A
intra.
23
Q
agents with a high degree of protein binding will have a ___duration
A
prolonged
24
Q
pka determines __ of onset of neural blockade
A
speed
25
which fibers are more easily blocked, thin or thick??
thin.
26
which fibers are more readily blocked, myelinated or unmyelinated?
myelinated
27
what plays the greatest role in conduction speed of a nerve fiber
diameter / myelinaton
28
which fibers are the biggest
A
29
which fibers are the smallest
C
30
A alpha
skeletal muscle - motor. and proprioception
31
A beta
touch pressure proprioception
32
a gamma
skeletal muscle tone
33
a delta
fast pain, temp and touch
34
B fibers act where? myelinated?
pre-ganglionic ANS fibers. light myelination
35
C fibers are myelinated?
NO
36
C fiber sympathetic function
postganglionic ANS fibers
37
C fiber dorsal root function
slow pain, temp, touch.
38
which fibers are blocked first
B
39
which fibers are blocked second
c
40
which fibers are blocked last
A - gamma/delta, then alpha/beta
41
sequence of block
ATP-TP-MVP
42
ATP-TP-MVP
autonomic, temp, pain, touch, pressure, motor, vibration, proprioception
43
b fibers are __ sized and ___ myelinated
small , lightly
44
how are esters metabolized
plasma cholinesterase break them down in the blood
45
how are amides metabolized
in the liver
46
what is basicity
density relative to the desntiy/ specific gravity of CSF
47
hypobaric will ___ while hyperbaric will
float, sink
48
addition of water makes a solution ___
hypobaric
49
addition of dextrose makes a solution
hyperbaric
50
addition of epi to an LA will ___ the risk of systemic toxicity
decrease. it decreases the rate of absorption, thus minimizing peak blood levels of LA's
51
epi ___ the intensity of a block
increases
52
how does epi effect the duration of anesthesia
prolongs
53
when would you not add epi?
areas with poor circulation (fingers toes penis), beir block, htn, CAD, arrhythmia, hyperthyroid, utero-placental insufficiency
54
how does sodium bicarb affect spinal
raises the ph and increases the conc of non-ionized base, which increases the rate of diffusion across the nerve membrane and speeds the onset of blockade.
55
addition of fentanyl to LA ___ onset, ___ level , and ___ duration
shortens, increases, prolongs
56
action of opioids is ___ with LA's
synergistic
57
amide allergic reaction is caused by
methyl paraben preservative
58
ester allergic reaction is caused by
PABA (metabolite )
59
number one contraindicatio to a spinal is
patient refusal
60
if you threaten someone into something it is ___, if you actually do it, its ____
assault, battery
61
what is the most anterior ligament
ligamentum flavum
62
what is the most posterior ligament
supraspinous ligament
63
where does the spinal cord end at birth
L3
64
where does the spinal cord end in an adult
L1
65
what are the 3 meninges of the spinal cord
pia mater, dura mater, arachnoid mater
66
csf specific gravity
1.004-1.009
67
volume of csf in spinal canal
30-80
68
total volume of CSF
140
69
the level of anesthetic varies ___ with the dose of LA used
directly
70
the greater the volume of injected drug, the ___ the spread
farther
71
turbulence ___ the spread of the drug and the level of blockade obtained
increases
72
if you increase ABD pressure, you will get ___ of a spread
more
73
most commonly used LA's are ____baric
hyper
74
hyperbaric solutions flow to the most ____ part of the CSF column
dependent
75
fibers conveying sensation are ___ easily blocked than larger motor fibers
more
76
in the lumbar region the epidural space is ___ wide at midline
5-6mmm
77
in the mid-thoracic region the epidural space is __ wide
3-5mm
78
the thoracic epidural requires ___ dose of LA
smaller
79
the thoracic epidural requires ___ dose of LA
smaller
80
CNS toxicity presents as
lightheadedness, tinnitus, metallic taste, visual disturbance, numbness of tongue and lip
81
which LA is the most CV toxic
bupivocaine
82
if you suspect toxicity, ___ ventilate
hyper (to blow off CO2)
83
absolute contraindicatoins
significant coagulopathy, increased ICP, lack of pt cooperation, infection at site
84
relative contraindications
hypovolemia, spinal cord disease, surgical time, musculoskeletal deformity, patients with a fixed volume cardiac state such as idiopathic hypertrophic aortic stenosis , difficult airway
85
new onset lower limb weakness, new onset back pain , new onset bowel or bladder dysfunction would make you concerned about
spinal or epidural hematoma
86
segmental level for lower extremities
T12
87
segmental level for hip, vag/utuerus, bladder, prostate
T10
88
lower extrem
T8
89
testes/ovaries
T8
90
lower intraabdominal
T6
91
which ligament is the closest point to the epidural space
ligamentum flavum
92
which ligament connects the spinous processes
interspinous ligament
93
which ligament connects the apices of spinous processes
supraspinous ligament
94
which ligament is most anterior and most dense
ligamentum flavum
95
what is the end of the spinal cord
conus medularis
96
what forms the cauda equina
conus medlars, lumbar, sacral, and coccygeal nerve roots
97
what forms the cauda equina
conus medlars, lumbar, sacral, and coccygeal nerve roots
98
what 3 meninges cover the spinal cord
pia mater, dura mater, arachnoid
99
what is the tough fibrous sheath running through the length of the cord
dura mater
100
how does increased pressure effect level of spinal blockade
pressure against the inferior vc causes epidural venous engorgement, and reduces the volume of csf. LA spreads farther.
101
increasing the dose of an isobaric anesthetic will affect ___ more than ___
duration, spread.
102
for lateral - affected side ___ if using hyperbaric technique
up
103
for lateral - affected side ___ if hyperbaric technique
down
104
sitting position, use ___baric anesthetics
hyper
105
prone technique is good for which procedures
rectum, perineum, anus
106
prone Is used with ___baric anesthesia
hypo
107
midline approach- needle is angled ___
cephalad
108
paramedian approach - needle is angled
medially and slightly cephalad and passed lateral to the supraspinous ligament
109
how to reduce the incidence of post-dural puncture HA with needle insertion
insert so the bevel is parallel to the fibers that run longitudinal
110
how is correct placement of a spinal confirmed
free flow of CSF into the hub of the needle
111
fixation of LA takes approx
20 min
112
neural block >>>
autonomic > sensory > motor
113
from skin to epidural space ranges
3-9mm
114
epidural blockade develops in a ___ type manner
segmental
115
___ block has greater control of sensory and motor blockade
epidural
116
epidural medication spreads in a ___ direction
cephalad
117
epidural meds get to the subarachnoid space by the process of
diffusion
118
why should the epidural needle always enter the epidural space in the midline
widest and risk of puncturing epidural veins, spinal arteries , or spinal nerve roots is decreased
119
technique for lumbar epidural - which two techniques to locate the epidural space
loss of resistance or hanging drop
120
thoracic epidural - needle
insert in cephalad direction due to sharp downward angulation of the thoracic vertebral spinous processes
121
what does the epidural test dose consist of
3ml local with 1:200,000 epi
122
onset of sympathetic block is ___ with epidural
slower
123
onset of sympathetic block is ___ with epidural
slower
124
list everything from skin to spinal cord
skin, subcutaneous tissue, muscle, supraspinous ligament, interspinous ligament, ligamentum flavor, epidural space, dura mater, subdural space, arachnoid mater, subarachnoid space, pia mater , spinal cord
125
what happens when you accidentally inject LA into the subdural space during an epidural
either high spinal with delayed onset (epidural dose) or failed spinal (spinal dose)
126
what spinal nerve root for thumb
c6
127
what spinal nerve root for 2nd and third digits
c7
128
what spinal nerve root for 4th and 5th digits
c8
129
site of action for spinals
myelinated preganglionic fibers of the spinal nerve roots
130
site of action for epidural
must diffuse thru the dural cuff before they can block the nerve roots
131
what factors influence spread of SAB the most
basicity, pt position, site, volume of csf, density of csf
132
what is the primary determinant of spread for epidural anesthesia
volume
133
how is differential blockade different with epidural anesthesia?
there is no autonomic differential blockade with epidural anesthesia. sensory block is 2-4 dermatomes higher than motor block.
134
dont do a spinal/epidural if platelets are
<100,000
135
dont do a spinal/epidural if PT, aPTT and or bleeding is
twice the normal value
136
2 classifications of spinal needles
cutting tip and non cutting tip
137
which tip has the higher risk of PDPH
cutting
138
which tip needle is more easily deflected
cutting
139
cutting tip names
quincke, pitkin
140
which needle requires less force
cutting
141
which needle is less likely to injure the caudal equina?
non-cutting
142
what are the 3 epidural needles
crawford, hosted, tuohy
143
what epidural needle has the most pronounced curvature
tuohy - 30degrees - helps prevent dural puncture
144
which epidural needle has no curve
crawford
145
hustead needle curve
15
146
neuraxial opioids do not cause
sympathectomy, skeletal muscle weakness, changes in proprioception
147
where does the subarachnoid space terminate in an adult
S2 dural sac
148
subarachnoid space ending in infant
S3
149
where is the conus medularris in adult
L1-L2
150
where and what is Tuffier's line
line formed between the tops of the iliac crests at l3-l4 or l5-s1
