Considerations for Epidural & Spinal Anesthesia Flashcards
(183 cards)
1
Q
What is an epidural anesthetic?
A
injection of a local anesthetic into the epidural
space for spread to the region of the dural cuffs
– Leaks into intravertebral foramen and paravertebral spaces
– Medication spread is diffusion dependent
– Onset is longer
2
Q
What is the idea behind epidural/spinal anesthesia?
A
Reversible chemical blockade of neuronal transmission
3
Q
What lasts longer, epidural or spinal?
A
epidural
4
Q
What is interrupted with administration of an epidural or spinal?
A
autonomic, sensory and
motor nerve fiber transmission
[EPIDURAL} results are related to drug concentration & volume
5
Q
Results of an epidural is related to?
A
drug concentration & volume
6
Q
What are 2 major differences between a spinal and epidural?
A
- Spinal directly bathes spinal cord in local anesthetic
- Epidural is titratable & can be redosed
[spinal catheter CAN be placed but it is RARE!]
7
Q
What are 2 other names for a spinal?
A
- subarachnoid block
2. intrathecal block
8
Q
What are 6 advantages of an epidural?
A
- ↓ surgical stress
- ↓ opioid consumption
- ↓ overall blood loss
- ↓ risk of DVT
- provides anesthesia OR analgesia (can re-dose, or convert from pain to primary anesthetic in laboring mother)
- versatile
- can use with or without adjunctive medications
- can control extent of sensory or motor blockade based on concentration of local anesthetic used
9
Q
What are 4 disadvantages of an epidural?
A
- post dural puncture headache (PDPH)
- sympathetic blockade occurs 100% of the time
- block may last longer than the procedure
- urinary retention
10
Q
What is more difficult, an epidural or spinal?
A
epidural
11
Q
What are considerations when deciding to do an epidural?
A
- length of surgery
- multimodal pain management
- procedure
[involving abdomen, lower extremities] - certain comorbidities
[pulmonary disease; will keep the pt breathing, no GA necessary]
12
Q
What are 5 absolute contraindications to an epidural?
A
- pt refusal
- increased ICP
- severe aortic or mitral valve stenosis
- severe hypovolemia
- infection at injection site
13
Q
What are relative contraindications for an epidural?
7
A
1. Uncooperative patient
• Inability to communicate / obtain informed consent
• Unable to assist
2. Local anesthetic allergy
3. Patient on anticoagulant or thrombolytic therapy [why are they on it? afib, DVT?] --- this might be why doing an epidural is GOOD for them...
4. Preexisting neurologic deficit
5. Chronic headache or backache
6. Severe spinal deformity
7. Valvular stenosis
14
Q
Pre-procedure medications for epidural placement?
A
- anxiolytic, do not over sedate!
- follow NPO guidelines
- consider IV bolus if pt is dehydrated?
15
Q
Minimum pre-procedure monitoring for epidural placement?
A
- IV
- Suction
- Airway supplies
- ECG, BP, SpO2,
- oxygen
16
Q
What should be available when performing an epidural?
A
- suction
- airway supplies
- supportive medications [induction agent, paralytic, atropine, vasoactive meds, zofran]
17
Q
What type of regional anesthesia is high volume?
A
epidural
18
Q
What are the 2 needle approaches for spinal/epidurals?
A
- midline
2. paramedian
19
Q
What vertebral body aligns with the lower scapula tip?
A
T7
20
Q
What vertebral body aligns with the end of an adult spinal cord?
A
L1
21
Q
What vertebral body aligns with superior iliac crests?
A
L4
22
Q
What vertebral body aligns with the posterior superior iliac spines? (dimples)
A
S2
23
Q
What movement of the spine will create larger interspinous spaces?
A
flexion
24
Q
What do you check right before performing an epidural?
A
- patent IV
- monitoring devices
- oxygen attached & functioning
- resuscitation equipment is available
25
What are characteristics of a Tuohy needle?
- pronounced curve
- easier for novice
- directional placement of catheter
26
What are characteristics of a crawford needle?
- not curved
- easier to insert
- higher rate of dural puncture
27
How long is a standard epidural needle?
9cm
28
What are 2 factors that alter distance to the ligamentum flavum?
1. body habitus
| 2. level of placement
29
What is the standard depth of the epidural space in the lumbar region?
5cm
30
What type of needle requires an introducer?
spinal needle
31
How is the bevel situated when doing a spinal or epidural?
bevel "up" towards patient's head
32
What is the needle advanced through when placing an epidural?
1. skin
2. SQ tissue
3. supraspinous ligament
4. interspinous ligament
5. ligamentum flavum
6. epidural space!
33
How is the needle inserted/advanced when placing an epidural?
VERY SLOW!! mm BY mm!!
tap plunger of syringe between movements
TAP EVERY mm!!!
34
If using the "loss of resistance" technique for epidural placement, how much NS or air is in the syringe?
2-3mL
35
What are you waiting for when advancing an epidural needle?
loss of resistance
36
How does an epidural catheter compare to the epidural needle?
the catheter is 2 gauge sizes smaller
37
Dashed lines on an epidural catheter represent, what?
1cm
38
Two dashed lines on an epidural catheter represent, what?
10cm
39
Two thick lines on an epidural catheter represent, what?
12cm
40
What is the distance from the hub of the epidural needle to the tip?
12cm
41
How far should the epidural catheter be left in the epidural space?
3-5cm
42
What can happen if the epidural catheter is left inserted too deep?
1. puncture of the dura
2. passage into epidural veins
3. migration through intervertebral foramen
43
What must be remembered when manipulating the epidural catheter and needle?
NEVER attempt to withdrawal the catheter through the needle
-catheter can break & shear, leaving pieces in the patient!
44
After placement of an epidural catheter, the needle is removed, then what?
attach adapter to free end, look for blood or CSF, gently aspirate
45
After attaching the adapter to the epidural catheter, looking for blood or CSF, and gently aspirating, what next?
administer test dose
1.5% lidocaine with 1:200000 epi
46
What medication is used as the test dose for an epidural?
1. 5% Lidocaine
1: 200,000 epi
total: 3mL = 45mg lidocaine with 15mcg epi
47
How will you know if the epidural is in place?
3mL test dose will cause profound spiral block
OR
HR/BP will ↑ more than 20% if the test dose is administered into the vasculature
48
What must be remembered before giving an epidural "test dose"?
* ask patient, are you about to have/are having a contraction?
- tell me if you hear ringing in your ears, taste metal, or feel your bottom get heavy
49
What will happen if your epidural test dose is administered as a spinal?
heavy SADDLE BLOCK within 30 seconds
50
When is the paramedian epidural approach useful?
when the patient cannot flex their spine. [Hx spinal surgery, rheumatoid arthritis, hip or upper leg trauma]
51
Where is the skin wheal placed when performing a paramedian approach?
1cm lateral and 1cm caudal to spinous process
52
When using a paramedian approach for epidural placement, what does the needle advance through?
1. skin
2. SQ
3. paraspinous muscles
4. ligamentum flavum
(does NOT pass through supraspinous or interspinous ligaments
53
What do you do if a patient reports paresthesia?
stop moving, ask if it stops
if the paresthesia goes away, continue
if paresthesia does not stop, remove needle & catheter together and restart at interspinous space above
54
How do you redirect the epidural needle after hitting bone?
pull the needle and stylet back into SQ fat, reposition the introducer then reinsert the needle
55
What do you do if you get blood in the epidural needle?
withdrawal the needle & catheter and replace
56
What are 3 indications of caudal anesthesia?
1. hemorrhoidectomy
2. chronic pain patients
3. pediatric analgesia (inguinal herniorrhaphy, circumcision, perineal procedures)
57
How is a patient positioned for a caudal block?
1. prone on a flexed table or with a pillow under pelvis, legs spread and externally rotated
2. laterally
58
What is the dose of a caudal block?
0. 5-1mL/kg
- varying LA concentrations
2.5mg/kg
59
When doing a caudal block, ensure you are not in which two spaces?
bone
| subcutaneous
60
What is the volume for adult caudal sacral anesthesia?
12-15mL
61
What is the volume for adult caudal lower extremity block
20-30mL
62
What are 3 complications of adult caudal anesthesia?
1. high failure rate (false passage)
2. inadvertent IV injection or catheter placement
3. dural puncture
63
What are the two types of combined spinal epidural?
1. 2 level; spinal placed then epidural catheter placed 1-2 levels above
2. 1 level; placement of epidural needle, spinal needle is passed through & small intrathecal dose injected, then epidural catheter placed through epidural needle
64
What are concerns of combined spinal epidural in the partruient?
1. intrathecal opioid effects on fetus
2. inability to ambulate after receiving narcotics
3. maternal hypotension & itching
65
What are 6 potential complications of combined spinal epidural?
1. failure to obtain either block
2. catheter migration
3. increased spinal level
4. metallic particles
5. PDPH
6. neurologic injury
66
What 2 things does neuraxial imaging facilitate in spinal/epidural placement?
1. identify interspaces
| 2. determine depth to epidural space
67
How much metabolism of local anesthetics occurs in the CSF?
little to no
68
What does added vasopressor do to local anesthetics?
slows absorption and prolongs block
69
What are 3 ester local anesthetics?
1. procaine
2. Chloroprocaine
3. Tetracaine
70
What are 4 amide local anesthetics?
1. lidocaine
2. mepivacaine
3. ropivacaine
4. bupivacaine
71
What is the onset & duration of procaine?
slow / 60-90m
72
What is the onset & duration of Chloroprocaine?
Fast 30-60m
73
What is the onset & duration of tetracaine?
slow / 180-600m
74
What is the onset and duration of lidocaine?
fast, 90-20m
75
What is the onset & duration of mepivacaine?
fast 120-240m
76
What is the onset & duration of ropivacaine?
slow / 180-600m
77
What is the onset & duration of bupivacaine?
slow / 180-600m
78
Density of the block is most affected by, what?
concentration of the local anesthetic
79
Spread of a block is most affected by, what?
volume of the local anesthetic used
80
No more than ___ amount per injection?
3-5mL
81
Injection of neuraxial local anesthetic occurs after what?
aspiration attempt
82
If the needle is placed caudal, how much volume is administered per segment to raise the level of the block?
2mL / segment
83
If the needle is placed lumbar, how much volume is administered per segment to raise the level of the block?
1mL / segment,
non-pregnant, non-obese pts can go up to 2mL/segment
84
If the needle is placed thoracic how much volume is administered per segment to raise the level of the block?
0.7mL / segment
85
What type of medication is clonidine and why is it added to epidurals?
alpha 1 agonist
when mixed with lidocaine or bupivacaine, has synergistic effects for labor analgesia
86
When using opioids in a spinal or epidural, what kind need to be use?
PRESERVATIVE FREE
87
What are the two most commonly used opioids in spinal/epidurals?
fentanyl
| morhpine
88
What is the dose of Fentanyl in epidural anesthesia?
50-100mcg
89
What is the onset of Fentanyl in spinal/epidural anesthetics?
10-15m
90
What is the duration of Fentanyl in spinal/epidural anesthesia?
1-2H
91
What is the dose of morphine in epidural anesthesia?
2-4mg
92
Is morphine polar or non-polar?
polar
93
Is morphine lipid soluble?
not very
94
What are 2 adverse effects of using morphine in spinal/epidural anesthetics?
1. itching
| 2. urinary retention
95
The goal of neuraxial anesthesia is to block what?
Adelta & C fibers
96
What type of nerve fibers are blocked first?
Type B; preganglionic autonomic vasomotor
97
What are Adelta fibers?
pain, cold temperature, touch
heavy meylination
intermediate block onset
98
What are C fibers?
pain, warm and cold temperature, touch
no myelination
early block onset
99
At what level are cardiac accelerator fibers?
T4
100
What is the first sign a local anesthetic block is working?
flushing/hypotension
101
What mirrors sensory loss?
temperature discrimination
102
How often should dermatome level of block be checked?
every 2-3 minutes
103
Autonomic blockade is usually where compared to sensory?
two dermatome levels higher
104
Upper limit of MOTOR block is usually where compared to sensory block?
two levels BELOW sensory block
105
Two risk factors for PDPH?
1. needle size & type
| 2. young, female, pregnant
106
PDPH in the first 24 hours?
conservative
- recumbent position
- analgesics
- fluid administration
- caffeine
- stool softeners & soft diet
107
What is an epidural blood patch?
- access epidural space
- someone else sterile obtains 15-20mL of blood
- infuse 15-20mL of blood into epidural space BELOW initial puncture site
108
No more than how much LA is injecting during spinal?
2mL
109
To anesthetize motor & sensory, local anesthetic concentration should be?
0.5% or higher
110
What is the specific gravity of CSF?
1.003 - 1.009
111
What additive is used to make a hyperbaric spinal local anesthetic?
dextrose
112
What additive is used to make a hypobaric spinal local anesthetic?
water
113
What should you call bone when you hit it with the needle?
Oss
114
What should you call blood if you see it during a spinal or epidural?
Heme
115
If 2 intervertebral spaces look "good", which one should you use first?
the lower then move up if you need to
116
What is the swirl between NS and hyperbaric local anesthetic called?
biferengence
117
What is rechecking aspiration called?
barbitage
118
If a patient tells you they can't breathe after placement of a spinal or epidural, what should you have them do?
squeeze your hand and let go
119
At what anatomical location does a spinal block occur?
ventral and dorsal nerve roots
120
What can be controlled when using a spinal block?
block distribution
121
What are 4 indications of using a spinal block?
1. full stomach (↓ aspiration risk compared to general)
2. difficult airway (keeps them awake & breathing)
3. minimal metabolic impact (liver dz, kidney dz, diabetes)
4. reduction in systemic BP leads to ↓ risk of DVT & ↓ risk of blood loss
122
What is a normal aortic cross sectional area?
2 cm^2
123
What is CSA of mild aortic valve stenosis?
>1.5 cm^2
124
What is CSA of severe aortic valve stenosis?
<1 cm^2
125
What vital sign needs to be considered when choosing to do neuraxial block?
Blood pressure...
| severe chronic HTN will not tolerate the generalized vasodilation
126
What is the most prominent cervical process?
C7
127
What vertebral body lies at the inferior tip of the scapula?
T7
128
What factors influence the local anesthetic level of a spinal block?
1. baricity of the local anesthetic used
2. position of the patient
3. drug dose
4. site of injection
also..
[patient's height, pregnancy, age, CSF volume, curvature of the spine, drug volume, intra-abdominal pressure, needle direction]
129
What is the most dependent area of the supine spine?
T4-T8
130
How is a 25G or smaller spinal needle used?
1. place introducer midline in lower third of the interspace
(where lidocaine wheal should have been placed)
2. then pass spinal needle through introducer
3. advance through 2 ligaments (which are?)
- supraspinous
- interspinous
4. you may feel 2 "pops"
- ligamentum flavum
- dura
131
How slow should local anesthetic be injected into the spinal canal?
doesn't matter
132
How should local anesthetic be injected into the spinal canal?
1. aspirate gently (make sure you get CSF)
2. administer 50% of medication
3. aspirate gently again
4. administer 2nd half of medication
133
If a bilateral spinal block is desired, how should the patient be placed immediately after medication administration?
supine with head slightly elevated
134
If a unilateral block is desired, how should the patient be positioned immediately after medication administration?
leave the patient in the lateral position for at least 3 minutes prior to returning supine, slightly elevate the patient's HOB
135
What are the 2 "types" of spinal needles?
cutting vs pencil point
136
What should you do if you are using a pencil needle and feel the dural "pop" but do not get CSF?
ensure stylet is in needle, advance spinal needle by 1-2mm and/or spin needle
[bevel might be covered or not fully inside the dura]
137
What is one benefit of using a pencil spinal needle vs a cutting spinal needle?
less reports of PDPH
138
What should you do if you get blood when performing a spinal block?
1. frank blood = pull all equipment out and start over
| 2. blood or pink tinged CSF. Allow CSF to flow for several seconds to see if it clears
139
What do you do if the spinal needle is FAR in and you hit bone?
traversed dura? possibly
1. remove stylet
2. attach syringe to needle
3. slowly remove needle while gently aspirating
*pt is at increased risk for PDPH
140
What type of nerve block is rapid?
B fiber, will cause hypotension
141
What sensation mirrors sensory loss?
temperature discrimination
142
In a good sensory block, a patient is unable to discriminate what 2 sensations?
1. light touch
| 2. temperature
143
Blocking which nerve fibers leads to surgical muscle relaxation?
Aalpha
Abeta
Agamma
144
If A alpha, beta, & gamma fibers are blocked what may the patient still feel?
pressure
145
How often should vital signs be checked when a patient has a spinal block?
2-3 minutes
146
What should be checked along with vital signs every 2-3 minutes when a patient has a spinal block?
assess the level/degree of block.
use alcohol pad = cold
147
What is the easiest way to adjust the level of a patient's spinal or epidural block?
reposition/change their position
148
Autonomic blockade relates to sensory blockade, how?
autonomic block is usually 2 levels HIGHER than sensory
149
Motor blockade relates to sensory blockade, how?
motor block is usually 2 levels LOWER than sensory
150
At what location does a saddle block occur?
S2-S5
** little autonomic effect
151
At what level does a "low spinal" block occur?
T10
**blocks lumbar and sacral nerve roots
152
What is the most common level for a spinal block?
T4
153
What procedures can be done with a spinal block at T4?
abdominal and lower extremity procedures
154
What procedures can be done with a spinal block at T10?
low abdominal & lower extremity vascular & ortho procedures
155
At what level does a "high spinal" block occur?
C8
156
What is the onset of morphine when used in an epidural?
10-15 minutes
157
What is the duration of action of morphine when used in an epidural?
8-10 hours
158
What is the lumbosacral "Taylor" approach for a spinal block?
modified paramedian approach
uses L5-S1 interspace
159
How is the "Taylor" lumbosacral approach completed?
1. identify posterior superior iliac spine
2. make skin wheal 1cm medial and 1mc caudal to the spine
3. insert needle at 45-55d angle medial and cephalad to the dorsal surface of the sacrum toward the midline of the lumbosacral foramen
160
What size epidural needle is used for placement of a SPINAL catheter?
17G
161
How is medication given through a SPINAL catheter?
small, slow doses
slow onset of hypotension
162
What is one situation in which a spinal catheter could be placed?
if a "wet tap" occurs when attempting placement of an epidural catheter
163
What are 3 additive medications to a spinal block?
1. epinephrine
2. phenylephrine
3. clonidine
164
What is the dose of epinephrine in a spinal or epidural?
0.1 - 0.2 mL of 1:1000 = 100-200mcg of epinephrine
165
Epinephrine has the greatest effect when added to what local anesthetic?
tetracaine
166
How much phenylephrine is added to local anesthetic?
0.05-0.2mL of 1% phenylephrine
^^
10mg/mL = 0.5-2mg of phenylephrine
167
Phenylephrine has the greatest effect when added to what local anesthetic?
tetracaine
168
Is clonidine a vasoconstrictor?
no
169
What is the MOA of clonidine?
selective alpha 2 agonist
170
When is clonidine used in local anesthetics?
when epinephrine is contraindicated
171
Clonidine has synergistic effects with what local anesthetics?
lidocaine
bupivacaine
172
The central action of clonidine helps with what?
tourniquet pain
173
What are 2 benefits of Fentanyl's high lipid solubility when used in spinal/epidurals?
1. binds directly to lipid elements of the spinal cord
| 2. less drug available to diffuse systemically
174
When administered in a spinal anesthetic, when will morphine reach the respiratory center?
6-8 hours
175
How does morphine act in the spinal column?
drifts freely in the CSF
176
What is the dose of Fentanyl in spinal anesthesia?
12.5-25mcg mixed with local anesthetic
177
What is the onset of Fentanyl in spinal anesthesia?
5-10 minutes
178
What is the duration of action of Fentanyl in spinal anesthesia?
2-4H
179
What is the dose of morphine in spinal anesthesia?
0.1-0.25mg mixed with local anesthetic
180
What is the onset of morphine when used in spinal anesthesia?
60-90 minutes
181
What is the duration of action of morphine when used in spinal anesthesia?
~24 hours
182
What is one adverse effect of morphine that is specific to SPINAL anesthesia?
DELAYED RESPIRATORY DEPRESSION
183
What are some complications of spinal anesthesia?
- hypotension
- intercostal muscle paralysis
- apnea/phrenic nerve paralysis
- paresthesia
- subarachnoid or epidural hematoma
- meningitis/epidural abcess
- chemical meningitis
- cauda equina syndrome
- transient neurologic symptoms
- new nervous system lesion
- exacerbation of preexisting neurologic disease
- N/V
- urinary retention
- PDPH
