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931: Advanced Principles of Anesthesia I > Considerations for epidural anesthesia > Flashcards

Considerations for epidural anesthesia Flashcards

1
Q

What is an epidural anesthetic?

A

reversible chemical blockade of neuronal transmission produced by the injection of a local anesthetic into the epidural space to the region of the dural cuffs

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2
Q

An epidural anesthetic results in

A

temporary interruption of autonomic, sensory, and motor nerve fiber transmission related to drug concentration & volume

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3
Q

The danger with using hypobaric solution in a sitting position:

A

it can spread up & if it reaches cardioaccelerator fibers (T4, T5) then it can have hypotension & bradycardia

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4
Q

Describe the difference in volume administration for an epidural versus a spinal.

A

Need higher volume for an epidural because we are counting on diffusion

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5
Q

The onset for an epidural is

A

longer

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6
Q

The medication spread for an epidural is

A

diffusion dependent

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7
Q

The epidural anesthetic leaks into the

A

intravertebral foramen & paravertebral spaces

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8
Q

The advantages to epidural includes it reduces

A

surgical stress (thus opioid consumption)
possibly it decreases overall blood loss
risk of DVT

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9
Q

Advantages to epidurals include

A

it provides anesthesia and/or analgesia (can be titrated)- ability to re-dose with catheter) or convert from pain management to primary anesthetic (labor epidural)
-versatile- control extent of sensory & motor blockade, used wit or without adjunct medications

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10
Q

Every time you dose your epidural you must

A

always aspirate first & inject 5 cc max at a time

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11
Q

Disadvantages to epidural anesthesia include:

A

post dural puncture headache- large CSF leaks
sympathetic blockade occurs 100% of the time–> hypotension or bradycardia
block may last much longer than the procedure
urinary retention–> most common with spinal
regional takes “too much time”- more difficult than a spinal

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12
Q

Epidural selection is based upon:

A

surgeon expertise/preference- discuss case with surgeon, part of multimodal management in ERAS protocols
management of labor pain
procedures involving- abdomen & lower extremities
certain comorbidities- pulmonary disease

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13
Q

Absolute contraindications to epidurals include:

A

patient refusal
increased ICP
severe aortic or mitral valve stenosis (now more of a relative)
coagulopathy or bleeding diathesis
severe hypovolemia-> leads to hypotension
infection at the injection site

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14
Q

Relative contraindications to epidurals include:

A

local anesthetic allergy (more likely w/ esters)
patient on anticoagulant or thrombolytic therapy
preexisting neurologic deficit
chronic headache or backache
severe spinal deformity
valvular stenosis
uncooperative patient–> inability to communicate/obtain informed consent; unable to assist

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15
Q

Patients with these comorbidities may be a relative contraindication due to anticoagulant therapy:

A

atrial fibrillation
previous DVT
postsurgical administration- initiation of DVT prophylaxis

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16
Q

The preoperative patient assessment for the patient getting an epidural includes:

A

does patient understand proposed surgical technique
explain the spinal anesthetic and rational for preference
age considerations
never force or coerce a patient into any procedure
address any patient concerns–> some patients fear loss of control, reassure patient all appropriate medications will be administered

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17
Q

Documentation of informed consent includes:

A

advantages & disadvantages
block appropriate for procedure but not guaranteed
risks & benefits
ensure patient understands
allow patient to ask questions
do not attempt to dissuade from a general if already agreed to

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18
Q

Documentation does not exonerate you from

A

negligence!

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19
Q

When considering pre-procedure medication, considerations include:

A

reduce anxiety & provide some amnesia & analgesia- but do not over sedate
follow NPO standards for elective cases
consider bolus administration of IV solution

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20
Q

At a minimum prior to beginning epidural placement, have

A

peripheral IV, suction, airway supplies, ECG, blood pressure cuff, pulse oximeter–> possibly oxygen, supportive medications (induction agent, paralytic, atropine, vasoactive medication), support person

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21
Q

Describe the difference between spinal & epidural.

A

spinal- single shot (usually), dosage is less than epidural, baricity, patient position
epidural- catheter, volume block (isobaric medications because using volume to help with spread)

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22
Q

Describe the positions that can be used:

A

sitting, lateral decubitus, prone

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23
Q

Describe the needle approaches that can be used:

A

midline

paramedian–> ligamentum flavum will b the first you encounter (miss the other ligaments)

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24
Q

Placement options for the epidural include:

A

thoracic, lumbar, & caudal

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25
Q

In terms of positioning and landmarks, an assistant must

A

stand in front of the patient and not leave the patient

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26
Q

To position the patient correctly in the sitting position

A

hold a pillow or blanket or lean over table, drop their head down
roll their back- “angry cat” or “shrimp” position

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27
Q

When performing the lateral approach, it is important to

A

maintain midline positioning & limit spine rotation

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28
Q

Flexing the spine will create

A

larger interspinous space

need to optimize your positioning

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29
Q

Prior to starting the procedure, it is important to verify

A

patent IV
monitoring devices/oxygen attached & functioning
resuscitation equipment available
“walk” patient through the procedure

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30
Q

The procedure itself is

A

sterile

at a minimum, you must wear: a surgical hat, surgical mask, and sterile gloves

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31
Q

Prior to starting the sterile portion of the procedure, you should

A

palpate major landmarks- iliac crests & spinous processes of lumbar vertebrae

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32
Q

When deciding where to insert your epidural, you should

A

use the most identifiable interspace
L2-3 is the most common
examine one level above & below target
If processes are not palpable consider US

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33
Q

The site should be cleansed with

A

chlorhexidine gluconate & a sterile drape should be applied

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34
Q

Epidural needles are marked in

A

1 cm increments

standard needle is 9 cm

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35
Q

Describe the Tuohy needle.

A

pronounced curve, easier for novices, directional placement of catheter

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36
Q

Describe the Crawford needle

A

is not curved, easier to insert, higher rate of dural punctures

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37
Q

The hand position prior to needle insertion involves

A

straddling the selected interspace with the middle and index fingers of your non-dominant hand
raise a small intradermal skin wheal of local anesthetic with a 25-27 gauge needle

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38
Q

The distance to ligamentum flavum varies with

A

body habitus
level of placement- standard depth at lumbar level is 5 cm- depth within epidural space also varies
needle angle changes with level

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39
Q

Epidural needles are

A

larger and more rigid; do not require an introducer & provide better directional control

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40
Q

Describe the “bromage” grip.

A

hand firm support to stabilize needle
attach and secure syringe
passing catheter through needle
- the needle is placed with bevel cephalad
-advanced through supraspinous ligament & interspinous ligament

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41
Q

The alternative to the “Bromage” grip is to

A

attach and secure syringe
needle placed with bevel cephalad
hands stabilize needle on both sides
advanced through supraspinous ligament & interspinous ligament

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42
Q

Describe the loss of resistance method.

A

most common method
involves glass or plastic syringe filled with 2-3 mL of saline with air bubble
attach to epidural needle- resistance noted while needle is in ligament until epidural space is entered
tap on plunger with every movement

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43
Q

Describe the hanging drop method.

A

hub of epidural needle filled with saline until a small drop is visible
negative pressure created as needle passes into epidural space “sucks” drop in- more pronounced at thoracic levels

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44
Q

Once needle passes through the epidural space, an

A

immediate loss of resistance is noted

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45
Q

After loss of resistance is felt, the contents of the syringe are

A

injected into the epidural space

air (could give someone a pneumocephalus) vs. fluid (allows for dilation)

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46
Q

Epidural catheters are typically

A

two gauges smaller than needle
open-ended
multiport- lower incidence of inadequate analgesia & higher incidence of accidental vein cannulation

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47
Q

Markings help identify the depth of catheter placement described what the following indicate:
dashed lines
two-dashed lines
thick line

A

dashed lines- 1 cm
two-dashed lines= 10 cm
thick line= 12 cm

48
Q

If paresthesia occurs

A

stop, withdraw slightly and redirect your needle

49
Q

Describe how far the catheter should be advanced.

A

3-5 cm past the needle hub

50
Q

Shallow placement of an epidural catheter will result in

A

dislodgement from the epidural space

51
Q

Too deep of a placement of an epidural catheter will result in

A

puncture of dura
passage into epidural vein
migration through intervertebral foramen

52
Q

Once you remove your needle, it is important to note the depth of the catheter at the skin. If the depth is

A

less than 1 cm to the epidural space, it needs to be replaced

53
Q

You should NEVER attempt to

A

withdraw the catheter through the needle

it could result in catheter shear

54
Q

Once the needle is safely removed:

A

attach adaptor to free end
look for presence of blood or CSF
“gently” aspirate

55
Q

The test dose is

A

1.5% lidocaine with epinephrine 1:200,000

inject 3 mL- 45 mg lidocaine & 15 mcg of epinephrine

56
Q

If you inject your needle and the test dose is administered in the subarachnoid space it becomes

A

a spinal

57
Q

If you inject your needle and the test dose is administered in the intravascular space you will see

A

> 20% increase in HR & BP

58
Q

To secure the catheter it should be

A

looped and taped away from midline- minimizes the chance of dislodgement & keeps off spinous processes
placed over shoulder
secure label to the end of the catheter

59
Q

Describe the paramedian approach.

A

Useful when patient cannot flex spine-hx of previous spine surgery, RA or hip or upper leg trauma
skin wheal 1 cm lateral and 1 cm caudal to spinous process
Advance needle toward midline- needle passes through paraspinous muscles to ligamentum

60
Q

The biggest difference with the paramedian approach includes:

A

it does NOT pass through supraspinous or interspinous ligaments

61
Q

Trouble shooting can include

A

contacting bone, paresthesia, & blood in catheter

62
Q

If you are contacting bone, you should

A

withdraw the needle and stylet to the subcutaneous fat. reposition the introducer and reinsert the needle

63
Q

If the needle is touching the superior crest of spinous process below the interspace,

A

redirect cephalad

64
Q

If the needles is touching the inferior surface of the spinous process above the interspace,

A

redirect caudal

65
Q

If you repeatedly encounter bone,

A

remove the needle and reassess landmarks

66
Q

If you see blood in the catheter,

A

withdrawal the catheter and replace it

67
Q

If the patient experiences paresthesia during catheter insertion,

A

stop. if it resolves then can continue

if it is persistent- withdrawal and reposition

68
Q

Caudal anesthesia is a

A

distal approach to the epidural space

69
Q

Indications for a caudal approach includes

A

hemorrhoidectomy, chronic pain patients, & pediatric analgesia- inguinal herniorrhaphy, circumcision, perineal procedures

70
Q

Describe the anatomy for the caudal approach.

A

technically difficult approach (especially in adults)- overall failure rate is 5%
more reliable in pediatrics
more difficult in adults due to variation in size, shape, and orientation of the sacral anatomy

71
Q

The positioning for the caudal approach is

A

prone on a flexed table or with a pillow under the pelvis
legs spread and externally rotated
pediatrics- laterally positioned

72
Q

For the caudal approach, care must be taken to ensure

A

not in subcutaneous

not in bone

73
Q

Dosing for the caudal approach is

A

0.5-1 mL/kg body weight
varying LA concentrations
2.5 mg/kg body weight

74
Q

When performing the caudal approach, you should

A

puncture the sacral hiatus

-adjust needle angle and advance 1-2 cm

75
Q

Complications of the caudal approach include

A

high failure rate (false passages)
inadvertent IV injection or catheter placement
dural puncture

76
Q

Adult considerations for performing the caudal approach include

A

test dose
incremental injections following negative aspiration
sacral anesthesia: 12-15 mL
lower extremity procedures: 20-30 mL

77
Q

A combined spinal epidural offers

A

advantages of both while reducing disadvantages

78
Q

Describe a two-level combined spinal-epidural.

A

spinal placed first

epidural catheter placed 1-2 levels above

79
Q

Describe a one-level combined spinal epidural

A

placement of epidural needle
spinal needle passed through
small intrathecal dose injected
epidural catheter placed

80
Q

Additional concerns for the combine spinal epidural include

A

intrathecal opioid effects on fetus
inability to ambulate after receiving narcotics
maternal hypotension & itching

81
Q

Potential complications of combined spinal epidural are

A 
failure to obtain either intrathecal or epidural block
catheter migration
increased spinal level
metallic particles
PDPH
neurologic injury
82
Q

For the obese patient it is more difficult to

A

palpate spinous processes as adipose tissue distorts anatomic landmarks
sitting position may provide more flexion- feet resting on a stool or “Indian” style
consider ultrasound

83
Q

Neuraxial imaging facilitates

A

successful blocks in both normal and abnormal spinal anatomy because you can identify interspaces& determine depth to epidural space

84
Q

Ultrasound has been shown to improve

A

patient safety and comfort

85
Q

The ultrasound assisted neuraxial imaging is the most

A

common approach in adults

two scanning planes are required to determine level and midline

86
Q

The real-time approach is

A

feasible in the pediatric population

87
Q

Describe the two planes that must be scanned for neuraxial imaging.

A

parasagittal- paramedian, longitudinal view

axial- transverse, midline view

88
Q

These factors regarding local anesthetic varies according to level and duration of block desired

A

type, volume and total dose

tailored to each patient & the surgeon’s needs

89
Q

Little to no metabolism of local anesthetic in the

A

CSF

absorbed into plasma and metabolized based on its physiochemical properties

90
Q

Adding vasoconstrictors will

A

slow absorption and prolong block

91
Q

Considerations of the local anesthetics include:

A

density of block- concentration
spread of block- volume
think cephalad & caudal spread, positioning, elderly & pregnant
no more than 3-5 mL per injection & only after negative aspiration

92
Q

The quickest onset of the esters is

A

chloroprocaine

93
Q

The quickest onset of the amides is

A

lidocaine: DOA is 90-120 minutes

mepivacaine DOA is 120-240 minutes

94
Q

Describe how the dosing differs between caudal, lumbar, & thoracic.

A

caudal: 2 mL/segment
lumbar: 1 mL/segment
thoracic: 0.7 mL/segment

95
Q

Describe why epinephrine would be added.

A

alpha 1 agonist
concentration: 1:200,000 (15 mcg/mL)
prolong effect of short-acting local anesthetics

96
Q

Describe why clonidine would be added.

A

it is NOT a vasoconstrictor
-selective alpha 2 agonist
when mixed with lidocaine or bupivacaine it has synergistic effects for labor analgesia

97
Q

Describe the most commonly used epidural opiods.

A

fentanyl & morphine
a combination of preservative free opioids and local anesthetics provides better analgesia than if either drug is used alone

98
Q

Describe the dose, onset, & duration of fentanyl.

A

dose: 50-100 mcg
onset: 3-5 minutes
duration: 1-2 hours

99
Q

Describe the dose, onset, and duration of morphine

A

dose: 2-4 mg
onset is 10-15 minutes
duration: 8-10 hours

100
Q

The adverse effects of morphine include:

A

itching & urinary retention

highly polarized, not very lipid soluble

101
Q

The goal of epidurals is to block

A

A delta & C fibers

drug concentration typically exceeds requirements for all nerve types

102
Q

A patient controlled epidural is a

A

low concentration infusion with additive
it augments effects of local anesthetic
patient has the ability to inject additional LA if needed

103
Q

Describe the conservative treatment for PDPH.

A

first 12-24 hours

recumbent position, analgesics, fluid administration, caffeine, stool softeners and soft diet

104
Q

An epidural blood patch can be used to

A

treat PDPH
injecting 15-20 mL of autologous blood
below initial puncture site (1-2 levels)
90% will respond to initial therapy

105
Q

Signs and symptoms of PDPH include

A

bilateral frontal or retroorbital or occipital, extends into next, photophobia, nausea, positional

106
Q

Risk factors for the PDPH include

A 
needle size & type
patient population (younger, female & pregnancy)
107
Q

A postdural puncture headache results from

A

compromise in the dura

may be obvious or may follow uncomplicated procedure

108
Q

List the complications associated with epidurals:

A

hypotension, intercostal muscle paralysis, apnea/phrenic nerve paralysis, paresthesia, SAH or epidural hematoma, meningitis/epidural abscess, chemical meningitis, cauda equina syndrome, transient neurologic symptoms, new nervous system lesion, exacerbation of preexisting neurologic disease, N/V, urinary retention, and post dural puncture HA

109
Q

Documentation should include.

A

informed consent
oxygen/monitors applied; baseline VS
patient properly positioned
prepping and draping accomplished in sterile fashion
desired interspace identified
skin wheal of subcutaneous local anesthetic
introducer placed with spinal needle passed through introducer
positive clear CSF noted
dose of LA & any adjuncts
patient placed in desired surgical position
final dermatome level achieved

110
Q

The autonomic blockade is usually

A

two dermatome levels higher than level of sensory block

111
Q

The upper limit of motor block is generally

A

two levels below sensory block

112
Q

Evaluation of your block should be assessed

A

every 2-3 minutes

113
Q

Post block, it is important to assess

A

blood pressure & vital signs frequently

114
Q

Physiologic changes closely resemble

A

block level
level is determined easiest by assessing sensory changes
-distribution of spread can be manipulated by adjusting level of OR table

115
Q

B fiber block

A 
is rapid
-hypotension related to level
T4= cardiac accelerator fibers
drop in BP first sign
N/V may follow
116
Q

A delta & C pain fibers and temperature follow

A

B fibers

  • unable to discriminate light touch or temperature
  • temperature discrimination mirrors sensory loss
117
Q

A alpha, A beta, & A gamma are last and include

A

touch & proprioception, surgical muscle relaxation, may feel pressure

931: Advanced Principles of Anesthesia I (22 decks)

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