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

Considerations for epidural anesthesia Flashcards

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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
In terms of positioning and landmarks, an assistant must
stand in front of the patient and not leave the patient
26
To position the patient correctly in the sitting position
hold a pillow or blanket or lean over table, drop their head down roll their back- "angry cat" or "shrimp" position
27
When performing the lateral approach, it is important to
maintain midline positioning & limit spine rotation
28
Flexing the spine will create
larger interspinous space | need to optimize your positioning
29
Prior to starting the procedure, it is important to verify
patent IV monitoring devices/oxygen attached & functioning resuscitation equipment available "walk" patient through the procedure
30
The procedure itself is
sterile | at a minimum, you must wear: a surgical hat, surgical mask, and sterile gloves
31
Prior to starting the sterile portion of the procedure, you should
palpate major landmarks- iliac crests & spinous processes of lumbar vertebrae
32
When deciding where to insert your epidural, you should
use the most identifiable interspace L2-3 is the most common examine one level above & below target If processes are not palpable consider US
33
The site should be cleansed with
chlorhexidine gluconate & a sterile drape should be applied
34
Epidural needles are marked in
1 cm increments | standard needle is 9 cm
35
Describe the Tuohy needle.
pronounced curve, easier for novices, directional placement of catheter
36
Describe the Crawford needle
is not curved, easier to insert, higher rate of dural punctures
37
The hand position prior to needle insertion involves
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
38
The distance to ligamentum flavum varies with
body habitus level of placement- standard depth at lumbar level is 5 cm- depth within epidural space also varies needle angle changes with level
39
Epidural needles are
larger and more rigid; do not require an introducer & provide better directional control
40
Describe the "bromage" grip.
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
41
The alternative to the "Bromage" grip is to
attach and secure syringe needle placed with bevel cephalad hands stabilize needle on both sides advanced through supraspinous ligament & interspinous ligament
42
Describe the loss of resistance method.
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
43
Describe the hanging drop method.
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
44
Once needle passes through the epidural space, an
immediate loss of resistance is noted
45
After loss of resistance is felt, the contents of the syringe are
injected into the epidural space | air (could give someone a pneumocephalus) vs. fluid (allows for dilation)
46
Epidural catheters are typically
two gauges smaller than needle open-ended multiport- lower incidence of inadequate analgesia & higher incidence of accidental vein cannulation
47
Markings help identify the depth of catheter placement described what the following indicate: dashed lines two-dashed lines thick line
dashed lines- 1 cm two-dashed lines= 10 cm thick line= 12 cm
48
If paresthesia occurs
stop, withdraw slightly and redirect your needle
49
Describe how far the catheter should be advanced.
3-5 cm past the needle hub
50
Shallow placement of an epidural catheter will result in
dislodgement from the epidural space
51
Too deep of a placement of an epidural catheter will result in
puncture of dura passage into epidural vein migration through intervertebral foramen
52
Once you remove your needle, it is important to note the depth of the catheter at the skin. If the depth is
less than 1 cm to the epidural space, it needs to be replaced
53
You should NEVER attempt to
withdraw the catheter through the needle | it could result in catheter shear
54
Once the needle is safely removed:
attach adaptor to free end look for presence of blood or CSF "gently" aspirate
55
The test dose is
1.5% lidocaine with epinephrine 1:200,000 | inject 3 mL- 45 mg lidocaine & 15 mcg of epinephrine
56
If you inject your needle and the test dose is administered in the subarachnoid space it becomes
a spinal
57
If you inject your needle and the test dose is administered in the intravascular space you will see
>20% increase in HR & BP
58
To secure the catheter it should be
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
Describe the paramedian approach.
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
The biggest difference with the paramedian approach includes:
it does NOT pass through supraspinous or interspinous ligaments
61
Trouble shooting can include
contacting bone, paresthesia, & blood in catheter
62
If you are contacting bone, you should
withdraw the needle and stylet to the subcutaneous fat. reposition the introducer and reinsert the needle
63
If the needle is touching the superior crest of spinous process below the interspace,
redirect cephalad
64
If the needles is touching the inferior surface of the spinous process above the interspace,
redirect caudal
65
If you repeatedly encounter bone,
remove the needle and reassess landmarks
66
If you see blood in the catheter,
withdrawal the catheter and replace it
67
If the patient experiences paresthesia during catheter insertion,
stop. if it resolves then can continue | if it is persistent- withdrawal and reposition
68
Caudal anesthesia is a
distal approach to the epidural space
69
Indications for a caudal approach includes
hemorrhoidectomy, chronic pain patients, & pediatric analgesia- inguinal herniorrhaphy, circumcision, perineal procedures
70
Describe the anatomy for the caudal approach.
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
The positioning for the caudal approach is
prone on a flexed table or with a pillow under the pelvis legs spread and externally rotated pediatrics- laterally positioned
72
For the caudal approach, care must be taken to ensure
not in subcutaneous | not in bone
73
Dosing for the caudal approach is
0.5-1 mL/kg body weight varying LA concentrations 2.5 mg/kg body weight
74
When performing the caudal approach, you should
puncture the sacral hiatus | -adjust needle angle and advance 1-2 cm
75
Complications of the caudal approach include
high failure rate (false passages) inadvertent IV injection or catheter placement dural puncture
76
Adult considerations for performing the caudal approach include
test dose incremental injections following negative aspiration sacral anesthesia: 12-15 mL lower extremity procedures: 20-30 mL
77
A combined spinal epidural offers
advantages of both while reducing disadvantages
78
Describe a two-level combined spinal-epidural.
spinal placed first | epidural catheter placed 1-2 levels above
79
Describe a one-level combined spinal epidural
placement of epidural needle spinal needle passed through small intrathecal dose injected epidural catheter placed
80
Additional concerns for the combine spinal epidural include
intrathecal opioid effects on fetus inability to ambulate after receiving narcotics maternal hypotension & itching
81
Potential complications of combined spinal epidural are
``` failure to obtain either intrathecal or epidural block catheter migration increased spinal level metallic particles PDPH neurologic injury ```
82
For the obese patient it is more difficult to
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
Neuraxial imaging facilitates
successful blocks in both normal and abnormal spinal anatomy because you can identify interspaces& determine depth to epidural space
84
Ultrasound has been shown to improve
patient safety and comfort
85
The ultrasound assisted neuraxial imaging is the most
common approach in adults | two scanning planes are required to determine level and midline
86
The real-time approach is
feasible in the pediatric population
87
Describe the two planes that must be scanned for neuraxial imaging.
parasagittal- paramedian, longitudinal view | axial- transverse, midline view
88
These factors regarding local anesthetic varies according to level and duration of block desired
type, volume and total dose | tailored to each patient & the surgeon's needs
89
Little to no metabolism of local anesthetic in the
CSF | absorbed into plasma and metabolized based on its physiochemical properties
90
Adding vasoconstrictors will
slow absorption and prolong block
91
Considerations of the local anesthetics include:
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
The quickest onset of the esters is
chloroprocaine
93
The quickest onset of the amides is
lidocaine: DOA is 90-120 minutes | mepivacaine DOA is 120-240 minutes
94
Describe how the dosing differs between caudal, lumbar, & thoracic.
caudal: 2 mL/segment lumbar: 1 mL/segment thoracic: 0.7 mL/segment
95
Describe why epinephrine would be added.
alpha 1 agonist concentration: 1:200,000 (15 mcg/mL) prolong effect of short-acting local anesthetics
96
Describe why clonidine would be added.
it is NOT a vasoconstrictor -selective alpha 2 agonist when mixed with lidocaine or bupivacaine it has synergistic effects for labor analgesia
97
Describe the most commonly used epidural opiods.
fentanyl & morphine a combination of preservative free opioids and local anesthetics provides better analgesia than if either drug is used alone
98
Describe the dose, onset, & duration of fentanyl.
dose: 50-100 mcg onset: 3-5 minutes duration: 1-2 hours
99
Describe the dose, onset, and duration of morphine
dose: 2-4 mg onset is 10-15 minutes duration: 8-10 hours
100
The adverse effects of morphine include:
itching & urinary retention | highly polarized, not very lipid soluble
101
The goal of epidurals is to block
A delta & C fibers | drug concentration typically exceeds requirements for all nerve types
102
A patient controlled epidural is a
low concentration infusion with additive it augments effects of local anesthetic patient has the ability to inject additional LA if needed
103
Describe the conservative treatment for PDPH.
first 12-24 hours | recumbent position, analgesics, fluid administration, caffeine, stool softeners and soft diet
104
An epidural blood patch can be used to
treat PDPH injecting 15-20 mL of autologous blood below initial puncture site (1-2 levels) 90% will respond to initial therapy
105
Signs and symptoms of PDPH include
bilateral frontal or retroorbital or occipital, extends into next, photophobia, nausea, positional
106
Risk factors for the PDPH include
``` needle size & type patient population (younger, female & pregnancy) ```
107
A postdural puncture headache results from
compromise in the dura | may be obvious or may follow uncomplicated procedure
108
List the complications associated with epidurals:
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
Documentation should include.
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
The autonomic blockade is usually
two dermatome levels higher than level of sensory block
111
The upper limit of motor block is generally
two levels below sensory block
112
Evaluation of your block should be assessed
every 2-3 minutes
113
Post block, it is important to assess
blood pressure & vital signs frequently
114
Physiologic changes closely resemble
block level level is determined easiest by assessing sensory changes -distribution of spread can be manipulated by adjusting level of OR table
115
B fiber block
``` is rapid -hypotension related to level T4= cardiac accelerator fibers drop in BP first sign N/V may follow ```
116
A delta & C pain fibers and temperature follow
B fibers - unable to discriminate light touch or temperature - temperature discrimination mirrors sensory loss
117
A alpha, A beta, & A gamma are last and include
touch & proprioception, surgical muscle relaxation, may feel pressure

931: Advanced Principles of Anesthesia I (22 decks)

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