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2-General Anesthesia Exam 2 > Epidural/Caudal Blocks > Flashcards

Epidural/Caudal Blocks Flashcards

1
Q

What can epidural anesthesia be titrated to?

A

Can be titrated to deliver either analgesia or anesthesia

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2
Q

What is one key difference of the epidural block?

A

More control over the extent of sensory and motor blockade than with SAB

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3
Q

What is nice about the catheter with epidural anesthesia?

A

Ability to place a catheter allows for more flexibility/redosing, e.g. long procedures, post-operative pain control

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4
Q

Because epidural anesthesia is diffusion dependent, ____________ must be used than in SAB

A

larger volumes of local anesthetics

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5
Q

What is the standard epidural needle?

A

Standard needle is 16-18 gauge and 3 inches long

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6
Q

Epidural needles are Blunted bevel and gentle curve of ________ at the tip

A

15-30 degrees

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7
Q

What are the most common epidural needles?

A

Touhy and Hustead

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8
Q

What is the touhy needle?

A

most pronounced curve (30 degrees) and easiest for beginners

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9
Q

What is the hustead needle?

A

15 degree curvature allows for easier passage thru skin and ligamentum flavum

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10
Q

What is the crawford needle?

A

no curve so easier to access steep angles (e.g. thoracic spine) but increased incidence of dural penetration

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11
Q

What are the layers of anatomy that need to be transversed from posterior to anterior with an epidural anesthetic?

A 
Skin
Subcutaneous fat
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
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12
Q

What should the catheter diameter be size wise?

A

Catheter diameter should be 2 gauges smaller than the needle

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13
Q

Epidural catheters: Should be

__________

A

radiopaque

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14
Q

What are the most common epidural catheters?

A

are the single-holed, open-ended (uniport) and the lateral-holed, closed tip (multiport)

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15
Q

What do the markings on the catheter indicate?

A

1cm depth increments

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16
Q

How far should the epidural catheter be inserted into the epidural space?

A

3-5cm

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17
Q

What is the test dose?

A

administered to determine whether the catheter or needle has inadvertently entered the subarachnoid space or threaded into an epidural vein

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18
Q

What is the typical LA dose for epidural test?

A

Typically 3mL of rapid acting, low toxicity LA used with epi

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19
Q

Which are the two medications used often for the epidural test dose?

A
  • Lidocaine 1.5% with 1:200,000 epi

- 45mg lidocaine / 15mcg epi

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20
Q

How soon will the epidural test indicate spinal anesthetic?

A

3min

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21
Q

How soon will the epidural test indicate intravascular injection?

A

30 seconds

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22
Q

What effects the clinical success of an epidural and dermatomal blockade?

A

primarily dependent upon dose of medication and site of injection

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23
Q

What is true about the size of segmental epidural spaces?

A

increases down the spinal cord as the spinal cord occupies less and less space

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24
Q

Suggested volumes per segment at cervical and thoracic levels are ________ per segment

A

0.7-1mL

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25
What is the dose for cervical and thoracic levels?
Dose of 10mL will achieve a 10-14 dermatomal spread
26
What are the suggested volumes per segment at the lumbar levels?
1.25-1.5mL per segment
27
What are the suggested dose per segment at the lumbar levels?
15-20mL will achieve a 12-16 dermatomal spread
28
What is the common clinical practice to insert the epidural needle?
at a vertebral interspace such that the catheter tip falls near the middle of the spinal dermatomes of the proposed surgical incision
29
What effect dose height and weight have on epidural blockade?
Likely only relevant at the extremes
30
What effect dose age have on epidural blockade?
Spread may be 3-4 dermatomes greater in elderly patients because of less compliant tissues and less leaky epidural space
31
What effect dose pregnancy have on epidural blockade?
- Epidural spread greater | - Limit dose to 0.5-1mL per segment initially
32
What is the speed or mode of injection of epidural blockade?
Inject slowly to avoid increases in CSF pressure, headache and increased ICP
33
What is the concentration of epidural?
The lower the concentration the lower the effect the local anesthetic will have on the degree of sensory and motor blockade (the “density” of the block)
34
What can a lower concentration of epidural medications?
Lower concentrations of local anesthetics used to facilitate analgesia (e.g. labor) or to provide a sympathectomy
35
What are higher concentration of epidural medications?
Higher concentrations used to provide complete surgical anesthesia
36
What is a differential blockade?
the local anesthetics (sympathetic blockade may be a high as 2-6 dermatomes higher than the sensory)
37
What analgesia can be achieved with a epidural differential blockade?
Analgesia (loss to sharp pain) 2+ segments cephalad than touch- sometimes patient still feel “touch” or pulling sensations on less dense blocks- shouldn’t be painful
38
Review Table 49.4
Nagelhaut
39
What is the increments of epidural injection?
in increments of 3-5mL every 3 minutes and titrated to desired anesthetic level
40
What should be done before any injection of an epidural?
Aspiration should occur before any injection, including into an epidural catheter
41
Epidural medications: __________ is then maintained with either a continuous infusion or intermittent injections
Anesthetics
42
What is important about the infusions?
a lower concentration of local
43
What is important about the level of block for the epidural?
Level of block should be assessed at regular intervals (usually with cold sensation or skin ”pricking”
44
Epidural: _________ can be added to infusions
Opioids
45
What is the spread of dermatomal blocks?
10-25 minutes post injection
46
Level of the block will ________ over time
regress
47
When level of sensory block has decreased by 1-2 dermatomes another dose, ________ of initial dose can be given
30-50%
48
When can tachyphylaxis?
can occur if regression allowed beyond 2 dermatomal segments
49
When is tachyphylaxis more often to occur?
More often seen with shorter-acting agents than longer-acting agents
50
What is an inadequate epidural block?
one-sided block or single-sensory dermatome segment failure
51
What can be done for an inadequate block?
- Reposition patient with the unblocked segment down - Administer additional local - Not using air in loss of resistance technique
52
What is the steps if an intradural catheter placement suspected?
- Remove catheter | - Do not replace until after resolution of side effects, (e.g. hypotension, bradycardia)
53
If reattempting epidural, place catheter __________ to the interspace previously attempted
one dermatome level more cephalad
54
What are the epidural complications?
Hypotension Bradycardia Backache PDPH
55
What is the incidence of backache?
30-45% incidence in the obstetric patient population
56
What is the incidence of PDPH?
- Incidence 1-2% | - Much lower incidence than with SAB
57
What is the two level technique of CSE?
- Each component of the block performed separately at two different interspaces - Epidural inserted first and spinal inserted second 1 or 2 interspaces below epidural
58
What single level CSE technique?
Epidural needle placed in the epidural space. Then used as an introducer for the spinal needle. Spinal needle removed and epidural catheter threaded into place.
59
What needle is used for CSE technique?
Small pencil point needle (25, 27 or 29 gauge) inserted through epidural needle into subarachnoid space and injection administered
60
What is the specialixed CSE needles?
- Needle with two channels – one for epidural catheter and one for spinal needle - Needle is placed, epidural catheter is threaded, then spinal needle placed
61
What is the failure rate for CSE complications?
3.1-17%
62
What is the failure rates greater with?
Greater failure rates with single level technique compared with the two level technique
63
What is the theories behind increased spinal level after epidural administration?
- Volume of fluid injected into the epidural space compresses subarachnoid space and CSF within it, increasing the spread of local - A leak or flow of local from the epidural space into the subarachnoid space through the dural puncture
64
What is the CSE complications?
``` Failure rate Catheter migration PDPH Infection Neurologic injury ```
65
What is the caudal anesthesia?
Distal approach to the epidural space
66
Where dose caudal anesthesia act?
Will act on the sacral dermatomes
67
When is a caudal anesthesia?
Perirectal surgery, urologic and orthopedic surgery of the lower extremity
68
Caudal is often used with a light ________ in preadolescent pediatric patients
GA
69
What is the age requirement for caudal anesthesia?
After age 12 years sacral anatomy changes and bone growth makes identification of the epidural space difficult but not impossible
70
Caudal anesthesia: Can use a __________ technique
continuous catheter
71
What is the pediatric dose of caudal medications?
0.5-1mL of solution per kg of body weight will reliably achieve a level of analgesia to the umbilicus
72
What is the concentration for caudal medications of bupivacine or ropivacaine?
in concentrations of 0.125-0.5% are usually administered with 1:200,000 epi to a maximum dose of 2.5mg/kg body weight
73
Caudal dose for adults?
Use same dosing principles as with epidurals, not typically done
74
What are the complications of caudal anesthesia?
-Similar to epidural – intravascular or subarachnoid injection -High failure rate – 10-15% Infection

2-General Anesthesia Exam 2 (11 decks)

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