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Methods II > Neuraxial Anesthesia and Local Anesthetic > Flashcards

Neuraxial Anesthesia and Local Anesthetic Flashcards

1
Q

Where does the spinal cord end in adults?

A

L1-L2

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2
Q

Where does the dural sac end in adults?

A

S2

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3
Q

Where does the spinal cord end in children?

A

L2-L3

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4
Q

Where does the dural sac end in children?

A

S3

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5
Q

Name the 7 layers of the spine from skin to CSF

A
  1. Skin
  2. Supraspinous ligament
  3. Interspinous ligament
  4. Ligamentum flavum
  5. Epidural space
  6. Dura mater
  7. Subarachnoid space (contains CSF)
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6
Q

the epidural space extends superiorly to the _____ and inferiorly to the _____

A

foramen magnum

sacral hiatus

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7
Q 
\_\_\_\_ cervical vertebrae 
\_\_\_\_ thoracic vertebrae
\_\_\_\_ lumbar vertebrae
\_\_\_\_sacral vertebrae
\_\_\_\_ coccyx vertebrae
\_\_\_ total vertebrae
A 
7
12
5
5
4
33
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8
Q 
\_\_pair of cervical nerve roots
\_\_ pair of thoracic nerve roots
\_\_ pair of lumbar nerve roots
\_\_ pair of sacral nerve roots
\_\_ pair of coccygeal nerve roots
\_\_total spinal nerve roots
A 
8
12
5
5
1
31
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9
Q

As nerve roots exit the spinal canal they are covered by dural sheath.

  1. . Roots close to the spinal cord tend to float in the dural sac, and are thus usually (pushed away/ pierced) by an advancing needle
  2. Nerve blocks close to the intervertebral foramen carry a risk of ____
A
  1. pushed away

2. subdural injection

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10
Q

For adults, what interspace is the most common starting insertion site for a spinal or a lumbar epidural?

A

L3-L4

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11
Q

If an L3-L4 spinal/epidural fails, what interspace should be the next option?

A

L4-L5

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12
Q

If an L3-L4 AND L4-L5 spinal/ epidural fails, what interspace should be the next option?

A

L2-L3

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13
Q

an imaginary line that is drawn between the superior aspects of the iliac crests

A

Tuffier’s line

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14
Q

What interspace does Tuffier’s line estimate?

A

L4-L5 interspace
-In order to find L3-4, the anesthetist simply palpates the superior aspects of the iliac crests, and moves up one interspace above Tuffier’s line

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15
Q

What does the T10 dermatome represent?

A

umbilicus

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16
Q

What 3 surgeries is a T10 level of analgesia needed for?

A
  1. Spontaneous vaginal delivery
    - T10-L1 is the goal dermatome level of a block for laboring patients planning on regular vaginal delivery
  2. Inguinal surgery
  3. Testicular surgery
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17
Q

What does the T4 dermatome represent?

A

Nipple

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18
Q

What dermatome level is needed for a C-section

A

T4

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19
Q

What dermatome level is the most dependent area of the spine when the patient is supine?

A

T4

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20
Q

Why is having the T4 dermatome as the most dependent area of the spine conveneint?

A
  1. if we lay patients supine after a spinal block it will USUALLY go to the perfect height necessary for analgesia for a C-section (T4)
  2. It helps prevent the spread of local anesthetic above T4, which helps prevent high spinal or total spinal anesthesia
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21
Q

What dermatomes represent vasomotor tone?

A

T5-L1

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22
Q

When ___ nerves are blocked with a spinal or epidural, it causes a sympathectomy

A

T5-L1

Because spinal blocks will typically settle at T4 in supine patients, virtually all patients laid in the supine position after a spinal block will have some degree of sympathectomy

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23
Q

What is the earliest sign of an intense sympathectomy?

A

nausea and vomiting

-profound hypotension causes nausea

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24
Q

how is nausea in a sympathectomy best treated?

A

by raising the patient’s blood pressure

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25
Q

sympathectomies are more severe with (spinal/ epidural)

A

spinal

-Epidural boluses can still produce a sympathectomy (if they happen to rise above T1

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26
Q

What dermatomes represent the cardiac accelerator fibers?

A

T1-T4

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27
Q

What happens if the neuraxial block rises above the T4 dermatome?

A

the patient can have significant bradycardia

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28
Q

What dermatome represents the phrenic nerve?

A

C3-C5

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29
Q

What happens if the neuraxial block gets to C3-C5 dermatome level?

A

the phrenic nerve will be knocked out and the patient will go apneic

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30
Q

What dermatomes represent the hands/fingers?

A

C6-C8

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31
Q

How do we know if the neuraxial block is getting to C6-C8 dermatome?

A

patient will experience tingling, numbness, and/or weakness in their fingers

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32
Q

What are we concerned about if the neuraxial block gets to C6-C8?

A

we are in danger of knocking out the patient’s respiratory drive, because if we get any higher we’d be knocking out C3-C5 (the phrenic nerve)

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33
Q

If a patient starts to experience tingling/ numbness in their fingers after a neuraxial block, what should the anesthetist do?

A

Place the patient in reverse trendelenburg to cause the medicine to sink in the spinal cord

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34
Q

T4-T5 dermatome landmark

A

carina

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35
Q

T6 dermatome landmark

A

xyphoid process

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36
Q

T6-T11 dermatome landmark

A

liver

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37
Q

T7 dermatome landmark

A

inferior border of the scapula

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38
Q

T8-L1 dermatome landmark

A

kidney

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39
Q

T10 dermatome landmark

A

orchiectomy

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40
Q

S2-S4 dermatome landmark

A

bladder

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41
Q

What type of blockade has the potential to produce hypotension and bradycardia?

A

sympathetic blockade

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42
Q

What type of blockade produces an absence of pain?

A

Sensory blockade

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43
Q

What type of blockade will block the patient’s ability to move those limbs?

A

motor blockade

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44
Q

Sympathetic blockade is typically___levels higher than sensory blockade, and sensory blockade is typically ___ levels higher than motor blockade

A

2

2

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45
Q

If a patient has a sensory block at T4, where will the motor and sympathetic block be?

A

motor: T6
sympathetic: T2

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46
Q

nerves are more easily blocked if they are (smaller/bigger) and (myelinated/ unmyelinated)

A

smaller

myelinated

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47
Q

What size Tuohy needle is used for an epidural?

A

17 ga

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48
Q

4 advantages to an epidural compared to a spinal

A
  1. we can give analgesia as long as necessary
  2. we have more control over the analgesic level
    - can alter the dose
  3. patients experience a less profound sympathectomy
    - the block is less dense than the spinal
  4. better preservation of motor block
    - The better preservation of motor function with epidurals allows more effective “pushing” during a spontaneous vaginal delivery
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49
Q

4 disadvantages to an epidural compared to a spinal

A
  1. epidural block is not as dense as a spinal block
    - patients undergoing C-sections under epidural anesthesia are not as likely to be as comfortable as if they had had a spinal block
  2. There is a very high probability for post dural puncture headache (PDPH) if the dura is accidentally punctured
    - The larger the needle used for the block, the larger the hole in the dura, which leads to a larger CSF leak, and a higher chance for post dural puncture headache
  3. the onset of action for local anesthetics is longer for epidurals than it is for spinals
    - Spinal onset is immediate, whereas epidurals are several minutes
  4. There is more potential for local anesthetic toxicity with epidurals than there is with spinals
    - the overall local anesthetic dose with epidurals is higher than it is with spinals
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50
Q

What is a “walking epidural” and what 2 things is the epidural usually dosed with?

A

preserves motor function and allows the patient to walk

can be dosed with narcotics only OR Lower doses/infusion rates of local anesthetic

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51
Q

is the dura punctured in an epidural? where is the local anesthetic injected in an epidural?

A

no

injected in the epidural space before the dura via a catheter infusion

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52
Q

is the dura punctured with a spinal? where is the local anesthetic injected in a spinal?

A

yes

in the subarachnoid/ intrathecal space via a single shot

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53
Q

What are the 4 different sizes used for a spinal needle?

A

27 ga, 25 ga, 22ga, 20 ga

smaller than an epidural needle

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54
Q

Why are smaller needles used in a spinal?

A

because the dura will be punctured and a smaller hole in the dura reduces the chance of a post dural puncture headache

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55
Q

pencil point spinal needle with the smallest opening

A

Whitacre

-opening (CSF aspiration will be the hardest/slowest)

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56
Q

pencil point spinal needle with a bigger opening

A

Sprotte

-Has a longer opening (easier to aspirate CSF, but a higher chance of injecting epidurally)

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57
Q

spinal needle with a cutting tip

A

quincke

-Cuts through ligaments better, but makes a larger hole in the dura

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58
Q

What size is the spinal introducer needle?

A

18 ga

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59
Q

What is the purpose of the introducer needle in a spinal?

A

allows much less bending of the spinal needle as the spinal needle passes through the spinal ligaments

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60
Q

When do you usually use an introducer needle in a spinal?

A

When the spinal needle is smaller than 22 ga

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61
Q

What is the advantage of a 22 ga spinal needle?

A

an introducer needle is not needed

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62
Q

What is the disadvantage of a 22 ga spinal needle?

A

there is a higher risk of spinal headache due to the larger hole in the dura

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63
Q

What are the 2 common uses for a 22 ga spinal needle?

A
  1. Elderly patients
    - carry a lower risk of post dural puncture headache
    - larger needles can pass through calcified ligaments more easily
  2. obese patients
    - A larger needle is less likely to bend/break when passing through the excess tissue
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64
Q

What is the most common size spinal needle in adults?

A

25 ga

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65
Q

what is the advantage of using a 25 ga spinal needle?

A

it’s way less likely for the patient to get a spinal headache (due to a smaller hole in the dura)

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66
Q

What is the disadvantage of using a 25 ga spinal needle?

A

it’s more likely to bend when passing through the spinal ligaments, and especially if the spinal ligaments are calcified (like in elderly patients). Because of this, a 25ga spinal needle is commonly used with an 18ga introducer

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67
Q

What is the advantage to the 27 ga spinal needle?

A

it creates the smallest hole in dura= least chance for PDPH

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68
Q

what is the disadvantage of the 27 ga spinal needle?

A

it has the highest chance of bending through the spinal ligaments

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69
Q

When is the 27 ga spinal needle typically used?

A

if we are performing a combined spinal epidural (CSE) block, where a Tuohy needle is used as the introducer needle
-Tuohy needle completely bypasses the spinal ligaments (which means that the 27ga spinal needle will only need to pass through the Dura and won’t really have any risk of bending/breaking)

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70
Q

______is currently a rare technique that provides repeated doses of local anesthetic into the intrathecal space through a catheter

A

continuous spinal anesthesia

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71
Q

what is the difference between an epidural and continuous spinal anesthesia?

A

continuous spinal anesthesia is dosed through a catheter in the intrathecal space and the dose is significantly lower and usually dosed in boluses instead of an infusion

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72
Q

Why are small micro catheters NOT used for continuous spinal anesthesia?

A

problem with these smaller microcatheters (24-32ga) is that their use is associated with neurotoxicity and cauda equina syndrome, possibly due to pooling of local anesthetics in a localized certain area

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73
Q

When is the only time continuous spinal anesthesia is acceptable?

A

when its through a large epidural catheter

-the only real practical use for continuous spinal anesthesia is if an anesthetist unintentionally punctures the dura with a Tuohy needle during epidural placement, and then decides to just thread the catheter into the intrathecal space and provide analgesia with a much lower dose of local anesthetic rather than attempt another epidural

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74
Q

How far should the catheter be threaded into the intrathecal space for continuous spinal anesthesia?

A

2-3 cm

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75
Q

How is analgesia maintained in continuous spinal anesthesia? (bolus/infusion)

A

bolus

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76
Q

what should the continuous spinal catheter be flushed with after each injection of local anesthetic?

A

previous aspirated CSF fluid after each

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77
Q

How long should you wait between dosing a continuous spinal?

A

45-90 minutes

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78
Q

if you bolus a continuous spinal too frequently, what can happen?

A

sacral pooling of the anesthetic and caudal equine syndrome

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79
Q

The dose of local anesthetic via continuous spinal infusion is approximately ____ the epidural infusion rate and titrated to effect

A

one-tenth

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80
Q

side effects associated with opioids (pruritus) are more common when the agent is delivered into the ______

A

subarachnoid space

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81
Q

When the two techniques (placement at a second lumbar epidural space versus continuous spinal infusion with an epidural catheter) are compared, a lower incidence of postdural puncture headache is noted with a ____

A

continuous spinal infusion

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82
Q

_____refers to how dense (heavy) the drug is compared to CSF, and the density of drug determines whether the drug will sink or rise when injected into the CSF

A

baricity

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83
Q

(hyperbaric/ hypobaric/ isobaric) spinal drug means that the spinal drug is denser (heavier) than CSF, so the drug will sink (follow gravity)

A

hyperbaric

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84
Q

Drugs are made hyperbaric by adding an equal VOLUME of ______ to the local anesthetic

A

10% dextrose/glucose

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85
Q

hyperbaric solutions have a:

  1. (shorter/longer) time to peak concentration
  2. (Shorter/longer) duration of action than plain local anesthetics
A
  1. shorter

2. shorter

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86
Q

A ______is performed by allowing the patient to remain sitting for several minutes after injecting hyperbaric spinal medication

A

saddle block
-This causes the medication to sink to the pelvis, anesthetizing the sacral nerves, buttocks, perineal area, and inner thighs

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87
Q

When anesthetizing this area with an epidural bolus, the term______ is used interchangeably with the term “saddle block”

A

perineal dose

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88
Q

what 2 common things are “saddle blocks” used for?

A
  1. genitourinary procedures

2. relieves 2nd stage labor pain

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89
Q

A (hyperbaric/ hypobaric/ isobaric) spinal drug means that the spinal drug is lighter than CSF, so the drug will rise (travel opposite to gravity)

A

hypobaric

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90
Q

Drugs are made hypobaric by adding ______

A

sterile water

  • 3mL sterile water per 1mL local anesthetic
  • 1mL sterile water per 1mg local anesthetic
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91
Q

what is the most common use for a hypobaric spinal?

A

hip surgery

-The spinal is performed with the patient in lateral position with the operative hip up

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92
Q

An (hyperbaric/ hypobaric/ isobaric) spinal drug means that the spinal drug has the same specific gravity as CSF, so it remains at the level of injection

A

isobaric

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93
Q

Drugs are made isobaric by adding an equal VOLUME of ____ or ______ to the local anesthetic

A

CSF or normal saline

94
Q

Baricity applies to (spinals/epidurals/ both) and the baricity settles after ______ depending on the onset of the local anesthetic

A

spinals
10-15 minutes

after 15 minutes, the drug shouldn’t rise or sink as much based on the patient’s position

95
Q

How is the combined spinal epidural (CSE) performed?

A
  1. Advances a CSE Tuohy needle into the epidural space
  2. Threads a spinal needle THROUGH a small hole in the CSE Tuohy needle and performs a spinal block, and removes the spinal needle while keeping the epidural needle in place
  3. Threads an epidural catheter after the patient has been dosed with spinal drugs
96
Q

in a CSE, the spinal is used for _____ anesthesia and the epidural is used for _____ anesthesia

A

operative

postoperative

97
Q

What is the most common CSE needle set and what does it contain?

A

Espocan

27 ga spinal needle and a Touhy needle with hole in the end for passage of the spinal needle

98
Q

3 advantages of a CSE

A
  1. provides a denser block for a procedure than an epidural alone would
  2. allows a spinal to be performed with a 27 ga which leads to the smallest chance of a PDPH
  3. It allows postop analgesia with an epidural in case the anesthetist doesn’t want to use Duramorph in the spinal
99
Q

What is the main disadvantage of a CSE?

A

an anesthetist can’t perform a test dose through the epidural catheter to make sure that it’s in the right place (to make sure that it’s not intrathecal or intravascular), because the patient is already numb from the spinal block by the time the epidural catheter gets threaded

100
Q

How is a Dural Puncture Epidural technique performed?

A
  1. an epidural needle is placed
  2. spinal needle is inserted through the Touhy needle and punctures the dura
  3. the spinal needle is removed WITHOUT injecting any medication into the intrathecal space (leaves a small hole in the dura)
  4. epidural catheter is placed and hooked up to an infusion pump
  5. the local anesthetic primarily goes into the epidural space but a small portion LEAKS into the intrathecal space through the small hole
101
Q

3 advantages to a Dural Puncture Epidural technique

A
  1. faster sacral onset
  2. greater sacral spread of local anesthetic
  3. lower incidence of unilateral block
102
Q

What is the primary disadvantage of a dural puncture epidural technique?

A

small chance of PDPH

103
Q

This is the site of needle insertion, and it is covered by the sacrococcygeal ligament

A

sacral hiatus

104
Q

These are bony prominences just to the sides of the sacral hiatus
The anesthetist palpates these landmarks to find the sacral hiatus

A

sacral cornu

105
Q

how is a caudal block performed?

A

inserting a needle through the sacrococcygeal ligament and into the sacral hiatus, the medication is injected into the epidural space

106
Q

What are 2 ways in which a caudal block differs from an epidural block?

A
  1. Performed at the sacral level

2. Dosed with a single shot of drug (instead of a catheter infusion)

107
Q

in a caudal block, how is the needle inserted into the sacral hiatus

A

at a 45 degree angle cephalad until a pop is felt

108
Q

What is a common anesthetic dose for a caudal block?

A

1-1.25mL/kg of 0.125% marcaine with epi

109
Q

Why are caudal blocks performed mostly in children and epidurals performed mostly in adults?

A

when epidurals are performed in the lumbar or thoracic region, it is vital that the patient be awake (so that they can alert the anesthetist of any parasthesias) to reduce the chance of nerve injury- closer to the spinal cord

kids will not tolerate holding still so caudal blocks can be safely performed in asleep patients, because the patient doesn’t need to be awake to alert the anesthetist of any parasthesias- farther away from the spinal cord

110
Q

3 advantages of caudal anesthesia

A
  1. They can be performed in asleep patients, which makes it a popular epidural block for children
  2. They provide more reliable perineal anesthesia than lumbar epidurals do
  3. There is a less likely chance of dural puncture and nerve damage when compared with a lumbar epidural
111
Q

5 disadvantages of caudal anesthesia

A
    1. The dura can still be theoretically punctured if the needle is advanced too far
  2. The rectum can be punctured if the needle is advanced at too steep of an angle
  3. The block is technically more difficult in adults
  4. It requires approximately twice as much local anesthetic drug as a lumbar epidural
    - “However, if the catheter is threaded to the S1 level, the dosage can be decreased by one-third”
  5. There is a relatively higher risk of urinary retention with this block
112
Q

why aren’t caudal blocks performed in adults?

A
  1. anatomy can be difficult to find

2. larger doses are needed leading to greater chance of drug toxicity

113
Q

How does epi affect the strength and spread of a neuraxial block?

A

prolongs the block but does not increase the spread

114
Q

Does volume or dose play a bigger role in the spread or strength of local anesthetics?

A

volume and dose both affect the spread of local anesthetic but dose has a stronger effect than volume

115
Q

higher doses of local anesthetic spread (more/ less) than lower doses

A

more

116
Q

what do the addition of narcotics do to local anesthetics?

A

increases the density or “strength” of the block

117
Q

shorter patients should recieve a (lower/higher) dose of local anesthetic

A

lower

-The shorter you are, the more likely the block will travel “too high”

118
Q

The more obese the patient:

  1. the (higher/ lower) the anesthetic will spread
  2. the (higher/lower) the local anesthetic dose requirement
A
  1. higher
    - these patients have increased intraabdominal pressure and compression of the inferior vena cava, which causes engorgement of the epidural veins, and engorgement of the epidural veins decreases CSF volume (which causes the higher spread of local anesthetic)
  2. lower
119
Q

Geriatric patient have:

  1. (higher/lower) dosing requirement for spinal anesthetics
  2. (longer/shorter) onset of epidural and spinal anesthesia
A
  1. lower

2. shorter

120
Q

What happens to the duration of local anesthetics in geriatric patients?

A

unknown

-some sources say shorter, or longer, or no effect

121
Q

8 contraindications for neuraxial anesthesia

A
  1. patient refusal
  2. infection at the injection site
    - a block could lead to possible meningitis or an epidural abscess
  3. severe hypovolemia
    - patient wouldn’t tolerate sympathectomy
  4. coagulopathy
    - could lead to a possible epidural hematoma
  5. severe aortic stenosis
    - Sympathectomy drops preload & afterload, and preload/afterload should be maintained with aortic stenosis
  6. severe mitral stenosis
  7. sepsis
    - Block placement could lead to possible meningitis and/or epidural abscess
  8. elevated ICP
    -Patients with increased ICP can’t tolerate the sympathectomy because a high MAP is required to perfuse the head in patients with intracranial hypertension
    (Cerebral perfusion pressure = MAP – ICP
122
Q

4 relative contraindications to neuraxial anesthesia

A
  1. neurologic deficiencies
    - (MS)
  2. Sepsis
  3. previous back surgery
    - may affect the spread of local anesthetics
  4. severe COPD
    - COPD patients rely on accessory muscles to breathe
123
Q

there is roughly a _____ % incidence of back pain after spinal anesthesia

A

25%

124
Q

What are 5 possible etiologies of back pain following a spinal anesthesia?

A
  1. common backache from the needle or lying flat too long
  2. epidural abscess
  3. epidural/ spinal hematoma
  4. transient neurologic symptoms
  5. cauda equina syndrome
125
Q

_____ is caused by an infection, potentially after back surgery or a neuraxial block

A

epidural abscess

126
Q

3 symptoms of an epidural abscess

A
  1. back pain intensified by spine percussion
  2. signs of infection (fever, elevated WBC count
  3. sensory AND motor deficits
127
Q

how is an epidural abscess diagnosed and treated?

A

diagnosed with a CT scan and may require surgical decompression via a lamenectomy

128
Q

What are the 2 different symptoms that an epidural hematoma produces when compared to an epidural abcess

A
  1. shorter onset of symptoms

2. WBC count should be normal

129
Q

What is the treatment for epidural hematoma?

A

immediate surgical evacuation

130
Q

What does a patient experience with Transient neurologic symptoms (TNS)?

A

back pain WITHOUT motor deficits

  • back pain in first 24 hours that resolves on its own
  • usually does not require a neuro consult
131
Q

What does a patient experience in Cauda Equina Syndrome (CES)?

A

back pain AND motor deficits

  • (paresis of the legs) and/or bladder and bowel dysfunction
  • The etiology has been linked to nerve root and/or spinal cord trauma, highly concentrated spinal local anesthetics, and continuous spinal anesthesia through a microcatheter
  • needs a stat neuro consult
132
Q

What 2 options does an anesthetist have if they accidentally give the patient a wet tap?

A
  1. Thread the catheter ≈2cm intrathecally for continuous spinal anesthesia
  2. Remove the needle and start another epidural at higher dermatome level
133
Q

What are the symptoms of a PDPH and what aggravates the pain?

A

Symptoms include bilateral, frontal, occipital, and extends into the neck

Pain is aggravated by sitting or standing and may last for a few weeks
-The reason is that the pain is aggravated by sitting and standing is that venous return decreases in those positions, and decreased venous return engorges the epidural veins and drives more CSF out (which worsens the symptoms of the headache)

134
Q

the incidence of PDPH (increases/decreases) with age

A

decreases

135
Q

What is the gold standard for PDPH?

A

blood patch

136
Q

If a blood patch is attempted before the local spinal anesthetic has worn off, what will happen?

A

total spinal anesthesia

137
Q

What 4 other strategies can also treat PDPH?

A
  1. caffeine
  2. analgesics
  3. steroids
  4. generous fluid administration
138
Q

What combo of 2 drugs can treat PDPH and what are the doses?

A
  1. Neostigmine (0.02 mg/kg)

2. Atropine (0.01 mg/kg)

139
Q

What are the 4 benefits of neuraxial anesthesia over general anesthesia?

A
  1. decreased anesthetic requirements
    - (decreased post op N/V)
  2. decreased respiratory complications
  3. decreased surgical blood loss
  4. Decreased incidence of thrombosis (due to decreased platelet aggregation)
140
Q

Esters:
Have (one/two) “I” in the name
Are metabolized by ______, and produce _____ as a byproduct
Are (more/less) likely to cause allergic reactions than amides

A

one
-Tetracaine, chloroprocaine, cocaine, Novocaine, etc

plasma esterases

p-aminobenzoic acid (PABA)

more

141
Q

Amides:
Have (one/two) “i” in the name

Are metabolized by the ____

A

two
-Bupivacaine, ropivacaine, lidocaine, etc

liver

142
Q

Local anesthetics (without epi) are slightly (acidic/basic) in the vial they come in

why?

A

acidic (pH 6-7)

The acidity prolongs the shelf life of the local anesthetic

143
Q

Local anesthetics are even more (acidic/basic) when epi is added

why?

A

acidic (pH 4-5)

They have to be more acidic with epi because epi is unstable in basic environments

144
Q

is tetracaine primarily used in spinals or epidurals?

A

spinals

145
Q

What is the longest acting spinal anesthetic?

A

tetracaine

146
Q

What does epinephrine do to the duration of tetracaine?

A

prolongs its duration the longest out of all the local anesthetics

147
Q

What is the most common local anesthetic we use for spinal anesthesia?

A

0.75% marcaine (bupivicaine)

148
Q

What is the duration of 0.75% marcaine?

A

2 hours

149
Q

What does epinephrine do to the duration of 0.75% marcaine?

A

prolonging its duration is the LEAST affected by epi

150
Q

If a spinal block needs to last more than 2 hours, what local anesthetic should be used?

A

tetracaine

151
Q

When would lidocaine be considered in spinal anesthesia?

A

if the procedure were very short and the anesthetist wanted the spinal to wear off as fast as possible

152
Q

Why isn’t lidocaine commonly considered for spinal anesthesia?

A

because its intrathecal use has been associated with transient neurologic symptoms and cauda equina syndrome

153
Q

What drug is contraindicated in spinal anesthesia?

A

Chloroprocaine

154
Q

What are the 4 most common local anesthetics for epidural anesthesia?

A
  1. 0.1-0.25% marcaine
  2. ropivacaine
  3. lidocaine
  4. chloroprocaine
155
Q

What is the most common local anesthetic for labor epidurals?

why?

A

0.1-0.25% Marcaine

Marcaine is “motor sparing,” meaning that it doesn’t block the motor nerves as well

This is great in OB, because it can provide a sensory block to relieve pain, without blocking the ability of the mother to “push” more effectively during delivery

156
Q

Which local anesthetic is the LONGEST acting in labor epidurals?

A

0.1-0.25% marcaine

157
Q

3 disadvantages to epidural marcaine

A
  1. has the lowest onset of all the epidural local anesthetics
  2. cardiotoxic
  3. less effective at blocking the larger sacral nerves
    - marcaine epidurals have a higher chance of losing their effectiveness during stage two labor
158
Q

What is the toxic dose of epidural marcaine with epi and without epi?

A

w/out epi: 2.5 mg/kg

w/epi: 3 mg/kg

159
Q

What is the treatment for Marcaine/bupivicaine toxicity?

A

CPR

Intralipid 20%

160
Q

What is the concentration of epidural ropivicaine (naropin)?

A

0.2%

161
Q

What is the difference between marcaine and ropivacaine?

A

same pharmacology

but ropivacaine is less cardiotoxic and more expensive

162
Q

What is the maximum dose of ropivacaine?

A

3 mg/kg

163
Q

what is the concentration of epidural lidocaine?

A

2%
OR
1.5% with Epi

164
Q

What are the 2 advantages of using epidural lidocaine?

A
  1. more effective at blocking the larger sacral nerves
    - This makes it a great drug to bolus during stage II labor in situations where epidural Marcaine isn’t producing satisfactory analgesia
  2. fast onset
165
Q

What are the 2 disadvantages of epidural lidocaine?

A
  1. produces a more significant motor blockade than marcaine (more concentrated)
    - It is therefore more likely to inhibit a parturient from “pushing” effectively during delivery
  2. If the toxic dose is exceeded, the patient can exhibit neurologic symptoms (confusion, tinnitus, oral numbness, and even seizures)
166
Q

What is the toxic dose of epidural lidocaine?

A

4mg/kg w/o epi, and 7mg/kg with epi

167
Q

What is the concentration of epidural chloroprocaine?

A

2% or 3%

168
Q

2 advantages of epidural chloroprocaine

A
  1. produces the fastest epidural onset (which makes it the perfect choice for bolusing an epidural for an emergency C-section)
  2. has minimal drug transfer across the placenta
169
Q

Why does chloroprocaine have the fastest onset?

A

pseudocholinesterase metabolism

170
Q

2 disadvantages of epidural chloroprocaine

A
  1. produces the highest degree of motor block
    - Chloroprocaine is not used for labor analgesia due to its increased motor block
  2. chloroprocaine has the shortest duration
    - needs to be re-dosed more frequently
171
Q

What are the 5 situations in which we would bolus an epidural?

A
  1. initial test dose
  2. loading dose
  3. dose to increase the blocks density
  4. raising the block to T4 gradually
  5. raising the block level to T4 immediately
172
Q

What are 2 things the anesthetist should do prior to bolusing an epidural?

A
  1. verify the patient has stable vital signs in case of sympathectomy
  2. Aspirate (every time) to rule out intravascular or intrathecal injection
173
Q

how long should a patient be monitored by anesthesia after an epidural bolus?

A

10 minutes

174
Q

what are signs of intravascular injection from an epidural bolus?

A

fast heart rate (from the epi)
tinnitus (ringing in the ears from the lido)
oral/tongue numbness (from the lido)

175
Q

What is a sign of intrathecal injection from an epidural bolus?

A

immediate leg numbness

176
Q

the initial test dose of an epidural consists of what amount and concentration of mixed local anesthetic?

A

5mL dose of 1.5% lidocaine with 1:200,000 epi

177
Q

What amount and local anesthetic is the loading dose?

A

5 mL of marcaine or ropivacaine

178
Q

What is the advantage of the epidural loading dose?

A

speeds up the onset of the block

179
Q

What is the disadvantage of the epidural loading dose?

A

it can raise the level of the block above T10 and make a sympathectomy much more likely

180
Q

When a patient is still experiencing pain after an epidural is placed it is referred to as a _____

How can this be fixed?

A

patchy block

additional 5 mL of 2% lidocaine

181
Q

Whenever a laboring patient (who was planning on having a regular vaginal delivery) needs to have a non-emergent C-section, an anesthetist needs to (gradually/ immediately) raise the level of the epidural block to ____

A

gradually
-needs to be raised gradually because raising the block too rapidly increases the risk that the block could go too high

T4

182
Q

What are the 3 steps in which an anesthetist gradually raises the epidural block level to T4

A
  1. Gives an initial 10mL of local anesthetic, waits 3 minutes, and then checks the dermatome level
  2. Gives an additional 5mL of local if the block is not high enough, waits 3 minutes, and then checks the dermatome level again
  3. Gives a final 5mL of local (for a total of 20mL) if the block not high enough
183
Q

What happens if the local anesthetic is bolused to fast in an epidural?

A

The risk of high block and hypotension (from sympathectomy) is increased

184
Q

What happens if the anesthetist waits too long in between epidural boluses?

A

The block density will increase, but the block won’t rise

185
Q

When raising an epidural block from T10 to T4, the local anesthetic of choice is probably ____

Why?

A

lidocaine
-it has a relatively quick onset, but it lasts long enough that it probably wouldn’t need to be redosed during the surgery

186
Q

Whenever a laboring patient (who was planning on having a regular vaginal delivery) needs to have a emergent C-section, an anesthetist needs to (gradually / immediately) raise the level of the epidural block up to ___

A

immediately

T4

187
Q

How does the anesthetist immediately raise the block level to T4 in an emergent C-section?

A

in a STAT C-section, we bolus 20mL of epidural anesthetic all at once, because we’re willing to risk a high block or sympathectomy in order to have the faster onset

188
Q

What is the drug of choice for emergency c-sections?

A

20mL of 3% Chloroprocaine (600 total mg)
-has the fastest onset, and in an emergency, the last thing we care about is whether or not we will have to redose the epidural in the middle of the C-section

189
Q

_____ any kind of vial that may be used more than once and generally contains antibacterial preservatives

A

multiple-dose vial (MDV)

190
Q

_____ is intended to be used only once and contains no preservatives

A

single-dose container

191
Q

3 common preservatives in local anesthetics

A
  1. Sulfites (bisulfite, metabisulfite)
  2. Parabens (methylparaben)
  3. EDTA
192
Q

_____is a bacteriostatic preservative that is commonly added to multidose vials of local anesthetics

A

methylparaben

-Sensitive patients may experience anaphylactoid symptoms

193
Q

_____ preservatives are contraindicated for both epidural and intrathecal administration

A

methylparaben

194
Q

_____(along with citric acid) are added to local anesthetics that come premixed with epinephrine (or any other vasoconstrictor) in order to “prevent the degradation of epinephrine in an alkaline pH

A

sulfites

The resulting acidic solution tends to cause more pain on injection
Freshly mixed solutions of lidocaine with epinephrine (by an anesthetist) result in a less acidic solution; therefore less discomfort with injection

195
Q

the sulfite (epinephrine stabilizing) preservatives are safe for (epidural/ spinal/ both)

A

epidural only

196
Q

_____ has been added to local anesthetics in the past to prolong shelf life and enable the manufacturer to use an autoclave to sterilize the glass vial containing the local anesthetic. It also acts as a chelating agent

A

EDTA

197
Q

What happens when EDTA is injected epidurally?

A

severe pain at the injection site but no evidence of neurotoxicity

198
Q

What happens when sulfate is injected intrathecally?

A

development of arachadonitis, and administration of sulfites in general is capable of inducing anaphylactoid reactions

199
Q

What are the 2 things the anesthetist should check on the local anesthetic vial before injecting into the intrathecal space or epidural space?

A
  1. preservative free

2. “for epidural or spinal use”

200
Q

why should IV regional anesthesia like Beir blocks use preservative free local anesthetic?

A

to avoid irritation and anaphylaxis

201
Q

Why is bicarb added to lidocaine or chloroprocaine?

A

to speed up the onset and bring the pH of the drug closer to its pKa
-Mostly when raising the block level from T10 to T4

202
Q

that bicarb causes the local anesthetic to precipitate within ____

A

6 hours

203
Q

what 3 things do alpha agonists do to local anesthetic blocks?

A
  1. Prolongs block duration
  2. Limits toxic side effects
  3. Enhances analgesic quality
204
Q

If a local anesthetic is more lipid soluble, the advantage of adding epinephrine to the local anesthetic is (more/less) significant

A

less

205
Q

Which of the local anesthetics does epinephrine have the least effect on the duration?

A

bupivacaine

-it’s highly lipid soluble

206
Q

With what drug does the alpha agonist not apply for lipid soluble duration?

A

tetracaine
-epinephrine has the greatest effect on the duration of tetracaine, even though tetracaine has a higher lipid solubility than bupivacaine

207
Q

What do alpha agonists do to local anesthetics in addition to prolonging the duration?

A

cause potent analgesia by directly inhibiting sensory and motor neurons

208
Q

____ is associated with a greater decrease in blood pressure in some studies, and can prolong block duration even when administered orally

A

clonidine

209
Q

morphine without preservatives

A

duramorph

-which allows dosing in the intrathecal space

210
Q

Morphine causes (more/less) respiratory depression in fetus than fentanyl

A

more

211
Q

Intrathecal/epidural/intravenous morphine carries a (higher/lower) risk of urinary retention when compared to fentanyl

A

higher

212
Q

3 advantages of neuraxial opiods

A
  1. analgesia
  2. no motor blockade
  3. no sympathectomy
213
Q

3 disadvantages of neuraxial opiods

A
  1. puritis
  2. delayed respiratory depression
    - This is more likely to occur following intrathecal morphine than intrathecal fentanyl, due to the fact that Morphine is less lipid soluble than Fentanyl
  3. nausea/ vomiting
214
Q

What is the most common complication of neuraxial opiods?

A

puritis

215
Q

When should narcotics not be added to a spinal?

A

spinal if the procedure is outpatient
-There is a risk of exaggerated respiratory depression if the patient takes their PO narcotics at home before the spinal opioids have worn off

216
Q

2 advantages to using precedes (dexmedetomidine)

A
  1. sensory blockade was longer

2. similar analgesia and less pruritus and shivering compared with morphine

217
Q

The more polar a drug is, the ____ the onset

A

slower

218
Q

If an acidic drug is placed in a basic environment (less protons, higher pH), it will become _____charged,

A

negatively

-because the drug will donate protons to the environment

219
Q

If a basic drug is placed in an acidic environment (more protons, lower pH), it will become _____ charged,

A

positively

-because the environment will donate protons to the drug

220
Q

If the drug is placed in an environment with an “ideal pH,” it will have the highest nonpolar portion and the (fastest/slowest) onset

A

fastest
This “ideal pH” for the drug (the pH of the drug’s environment that will result in 50% ionization and 50% nonionization (which leads to the highest nonpolar portion possible) is referred to as the drug’s pKa

221
Q

We can speed up onset time by changing the ____ of the drug vial to get closer to the ____ of the drug

A

pH

pKa

222
Q

Acidic drugs have a (high/low) pKa

Basic drugs have a (high/low) pKa

A

low

high

223
Q

The closer a drug’s pKa is to physiologic pH (7.4), the (less/more) polar it will be in the body, and the (faster/ slower) onset it will have

A

less

faster

224
Q

local anesthetics by themselves are (basic/acidic)

A

basic

225
Q

local anesthetics in the vial are (basic/acidic)

A

acidic

-prolongs the shelf life

226
Q

Epinephrine containing solutions have a pH that is ____ units lower than the pH of plain solutions

A

1-1.5

227
Q

The pH of a drug solution is 4.5. The pKa of the drug is 10.7. Adjusting the pH of the drug to ____ will result in the fastest onset

  1. 5
  2. 0
  3. 4
  4. 7
A

10.7

228
Q

A drug solution has a pH of 6.5 and a pKa of 5.5. Adjusting the pH of the drug closer to physiologic pH will speed up the drug onset.
True or false?

A

false

229
Q

local anesthetics with a high lipid solubility with have a

  1. (faster/slower) onset
  2. (shorter/ longer) duration
  3. (incrased/decreased potency)
A
  1. slower
  2. longer
  3. increased
230
Q

other drugs (fentanyl) with high lipid solubility have a

  1. (faster/slower) onset
  2. (shorter/ longer) duration
  3. (incrased/decreased potency)
A
  1. faster
  2. shorter
  3. increased

Methods II (11 decks)

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