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APEX > Unit 8 - Neuraxial Anesthesia > Flashcards

Unit 8 - Neuraxial Anesthesia Flashcards

1
Q

curves of the spine

A
  • Cervical & lumbar lordosis
  • Thoracic & sacral kyphosis
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2
Q

what are the 5 divisions of the spinal column and how many vertebrae are in each

A

cervical = 7
thoracic = 12
lumbar = 5
sacral = 5 (fused)
coccyx = 4 (fused)

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3
Q

anterior and posterior segments of vertebrae

A

anterior segment = body
posterior segment = vertebral arch

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4
Q

connects anterior and posterior segments of vertebrae

A

laminae & pedicles

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5
Q

where do anterior and posterior vertebra segments connect

A

vertebral foramen

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6
Q

contained in vertebral foramen

A

spinal cord
nerve roots
epidural space

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7
Q

serves as a landmark to determine midline

A

spinous process

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8
Q

what vertebral level corresponds with the spine of scapula

A

T3

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9
Q

what vertebral level corresponds with PSIS

A

S2

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10
Q

what vertebral level corresponds with superior aspect of iliac crest

A

L4

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11
Q

what vertebral level corresponds with vertebral prominens

A

C7

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12
Q

what vertebral level corresponds with inferior angle of scapula

A

T7

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13
Q

what vertebral level corresponds with rib margin 10 cm from midline

A

L1

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14
Q

angle of spinous processes in cervical and thoracic vertebrae

A

caudad

requires more cephalad approach with needle

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15
Q

angle of spinous processes in cervical and thoracic vertebrae

A

caudad

requires more cephalad approach with needle

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16
Q

why is epidural/intrathecal access easier in lumbar vertebrae vs. cervical or thoracic

A

posterior direction of spinous processes

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17
Q

what provides stability & support to transverse & vertebral processes

A

muscular attachment

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18
Q

allow head rotation at atlantoaxial joint

A

C1 (atlas) and C2 (axis)

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19
Q

separates each vertebra and acts as a shock absorber

A

intervertebral disc

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20
Q

where do spinal nerves exit the vertebral column

A

via interverbal foramina

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21
Q

what forms anterior border of intervertebral foramina

A

vertebral body and intervertebral disc

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22
Q

what forms posterior border of intervertebral foramina

A

facet joints

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23
Q

how can disc degeneration cause nerve compression

A

can decrease size of intervertebral foramina

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24
Q

s/s spinal nerve compression

A

pain
parasthesia
motor deficits

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25
Q

how are facet joints formed

A

inferior articular process of vertebra directly above and superior articular process of vertebra below

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26
Q

guide & restrict movement of vertebral column

A

facet joints

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27
Q

what is Tuffier’s line

A

Intercristal line

Horizontal line drawn across the superior aspects of the iliac crest that connects L4 vertebra

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28
Q

what is the interspace above Tuffier’s line

A

L3-L4

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29
Q

what is the interspace below Tuffier’s line

A

L4-L5

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30
Q

Tuffier’s line in infants up to 1 year correlates with:

A

L5-S1 interspace

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31
Q

the sacral hiatus coincides with:

A

S5

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32
Q

provides entry point to epidural space in sacral area

A

sacral hiatus

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33
Q

what is the sacral cornua

A
  • Bony nodules that flank sacral hiatus
  • Results from incomplete development of facets
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34
Q

what is the conus medullaris

A

where spinal cords ends in a taper
* Adult = L1-L2
* Infant = L3

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35
Q

cauda equina

A

bundle of spinal nerves extending from conus medullaris to the dural sac

Comprised of nerves & nerve roots from L2-S5 nerve pairs and coccygeal nerve

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36
Q

where subarachnoid space terminates

A

dural sac
* Adult = S2
* Infant = S3

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37
Q

Filum Terminale

A
  • Continuation of pia mater caudal to conus medullaris
  • Anchors spinal cord to coccyx
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38
Q

where is filum terminale fixated

A

at conus medullaris & coccyx

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39
Q

internal position of filum terminale

A

extends from conus medullaris to dural sac

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40
Q

external position of filum terminale

A

extends from dural sac into sacrum

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41
Q

Structures needle will pass through when performing a spinal anesthetic, midline approach

A

skin - SQ tissue - supraspinous ligament - interspinous ligament - ligamentum flavum - epidural space - dura mater - subdural space - arachnoid mater - subarachnoid space

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42
Q

runs most of the length of the spine, joins tips of spinous processes

A

Supraspinous ligament

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43
Q

anatomy of the interspinous ligament

A

travels adjacent to & joins spinous processes

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44
Q

what is the ligamentum flavum

A

2 flat flava that run length of spinal canal to form dorsolateral margins of epidural space

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45
Q

where is the ligamentum flavum thickest

A

lumbar region

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46
Q

what causes loss of resistance when needle enters epidural space

A

piercing the ligamentum flavum

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47
Q

where does the Posterior longitudinal ligament travel

A

along posterior surface of vertebral bodies

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48
Q

attaches to anterior surface of vertebral bodies & extends entire length of spine

A

Anterior longitudinal ligament

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49
Q

what ligaments does the needle pass through in midline approach

A

1) supraspinous ligament 2) interspinous ligament 3) ligamentum flavum

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50
Q

what ligament does the needle pass through in a paramedian approach

A

ligamentum flavum only

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51
Q

what is the Taylor approach

A
  • Variation of paramedian performed at L5-S1 interspace
  • Needle entry site: 1 cm medial & 1 cm inferior to posterior superior iliac spine
  • Needle when inserted 45-55 degrees cephalad & directed medially
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52
Q

3 meningeal layers of spinal cord (outside in)

A

DAP – dura, arachnoid, pia

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53
Q

in the adult, what correlates with the termination of the dural sac?

A

superior iliac spines (S2)

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54
Q

what correlates with the sacral hiatus and sacrococcygeal ligament

A

S5

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55
Q

what correlates with the iliac crests

A

Tuffier’s line

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56
Q

used as landmarks for caudal anesthesia

A

sacral cornua

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57
Q

what spinal level coincides with the conus medullaris in an adult

A

L1-L2

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58
Q

what spinal level coincides with the conus medullaris in an infant

A

L3

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59
Q

what spinal level coincides with dural sac in an infant

A

S3

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60
Q
A
  1. supraspinous ligament
  2. interspinous ligament
  3. ligamentum flavum
  4. posterior longitudinal ligament
  5. anterior longitudinal ligament
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61
Q

what forms the dorsolateral margins of the epidural space

A

2 flava of ligamentum flavum that run the length of the spinal cord

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62
Q
A
  1. supraspinous ligament
  2. interspinous ligament
  3. ligamentum flavum
  4. posterior longitudinal ligament
  5. anterior longitudinal ligament
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63
Q
A
  1. spinal cord
  2. pia mater
  3. subarachnoid space
  4. arachnoid mater
  5. subdural space (potential space)
  6. dura mater
  7. epidural veins
  8. epidural space
  9. ligamentum flavum
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64
Q

where is epidural space deepest

A

lumbar region

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65
Q

where does the epidural space end

A

at the sacrococcygeal ligament

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66
Q

borders of the epidural space

A
  • Cranial: foramen magnum
  • Caudal: sacrococcygeal ligament
  • Anterior: posterior longitudinal ligament
  • Lateral: vertebral pedicles
  • Posterior: ligamentum flavum & vertebral lamina
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67
Q

how does the epidural space communicate with paravertebral space

A

via intervertebral foramina

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68
Q

contained in intervertebral foramina

A

nerve roots, fat pads, blood vessels

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69
Q

how does the intervertebral foramina affect bioavailability

A

acts as a lipid sink, decreasing bioavailablility

(bupivacaine > lidocaine/fentanyl > morphine)

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70
Q

how does the intervertebral foramina affect bioavailability

A

acts as a lipid sink, decreasing bioavailablility

(bupivacaine > lidocaine/fentanyl > morphine)

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71
Q

what is batson’s plexus

A

epidural veins that drain venous blood from spinal cord

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72
Q

why do obese and pregnant patients have increased risk for needle injury or cannulation during neuraxial techniques

A

increased IAP leads to plexus engorgement

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73
Q

what is the plica mediana dorsalis

A

band of connective tissue that courses between ligamentum flavum and dura mater

existence is controversial

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74
Q

what is the plica mediana dorsalis

A

band of connective tissue that courses between ligamentum flavum and dura mater

existence is controversial

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75
Q

Considered culprit for difficult epidural catheter insertion & unilateral epidural blocks

A

plica mediana dosalis

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76
Q

1st meningeal layer

A

dura mater

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77
Q

where does the dura mater begin and end

A

Begins at foramen magnum, ends at dural sac

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78
Q

what is the subdural space

A

Potential space between dura mater & arachnoid mater

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79
Q

thin layer of connective tissue that neighbors dura mater

A

arachnoid mater

2nd meningeal layer

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80
Q

thin layer of connective tissue that neighbors dura mater

A

arachnoid mater

2nd meningeal layer

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81
Q

what is contained in subarachnoid space

A

CSF, nerve roots, rootlets, spinal cord

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82
Q

target when performing spinal anesthetic

A

subarachnoid space

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83
Q

target when performing spinal anesthetic

A

subarachnoid space

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84
Q

layer deep to arachnoid mater

A

subarachnoid space

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85
Q

when is a characteristic “pop” felt while administering a spinal block

A

when needle passes through dura mater

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86
Q

external covering of spinal cord

A

pia mater

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87
Q

how many spinal nerves are in the spinal cord

A

31 paired nerves

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88
Q

what forms each spinal nerve

A

each formed by a posterior (dorsal) nerve root or anterior (ventral) nerve root

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89
Q

which nerve root carries sensory information

A

posterior (dorsal)

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90
Q

which type of nerve root carries motor and autonomic information

A

anterior (ventral)

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91
Q

what is a dermatoma

A

an area of skin that’s innervated by a dorsal (sensory) spinal nerve

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92
Q

cutaneous innervation of C6 nerve root

A

1st digit (thumb)

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93
Q

cutaneous innervation of C7 nerve root

A

2nd and 3rd digits

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94
Q

cutaneous innervation of C8 nerve root

A

4th and 5th digits

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95
Q

cutaneous innervation of T4 nerve root

A

nipple line

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96
Q

cutaneous innervation of T6 nerve root

A

xiphoid process

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97
Q

cutaneous innervation of T10 nerve root

A

umbilicus

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98
Q

cutaneous innervation of T12 nerve root

A

pubic symphysis

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99
Q

cutaneous innervation of L4 nerve root

A

anterior knee

100
Q

sensory input to the face

A

from 3 branches of trigeminal nerve (CN 5) - NOT a spinal nerve

  • V1 = ophthalmic n.
  • V2 = maxillary n.
  • V3 = mandibular n.
101
Q

sensory input to the face

A

from 3 branches of trigeminal nerve (CN 5) - NOT a spinal nerve

  • V1 = ophthalmic n.
  • V2 = maxillary n.
  • V3 = mandibular n.
102
Q

sensory level neuraxial block required for upper abd. surgery, c-sections, cystectomy

A

T4 (nipple line)

103
Q

sensory level neuraxial block required for lower abd surgery, appendectomy

A

T6-T7 (xiphoid process)

104
Q

sensory level neuraxial block required for THA, vaginal delivery, TURP

A

T10 (umbilicus)

105
Q

sensory level neuraxial block required for lower extremity surgery

A

L1-L3 (inguinal ligament)

106
Q

sensory level neuraxial block required for foot surgery

A

L2-L3

107
Q

sensory level neuraxial block required for hemorrhoidectomy

A

S2-S5

108
Q

epidural catheter insertion location for thoracic surgery, spread pattern, and dosing

thoracotomy, thoracic aneurysm, breast surgery

A
  • catheter: T2-T6 (upper thoracic)
  • spread pattern: T2-T6
  • dosing: 5-10 mL LA
109
Q

epidural catheter insertion location, spread pattern, & dosing for abd surgery

gastrectomy, esophagectomy, pancreatectomy, hepatic resection

A
  • catheter: T6-L1 (lower thoracic)
  • spread: T1-L4
  • dosing: 10-20 mL LA
110
Q

epidural catheter insertion location, spread pattern, & dosing for lower extremity surgery

TKA, THA

A
  • catheter: L2-L5
  • spread: T8-S5
  • dosing: 20 mL LA
111
Q

advantages of thoracic epidural over lumbar epidural

A
  • superior analgesia
  • minimizes surgical stress response
  • reduces the incidence of postop pulmonary complications
  • can spare nerves that innervate legs (allows for postop ambulation)
112
Q

increased risks assoc. with thoracic epidural + GA

A
  • bradycardia (blockade of cardioaccelerator nerves)
  • hypotension
  • changes in airway resistance (increased vagal influence on airways)
113
Q

primary site of action for spinal anesthetic

A

LA action on myelinated preganglionic fibers of spinal nerve roots

LAs also inhibit neural transmission in superficial layers of spinal cord

114
Q

primary site of action for spinal anesthetic

A

LA action on myelinated preganglionic fibers of spinal nerve roots

LAs also inhibit neural transmission in superficial layers of spinal cord

115
Q

LA site of action for epidural anesthesia

A
  • LA 1st diffuses through dural cuff before anesthetizing nerve roots
  • LAs also leak through intervertebral foramen to enter paravertebral area
116
Q

factors that significantly affect spread of spinal anesthesia

A

Controllable factors:
- Baricity of LA
- Patient position
- Dose
- Site of injection

Non-controllable factors:
- Volume of CSF
- Density of CSF

117
Q

most reliable determinant of intrathecal spread when using hypo- or isobaric solution

A

dose

118
Q

most reliable determinant of intrathecal spread when using a hyperbaric solution

A

Baricity

119
Q

factors that significantly affect spread of epidural anesthesia

A

Controllable factors:
- LA volume
- Level of injection
- LA dose

Non-controllable factors:
- Pregnancy
- Old age

120
Q

factors that have a small effect on epidural LA spread

A

Controllable factors:
- LA concentration
- Patient position

Non-controllable factors:
- Height
- Body weight
- Pressure in nearby body cavities

121
Q

most important drug-related determinant of epidural spread

A

LA volume

122
Q

most important procedure-related determinant of epidural spread

A

level of injection

123
Q

typical spread of lumbar epidural

A

mostly cephalad

124
Q

typical spread of midthoracic epidural

A

equally cephalad and caudad

125
Q

typical spread of cervical epidural

A

mostly caudad

126
Q

what is differential blockade

A

For a given LA dose, the heights of motor, sensory, and autonomic block will be different

127
Q

level of sensory block is (higher/lower) than motor block

A

higher

Sensory fibers (pain and touch) are blocked by LA concentrations that don’t affect motor neurons

128
Q

level of sensory block is (higher/lower) than motor block

A

higher

Sensory fibers (pain and touch) are blocked by LA concentrations that don’t affect motor neurons

129
Q

level of SNS block is (higher/lower) than sensory and motor block

A

higher

SNS fibers blocked by LA concentrations that don’t affect sensory or motor neurons

130
Q

level of SNS block is (higher/lower) than sensory and motor block

A

higher

SNS fibers blocked by LA concentrations that don’t affect sensory or motor neurons

131
Q

sensory block in spinal anesthesia in relation to motor block

A

sensory block is 2 dermatomes above motor block

132
Q

autonomic blockade in spinal anesthesia in relation to sensory block

A

autonomic block is 2-6 dermatomes above sensory block

133
Q

sensory and ANS blockade in relation to motor block in epidural anesthesia

A

Sensory and ANS blockade are 2-4 dermatomes above motor block

No autonomic differential blockade with epidural anesthesia

134
Q

sensory and ANS blockade in relation to motor block in epidural anesthesia

A

Sensory and ANS blockade are 2-4 dermatomes above motor block

No autonomic differential blockade with epidural anesthesia

135
Q

Modified Bromage Scale

A
  • 0 = no motor block
  • 1 = patient can’t raise extended leg but can move legs and feet
  • 2 = patient can’t raise extended leg or move knee but can move feet
  • 3 = complete motor block (can’t move legs, knees, or feet)

evaluates lumbosacral motor block

136
Q

Modified Bromage Scale

A
  • 0 = no motor block
  • 1 = patient can’t raise extended leg but can move legs and feet
  • 2 = patient can’t raise extended leg or move knee but can move feet
  • 3 = complete motor block (can’t move legs, knees, or feet)

evaluates lumbosacral motor block

137
Q

most significant controllable factors affecting spinal block height

A

dose, baricity, and patient position

138
Q

which typically causes a denser block - spinal or epidural

A

spinal

139
Q

what structure must be traversed by epidural LAs and what is their primary target

A

LAs in epidural space must first diffuse through dural cuff before anesthetizing nerve roots

140
Q

primary drug-related determinant of LA spread in epidural space

A

volume of LA administered

141
Q

what type of nerve fiber is blocked first after spinal anesthetic

A

type B - preganglionic ANS fibers

142
Q

function of A alpha peripheral nerves

A

skeletal muscle - motor
proprioception

143
Q

function of A beta peripheral nerves

A

touch
pressure

144
Q

function of A gamma peripheral nerves

A

skeletal muscle tone

145
Q

function of A delta peripheral nerves

A

fast pain
temp
touch

146
Q

function of C peripheral nerves

A

sympathetic: postganglionic ANS fibers
dorsal root: slow pain, temp, touch

147
Q

peripheral nerve fibers responsible for slow pain

A

C fibers (dorsal root)

148
Q

primary determinant of epidural block density

A

LA concentration

149
Q

for a spinal, how many mL of 0.75% bupivacaine are required to produce a T10 block?

A
  • 0.75% = 7.5 mg/mL
  • T10 dose = 10-15 mg
  • volume = 1.25-2 mL
150
Q

spinal dose & onset of bupivacaine 0.5-0.75% (no dextrose)

A

T10 block = 10-15 mg
T4 = 12-20 mg
onset = 4-8 min

151
Q

duration of spinal bupivacaine 0.5-0.75%

A

plain: 130-220 min
w/ epi: + 20-50%

152
Q

dose, onset, & duration of spinal 2-chloroprocaine 3% (+/- dextrose)

A

T10 dose = 30-40 mg
T4 dose = 40-60 mg
onset = 2-4 min
duration = 40-90 min

153
Q

primary determinant of epidural block height

A

LA volume

154
Q

initial epidural dose

A

1-2 mL per segment to be blocked

155
Q

“top up” epidural dose

A

50-75% of the initial dose
should be admin. before block recedes > 2 dermatomes

156
Q

why will a given volume of LA achieve greater spread in thoracic region compared to lumbar

A

Volume of epidural space is smaller in thoracic compared to lumbar region

157
Q

primary determinant of epidural block density

A

LA concentration

158
Q

how is a “walking epidural” achieved in OB

A

using a low enough concentration that provides analgesia while preserving motor function

159
Q

concentration, onset, & duration of epidural 2-chloroprocaine

A

concentration = 3%
onset = 5-15 min
duration = 30-90 min

160
Q

concentration, onset, & duration of epidural lidocaine

A

concentration = 2%
onset = 10-20 min
duration = 60-120 min

161
Q

concentration, onset, & duration of epidural bupivacaine

A

concentration = 0.0625-0.5%
onset = 15-20 min
duration = 160-220 min

162
Q

ratio of mass of substance relative to its volume (mass/volume)  varies inversely with temperature

A

density

163
Q

density of a substance relative to density of reference substance

A

specific gravity

164
Q

analogous to specific gravity, but ratio is density of LA solution to density of CSF

A

baricity

165
Q

density of water vs CSF

A

water = 0.9933
CSF = 1.003

166
Q

Specific gravity of water vs CSF

A

water = 1
CSF = 1.002-1.009

167
Q

baricity of water vs CSF

A

water = 0.9930
CSF = 1

168
Q

describes the density of LA solution relative to CSF

A

baricity

169
Q

baricity of isobaric LA solution

A

similar to CSF
Remains in place
As a general rule, solutions in saline are isobaric

Exception: procaine 10% in water  10% solution contains a lot of molecules, making it hyperbaric

170
Q

baricity of hyperbaric solution

A
  • LA solution with higher density than CSF
  • Baricity > 1
  • Solution will sink
171
Q

what LA additive increases baricity

A

dextrose

172
Q

LA solution with lesser density than CSF

A

hypobaric
baricity < 1

173
Q

solutions that are hypobaric as a general rule

A

solutions in water

*Exception: procaine 10% in water - 10% solution contains a lot of molecules, making it hyperbaric

174
Q

what happens to a hypobaric solution

A

will rise

175
Q

highest points of lordosis in supine position

A

C5 and L3

176
Q

highest points of kyphosis in supine position

A

T5-T7 and S2

177
Q

for a spinal, how many mL of 3% 2-chloroprocaine required to produce a T4 block?

A
  • 3% 2-chloroprocaine = 30 mg/mL
  • T4 dose = 40-60 mg
  • volume to give = 1.33-2 mL
178
Q

in sitting position, how will a hypobaric solution spread in intrathecal space

A

towards brain

179
Q

in supine position, how will hypobaric solution spread in intrathecal space

A

concentrate in lower lumbar region

180
Q

after admin. a hyperbaric solution, the block is not as high as you expected. what can you do?

A

if block hasn’t already set, can place pt in T-burg

181
Q

what happens after hyperbaric solution given if pt keeps sitting after block

A

solution will sink and anesthetize sacral nerve roots (saddle block)

182
Q

what happens after admin hyperbaric solution if we lay pt supine after block

A

solution will slide down lumbar lordosis and eventually pool in sacrum & thoracic kyphosis

183
Q

where does spinal anesthetic tend to level off

A

T4

184
Q

what happens if If the patient becomes hypotensive immediately after SAB with hyperbaric solution and pt placed in Trendelenburg

A

the highest point of kyphosis shifts to T1 & creates possibility of high spinal

185
Q

when is it safe to change positions after giving hyperbaric spinal solution

A

once the block is “set”

186
Q

why does hypobaric solution not float towards cervical region if supine after spinal block

A

this would require LA to sink into thoracic kyphosis

187
Q

what spinal levels give rise to cardioaccelerator fibers

A

T1-T4

188
Q

what reflex contributes to asystole in spinal anesthesia

A

Bezold Jarisch reflex

slows heart to allow refill time

189
Q

what reflex contributes to asystole in spinal anesthesia

A

Bezold Jarisch reflex

slows heart to allow refill time

190
Q

Primary mechanism of hypotension with neuraxial anesthesia

A

anesthetic blockade of pre-ganglionic B fibers in sympathetic chain (sympathectomy)

Also ↓ catecholamine output from adrenal glands, skeletal muscle paralysis, direct effects of LAs that diffuse into systemic circulation

191
Q

Primary mechanism of hypotension with neuraxial anesthesia

A

anesthetic blockade of pre-ganglionic B fibers in sympathetic chain (sympathectomy)

Also ↓ catecholamine output from adrenal glands, skeletal muscle paralysis, direct effects of LAs that diffuse into systemic circulation

192
Q

Complications assoc with hypotension from neuraxial block

A
  • N/V, impaired organ perfusion (heart/brain/gut), CV collapse
  • In pregnant patients, impaired placental perfusion puts fetus at risk of ischemia & acidosis
193
Q

how does neuraxial anesthesia affect preload

A

decreases

sympathectomy = complete dilation of venous circulation = blood pools in periphery = decreased venous return = decreased preload

194
Q

how does neuraxial anesthesia affect afterload

A

decreased

Sympathectomy = partial dilation of arterial circulation

195
Q

how does neuraxial anesthesia affect afterload

A

decreased

Sympathectomy = partial dilation of arterial circulation

196
Q

SVR changes with neuraxial anesthesia in healthy pts vs. elderly pts with CV disease

A

healthy = decreases ~15%
elderly = decreases ~25%

197
Q

how is CO affected by neuraxial anesthesia

A

variable
* dec VR = dec SV = dec CO
* dec SVR = dec CO

198
Q

how is HR affected by neuraxial anesthesia

A

increased or decreased
* inc: hypotension = baroreceptor reflex activated
* dec: cardioaccelarator fibers blocked = inc PNS tone, Bezold Jarish reflex

199
Q

how does a spinal to T4 affect Vm in healthy patients

A

negligible effect

200
Q

most likely cause of apnea with spinal anesthesia

A

brainstem hypoperfusion

201
Q

likely mediators of Bezold Jarisch Reflex

A

5-HT3 receptors in vagus n. & ventricular myocardium

202
Q

how does neuraxial anesthesia affect accessory muscles

A

reduced function

Impaired intercostal muscles (inspiration & expiration

202
Q

how does neuraxial anesthesia affect accessory muscles

A

reduced function

Impaired intercostal muscles (inspiration & expiration

203
Q

how does neuraxial anesthesia affect accessory muscles

A

reduced function

Impaired intercostal muscles (inspiration & expiration

204
Q

why might pt c/o dyspnea with neuraxial anesthesia

A

Loss of proprioception from chest

205
Q

how can neuraxial anesthesia cause drowsiness

A

↓ sensory output to RAS

206
Q

how does neuraxial anesthesia affect neuroendocrine stress response

A

By inhibiting afferent traffic from surgical site, neuraxial anesthesia ↓ surgical stress response

also↓ circulating catecholamines, renin, angiotensin, glucose, TSH, and growth hormone

207
Q

how does neuraxial anesthesia affect neuroendocrine stress response

A

By inhibiting afferent traffic from surgical site, neuraxial anesthesia ↓ surgical stress response

also↓ circulating catecholamines, renin, angiotensin, glucose, TSH, and growth hormone

208
Q

how does spinal anesthesia affect hepatic blood flow

A

not affected as long as systemic BP is maintained

209
Q

GI effects of neuraxial anesthesia

A
  • inhibit SNS tone, which ↑ PNS tone to gut
  • Sphincters relax, peristalsis ↑
210
Q

MOA of neuraxial opioids

A

Inhibit afferent pain transmission in substantia gelatinosa (lamina 2 of dorsal horn)

exerts analgesic effect by binding to mu receptors in substantia gelatinosa of dorsal horn

211
Q

effect of neuraxial opioids combined with LAs

A

denser block

212
Q

3 things neuraxial opioids do NOT cause

A
  1. sympathectomy
  2. skeletal muscle weakness
  3. changes in proprioception
213
Q

3 directions opioid in intrathecal space can travel

A
  1. diffuse into spinal cord
  2. diffuse. outof intrathecal space
  3. ascend intrathecal space (rostral spread)
214
Q

ranking opioids from most to least lipophilic

A

Sufentanil > fentanyl > meperidine > hydromorphone > morphine

Sexy Fathers Make Happy Mothers

215
Q

ranking opioids from most to least lipophilic

A

Sufentanil > fentanyl > meperidine > hydromorphone > morphine

Sexy Fathers Make Happy Mothers

216
Q

how do hydrophilic vs. lipophilic drugs tend to behave in the CSF

A
  • Lipophilic drugs tend to leave CSF early
  • Hydrophilic drugs tend to remain in CSF longer

The longer the drug remains in CSF, the more it spreads in intrathecal space and more likely it is to reach the brainstem

217
Q

which tends. toproduce a more narrow band of neuraxial analgesia - fentanyl or morphine

A

fentanyl (more lipophilic)

218
Q

onset of neuraxial fentanyl vs morphine

A

fentanyl: 5-10 min
morphine: 30-60 min

219
Q

duration of neuraxial morphine vs. fentanyl

A

fentanyl: 2-4 hours
morphine: 6-24 hours

220
Q

respiratory depression with hydrophilic vs. lipophilic neuraxial opioids

A
  • lipophilic (fentanyl): early only
  • hydrophilic (morphine): early + late

early < 6h, late > 6 h

221
Q

diffusion of neuraxial opioids deposited into intrathecal vs. epidural space

A

intrathecal space - can easily diffuse into spinal cord
epidural space - diffuse within epidural tissue

222
Q

why is a higher dose of neuraxial opioid required for epidural opioids

A

only a fraction reaches the subarachnoid space

223
Q

sufentanil:
* intrathecal dose
* epidural dose
* epidural infusion

A
  • intrathecal dose: 5-10 mcg
  • epidural dose: 25-50 mcg
  • epidural infusion: 10-20 mcg/hr
224
Q

fentanyl:
* intrathecal dose
* epidural dose
* epidural infusion

A
  • intrathecal dose: 10-20 mcg
  • epidural dose: 50-100 mcg
  • epidural infusion: 25-100 mcg/hr
225
Q

hydromorphone:
* intrathecal dose
* epidural dose
* epidural infusion

A
  • intrathecal dose: N/A
  • epidural dose: 0.5-1 mg
  • epidural infusion: 0.1-0.2 mg/hr
226
Q

meperidine:
* intrathecal dose
* epidural dose
* epidural infusion

A
  • intrathecal dose: 10 mg
  • epidural dose: 25-50 mg
  • epidural infusion: 10-60 mg/hr
227
Q

morphine:
* intrathecal dose
* epidural dose
* epidural infusion

A
  • intrathecal dose: 0.25-0.3 mg
  • epidural dose: 2-5 mg
  • epidural infusion: 0.1-1 mg/hr
228
Q

4 key side effects of neuraxial opioids

A
  1. Pruritis
  2. Respiratory depression
  3. Urinary retention
  4. N/V
229
Q

most common side effect of neuraxial opioids

A

pruritis

230
Q

neuraxial opioid SE that’s most common in OB patients

A

pruritis

231
Q

MOA of pruritis with neuraxial opioids

A

Likely caused by stimulation of opioid receptors in trigeminal nucleus or some other type of opioid-triggered neural process

232
Q

management of pruritis with neuraxial opioids

A
  • Can be treated with opioid antagonist like naloxone
  • Diphenhydramine doesn’t fix the cause but sedative effects may be beneficial
233
Q

what causes early respiratory depression from neuraxial opioids

A

systemic absorption

(occurs in < 6 h)

234
Q

what causes late respiratory depression with neuraxial opioids

A

results from tendency to ascend towards brainstem, where they can inhibit respiratory center (occurs between 6-12 hours)

235
Q

6 factors that increase resp depression with neuraxial opioid use

A
  • high opioid doses
  • co-administered sedatives
  • low lipid solubility
  • advanced age
  • opioid naivety
  • increased intrathoracic pressure
236
Q

SE of neuraxial opioids most common in young males

A

urinary retention

237
Q

MOA of urinary retention with neuraxial opioids

A

inhibition of sacral PNS tone causes bladder detrusor muscle relaxation & urinary sphincter contraction

Can be reversed with naloxone

238
Q

MOA of N/V with neuraxial opioids

A

activation of opioid receptors in area postrema of medulla & vestibular apparatus

239
Q

neuraxial opioid that can reactivate HSV type 1 in OB & postpartum pts

A

epidural morphine

Usually presents 2-5 days after admin.

240
Q

MOA of HSV1 reactivation by epidural morphine

A

Best explained by cephalad spread of morphine to trigeminal nucleus

241
Q

neuraxial LA that decreases efficacy of epidural opioids

A

2-chloroprocaine

242
Q

neuraxial opioid most assoc. with sedation

A

sufentanil

243
Q

how do neuraxial opioids affect peristalsis

A

slows, increasing gastric transit time

(opposite effect caused by neuraxial LAs)

244
Q

how do neuraxial opioids cause an antidiuretic effect

A

increasing vasopressin release

245
Q

how does epidural opioid admin affect breast milk

A

Minimal transfer of opioids from epidural space to breast milk

246
Q
A

A = transverse process
B = superior articular process
C = lamina
D = spinous process

APEX (54 decks)

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