Regional Anesthesia Flashcards

1
Q

How long does it take for the spinal cord to go from L3 in the newborn to L1?

A

20-24mos

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2
Q

Which ligament binds the epidural space posteriorly?

A

ligamentum flavum

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3
Q

Where is the epidural space the widest?

A

L2

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4
Q

Where is the epidural space the narrowest?

A

C5

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5
Q

What are the two high points of the vertebral column when the patient is lying supine?

A

L3 and C3

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6
Q

What are the two low points of the vertebral column when the patient is lying supine?

A

S2 and T6

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7
Q

What is ALWAYS going to be the principle site of action for spinals or epidurals?

A

the nerve root

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8
Q

Name the 3 main structures you pass through to get to the epidural space.

A

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

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9
Q

What are the 3 primary layers of the spinal meninges before reaching the cord?

A

1) dura mater (outermost–> toughest–> extends from foramen magnum to S2-3)
2) arachnoid mater (middle layer–> delicate, nonvascular–> ends at S2–> almost like spiderweb)
3) pia mater (closely adheres to spinal cord–> delicate, highly vascular)

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10
Q

Where is the subarachnoid space and CSF found?

A

between the arachnoid and pia mater

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11
Q

What is the easy way to remember the 3 outer layers and location of the subarachnoid space before the spinal cord?

A
DASP
Dura
Arachnoid
Subarachnoid space
Pia
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12
Q

Where is the epidural space located?

A

it is a potential space bound by the dura mater and the ligamentum flavum

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13
Q

Describe the blood supply to the spinal cord and nerve roots.

A

blood supply to the spinal cord and nerve roots is derived from a single anterior spinal artery and paired posterior spinal arteries

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14
Q

The principal site of action for neuraxial blockade is the ______.

A

nerve root

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15
Q

How much CSF do we have at any time? in the subarachnoid space?

A

100-150ml; 25-35ml

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16
Q

How much CSF do we produce per day?

A

500mL

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17
Q

How do vasoconstrictors prolong a spinal block?

A

decrease absorption

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18
Q

When administering a spinal, where is the concentration the greatest?

A

at the site of injection

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19
Q

What is the normal specific gravity of CSF?

A

1.004-1.009

James Bond 1.007 is in the middle

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20
Q

Label in relation to CSF: SAME, GREATER, LESS

Isobaric

A

same

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21
Q

Label in relation to CSF: SAME, GREATER, LESS

hyperbaric

A

greater

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22
Q

Label in relation to CSF: SAME, GREATER, LESS

hypobaric

A

less

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23
Q

Is sterile water hypo, hyper, or iso baric?

A

hypobaric

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24
Q

Is dextrose 5-8% hypo, hyper, or iso baric?

A

hyperbaric

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25
Q

What direction will a hyperbaric spinal given at L2 while the patient was sitting go if the patient is immediately laid supine?

A

cephalad. Think of the high and low points

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26
Q

What determines the duration of spinal anesthesia?

A

rate of elimination

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27
Q

What is the predominant action of a sympathetic blockade d\t local anesthetics?

A

venodilation

venodilation–> reduces venous return, SV, CO, and BP

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28
Q

What are the two causes for bradycardia following local anesthetic administration?

A

1) blockade of cardiac accelerator fibers
2) decreased venous return (from venodilation)
* Bainbridge reflex (unopposed vagal stimulation)

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29
Q

What is the BEST means for treating hypotension during spinal anesthesia?

A

physiologic not pharmacologic

*give fluids if not normovolemic, if normovolemic give ephedrine

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30
Q

Why do you not want to give fluids that are rich in glucose, but instead give balanced salt solutions for hypotension?

A

b\c glucose can act as a diuretic

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31
Q

What is the difference between a high spinal and a total spinal?

A

high spinal is >T4

total spinal goes all the way

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32
Q

What is an advantage of a spinal over epidural?

A

ability to control the spread of anesthetic by controlling the specific gravity of the solution and the position of the patient

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33
Q

Are there any time restraints to receiving neuraxial anesthesia for patients taking NSAIDs or aspirin?

A

No

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34
Q

When can a catheter be removed from a patient on IV heparin therapy?

A

2-4 hours after the last heparin dose; heparinization can occur one hour after catheter removal

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35
Q

What are the special considerations for patients on warfarin therapy?

A

controversial

  • should d\c at least 4 days before surgery
  • should check INR (neuraxial block may be given if perioperative INR is <1.5)
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36
Q

What is an acceptable INR in order to administer a neuraxial block to a patient on warfarin?

A

<1.5

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37
Q

The catheter should not be removed until INR is _____.

A

<1.5

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38
Q

Do not place or remove a neuraxial catheter if INR is ______.

A

> 1.5

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39
Q

What considerations for neuraxial anesthesia should be made for a patient who has received, is receiving, or will be receiving fibrinolytic or thrombolytic drug therapy?

A

should NOT receive neuraxial for 10 DAYS

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40
Q

First dose of LMWH can be given _____ hours after removal of the catheter.

A

2 hours

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41
Q

What are two other names for L4?

A

1) Tuttier’s line

2) intercristal line

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42
Q

Spinal, epidural, and caudal blocks are all considered ________.

A

neuraxial anesthesia

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43
Q

Describe the distribution of local anesthetic when injected into the subarachnoid space.

A

spreads to nerves of the cauda equina and laterally to the nerve rootlets and nerve roots–> may also diffuse into the spinal cord

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44
Q

Which two structures will you not pass through during a lateral approach to a spinal?

A

1) supraspinous ligament

2) interspinous ligament

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45
Q

Infection as a result of spinal anesthesia:

predisposing factors?? (5)

A

1) advanced age
2) diabetes mellitus
3) alcoholism
4) cancer
5) AIDS

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46
Q

Infection as a result of spinal anesthesia:

classic symptoms?? (3)

A

1) high fever (only seen with meningitis, not PDPH)
2) nuchal rigidity
3) severe headache

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47
Q

Nausea and vomiting should be viewed as signs of ______ until proven otherwise.

A

central hypoxia

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48
Q

What is the most common complication of spinal anesthesia? second?

A

backache; headache (PDPH)

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49
Q

When does the patient start to feel a PDPH?

A

within 12-72 hours; the earlier the onset, the more severe

  • self limiting
  • can last 10 days
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50
Q

Name s\s of PDPH (caused by traction on cranial nerves).

A

1) nausea and loss of appetite
2) photophobia
3) changes in auditory acuity
4) tinnitus
5) depression
6) feel miserable
7) tearful
8) bed-ridden
9) dependent
10) diplopia and cranial nerve palsies

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51
Q

What cause a PDPH?

A

loss of CSF in the subarachnoid space–> medulla and brainstem drop into the foramen magnum, stretching the meninges, vessels, and nerves–> headache

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52
Q

Blood patch should be _____ to _____mL.

A

10-30ml aseptically drawn blood

  • injected into epidural space until the patient can feel pressure in back
  • after the blood patch, bed rest for 1-2 hours before ambulating
  • 1st= 89-95% resolution
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53
Q

What are the conservative treatments for PDPH?

A

1) lie flat
2) hydration
3) caffeine (IV/oral)–> cerebral vasoconstriction

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54
Q

In regards to nerve types, what is the order in which they are blocked with local anesthesia?

A

B fibers–> C fibers and A-delta–> A-gamma–> A-beta–> A-alpha

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55
Q

In regards to nerve types, what is the order of most to least sensitive?

A

“LSU”
Large myelinated
Small myelinated
Unmyelinated

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56
Q

Label whether the following is a characteristic of a spinal (S) or epidural (E):
takes less time to perform

A

S

57
Q

Label whether the following is a characteristic of a spinal (S) or epidural (E):
catheter used for post op pain management

A

E

58
Q

Label whether the following is a characteristic of a spinal (S) or epidural (E):
pain during surgery is less

A

S

59
Q

Label whether the following is a characteristic of a spinal (S) or epidural (E):
rapid onset

A

S

60
Q

Label whether the following is a characteristic of a spinal (S) or epidural (E):
less hypotension

A

E

61
Q

Label whether the following is a characteristic of a spinal (S) or epidural (E):
sensory and motor block quality is better

A

S

62
Q

Label whether the following is a characteristic of a spinal (S) or epidural (E):
can prolong block with catheter

A

E

63
Q

Distance from skin to epidural space:

Average adult?

A

4-6cm

64
Q

Distance from skin to epidural space:

Fat, I mean obese person?

A

up to 8cm

65
Q

Distance from skin to epidural space:

thin person?

A

approximately 3cm

66
Q

Is a lumbar epidural injection associated with a more cranial or caudal spread?

A

cranial

67
Q

Why may there be a delay in onset to an epidural at L5 or S1?

A

b\c of the larger size of the nerve roots

68
Q

What is the prevalence of a epidural hematoma?

A

1:150,000

69
Q

What are the s\s of a epidural hematoma?

A

sharp back and leg pain–> numbness and weakness, sphyncter dysfunction

70
Q

What is the best test for epidural hematoma?

A

MRI or CT scan

71
Q

What ensures a good outcome for a patient with a epidural hematoma?

A

surgical decompression within 8-12 hours

72
Q

Name some complications of epidural blockade:

A
  • penetrate a blood vessel
  • epidural hematoma
  • dural puncture
  • back ache
  • neural trauma
  • air embolism (children)
  • subdural catheterization
  • intravascular catheterization (small alloquots)
  • infection
  • headache
  • hypotension
  • resp depression/resp failure
  • bradycardia
  • total spinal secondary to subarachnoid injection (intubate and sedate)
  • Horner’s syndrome
  • trigeminal nerve palsy
73
Q

Why do you perform a test dose after satisfactory placement of a epidural catheter?

A

to detect both subarachnoid and intravascular injection

74
Q

What is the most common regional anesthetic in children?

A

caudal block

75
Q

Where do you insert the needle when doing a caudal block?

A

through the sacrococcygeal membrane

  • the injection should feel like an injection into the epidural space
  • should be NO local pain on injection
76
Q

When doing a caudal block should you be able to aspirate CSF, air, or blood?

A

No

77
Q

What is the “whoosh” test?

A

for caudal blocks–> whoosh test with air while listening with stethoscope over midline lumbar spine

78
Q

When performing a caudal block, the patient reports a feeling of fullness or paresthesia from the sacrum to the soles of the feet. What should you do?

A

nothing, this is normal during injection and will cease upon completion

79
Q

A volume of _____ml is required to get a sensory level block at T10 to T12.

A

25-35mL

80
Q

Is caudal or epidural anesthesia associated with higher plasma levels?

A

caudal

81
Q

Is distribution time longer for epidural or for caudals?

A

caudal; d\t nerve size

82
Q

What is the most frequent problem with caudal blocks?

A

ineffective blockade

83
Q

What is the most common post-op complaint after a caudal block?

A

pain at insertion site

84
Q

What are the two greatest advantages of US guided regional anesthesia?

A

1) ability to see where the tip of needle is in relation to anatomical structures
2) see the spread of local anesthesia

85
Q

What are high frequency sound waves generated in specific frequency ranges and sent through tissues?

A

ultrasound waves

86
Q

_____ frequencies penetrate deeper than _____ frequencies.

A

lower; higher

87
Q

What is best to visualize shallow structures less than 4cm from the skin?

A

high frequency (10-13mHz)

88
Q

What is best for visualizing deeper structures?

A

low frequency (2-5mHz)

89
Q

As sound passes through tissue it is ______, _______, or allowed to _________, depending on the echodensity of the tissue.

A

absorbed, reflected, pass through

90
Q

Substances that absorb sound well are termed ______.

A

anechoic (echolucent)

91
Q

Anechoic substances like blood and CSF (high water content) appear _____ on a US.

A

dark

92
Q

Substances low in water content or high in materials that are poor sound conductors are called _______. Give examples.

A

hyperechoic (they bounce the sound back)

-air and bone

93
Q

How do hyperechoic substances appear on the US?

A

very bright

94
Q

The middle “shades of gray” on a US are due to substances that fall in the middle of anechoic and hyperechoic. These are called _____.

A

hypoechoic (vessels, etc)

95
Q

If you are doing a caudal block for a child, what is the initial dose?

A

0.5-1.0mg/kg of 0.125% to 0.25% bupivacaine

96
Q

Where in the plexus is the phrenic nerve located?

A

C3-C5, but C4 is 70% contribution

97
Q

What is the cervical plexus?

A

C1-C5

98
Q

What is the brachial plexus?

A

C5-C8, T1

99
Q

Name the dermatome and nerve involved.

pain in small finger

A

ulnar nerve, C8

100
Q

What two nerves innervate the thumb?

A

radial and median

101
Q

What is the only nerve that gives extension in the hand?

A

radial nerve

102
Q

Name the nerve:

supination of forearm

A

radial

103
Q

Name the nerve:

pronation of forearm

A

median

104
Q

What nerve provides flexion at the wrist?

A

median and ulnar

105
Q

________ nerve provides extension at the elbow, while ________ nerve provides flexion at the elbow.

A

radial; musculocutaneous

106
Q

What surgery is a good indication for use of a cervical block?

A

CEA

107
Q

Ipsilateral means _______.

A

same side

108
Q

Contralateral means ______.

A

opposite side

109
Q

A cervical plexus block is performed for C____ to C_____ by injecting ____mL of local anesthetic at each level.

A

C1-C4; 4mL

110
Q

What are 4 complications that can result from a cervical plexus block?

A

1) block phrenic nerve (hiccups)
2) Horner’s syndrome (ipsilateral ptosis, miosis, facial and arm flushing, anhydrosis, and nasal congestion)
3) hoarseness (RLN block)
4) accidental subarachnoid or epidural injection

111
Q

Which plexus block provides adequate analgesia for shoulder and proximal humerus?

A

interscalene

Intense C5-C7, Least C8-T1

112
Q

______ is the level of the cricoid cartilage.

A

C6

113
Q

What nerve may not be blocked with a interscalene block?

A

ulnar nerve

114
Q

Puncture of the _______ artery is a complication of an interscalene block.

A

vertebral artery

115
Q

What block: Where is the brachial plexus MOST compact (3 trunks)?

A

supraclavicular block

116
Q

What is the most homogenous block of the brachial plexus that even includes the ulnar nerve?

A

supraclavicular

117
Q

What is the biggest risk associated with supraclavicular blocks?

A

pneumothorax

118
Q

What is “X” marks the spot for a supraclavicular block?

A

1) most inferior part of the interscalene groove

2) 2 cm’s from midpoint of the clavicle

119
Q

What is the major concern when performing a infraclavicular block?

A

1) pneumothorax

2) hemothorax

120
Q

Which plexus block ensures blockade of the musculocutaneous nerve?

A

infraclavicular

121
Q

Brachial Plexus Anatomy at the Axilla:

What nerves are in the bundle at this level?

A

1) musculocutaneous (but lies outside the sheath–> requires a separate block to cover)
2) median
3) radial
4) ulnar

122
Q

Can you do both a ulnar and radial block at the hand?

A

not at the same time–> compromise circulation

123
Q

EPI should not be added to blocks __________.

A

below the elbow

124
Q

What is the BEST block for knee surgery?

A

femoral and sciatic

125
Q

What is the largest nerve trunk in the body?

A

sciatic (lumbosacral trunk)

126
Q

What nerves compose the lumbosacral trunk?

A

L4-5, S1-3

127
Q

The sciatic provides sensory to where?

A

sensory fibers to the posterior hip capsule as well as the knee; ALL sensory distal to the knee except the anteromedial aspect which is covered by the saphenous; motor to the hamstrings and to all the lower extremity muscles distal to the knee

128
Q

What are the complications associated with a retrobulbar block?

A

1) retrobulbar injection
2) retrobulbar hemorrhage: bleeding in eye, temp loss of vision, lens occluded by blood, IOP may decrease
3) Intra-arterial injection (MOST COMMON; 1-3%)
4) injection into optic nerve sheath
5) oculocardiac refex

129
Q

How long must you leave the tourniquet up for following a Bier block?

A

20 min or you can get LA toxicity

130
Q

The most common causative organism in epidural abscesses is: ________.

A

staphylococcus aureus

131
Q

When doing a CSE, how far should the spinal needle extend beyond the tip of the epidural needle?

A

7-10mm

132
Q

How much clonidine should you add to your spinal anesthetic?

A

15-45mcg

133
Q

What is the recommended dose (mg) for epinephrine when added to tetracaine?

A

0.2 to 0.3

134
Q

What level of spinal anesthesia will be necessary to eliminate thigh tourniquet discomfort?

A

T12

135
Q

What is the easiest, most frequently used, and lowest complication risk of the brachial plexus blocks?

A

axillary

136
Q

The axillary approach to the brachial plexus block is best suited for procedures where?

A

elbow, hand, forearm

137
Q

How much pressure should you apply on the proximal tourniquet when administering an IV regional anesthetic in the upper extremity?

A

SBP + 100

138
Q

What nerve is immediately lateral to the achilles tendon in the patients ankle?

A

sural