Regional Anesthesia Flashcards Preview

Board Review CRNA (Sweat Book) > Regional Anesthesia > Flashcards

Flashcards in Regional Anesthesia Deck (138):
1

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

20-24mos

2

Which ligament binds the epidural space posteriorly?

ligamentum flavum

3

Where is the epidural space the widest?

L2

4

Where is the epidural space the narrowest?

C5

5

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

L3 and C3

6

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

S2 and T6

7

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

the nerve root

8

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

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

9

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

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)

10

Where is the subarachnoid space and CSF found?

between the arachnoid and pia mater

11

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

DASP
Dura
Arachnoid
Subarachnoid space
Pia

12

Where is the epidural space located?

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

13

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

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

14

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

nerve root

15

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

100-150ml; 25-35ml

16

How much CSF do we produce per day?

500mL

17

How do vasoconstrictors prolong a spinal block?

decrease absorption

18

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

at the site of injection

19

What is the normal specific gravity of CSF?

1.004-1.009
James Bond 1.007 is in the middle

20

Label in relation to CSF: SAME, GREATER, LESS
Isobaric

same

21

Label in relation to CSF: SAME, GREATER, LESS
hyperbaric

greater

22

Label in relation to CSF: SAME, GREATER, LESS
hypobaric

less

23

Is sterile water hypo, hyper, or iso baric?

hypobaric

24

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

hyperbaric

25

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

cephalad. Think of the high and low points

26

What determines the duration of spinal anesthesia?

rate of elimination

27

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

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

28

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

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

29

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

physiologic not pharmacologic
*give fluids if not normovolemic, if normovolemic give ephedrine

30

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

b\c glucose can act as a diuretic

31

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

high spinal is >T4
total spinal goes all the way

32

What is an advantage of a spinal over epidural?

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

33

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

No

34

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

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

35

What are the special considerations for patients on warfarin therapy?

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

36

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

<1.5

37

The catheter should not be removed until INR is _____.

<1.5

38

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

>1.5

39

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?

should NOT receive neuraxial for 10 DAYS

40

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

2 hours

41

What are two other names for L4?

1) Tuttier's line
2) intercristal line

42

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

neuraxial anesthesia

43

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

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

44

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

1) supraspinous ligament
2) interspinous ligament

45

Infection as a result of spinal anesthesia:
predisposing factors?? (5)

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

46

Infection as a result of spinal anesthesia:
classic symptoms?? (3)

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

47

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

central hypoxia

48

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

backache; headache (PDPH)

49

When does the patient start to feel a PDPH?

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

*self limiting
*can last 10 days

50

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

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

51

What cause a PDPH?

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

52

Blood patch should be _____ to _____mL.

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

53

What are the conservative treatments for PDPH?

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

54

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

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

55

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

"LSU"
Large myelinated
Small myelinated
Unmyelinated

56

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

S

57

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

E

58

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

S

59

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

S

60

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

E

61

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

S

62

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

E

63

Distance from skin to epidural space:
Average adult?

4-6cm

64

Distance from skin to epidural space:
Fat, I mean obese person?

up to 8cm

65

Distance from skin to epidural space:
thin person?

approximately 3cm

66

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

cranial

67

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

b\c of the larger size of the nerve roots

68

What is the prevalence of a epidural hematoma?

1:150,000

69

What are the s\s of a epidural hematoma?

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

70

What is the best test for epidural hematoma?

MRI or CT scan

71

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

surgical decompression within 8-12 hours

72

Name some complications of epidural blockade:

- 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

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

to detect both subarachnoid and intravascular injection

74

What is the most common regional anesthetic in children?

caudal block

75

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

through the sacrococcygeal membrane
* the injection should feel like an injection into the epidural space
*should be NO local pain on injection

76

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

No

77

What is the "whoosh" test?

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

78

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?

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

79

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

25-35mL

80

Is caudal or epidural anesthesia associated with higher plasma levels?

caudal

81

Is distribution time longer for epidural or for caudals?

caudal; d\t nerve size

82

What is the most frequent problem with caudal blocks?

ineffective blockade

83

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

pain at insertion site

84

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

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

85

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

ultrasound waves

86

_____ frequencies penetrate deeper than _____ frequencies.

lower; higher

87

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

high frequency (10-13mHz)

88

What is best for visualizing deeper structures?

low frequency (2-5mHz)

89

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

absorbed, reflected, pass through

90

Substances that absorb sound well are termed ______.

anechoic (echolucent)

91

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

dark

92

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

hyperechoic (they bounce the sound back)
-air and bone

93

How do hyperechoic substances appear on the US?

very bright

94

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

hypoechoic (vessels, etc)

95

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

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

96

Where in the plexus is the phrenic nerve located?

C3-C5, but C4 is 70% contribution

97

What is the cervical plexus?

C1-C5

98

What is the brachial plexus?

C5-C8, T1

99

Name the dermatome and nerve involved.
pain in small finger

ulnar nerve, C8

100

What two nerves innervate the thumb?

radial and median

101

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

radial nerve

102

Name the nerve:
supination of forearm

radial

103

Name the nerve:
pronation of forearm

median

104

What nerve provides flexion at the wrist?

median and ulnar

105

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

radial; musculocutaneous

106

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

CEA

107

Ipsilateral means _______.

same side

108

Contralateral means ______.

opposite side

109

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

C1-C4; 4mL

110

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

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

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

interscalene
Intense C5-C7, Least C8-T1

112

______ is the level of the cricoid cartilage.

C6

113

What nerve may not be blocked with a interscalene block?

ulnar nerve

114

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

vertebral artery

115

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

supraclavicular block

116

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

supraclavicular

117

What is the biggest risk associated with supraclavicular blocks?

pneumothorax

118

What is "X" marks the spot for a supraclavicular block?

1) most inferior part of the interscalene groove
2) 2 cm's from midpoint of the clavicle

119

What is the major concern when performing a infraclavicular block?

1) pneumothorax
2) hemothorax

120

Which plexus block ensures blockade of the musculocutaneous nerve?

infraclavicular

121

Brachial Plexus Anatomy at the Axilla:
What nerves are in the bundle at this level?

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

122

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

not at the same time--> compromise circulation

123

EPI should not be added to blocks __________.

below the elbow

124

What is the BEST block for knee surgery?

femoral and sciatic

125

What is the largest nerve trunk in the body?

sciatic (lumbosacral trunk)

126

What nerves compose the lumbosacral trunk?

L4-5, S1-3

127

The sciatic provides sensory to where?

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

What are the complications associated with a retrobulbar block?

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

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

20 min or you can get LA toxicity

130

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

staphylococcus aureus

131

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

7-10mm

132

How much clonidine should you add to your spinal anesthetic?

15-45mcg

133

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

0.2 to 0.3

134

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

T12

135

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

axillary

136

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

elbow, hand, forearm

137

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

SBP + 100

138

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

sural