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Regional 1 > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Benefits of PNB for regional anesthesia

A

Reduced narcotics

Decreased length of stay

Improved satisfaction scores

Decreased turnover times

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2
Q

Indications for PNB

A
  • mod to severe pain in 1st 24 hours post op
  • do not want to put to sleep for GETA (diff intubation, cardiac instability)
  • analgesia postop
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3
Q

Contraindications for regional anesthesia

A
  • pt refusal
  • preexisting neurologic injury (esp. if acute injury)
  • coagulopathies (esp deep plexus blocks and neuraxial blocks)
  • infection at site of injection
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4
Q

Covering around each fascicle

A

Perineurium

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5
Q

Covering around each axon

A

Endoneurium

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6
Q

Covers the entire nerve

A

Epineurium

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7
Q

Terminal point where LA will work to block motor and/or sensory

A

Axon

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8
Q

Where want to inject LA

A

External epinurium

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9
Q

What is focused more on internal portion of a nerve

A

Blood vessels and motor components

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10
Q

Where do we want do inject the block

A

External epinurium

- want to fill the space between connective tissue sheath and external epinurium

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11
Q

LA targets Nodes of Ranvier. Why?

A

Highest amount of voltage gated Na channels

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12
Q

3 methods to prevent nerve injury with PNB

A

Ultrasound
Pressure monitor
Nerve stimulator

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13
Q

What are we trying to prevent by using US, nerve stimulator, and pressure monitor

A

Neural injury
Neurotoxicity
LAST (local anesthetic systemic toxicity)

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14
Q

Where do you place the red and black lead on nerve stimulator for PNB

A

Red - on skin close to where putting block

Black- block needle

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15
Q

Which is negative/positive red or black

A

Red positive (cathode)

Black negative (anode)

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16
Q

If reverse red and black lead on nerve stimulator what can occur

A

Hyperpolarization and need more input to stimulate nerve

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17
Q

Initial settings for nerve stimulator

A

<2 Ma output

1-2 Hz. Frequency of stimulation

0.1ms pulse duration

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18
Q

Most effective settings to elicit and action potential in a motor fiber

A

Low amplitude and short pulse duration

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19
Q

Law relative to proximity of needle tip to nerve is directly correlated with voltage required to stimulate

A

Coulombs’s Law

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20
Q

3 parts of Coulombs’s Law

A
  • minimum current required to stimulate nerve is directly proportional to square of distance from the nerve
  • low intensity current- nerve will only get stimulated when needle tip is very close to it
  • current required to initiate nerve response determines distance of nerve to needle
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21
Q

< 0.2 Ma stimulus produces a response. What does this mean

A

Intraneural

High specificity, low sensitivity

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22
Q

0.2-0.4 Ma stimulus elicits a motor response. What does this mean?

A

Ideal block position. Inside neural sheath

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23
Q

0.4 Ma stimulus elicits motor response. What does this mean?

A

Outside neural sheath. Poor block success

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24
Q

For superficial blocks starting voltage should be?

Deep blocks

A

1 mA for superficial

1.5 mA for deep

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25
Q

When needling if you lose a twitch what should you do

A

Advance or reposition needle until twitch in 0.2-0.4Ma range

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26
Q

When needling if twitch continues at voltage <0.2Ma what should you do?

A

Reposition needle. You are too close to the nerve/in the nerve.

Withdraw until twitch occurs in 0.2-0.4Ma range

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27
Q

Coating/insulating needles results in

A

Improved voltage and the distance to nerve interrelationship

More focused/accurate

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28
Q

Ideal block needle should be

A

Echogenic

Insulated to the tip

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29
Q

More difficult to get into fascicle but cause more damage when do

A

Short bevel needle

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30
Q

Easier to enter fascicle but it do cause less damage

A

Long bevel needle

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31
Q

What are the initial settings when using a nerve stimulator

A

0.1ms. 1-2 Hz. ,2Ma

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32
Q

What complications might occur if stimulator set at 0.5 Hz

Or 4 Hz

A

0.5 Hz twitch too slow so could pass the nerve and not realize it

4 Hz. Too fast, the muscle could fatigue before get near it

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33
Q

Goal of pressure monitor to prevent intraneural injection

A

<15psi

34
Q

Sudden high to low pressure drop with pressure monitor in PNB signifies what

A

Injection is intrafascicular

35
Q

If psi > 15 on pressure monitor with PNB this means

A

Could be in bone, tendon, clotted needle, or nerve

36
Q

Pressure monitor r/t specificity and sensitivity

A

Low specificity but high sensitivity

37
Q

In regards to ultrasound 1 cycle/sec means

A

1 Hertz (Hz)

38
Q

Ultrasound frequency

A

5-20 MHz

39
Q

Transducer basic function

A

Converts electrical energy into acoustic sound waves and acoustic is what gets measured

40
Q

US- better the sound gets reflected means

A

Lighter the image

41
Q

Strength of the reflection of the sound wave is directly related to

A

The density of the tissue or the regularity of the surface being penetrated

42
Q

How to determine if linear or curved probe based on image

A

Linear has a square boundary (square)

Curved has outer boundary (looks like a pie)

43
Q

Short axis view is the preferred view because

A

Provides the thickest view of the nerve

44
Q

Hyperechoic image

A

Bight gray

Denser image

High reflection of US waves

45
Q

What appears hyperchoic on US

A

Fascial planes
Tendons
Bone edges
Nerves in periphery

46
Q

Hypoechoic on US means

A

More waves are absorbed

Less dense the tissue is

Appears as mix of dark and lighter grays

47
Q

What appears hypoechoic on US

A

Muscle

48
Q

Anechoic on US means

A

No waves reflected

Appear completely blackened

49
Q

What appears anechoic on US

A

Blood vessels and nerves above the clavicle

50
Q

Why are peripheral nerves more hyperechoic in the periphery

A

More connective tissue and less axonal density

51
Q

Blue flow on color Doppler indicates

A

Blood flow moving away from transducer

52
Q

Red blood flow on color Doppler means

A

Blood flow moving toward transducer

53
Q

4 causes of air artifact on US

A

Poor probe contact
Not enough pressure on probe
More conducting gel needed
Drop-out effect

54
Q

Acoustic reverberations are caused by

A

Very solid objects

55
Q

Lower frequency on US results in

A

Low resolution

Longer depth

56
Q

Lower frequency means

A

Longer wavelength

Greater penetration

57
Q

High frequency results in

A

High resolution

Shorter depth

58
Q

Higher frequency means

A

Shorter wavelength

Better axial resolution

59
Q

Linear probe

8-13 MHZ results in

Which blocks used for

A

Higher resolution, less depth

Good for interscalene, supraclavicular, femoral, ankle

60
Q

Linear probe at 6-10 MHz
Results in

Blocks used for

A

Poorer resolution
Good for deeper blocks

Infraclavivular, subgluteal, TAP blocks

61
Q

Curved probe 2-5 MHz

Used for

A

Very deep blocks

Transgluteal sciatic, lumbar plexus

62
Q

Adjusting gain on US results in

A

Increase gain makes brighter

Decreasing gain makes darker

63
Q

Grays in regards to US

A

Greys are good

64
Q

5 ways to improve US image

A 
Pressure
Alignment
Rotation
Rock
Toggle or Tilt
65
Q

Goal of angle of intonation

A

Want angle parallel to nerve

66
Q

What do you move to locate the needle when performing PNB

A

Always find the needle by moving the probe

Never move the needle without locating the tip

67
Q

3 methods to locate needle with US

A

Spinning the needle

Hydrolocating with D5W or NS

Rocking the probe

68
Q

LA work by

A

Blocking voltage gated sodium channels

69
Q

What fibers blocked easier

A

Myelinated

Small

70
Q

Motor fiber blockade

A

Blocked last but recover the quickest

71
Q

Block onset and recovery order

A

Onset:
B-Adelta-Agamma-Abeta-Aalpha-C

Recovery is reverse

72
Q

1st to disappear with LA blockage

A

Type A delta

73
Q

Most resistant to LA

A

Type C

74
Q

5 factors affecting duration, onset, and binding properties of LA

A 
Lipid solubility
Concentration
Proximity to nerve
Char of surrounding tissue (vascular)
PH
75
Q

Form of LA that crosses lipid bilayer

A

Non-ionized (unprotonated)

76
Q

Effect of adding NaHCO3 to LA

A

Speeds onset bc increases amount of LA in non-ionized (unprotonated)form

77
Q

LA primarily bind to which type of channels

A

Inactivated voltage gated Na channels

78
Q

Senses stretch and speed of stretch

A

Muscle spindle

79
Q

Senses tension

A

Golgi tendon organ

80
Q

% of drug bound ______ as pH of plasma decreases

Means

A

%bound decreases as pH decreases

Amount of free drug increases

Regional 1 (8 decks)

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