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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
When needling if you lose a twitch what should you do
Advance or reposition needle until twitch in 0.2-0.4Ma range
26
When needling if twitch continues at voltage <0.2Ma what should you do?
Reposition needle. You are too close to the nerve/in the nerve. Withdraw until twitch occurs in 0.2-0.4Ma range
27
Coating/insulating needles results in
Improved voltage and the distance to nerve interrelationship More focused/accurate
28
Ideal block needle should be
Echogenic Insulated to the tip
29
More difficult to get into fascicle but cause more damage when do
Short bevel needle
30
Easier to enter fascicle but it do cause less damage
Long bevel needle
31
What are the initial settings when using a nerve stimulator
0.1ms. 1-2 Hz. ,2Ma
32
What complications might occur if stimulator set at 0.5 Hz Or 4 Hz
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
33
Goal of pressure monitor to prevent intraneural injection
<15psi
34
Sudden high to low pressure drop with pressure monitor in PNB signifies what
Injection is intrafascicular
35
If psi > 15 on pressure monitor with PNB this means
Could be in bone, tendon, clotted needle, or nerve
36
Pressure monitor r/t specificity and sensitivity
Low specificity but high sensitivity
37
In regards to ultrasound 1 cycle/sec means
1 Hertz (Hz)
38
Ultrasound frequency
5-20 MHz
39
Transducer basic function
Converts electrical energy into acoustic sound waves and acoustic is what gets measured
40
US- better the sound gets reflected means
Lighter the image
41
Strength of the reflection of the sound wave is directly related to
The density of the tissue or the regularity of the surface being penetrated
42
How to determine if linear or curved probe based on image
Linear has a square boundary (square) Curved has outer boundary (looks like a pie)
43
Short axis view is the preferred view because
Provides the thickest view of the nerve
44
Hyperechoic image
Bight gray Denser image High reflection of US waves
45
What appears hyperchoic on US
Fascial planes Tendons Bone edges Nerves in periphery
46
Hypoechoic on US means
More waves are absorbed Less dense the tissue is Appears as mix of dark and lighter grays
47
What appears hypoechoic on US
Muscle
48
Anechoic on US means
No waves reflected Appear completely blackened
49
What appears anechoic on US
Blood vessels and nerves above the clavicle
50
Why are peripheral nerves more hyperechoic in the periphery
More connective tissue and less axonal density
51
Blue flow on color Doppler indicates
Blood flow moving away from transducer
52
Red blood flow on color Doppler means
Blood flow moving toward transducer
53
4 causes of air artifact on US
Poor probe contact Not enough pressure on probe More conducting gel needed Drop-out effect
54
Acoustic reverberations are caused by
Very solid objects
55
Lower frequency on US results in
Low resolution Longer depth
56
Lower frequency means
Longer wavelength Greater penetration
57
High frequency results in
High resolution Shorter depth
58
Higher frequency means
Shorter wavelength Better axial resolution
59
Linear probe 8-13 MHZ results in Which blocks used for
Higher resolution, less depth Good for interscalene, supraclavicular, femoral, ankle
60
Linear probe at 6-10 MHz Results in Blocks used for
Poorer resolution Good for deeper blocks Infraclavivular, subgluteal, TAP blocks
61
Curved probe 2-5 MHz Used for
Very deep blocks Transgluteal sciatic, lumbar plexus
62
Adjusting gain on US results in
Increase gain makes brighter Decreasing gain makes darker
63
Grays in regards to US
Greys are good
64
5 ways to improve US image
``` Pressure Alignment Rotation Rock Toggle or Tilt ```
65
Goal of angle of intonation
Want angle parallel to nerve
66
What do you move to locate the needle when performing PNB
Always find the needle by moving the probe Never move the needle without locating the tip
67
3 methods to locate needle with US
Spinning the needle Hydrolocating with D5W or NS Rocking the probe
68
LA work by
Blocking voltage gated sodium channels
69
What fibers blocked easier
Myelinated Small
70
Motor fiber blockade
Blocked last but recover the quickest
71
Block onset and recovery order
Onset: B-Adelta-Agamma-Abeta-Aalpha-C Recovery is reverse
72
1st to disappear with LA blockage
Type A delta
73
Most resistant to LA
Type C
74
5 factors affecting duration, onset, and binding properties of LA
``` Lipid solubility Concentration Proximity to nerve Char of surrounding tissue (vascular) PH ```
75
Form of LA that crosses lipid bilayer
Non-ionized (unprotonated)
76
Effect of adding NaHCO3 to LA
Speeds onset bc increases amount of LA in non-ionized (unprotonated)form
77
LA primarily bind to which type of channels
Inactivated voltage gated Na channels
78
Senses stretch and speed of stretch
Muscle spindle
79
Senses tension
Golgi tendon organ
80
% of drug bound ______ as pH of plasma decreases Means
%bound decreases as pH decreases Amount of free drug increases

Regional 1 (8 decks)

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