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Pain Exam 2 > Module 5: Part 2 > Flashcards

Module 5: Part 2 Flashcards

17 - 32

1
Q

Ultrasound
wavelength & amplitude

A

air: 330 m/s
soft tissue : 15-40 m/s
bone: 3000-5000 m/s

U/S uses high frequency waves: 1-20 MHz
Waves consist of:
-compression of the medium-positive component
-rarefaction of the medium-negative component

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2
Q

The heart of most ultrasound systems is a device called a

A

transducer

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3
Q

piezoelectric crystals

A

Transducers use piezoelectric crystals

  • vibrate when electric signals applied producing high frequency sound pressure waves which we call “ultrasound.”
  • can work in reverse: produce electrical signals when it detects high-frequency sound pressure waves
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4
Q

When a transducer directs ultrasound waves into the body, they…

A

pass right through the skin into the internal anatomy

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5
Q

The transducer directs ultrasound waves into the body, which pass through skin into the internal anatomy. What happens next?

A
  1. waves produce echoes as they counter tissues with different characteristics and densities
  2. the echoes reflect back to piezoelectric crystals
  3. these echoes are converted to electric signals
  4. electrical signal converts into points of brightness on the image corresponding to the anatomical position
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6
Q

How often do the waves echoe back to piezoelectric crystals?

A

more than a thousand times a second.

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7
Q

A medical transducer contains a large array of crystals which allow it to….

A

make a series of image lines that together form a complete image frame-sonogram

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8
Q

How is the image created?

A
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9
Q

Ultrasound Terminology
Period

A
  • time for a sound wave to complete one cycle
  • measured in microseconds (µs)
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10
Q

Wavelength

A

the length of space over which one cycle occurs; it is equal to the travel distance from the beginning to the end of one cycle

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11
Q

Frequency

A

the number of cycles repeated per second and measured in hertz (Hz)

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12
Q

Acoustic velocity

A
  • the speed at which a sound wave travels through a medium.
  • frequency x wavelength
  • Speedcis determined by the density ρ and stiffness κ of the medium (c = (κ/ρ)1/2)
  • Densityis the concentration of a medium
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13
Q

Acoustic velocity
Speedc

A

determined by the density ρ and stiffness κ of the medium

c = (κ/ρ)^1/2

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14
Q

The concentration of a medium

A

Density

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15
Q

Acoustic velocityis equal to…

A

frequency x wavelength

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16
Q

Stiffness

A
  • resistance of a material to compression
  • Propagation speed increases if the stiffness is increased or the density is decreased.
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17
Q

Propagation speed increases if…

A

stiffness is increased
or
density is decreased

↑ propagation = ↑ stiffness
↑ propagation = ↓ density

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18
Q

Beam Shape and Focus

A

Near Zone: Fresnel
Far Zone: Fraunhofer

adjust focal zone to make image better quality via knobs

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19
Q

Components of the ultrasound (5)

A
  • Pulser - applies high amplitude voltage to energize the crystals
  • Transducer- converts electrical energy to mechanical energy & vice versa
  • Receiver – detects and amplifies weak signals
  • Display- displays ultrasound signals in a variety of modes
  • Memory – stores video display
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20
Q

T/F
The Pulser converts electrical energy to mechanical energy & vice versa

A

False - the transducer does this

  • Pulser - applies high amplitude voltage to energize the crystals
  • Transducer- converts electrical energy to mechanical energy and vice versa
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21
Q

“Band width”

A

range of frequencies that come out of a transducer

Transducer- converts electrical energy to mechanical energy and vice versa

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22
Q

Image quality is dependent on ____

A

frequency

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23
Q

High vs. Low Frequency

A

High frequency (6-13 MHz):
* higher resolution & less sound beam penetration
* good for superficial structures
* (i.e. interscalene and supraclavicular blocks)

Lower frequency (2-5MHz):
* lower resolution & deeper sound beam penetration
* scanning deeper structures
* (i.e. transgluteal sciatic)

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24
Q

For supraclavicular blocks, use a (low/high) frequency and set it to ___ MHz

A

High frequency
(6-13 MHz)

interscalene and supraclavicular blocks

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25
Q

For transgluteal sciatic blocks, use a (low/high) frequency and set it to ___ MHz

A

Lower frequency
(2-5MHz)

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26
Q

Transducers
The higher the frequency, the better the _____. The better the resolution, the better _____.

A

resolution
view of objects

↑ frequency = 👍🏼 resolution = better view of objects

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27
Q

Two types of transduces (probes)

A

linear:
* rectangular images
* higher frequency
* small area and depth

curved:
* Increases field view
* lower frequency waves & lower resolution
* Deeper penetration

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28
Q

Linear vs Curved
Which will increases field view but give you lower resolution?

A

curved:
* Increases field view
* lower frequency waves & lower resolution
* Deeper penetration

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29
Q

You need to scan a small area but need a really good view.
Do you use linear or curved?

A

linear:
* rectangular images
* higher frequency
* small area and depth

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30
Q

Modes

A
  • Doppler
  • A-mode: Amplitude
  • M-mode: Motion
  • B-mode: Brightness
31
Q

Modes
B vs M

A
32
Q

Modes: Doppler
Power vs Color

A
33
Q

In Power mode, we cannot see….

A
  • Direction is not seen
  • Velocity is not seen

Can show perfusion of organs
Sensitive assessment of presence of flow

34
Q

T/F
Power mode hows presence of vascularity and direction of flow.

A

False
Color mode

Power: Sensitive assessment of presence of flow
Color: presence of vascularity & direction of flow

35
Q

Mode used to differentiate vascular from non-vascular structures

A

Color

36
Q

Which mode can show perfusion of organs?

A

Power

37
Q

Knobology

A
  • Power
  • Gain
  • TGC, DGC, STC
  • Dynamic range
  • Depth
  • Zoom/magnification
  • Freeze
  • Calculations
  • Print
38
Q

Knobology
Power

A

Controls the strength or intensity of the sound wave

39
Q

Knobology
Gain

A
  • Degree of amplification of returning sound
  • Increasing gain: increases strength of the returning echoes and end result is a lighter image
  • Decreasing gain: decrease the returning echoes and end result darker image
40
Q

How to adjust gain to make the image lighter vs darker

A
  • Increasing gain: increases strength of the returning echoes and end result is a lighter image
  • Decreasing gain: decrease the returning echoes and end result darker image
41
Q

Controls the strength or intensity of the sound wave

A

Power knob

42
Q

T/F
Increasing the gain decreases the strength of the returning echoes and end result is a lighter image.

A

False
Increasing gain increases the strength of the returning echoes and end result is a lighter image

↑ gain = ↑ strength of returning echo = ↑ brightness

43
Q

In addition to potent analgesia, regional anesthesia may lead to…

A

reductions in:
* the stress response
* systemic analgesic requirements
* opioid-related side effects
* general anesthesia requirements
* development of chronic postoperative pain

Regional analgesia may accelerate postoperative convalescence/recovery

44
Q

fascial plane blocks

A
  • popular alternative to conventional peripheral nerve blocks or thoracic epidural analgesia
  • rely on depositing a large volume of LA into fascial planes in which target nerves are contained
45
Q

Where along the brachial plexus should we inject our LA depending on the surgical site?

A
  • interscalene: shoulder & proximal humerus
  • supraclavicular, infraclavicular, or axillary: distal to mid-humerus
46
Q

A properly performed interscalene block almost invariably blocks the _____ nerve. Caution in patients with….

A

ipsilateral phrenic

  • severe pulmonary disease
  • preexisting contralateral phrenic nerve palsy
  • Bilateral interscalene blocks are always contraindicated
47
Q

T/F
Brachial plexus block at the level of the cords provides excellent anesthesia for the upper arm and shoulder.

A

False
The upper arm and shoulder are not anesthetized with this approach.

Brachial plexus block @ level of the cords provides excellent anesthesia for procedures at or distal to the elbow.

48
Q

Brachial plexus block at the level of the cords & as with other brachial plexus blocks, the ____ is spared.
(nerve & dermatome)

A

intercostobrachial nerve
(T2 dermatome)

49
Q

Bier block
-what is it?
-when to use

A
  • IV regional anesthesia
  • intense anesthesia for relatively short (45–60 min) surgical procedures on an extremity
50
Q

Using a femoral nerve block alone. How adequate is the anesthesia?

A
  • alone will seldom provide adequate surgical anesthesia
  • but can provide postop analgesia for hip, thigh, knee, & ankle Sx
51
Q

____ blocks result in the highest blood levels of LA per dose injected of any nerve block procedure, and if multiple blocks will be performed, care must be taken to avoid toxic systemic levels of local anesthetic.

A

Intercostal

52
Q

Thoracic Paravertebral Space
defined by these surrounding landmarks

A

posterior: superior costotransverse ligament
anterolateral: parietal pleura
medial: vertebrae & intervertebral foramin
inferior & superior: heads of the ribs

53
Q

transversus abdominus plane (TAP) block
-target nerves
-area anesthetized

A
  • subcostal (T12)
  • ilioinguinal (L1)
  • iliohypogastric (L1)

anesthesia to ipsilateral lower abdomen below the umbilicus

54
Q

When doing risk vs. benefit of GA vs. regional, which pts benefit more from regional?

A
  • multiple comorbidities for whom a general anesthetic carries a greater risk
  • patients intolerant of opioids (OSA, high risk nausea) prolonged postop pain
  • chronic pain
  • opioid tolerance
55
Q

cooperation is key!
-examples of pts whp cannot remain still
-what do we do?

A
  • peds
  • developmental delay
  • dementia
  • movement disorders

risks of performing the block under deep sedation or general vs. benefit of the nerve block

56
Q

These blocks carry a risk of pneumothorax

A
  • paravertebral blocks
  • intercostal nerve blocks
  • supraclavicular brachial plexus blocks
57
Q

2 factors that heighten the risk of local hematoma or hemorrhage

A

Bleeding disorders and pharmacological anticoagulation

58
Q

T/F
Presence of local infection is a relative contraindication to performing a peripheral nerve block

A

True

59
Q

T/F
There is no specific time point when a catheter should be removed if it continues to provide benefit and no infection concerns are present

A

True

60
Q

Nerve injury is always a possibility with regional anesthesia
-patients at increased risk

A

preexisting nerve condition
* peripheral neuropathy
* previous nerve injury

prolonged/permanent sensorimotor block

Persistent neuropathic symptoms are more common after brachial plexus & distal upper extremity blocks versus lower extremity or truncal blocks

61
Q

standard ACLS vs. LAST resuscitation

A

LAST:
* reduction in epinephrine dose
* avoidance of lidocaine as an antiarrhythmic
* β-blockers
* calcium channel blockers
* vasopressin

62
Q

LAST

A

from IV injection or perivascular absorption

  • seizure activity & CV collapse
  • IMMEDIATE supportive measures
  • initiate CPR
  • incremental epi doses
  • IV lipid emulsion
  • if all else fails: prepare for cardiopulmonary bypass
63
Q

In a patient with severe pulmonary compromise or hemidiaphragmatic paralysis, this block could be catastrophic.

A

contralateral interscalene
or
cervical plexus block with resultant phrenic nerve block

If the pt has R sided diaphragm paralysis, do not do a L interscalene block, as these often paralyze the phrenic nerve. The pt would have B/L diaphragm paralysis.

64
Q

field block

A

local anesthetic injection that targets terminal cutaneous nerves

65
Q

Field blocks
When to use
When not to

A
  • surgeons use to minimize incisional pain
  • supplementary or sole anesthetic for minor, superficial procedures

blocks:
* superficial cervical plexus (neck or shoulder Sx)
* intercostobrachial nerve (Sx medial upper extremity proximal to the elbow) (with brachial plexus block)
* “ankle block”: subQ nerves innervating the foot & ankle

may be undesirable if:
* it obscures/distorts operative anatomy
* local tissue acidosis d/t infection prevents effective LA fxn

66
Q

Paresthesia Technique

A

(abnormal sensation) is elicited in the area of sensory distribution when a needle makes direct contact with a sensory nerve
generally avoided

67
Q

If paresthesia occurs while placing the block…

A

the needle should be redirected

it may indicate an intraneural location of the needle tip

68
Q

Nerve Stimulation Technique

A

insulated needle tip is placed in proximity to a motor nerve, specific muscle contractions are induced, and local anesthetic is injected

69
Q

Ultrasound Technique
hypoechoic vs. hyperechoic

A

hypoechoic
-Sound passes thru easily
-Appear dark or black

hyperechoic:
-structures reflecting more sound waves
-appear brighter or white

70
Q

T/F
High-frequency transducers are used predominantly for more superficial nerves.

A

True
high-resolution picture with a relatively clear image but offer poor tissue penetration

71
Q

In-Plane vs. Out-of-plane
technique

A

In-plane: Needle insertion is parallel

Out-of-plane: not parallel

In-plane more common as the entire shaft of the needle can be visualized as it approaches the target nerve and navigates surrounding structures

72
Q

Which probe offers higher resolution with less penetration

A

linear

73
Q

Which requires more volume of LA?
A) Nerve stimulation
B) Ultrasound Guidance

A

A) Nerve stimulation (30-40ml)

Ultrasound (10-30 ml)

74
Q

T/F
Ultrasound is an actual “sound.”

A

True

Pain Exam 2 (13 decks)

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