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OBGYN > 4: ENERGY SOURCES > Flashcards

4: ENERGY SOURCES Flashcards

1
Q

Incidence of thermal injuries related to electrosurgery

A

1-2/1,000

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2
Q

Definition and examples of electrocautery

A

Passive transfer of heat to tissue
Ex: Cattle branding, silver nitrate

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3
Q

Definition of electrosurgery

A

Application of electrical current to achieve tissue hemostasis

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4
Q

MOA of electrosurgery

A

Intracellular conversion of electromagnetic injury > kinetic energy > thermal injury
Produces tissue vaporization for transection or coagulation and dessication to achieve hemostasis

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5
Q

Definition, letter representation, and units of current

A

Flow of electrons past a point in the circuit/unit of time
Current (I)
Unit: Amperes (coloumbs/sec)

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6
Q

Definition, letter representation, and units of voltage

A

Difference in electrical potential between two points in the circuit; Effectively the force required to push charge along the circuit
Voltage (V)
Unit: Volts (joules/coulomb)

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7
Q

Definition, letter representation, and units of impedance

A

Degree to which the circuit impedes/resists current (flow of electrons/ions)
Impedance (R)
Unit: Ohms

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8
Q

Definition, letter representation, and units of energy

A

Energy transferred to a tissue; Product of work (P) x time
Energy (J)
Unit: Joules (watts * seconds)

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9
Q

Definition, letter representation, and units of power

A

Work; The amount of energy per unit time; Product of V * I
Power (P)
Unit: Watts (joules/second)

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10
Q

Ohms law

A

I (Amperes)=V(volts)/R(ohms)

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11
Q

What is adjusted on the elctrosurgical generator unit (ESU)?

A

Watts

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12
Q

Inherent tissue characteristics that affect impedance

A

Ex: Fat conducts electricity more poorly than muscle

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13
Q

Acquired tissue characteristics that affect impedance

A

Scar tissue/already coagulated tissue has more impedance

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14
Q

Constant polarity definition and example

A

Direct current/DC
Unidirectional flow of electrons
Ex: Battery - positive and negative ends do not change

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15
Q

Alternating polarity definition and example

A

Alternating current/AC
No net electron flow (rather, an electron moving back and forth)
Ex: Electricity in house, RADIOFREQUENCY ELECTROSURGERY (MONOPOLAR AND BIPOLAR)

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16
Q

What kind of polarity do monopolar and bipolar use?

A

AC/Alternating current

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17
Q

Electrodes in monopolar sertup

A

Active electrode and dispersive electrode

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18
Q

Electrodes in bipolar setup

A

Two active electrodes

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19
Q

CUT WAVEFORM:
___ voltage
Type of waveform?

A

Low voltage
Continuous (no breaks in this type of waveform)

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20
Q

COAGULATION WAVEFORM:
___ voltage
Type of waveform?

A

High voltage
Modulation/intermittent waveforms

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21
Q

Normal cellular temperature

A

37

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22
Q

Temperature at which cell death occurs over 1-6min

A

50

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23
Q

Temperature at which instant cell death occurs

A

60-95
Dessication (occurs as cell loses water) and protein denaturation/coagulation
Cell turns white when dessication and coagulation occur

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24
Q

Temperature at which cellular vaporization occurs

A

100

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24
Q

MOA of vaporization

A

Massive expansion and volume, ultimate explosion of cells

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25
Q

VAPORIZATION:
Waveform?
Voltage?
Electrode focus?
Temperature?
Contact or not?

A

Cut
Low voltage
Narrow
100+
Non-contact

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26
Q

Blend?

A

Modulated current

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27
Q

DESSICATION:
Waveform?
Voltage?
Electrode focus?
Temperature?
Depth?
Contact or not?

A

Cut
Low
Wider electrode
60-95
Deep hemostasis
Contact

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28
Q

COAGULATION:
Waveform?
Voltage?
Electrode focus?
Temperature?
Depth?
Contact or not?

A

Cut
Low
Wider electrode
60-95
Deep hemostasis
Contact

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29
Q

FULGURATION:
Waveform?
Voltage?
Electrode focus?
Depth?
Contact or not?

A

Coagulation
High
Type of dessication/coagulation
Large electrode
Superficial hemostasis
Non-contact

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30
Q

NARROW FOCUS?
___ power density
Tissue is ___

A

High power density
Tissue is vaporized

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31
Q

WIDE FOCUS
___ power density
Tissue is ___

A

Medium power density
Tissue is dessicated

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32
Q

Higher voltage ___ the zone of thermal injury

A

Increases

33
Q

___ for smaller diameter vessels/ooze

A

Fulguration (coag, non-contact)

34
Q

___ for large vessels

A

Coagulation/dessication (cut, contact)

35
Q

Lack of contact for fulguration prevents ___

A

Carmelization of tissues

36
Q

Ideal coaptive coagulation (for adequate seal)

A

Relatively slow
Low voltage continuous output (cut)
Slow elevation of tissue coagulation occurs

37
Q

Non-ideal coaptive coagulation

A

High voltage continuous output (coag)
If used, small arcs of energy to the tissue cause quick, superficial elevation in tissue - tissue no longer has ions and becomes less conductive

38
Q

Watt for bipolar electrosurgical generator

A

30 Watts

39
Q

Bipolar devices use what waveform to achieve hemostasis?

A

Cutting waveform

40
Q

Why are bipolar devices not coagulation?

A

If coag, bursts of voltage occur, resulting in localized areas of tissue coagulation that often cause carmelization and preserve the center of the vessel (therefore poor seal)

41
Q

Sensors in proprietary radiofrequency devices

A

Impedance
Temperature

42
Q

Types of lateral thermal injury

A

Lateral current pathway
Convection (steam/water vapor)
Conduction (direct contact= cautery)

43
Q

How to diminish lateral current pathway

A

Make sure tissue is compressed adequately, therefore less energy over time, therefore less lateral thermal spread

44
Q

Convection lateral thermal spread?

A

Water vapor from dessication dissects the layers of the tissue, propagating a thermal effect

45
Q

Example of reuseable bipolar device

A

Kleppinger

46
Q

Does Kleppinger use ESU?

A

No - Also does not have impedence or temperature-sensing technology

47
Q

Margin of safety for lateral thermal spread of bipolar devices

A

3mm

48
Q

Lateral thermal spread of bipolar instruments from lowest to highest

A

PlasaKinetics > Enseal > Ligasure

49
Q

What is burst pressure

A

Intraluminal pressure at which the seal fails
Can vary with diameter of vessel
Higher than any BP that would be encountered
Approved up to vessel size 7mm

50
Q

Seal parallel or perpendicular?

A

Perpendicular to decrease overall diameter that needs to be sealed

51
Q

Maximum vessel diameter for bipolar devices

A

7mm

52
Q

Seal time for ligasure

A

10sec

53
Q

Seal time for enseal

A

11.1sec

54
Q

Seal time for PlasaKinetics

A

19.2sec

55
Q

Ligasure 2mm lateral temp C

A

55.5

56
Q

Enseal 2mm lateral temp C

A

58.9

57
Q

PlasaKinetics lateral temp C

A

64.5

58
Q

Which bipolar device has the most plume

A

Ligasure

59
Q

Which bipolar device has the highest burst pressure

A

Ligasure

60
Q

Which bipolar device has the second highest burst pressure

A

Plasakinetics

61
Q

Vessel sealing and hemostasis - use which waveform?

A

CUT

62
Q

Clinically significant burns in how many patients?

A

~3/1,000

63
Q

When do burns usually present?

A

~4 days post-op (but can be earlier or later depending on injury)

64
Q

Is lateral spread higher in monopolar or bipolar and why?

A

Monopolar because dispersive electrode is remote from active

65
Q

Accidental cautery is highest with what type of devices?

A

Ultrasonic

66
Q

Direct coupling AKA

A

Conductive coupling

67
Q

MOA capacitative coupling

A

Occurs when radiofrequency electrocurrent induces electromagnetic field that can couple with a nearby conductor

68
Q

Definition of a capacitor

A

Two nearby conductors separated by a non-conducting medium
One conductor has electrical current

69
Q

Describe a dispersive electrode injuryq

A

If separation of dispersive electrode (ex: off leg), the current becomes concentrated at the attached part of the dispersive electrode, resulting in increased temperature at the level of the skin

70
Q

What to avoid when placing dispersive electrode

A

Be aware of placing over areas of scars if using high currents

71
Q

Impedance monitoring of dispersive electrode

A

Prevents firing if detached to avoid injury if not correctly attached

72
Q

MOA ultrasound technology

A

Converts alternating current to mechanical vibrations by activating a pieso-electrode > friction > heating > ‘cavitation’ > cutting/coagulation

Frictional heat > coagulation > lysis of hydrothermal bonds > denaturation of protein

73
Q

Does US technology have risk for current-diversion?

A

No

74
Q

US Level 1: 50 Microns
Coag or cut?

A

Maximal coagulation effectiveness

75
Q

US Level 5: 100 Microns
Coag or cut?

A

Maximal cutting effectiveness

76
Q

How to achieve maximal cutting effectiveness with ultrasonic technology?

A

Narrow blade
Maximal blade excursion
Increased tissue tension

77
Q

How to achieve maximal coagulation effectiveness with ultrasonic technology?

A

Wide blade
Minimal blade excursion
Decreased tissue tension and compress more lightly between jaws

78
Q

Compare lateral conduction of ultrasonic technologies with radiofrequency energy

A

Statistically insignificant difference

79
Q

What is cavitation

A

Formation of steam/water vapor that dissects through tissues with ultrasonic technologies

80
Q

What is conduction

A

Hot, oscillating blade causes damage (previously activated blade touches tissue) with ultrasonic technology
*If direct contact, this would be cautery

OBGYN (16 decks)

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