4: ENERGY SOURCES Flashcards by Samii Borno

Incidence of thermal injuries related to electrosurgery

1-2/1,000

How well did you know this?

Not at all

Perfectly

Definition and examples of electrocautery

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

How well did you know this?

Not at all

Perfectly

Definition of electrosurgery

Application of electrical current to achieve tissue hemostasis

How well did you know this?

Not at all

Perfectly

MOA of electrosurgery

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

How well did you know this?

Not at all

Perfectly

Definition, letter representation, and units of current

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

How well did you know this?

Not at all

Perfectly

Definition, letter representation, and units of voltage

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)

How well did you know this?

Not at all

Perfectly

Definition, letter representation, and units of impedance

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

How well did you know this?

Not at all

Perfectly

Definition, letter representation, and units of energy

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

How well did you know this?

Not at all

Perfectly

Definition, letter representation, and units of power

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

How well did you know this?

Not at all

Perfectly

Ohms law

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

How well did you know this?

Not at all

Perfectly

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

Watts

How well did you know this?

Not at all

Perfectly

Inherent tissue characteristics that affect impedance

Ex: Fat conducts electricity more poorly than muscle

How well did you know this?

Not at all

Perfectly

Acquired tissue characteristics that affect impedance

Scar tissue/already coagulated tissue has more impedance

How well did you know this?

Not at all

Perfectly

Constant polarity definition and example

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

How well did you know this?

Not at all

Perfectly

Alternating polarity definition and example

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

How well did you know this?

Not at all

Perfectly

What kind of polarity do monopolar and bipolar use?

AC/Alternating current

How well did you know this?

Not at all

Perfectly

Electrodes in monopolar sertup

Active electrode and dispersive electrode

How well did you know this?

Not at all

Perfectly

Electrodes in bipolar setup

Two active electrodes

How well did you know this?

Not at all

Perfectly

CUT WAVEFORM:
___ voltage
Type of waveform?

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

How well did you know this?

Not at all

Perfectly

COAGULATION WAVEFORM:
___ voltage
Type of waveform?

High voltage
Modulation/intermittent waveforms

How well did you know this?

Not at all

Perfectly

Normal cellular temperature

How well did you know this?

Not at all

Perfectly

Temperature at which cell death occurs over 1-6min

How well did you know this?

Not at all

Perfectly

Temperature at which instant cell death occurs

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

How well did you know this?

Not at all

Perfectly

Temperature at which cellular vaporization occurs

100

How well did you know this?

Not at all

Perfectly

MOA of vaporization

Massive expansion and volume, ultimate explosion of cells

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

Cut Low voltage Narrow 100+ Non-contact

Blend?

Modulated current

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

Cut Low Wider electrode 60-95 Deep hemostasis Contact

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

Cut Low Wider electrode 60-95 Deep hemostasis Contact

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

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

NARROW FOCUS? ___ power density Tissue is ___

High power density Tissue is vaporized

WIDE FOCUS ___ power density Tissue is ___

Medium power density Tissue is dessicated

Higher voltage ___ the zone of thermal injury

Increases

___ for smaller diameter vessels/ooze

Fulguration (coag, non-contact)

___ for large vessels

Coagulation/dessication (cut, contact)

Lack of contact for fulguration prevents ___

Carmelization of tissues

Ideal coaptive coagulation (for adequate seal)

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

Non-ideal coaptive coagulation

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

Watt for bipolar electrosurgical generator

30 Watts

Bipolar devices use what waveform to achieve hemostasis?

Cutting waveform

Why are bipolar devices not coagulation?

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)

Sensors in proprietary radiofrequency devices

Impedance Temperature

Types of lateral thermal injury

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

How to diminish lateral current pathway

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

Convection lateral thermal spread?

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

Example of reuseable bipolar device

Kleppinger

Does Kleppinger use ESU?

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

Margin of safety for lateral thermal spread of bipolar devices

3mm

Lateral thermal spread of bipolar instruments from lowest to highest

PlasaKinetics > Enseal > Ligasure

What is burst pressure

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

Seal parallel or perpendicular?

Perpendicular to decrease overall diameter that needs to be sealed

Maximum vessel diameter for bipolar devices

7mm

Seal time for ligasure

10sec

Seal time for enseal

11.1sec

Seal time for PlasaKinetics

19.2sec

Ligasure 2mm lateral temp C

55.5

Enseal 2mm lateral temp C

58.9

PlasaKinetics lateral temp C

64.5

Which bipolar device has the most plume

Ligasure

Which bipolar device has the highest burst pressure

Ligasure

Which bipolar device has the second highest burst pressure

Plasakinetics

Vessel sealing and hemostasis - use which waveform?

CUT

Clinically significant burns in how many patients?

~3/1,000

When do burns usually present?

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

Is lateral spread higher in monopolar or bipolar and why?

Monopolar because dispersive electrode is remote from active

Accidental cautery is highest with what type of devices?

Ultrasonic

Direct coupling AKA

Conductive coupling

MOA capacitative coupling

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

Definition of a capacitor

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

Describe a dispersive electrode injuryq

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

What to avoid when placing dispersive electrode

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

Impedance monitoring of dispersive electrode

Prevents firing if detached to avoid injury if not correctly attached

MOA ultrasound technology

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

Does US technology have risk for current-diversion?

US Level 1: 50 Microns Coag or cut?

Maximal coagulation effectiveness

US Level 5: 100 Microns Coag or cut?

Maximal cutting effectiveness

How to achieve maximal cutting effectiveness with ultrasonic technology?

Narrow blade Maximal blade excursion Increased tissue tension

How to achieve maximal coagulation effectiveness with ultrasonic technology?

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

Compare lateral conduction of ultrasonic technologies with radiofrequency energy

Statistically insignificant difference

What is cavitation

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

What is conduction

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