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Phase 1 > Ch. 15 Electrosurgery and Lasers > Flashcards

Ch. 15 Electrosurgery and Lasers Flashcards

1
Q

Voltage (V)

A

difference in potential between two points

Will drive charged particles across a potential difference

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2
Q

Electrical current (I)

A

flow of electrical charges and measured in amperes

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3
Q

Resistance (R)

A

impedance and measured in Ohms

A material property

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4
Q

V = IR

A

current is directly proportional to voltage and inversely proportional to resistance

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5
Q

W = VI

A

power or watts is equal to voltage times current

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6
Q

What current does electrosurgery work in

A

500 kHz

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7
Q

Pure cut electrosurgery: what kind of current and what wattage should be used?

A

Uninterrupted current

50-80 watts

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8
Q

Pure coagulation electrosurgery: what kind of current and what wattage?

A

Interrupted current

30-50 watts

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9
Q

Surgical diathermy

A

ability of electricity to form heat in living tissue

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10
Q

What factors influence thermal effects on tissue?

A
  • watts
  • electrode dwell time (length of exposure)
  • contact type of the tissue to the active electrode
  • the current
  • tissue impedance
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11
Q

At what temperature will collagen be heated and its intramolecular cross links broken?

A

50-70 degrees celsius

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12
Q

At what temperature does tissue desiccation occur?

A

90 degrees celsius

cellular water completely evaporates

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13
Q

At what temperature will tissues be destroyed by cell wall rupture from the volumetric explosion of superheated steam? And what is this process called?

A

100 degrees celsius

Vaporization

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14
Q

At what temperature will tissue carbonization from dehydration occur?

A

250 degrees celsius

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15
Q

What temperature will cause inflammation and edema in tissues?

A

40 degrees celsius

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16
Q

At what temperature will enzymatic activity become inactivated?

A

50 degrees celsius

17
Q

What is fulgration coagulation?

A

Holding the electrode slightly away from the tissue using coagulation mode, which results in an arc jumping the gap between the electrode and tissue.
The arc takes the form of a spark, which strikes the tissue in a dispersed and random pattern
High voltage sparking results in high temp tissue change and creates a superficial coagulum instead of vaporizing the tissue
Good for when a discrete bleeder cannot be found
But produces larges amounts of smoke as char forms and has deeper necrosis and thermal spread than cutting

18
Q

What is desiccation coagulation?

A

Direct contact using coagulation mode

heats tissue more efficiently than fulgration and can have deeper necrosis and thermal spread

19
Q

What is coaptive coagulation?

A

A type of desiccation coagulation
Metal instrument holds vessel
Heat denatures the adventitia, dehydrates the vessel, and blood flow stops

20
Q

What is the maximum diameter vessel that Monopolar electrosurgery can coagulate?

A

2 mm in diameter

21
Q

What is insulation failure in regards to electrosurgery with laparoscopic coagulation?

A

This occurs when there is damage or a defect to the material covering the active electrode
The active current may escape through this area and cause injury to adjacent organs
It is especially dangerous if the insulation failure is beyond the view of the scope

22
Q

What is direct coupling in regards to dangers of electrosurgery?

A

This is when an active electrode is in direct contact or close proximity to another metal instrument or trocar
Activation of the electrode may cause transfer of the electrical current to the adjacent metal object

23
Q

What is capacitive coupling?

A

This is when two conductors or instruments are separated by an insulator and form stored energy
then this can transfer to an adjacent conductor such as an outer cannula of the trocar sheath

24
Q

How does the Harmonic electrosurgical device work?

A

There is no transfer of electricity to or through the patient
Ultrasonic waves made at 55,500 vibrations
This causes an oscillating saw effect along with heat and coagulation
Uses lower temperatures - 50 to 100 degrees celsius
the vessels seal by a protein coagulum (but other electrosurgery and lasers use burning to coagulate at 150 to 400 degrees celsius)
Seals vessels less than 3 mm

25
Q

LASER

A

Light Amplification of Stimulated Emission of Radiation

26
Q

How does LASER work?

A

An external source of energy stimulates particles into a high energy state
When the particles revert to their original state, energy is released in the form of photons that travel in the same waveform (monochromic) and move parallel to (spatial coherence) and in phase with (temporal coherence) each other in a linear (collimated) direction
Photons producing a laser beam have consistent energy released at the same wavelength, amplitude, frequency, and time

27
Q

PD = watts/cm^2

A

Power density is directly proportional to the power (watts) that a laser can deliver and inversely proportional to the surface area that the beam strikes
Usually we talk about the surface area as a circle, so pi*r^2
This is called “spot size”

28
Q

What is focal length in regards to laser?

A

The distance from the aperture to the laser’s highest power intensity
most focal lengths are 1-3 mm

29
Q

With energy in the form of a laser, what four basic interactions can occur with tissue?
Of those four, which is the key to effective laser to tissue interaction?

A

Absorption, transmission, scatter, and reflection

Absorption is the key to effective laser to tissue interaction

30
Q

What is tissue ablation with regards to lasers?

A

photoablation = direct breakage of molecular bonds

31
Q

What wavelengths will penetrate tissues several mm?

A

Shorter wavelengths like Nd:YAG 1064 nm or diode 810 nm. These lasers are poorly absorbed by water and react more with pigments in the tissues
By contrast, CO2 laser works at 10,600 nm, Ho:YAG 2100 nm, and erbium:YAG 2940 nm

32
Q

Characteristics of CO2 laser

A

10,600 nm
long wavelength means it can strongly react with and be absorbed by cellular water
produces effects through instantaneous heating of intracellular water to the boiling point
used for cutting and vaporization of tissue
at the laser-tissue interphase, vessels less than 0.6 mm can be sealed

33
Q

Characteristics of Ho:YAG laser

A

2100 nm
highly absorbed by water
used in arthroscopic procedures because it causes minimal tissue necrosis
used for lithotripsy
laser will absorb water from the urolith and then a photothermal fragmentation of the stone occurs

34
Q

Characteristics of Er:YAG laser

A

2940 nm
an infrared wavelength that is strongly absorbed by water and hydroxyapatite
can be used to cut bone

35
Q

Characteristics of Nd:YAG laser

A

1064 nm
tissue penetration is deep
slightly absorbed by water and this allows tissue penetration up to 5 mm
coagulate larger blood vessels but also leads to a larger coagulation zone and damage to adjacent tissue

36
Q

Characteristics of a diode laser

A

590 to 5300 nm but usually for vet med around 810-980 nm
not easily absorbed by water so this leads to a greater depth of thermal injury… greater peripheral tissue heating
can be used with a variety of delivery fiber tips and used for feline onychectomy, removal of dermal, subdermal, and oral masses

37
Q

Characteristics of an argon laser

A

488-514 nm
visible blue green light that is highly absorbed by hemoglobin, therefore making it useful for the removal of vascular lesions
mainstay for controlling intraocular hemorrhage and are used for coagulation, vaporization and cutting in a bleeding environment
expensive
produces less charring

38
Q

Characteristics of excimer laser

A

193 nm
ultraviolet laser used in ophthalmic surgery
“excited dimer”
excimer laser adds enough energy to disrupt the molecular bonds of the surface tissue without causing water vaporization
depth of 1 mm
what is used for LASIK surgery

Phase 1 (35 decks)

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