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Surgical Techniques & Safety > Electrosurgery > Flashcards

Electrosurgery Flashcards

1
Q

What is electrosurgery?

A

Application of high radiofrequency electrical current to body tissue

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2
Q

Why is radiofrequency used?

A

High frequency so higher let go current threshold

- essential for safety

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3
Q

What is electrosurgery used for?

A

SURGICAL DIATHERMY

  • cut tissue
  • stop bleeding
  • remove lesions
  • benign skin tumors
  • remove warts
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4
Q

How to change the effect in surgical diathermy?

A

Change the waveform delivered to the tissue

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5
Q

What equipment is used?

A
  • Electrosurgical unit
  • Active electrode/probe
  • Dispersive/Passive electrode
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6
Q

What is an electrosurgical unit?

A
  • high frequency electrical current generator
  • plugged into main 50Hz
  • converts 50Hz to high radiofrequency signal for surgery
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7
Q

What is the active electrode/probe used for?

A

Directly apply to surgical site

- applies the current

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8
Q

What is the dispersive/passive electrode used for?

A
  • completes circuit for return current
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9
Q

What is the advantage over a scalpel?

A
  • damages tissue considerably less

- can stop bleeding far better

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10
Q

What are some contraindications for electrosurgery?

A

PACEMAKER! as current will flow through

- any transplanted devices! (prosthetic joint)

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11
Q

Define diathermy

A

Therapeutic generation of local heat in body tissues by high-frequency electromagnetic radiation
- conversion of electromagnetic energy into thermal energy to heat tissues (P=I^2 x R)

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12
Q

Define shortwave diathermy

A

Radiowaves of 11m wavelength
Frequency of 27 mHz
Not a surgery device
Greater heat retention and efficient healing as larger treatment area

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13
Q

Uses of shortwave diathermy

A 
Pain relief
Reducing muscle spasm
Decreasing joint stiffness
Contractions
Increasing blood flow
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14
Q

Uses of diathermy for musculo-skeletal disorders

A
  • osteomyelitis
  • strains & sprain
  • tendonitis
  • bursitis
  • carbuncles
  • capsule lesion
  • subacute & chronic arthritis
  • post-traumatic conditions (fracture/haematoma/contusion)
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15
Q

Uses of diathermy for cardiovascular disorders

A
  • angina pectoris

- HTN

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16
Q

Uses of diathermy for chest disorders

A

Relieve muscle spasm in bronchial asthma

Subacute & chronic bronchitis

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17
Q

Uses of diathermy for neurological disorders

A
  • neuritis
  • sciatica
  • migraine
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18
Q

Uses of diathermy for genitourinary disorders

A
  • endometritis
  • salpingitis
  • ovaritis
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19
Q

Uses of diathermy for mouth and teeth disorders

A
  • gingivitis

- cyst

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20
Q

Uses of diathermy for ENT disorders

A
  • sinusitis

- laryngitis

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21
Q

Define electrocautery

A
  • type of electrosurgery
  • probe heated by DC to be very hot
  • use to burn and cauterize tissue
  • will denature proteins with high heat
  • electricity used for heating effect
  • tool could be heated by another means for same result
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22
Q

What are some principles of electrosurgery?

A
  • need to make patient part of electronic circuit (current travels through probe tip and into patients and back out)
  • patient creates high resistance part of circuit (large voltage drop and its heating effect occur within the patient)
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23
Q

How does P relate to I and V?

A

P = IV

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24
Q

What is the current density?

A
  • AC used to heat tissue directly
  • tip of probe remains cool
  • larger resistance = greater current density
  • same current through smaller area = greater current density = greater heat
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25
Q

What is the effect of electrosurgery <45 degrees C?

A

Thermal damage to tissue is reversible

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26
Q

What is the effect of electrosurgery >45 degrees C?

A

Denature of proteins (intracellular & extracellular) = coagulation
- damage irreversible

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27
Q

What is the effect of electrosurgery >90 degrees C?

A
  • liquid in tissue evaporates

- results in either desiccation (if heat tissue slowly) or vapourisation (if heat tissue quickly)

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28
Q

What is the effect of electrosurgery >200 degrees C?

A

Everything turns to carbon

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29
Q

What is the frequency range of electrosurgery?

A

200kHz - 5MHz

- above 100KhZ (electricity doesn’t stimulate nervous system)

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30
Q

What do electrosurgery modalities refer to?

A
  • how you complete the electrical circuit
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31
Q

What are the 2 main methods/modalities?

A
  • monopolar

- bipolar

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32
Q

Monopolar Electrosurgery

A
  • most common method
  • easiest to use & most versatile
  • only 1 electrode at surgical site, passive electrode away from surgical site
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33
Q

Monopolar Electrosurgery Mechanism

A
  • generator creates current
  • enters patient through active electrode
  • dispersive electrode for return current path to generator
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34
Q

How do we ensure passive electrode is not functioning?

A

Make sure it is grounded

- placed where there is low resistance

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35
Q

How do we make sure active electrode has high current density?

A

Tip is pointed = smaller area = greater heat

NOTE: Current is still the same in whole circuit, even though density is different due to resistance

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36
Q

Bipolar Electrosurgery

A

Slightly more difficult
Safer Generally
2 electrodes

37
Q

Mechanism of bipolar electrosurgery

A
  • generator creates current
  • enters patient through active electrode
  • small piece of tissue gripped in forceps (current only travels through this & back to generator)
38
Q

Why is bipolar electrosurgery safer?

A

Current only confined to small area (small piece of tissue and 2 electrodes)
- doesn’t go across patient’s body

39
Q

What are the benefits of electrosurgery?

A
  • anaesthesia is not always necessary for small lesion electrosurgery (short bursts of low power current may be less uncomfortable)
  • can use mixture of local anaesthetics (EMLA) cream for small lesions (much safer than general/injected anaesthetic & very simple to use)
  • injectable lidocaine suitable before most more extensive electrosurgical techniques
40
Q

What is the purpose of lidocaine?

A
  • with epinephrine = further reduces blood loss
  • no need for general anaesthetic
  • do not use epinephrine at tips of digits or nose
41
Q

What is the most common source of operating room fires & explosions?

A
  • electrosurgical devices
42
Q

What are the risks associated with explosions & fire?

A

ANESTHESIA EQUIPMENT

  • ignite gaseous anaesthetics
  • paper/cloth/flammable liquids
  • betadine (70% alcohol)
  • electrosurgical devices
43
Q

What are some precautions to take when thinking about explosions & fire hazards?

A
  • keep equipment away from flammable surroundings
  • avoid preparing skin with alcohol
  • avoid highly flammable anaesthetics
  • do not use oxygen simultaneously
44
Q

What precautions to take when thinking about electrical shock & burns?

A
  • control the flow of current through the patient
  • monopolar is more dangerous than bipolar
  • any high resistance in the current path will lead to heating
  • require high resistance at active electrode contact & low resistance at the return electrode
45
Q

Dispersive Electrode

A
  • large SA = reduced current density
  • low resistance
  • excellent contact between return electrode & patient’s skin
  • must be placed on well vascularised muscle tissue (for low resistance as lots of liquid with ions which help currents move) (NOT UNDER BONY PROMINENCE)
46
Q

How can excellent contact of the electrode be compromised?/How can surface area impedance be increased?

A
  • excessive hair
  • adipose
  • bony prominences
  • presence of fluid/lotions
  • scar tissue
47
Q

What does BURN =?

A

BURN = (HEAT x TIME) / AREA

48
Q

What is the contact quality monitoring system?

A
  • SAFETY METHOD
  • monitors the resistance in the circuit
  • detects large resistance and abnormal current variations
  • will stop generator providing any current to patients if high level of impedance at patient/pad interface
  • will eliminate hazards of return electrode or alternate site burns
  • monitors return electrode contact quality and therefore resistance of it
  • actively monitors impedance amount at patient/pad interfae
49
Q

What proportion of electrosurgery injuries do burns account for?

A

70%

50
Q

When is the contact quality monitoring system deactivated?

A
  • if the patient return electrode path is broken
51
Q

What are the modes of operation of the electrosurgery unit?

A
  • CUT
  • COAGULATE
  • BLEND
52
Q

How does the BLEND mode work?

A

CUT & COAGULATE together by manipulating factors

  • waveform
  • power
  • electrode size
  • time
  • electrode positioning
  • tissue type
  • eschar
53
Q

What are the 2 most important factors to manipulate?

A
  • waveform and power

- changing these changes heat and regulates between cutting and coagulating

54
Q

CUTTING mode features

A
  • continuous high frequency alternating sine waves
  • high frequency
  • high current = lower voltage
  • 1300-2300V
  • power 50-80W
  • local intense heating which vaporizes tissue
  • minimal coagulation (hemostasis)
55
Q

CUTTING mode method

A
  • electrode held away from tissue
  • creates a spark gap or steam envelope through which current arcs to the tissue
  • maximises current intensity
  • rides on a vapour film as it moves through the tissue
  • heating up the atmosphere between the electrode & tissue
56
Q

Types of electrode tip in cutting mode

A 
Fine needles
Wire Loop
Diamond
Ellipse
Triangle
57
Q

What is the power level in cutting method?

A

Relatively low

  • minimal charring & tissue damage
  • stops effect spreading
58
Q

Advantages of cutting mode

A
  • clean margins and wound healing
  • cells only few layers deep remain undamaged
  • thermal energy lost in latent heat of evaporation of cell contents (>100 degrees C but not as high as 200)
  • power drops very quickly when point moves down to tissue
  • ## low power = minimal tissue damage
59
Q

Coagulation Mode Features

A
  • intermittent bursts of radiofrequency sine waves
  • 6% of the time is electrocurrent being applied
  • tissue heated when waveform spikes (proteins denature)
  • tissue cools between spikes
  • high voltage (3500-9000V, few X higher than cutting)
  • low current
  • lower power 30-50W
  • spikes of voltage at 9000V at 50W
  • necessary for current to pass through highly resistant, desiccated tissue
  • effect depends on amount of power dissipated (I^2R)
60
Q

Coagulation Mode Method

A
  • active electrode touching skin
  • forceps often used as active electrode to grip the required tissue = heat sealing
  • electrode shaped as 2-5mm metallic sphere (not as pointed)
  • temp around 55 degrees C ( protein denaturisation)
  • good for clotting small vessels (less than 2-3mm)
  • can cut tissue at high power but charring & tissue damage likely
61
Q

Blending Mode

A
  • if haemostasis is needed while cutting
  • total energy remains the same
  • ratio of voltage & current modified to increase haemostasis during dissection
  • discontinuous waveform by interrupting current & increasing voltage
62
Q

What are the different BLENDING variations?

A

1,2 and 3

Higher setting = more time between bursts of current -> greater coagulation

63
Q

BLENDING 1 variation

A

80% cut

20% coagulation

64
Q

BLENDING 2 variation

A

60% cut

40% coag

65
Q

BLENDING 3 variation

A

50% cut

50% coag

66
Q

What determines if a waveform vaporizes or produces a coagulum?

A
  • rate at which heat is produced
  • VAPORIZATION = high heat produced rapidly
  • COAGULUM = low heat produced more slowly
67
Q

What are some other methods of altering output?

A
  • electrode size
  • time
  • electrode positioning
  • eschar
68
Q

How does electrode size affect output?

A
  • small electrode = high current density = concentrated heating at contact
69
Q

How does time affect output?

A
  • long treatment = more heat travels through body
  • too long = wider & longer tissue damage
  • too litt;e = absence of desired effect
70
Q

How does electrode positioning affect output?

A
  • direct contact with tissue = coagulation

- sparking to tissue = vaporization

71
Q

How does tissue type affect output?

A
  • tissues have different electrical resistances
  • adipose + bone = high resistance and poor electrical conductors
  • muscle + skin = good conductors + low resistance
72
Q

How can eschar affect output?

A
  • scab formed when wound/skin sealed in electrosurgery
  • high resistance to current
  • must not build up as will cause power loss instead of tissue
73
Q

What is an example of tissue response technology?

A
  • constant output power
  • consistent tissue effect
  • requires continuous adjustment of voltage
  • feedback circuit as tissue liquid evaporates and then tissue resistance increases maintaining consistent power
  • constant heating effect
74
Q

Treatment modalities

A

Electrosection
Electrocoagulation
Electrofulguration
Electrodesiccation

75
Q

Electrosection

A

Pure cutting waveform

  • continuous high current density
  • just on skin surface
  • vapourisation of cells
76
Q

Electrocoagulation

A
  • also called coaptive coagulation or white coagulation
  • coagulation waveforms
  • huge range of waveforms
  • 6% duty cycle on
  • high voltage, low current
77
Q

Electrofulguration

A
  • to ablate or remove tissue
  • e.g. cancerous tissue, superficial lesions, basal cell carcinoma
  • specific waveform
  • blend between electrosection and electrocoagulation
  • also called black coagulation/spray coagulation
  • active electrode held away from skin & arcs like cutting
  • uses an intermittent waveform like coagulation
  • waveform can be manipulated and altered
78
Q

Electrodesiccation

A
  • another form of coagulation
  • use of different waveforms depending on heat required
  • active electrode touching the skin to produce tissue destruction = deeper necrosis & thermal spread
  • less current density & higher V
  • lower powers than cutting otherwise damage would be severe
  • cells dried to give coagulation
  • intermittent waveform
  • blend between 6% and 100%
79
Q

Monopolar Electrosurgery Uses

A
  • can cut and coagulate
  • can cut, fulguration & dessication
  • current density very large by probe tip
  • current rapidly spread out laterally after it hits body
  • within tissue direct travel of current or spark gap
80
Q

Bipolar Electrosurgery Uses

A
  • only treats gripped tissue
  • mimises surrounding damage
  • cannot be used for cutting
  • can coagulate & fuse tissue
81
Q

Laparoscopic electrosurgery Advantages

A
  • combined with electrosurgery
  • minimally invasive
  • using endoscopy
  • commonly abdomen
  • minor procedures
  • enables outpatient procedures
  • short hospital stays
  • lower hospital costs
  • faster/more comfortable recovery
82
Q

Laparoscopic electrosurgery Disadvantages

A
  • additional safety concerns with electrosurgery
  • limited field of view (electrode not visible)
  • insulation failure
  • direct coupling
83
Q

Insulation Failure

A

In active electrode covering

  • often out of view
  • frequent re-sterilization of instruments can weaken/break insulation
  • particularly a problem for coagulation waveform (high voltage output)
84
Q

How to deal with insulation failure?

A
  • lower current concentration by coagulating with a cutting current
  • use an active electrode monitoring system
85
Q

Direct Coupling

A
  • direct coupling of electrode with other metal instruments used internally
  • current can then flow through other instrument potentially to anywhere
86
Q

How to deal with direct coupling?

A
  • activate electrode only when fully visible & in contact with target tissue
  • avoid using other instruments as much as possible
87
Q

Capacitive Coupling

A
  • stray current from electrode burns tissue
  • capacitor creates an electrostatic field between the 2 conductors
  • higher peak voltage = greater chance for capacitive discharge
88
Q

How to deal with capacitive coupling?

A
  • activate electrode only when it is in contact with target tissues
  • limit time on coagulation setting (with high voltage peaks)
  • use metal cannulas that allow stray current to be dispersed through the patient’s abdominal wall
  • use different technology = insulation protective shells/layers

Surgical Techniques & Safety (5 decks)

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