Module 11 - Electrosurgery Flashcards
Up until what frequency does the Faradic effect occur?
20 kHz
How can faradic and electrolytic effects be largerly prevented?
By using frequencies of at least 300 kHz. The termal effect then largely dominates
= High Frequency (HF) surgery
The amount of heat created in the tissue mainly depends on (3 things):
- specific resistance of the target tissue
- the current density
- the duration of exposure
What is the basic principle of electrosurgery
The application of a high freuency current to biological tissue as a means to cut, coagulate, desiccate, or fulgurate itssue
done by denaturalizing the proteins in the cells
Benefits of electrosurgery are
Reduced blood loss
dry and rapid separation of tissue
decreased risk of accidental injury to personell
What is cutting, and what is coagulation
Cutting is separation of tissue, above 100 degrees, with fast heating and sparks. Cells expand so fast that they explode
With coagulation you harden the tissue by vaporizing water from the cells
Use low duty cycle and high modulated voltage. Seals blood vessols
What are the three effects of electricity, and which one occurs using electrosurgery?
—– electrolytic effect
produced by low frequency, under 5kHz
Damage to tissue because ions have time to move to opposite poles
—– faradic effect
Produced by frequencies > 20 kHz
stimulation of muscle cells happen, which is undesirable. therefore use frequency above 300 kHz
—– thermal effect
THIS ONE DURING ELECTROSURGERY
Produced by high frequency > 300 kHz
Tissue gets heated
Why is tissue with a lot of small blood vessels preferably cut using electrosurgery instead of with a scalpel or laser?
Because of homeostsis
Electrical current always finds the way of least resistance which is water. This ensures that all small blood vessels are coagulated immediately
Which factors determine the electrosurgical effect?
What can you change to use electrosurgery for cutting and for coagulation
Generator technology electrode typoe, contact surface movement speed of the electrode tissue properties controlled settings of equipment waveforms
explain the waveforms used to change between cuttnig and coagulation
Cutting = continuous sine wave coagulation = higher peak to peak sinewave, however an intermittent signal. give time to let heat get away, so no cutting temperatures
blend mode is optimal, creates homeostasis
fulguration mode
extreme coagulation
explain the difference between monopolar and bipolar techniques
monopolar:
- active electrode and return electrode (patient)
- surgical effect happens at the tip of the active electrode
- current travels over large distances through the body, has risks ofcourse
bipolar:
- both electrodes combined in one instrument
- surgical effect happens inbetween
- current travels smaller distances. Safer but not always usable
Models to describe electrosurgical effect
Still not well understood
Difference between surgical effect generator and power generator
surgical effect is voltage controlled. Uses feedback loop. Measures arc intensity. If only main frequency then the settings are too low. If you find alternating odd frequencies it is correct. If you find all even and odd frequencies then the settings are too high
Power is adjusted
Power controlled:
- activation away from the tissue
Power is kept at a constant level with changing impedance
- high air resistance results in high peak voltage settings -> initial high current upon application
Analyze the risks when using electrosurgery in the operating theatre, both for open surgery and minimally invasive
- cannot fuly control current path, leakage current
- patient plate risks
- — a small contact area can mean high current density without knowning it
- placement risks
open:
surgical glove perforation
fire
surgical smoke
minimally invasive
- no direct sight
- direct coupling
- insulation failure
- capacitative coupling
