Electrosurgery

Question 1

Differentiate between electrosurgery & electrocautery.

Answer 1

Electrosurgery:
AC
Patient’s body is part of electrical circuit
Tissue effect (cutting, dissection, coag) dependant on energy, time applied, tissue properties

Electrocautery:
DC
Patient’s body is not part of electrical circuit
Limited application (sole tissue effect is coagulation)

Question 2

Why don’t electrosurgery generators shock patients?

Answer 2

Frequency of current is so high that cells do not depolarize or react to current (neuromuscular stimulation ceases above a certain frequency)

Question 3

Why isn’t a patient return electrode required when using bipolar?

Answer 3

Current is confined between the two poles of the instrument

Allows use of lower voltages to achieve same effect, therefore hemostasis is achieved with less charring

Question 4

Differentiate between the cut & coag current waveforms.

Answer 4

Cut - low voltage continuous output (tissue vaporization with minimal coag effect)
Coag - high voltage intermittent output (cooling of cells in between spikes produces coagulation)

Question 5

Why is the patient return electrode typically placed on the thigh in gynecologic surgery?

Answer 5

Electrode should be as close to surgical site as possible (increased distance = increased resistance and therefore higher power required to achieve desired tissue effect)
Placement of electrode on large vascular muscle also reduces resistance