In this MRCS Part B scenario you are the surgical registrar. The anaesthetist for today’s list has some questions for you.
What is the difference between bipolar and monopolar diathermy?
In monopolar diathermy current passes from the active electrode through the tissues being operated on to an electrode plate on the patient.
The current is disseminated through a larger surface area (of at least 70 cm2) than it originated in, therefore preventing a heating effect at the plate electrode.
In bipolar diathermy, current passes between the two tips of the active electrodes, therefore only passing though tissue that lies between the tips. There is no plate electrode.
Bipolar diathermy is preferred to monopolar for use near end arteries, on structures with a narrow pedicle, and in patients with pacemakers.
