Diathermy dissection: While principles of open surgery should be applied to lap surgery, there are also some practices of lap surgery that can be extended back to open surgery.
Of course diathermy hook dissection is now well established in lap surgery, as two different techniques:
1. Hook and Cook, which pulls strands of tissue away from underlying structures to allow safe diathermy , for example exposing the cystic duct.
2. Paint and Push, where there is a kind of “dotted line” for dissection, for example separating gall-bladder from liver bed. [Perhaps someone has the secret for avoiding the occasional perforation of a thin gall-bladder at this stage].
The lap diathermy hook is typically blunt, which is a good safety precaution, because there is not the precise control of fine movement as in a “pen-holding grip” when the hand steadied on the work surface. Otherwise it might perforate fine structures.
In dissecting a mesentery or around the pancreas or axillary vein in open surgery, a much finer hook can be used. I hadn’t come across hook dissection in open surgery before my younger colleague tried it for the first time about 3 months ago. We now both recommend it as well worth trying. [He is a habitual diathermy dissector since a term in paediatrics some years ago].
By good luck, the only diathermy hooks available to fit ordinary Valley Lab handpieces in my hospital happen to be very fine ones, from a “Hyfrecator”.
Here are the dimensionss of the Valley Lab tip and the two hooks.
Open Lap Hifrecator
tip hook hook
length 20 mm 4.5 mm 3.7 mm
One of the nice things about pulling and separating loose fatty tissue is the way it becomes “soda-water” tissue, with a lot of air in it, though less conductive. A lot depends on the wattage and on the rate at which the diathermy tip is moved along the tissue, say 5 mm a second or 20 mm a second. To those who find this nit-picking detail I apologize, but I think an appreciation of comparative figures is useful.
Another is that the diathermy tip, or hook, can be used like a simple dissector, pulling or pushing tissue apart. My experience of this is that hardly any operators take advantage of this technique. It is more useful with a hook.