Page 157 - Clinical Manual of Small Animal Endosurgery

Operative Laparoscopy 145

Fig. 5.8 The laparoscopic spay hook has a weighted handle. The sharp tip
is inserted percutaneously and used to suspend the ovary from the body
wall during laparoscopic ovariectomy.

location. Occasionally, there may be minor bleeding associated with this
step; however, it is self-limiting as the ovary is subsequently removed.
The grasping forceps are removed and the energy modality device is
inserted in its place.
For rapid vessel occlusion of the ovarian pedicles, an energy system is
required. A bipolar vessel sealing system such as the LigaSure or the
ENSEAL can be used. The LigaSure system has a function that monitors
tissue impedence while energy is being applied. When coagulation is
complete the impedence rises, meaning that the tissue is dessicated and
no additional energy is flowing through it; the system detects it and gives
an audible signal or adjusts energy output to create the desired tissue
effect. A separate trigger is then activated to transect the tissue. The
ENSEAL system has a special design that includes a polymeric compound
in the jaw of the device that is responsive to temperature. When the
temperature of the polymer reaches 100°C, the conductive particles in
the polymer expand to disrupt the flow of electrical current. The result
is minimal lateral thermal spread, and reduced tissue scarring and stick-
ing of tissue to the electrodes. The tissue is then cut by applying a second
trigger. The technique for using both of these instruments is similar. The
blade is positioned across tissue, energy is applied and then the trigger
is pulled to cut the tissue.
The Harmonic Scalpel uses electrical energy to vibrate a piezoelectric
crystal in the handpiece of the instrument. Ultrasonic energy is transmit-
ted down the shaft of the instrument which then causes the blade to
vibrate rapidly at 55 000 cycles per second (cps, or Hz). When tissue is
captured between this active blade and the Teflon pad, heat from the
friction of the moving blade is transmitted to the tissue, disrupting hydro-
gen bonds and resulting in the collagen molecules in the tissue adhering