Page 30 - Clinical Manual of Small Animal Endosurgery

18 Clinical Manual of Small Animal Endosurgery

Fig. 1.17 Vessel-sealing electrosurgery unit with variety of handpieces for
endosurgery and open surgery This sophisticated bipolar electrosurgery
generator produces vessel sealing through a combination of a closely
monitored electrical current and pressure applied by the handpieces.
Copyright © 2011 Covidien. All rights reserved. Reprinted with the
permission of the Energy-based Devices Division of Covidien.

urethrocystoscopy) unless a non-conducting irrigating medium (e.g.
lysine solution) is used, rather than saline.
In bipolar electrosurgery devices, the electrodes are similar in size, and
the current passes only through the tissue confined between them, thus
limiting the amount of heat generated and minimising the risk of damage
to surrounding tissues. Recent advances in bipolar technology have intro-
duced electrothermal bipolar vessel-sealing devices (e.g. Ligasure, Val-
leylab, Boulder, CO, USA; Fig. 1.17), able to seal vessels up to 7 mm in
diameter, and lymphatics and tissue bundles, by denaturing collagen and
elastin within the vessel wall and connective tissue. These seals have
bursting strengths comparable to those of clips and ligatures; further-
more, since they are intrinsic to the vessel wall structure there is no risk
of dislodgement. The vessel-sealing devices have dedicated handpieces
for laparoscopy and thoracoscopy that allow both tissue sealing and
tissue division. The handpieces are relatively expensive (compared to
monopolar electrosurgery) and generally designed as disposable devices:
this is a limitation to their use in veterinary surgery.

Lasers in rigid endoscopy
Laser is an acronym which stands for light amplification by stimulated
emission of radiation: a laser beam is formed by light photons having
all the same wavelength and travelling all in the same direction. This
is achieved by passing light (or electrons) through a lasing medium,