Page 22 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 1 · Surgical principles and instrumentation

absorbed by the water content of oral tissues. The larger surface area of the ground plate minimizes the
thermal necrosis zones of 100–300 µm at cut tissue current density, so that the rest of the animal’s tissues are
VetBooks.ir CO 2 lasers can be utilized for various soft tissue surgeries good contact with the patient to avoid thermoelectric
minimally affected. The ground plate must be placed in
edges are less deep than those of diode and other lasers.
burns. Monopolar diathermy can cut as well as coagulate
of the head, including gingivectomy and gingivoplasty,
frenoplasty, ablation of stomatitis ulcers, marsupialization
of sublingual sialoceles (ranulae), tonsillectomy and tissue and works best in a relatively dry surgical field.
reduction of elongated soft palates, as well as various Bipolar diathermy: The tips of the handpiece are held
surgeries of the ears, nose, lips, cheeks, tongue and about 1 mm apart so the current can flow from the tip of one
pharynx (Holt and Mann, 2002). handpiece, through the tissue being held, to the opposite
tip. The risk of unintentional injury to surrounding tissues
Diode laser: Diode lasers come as small compact units. is greatly decreased. Bipolar diathermy is recommended
They emit wavelengths that are easily transmitted through when precise coagulation is required to reduce the risk of
small flexible optical fibres, allowing use with most flexible iatrogenic injury to important adjacent structures (e.g. the
and rigid endoscopes. Diode lasers penetrate deeply recurrent laryngeal nerves during neck surgery).
(1–2 mm) into most types of soft and hard tissue. Frequent
water irrigation is used as a ‘heat sink’ to decrease thermal Vessel-sealing devices
damage when using a diode laser in the oral cavity
(Bellows, 2002). Bipolar vessel-sealing devices and ultrasound-activated
scalpels are now available from several manufacturers.
They have the ability to induce heat to reliably seal vessels
Diathermy units
between 5 and 7 mm and may be particularly useful for
Diathermy (electrocoagulation) involves the application of a resecting the pericardium and mediastinum either at open
high-frequency current through tissue, which generates surgery or via thoracoscopic access to the chest.
heat that coagulates and seals the bleeding vessel. This is
in contrast to electrocautery, which is the application of a Solutions for rinsing, antisepsis and storage
heated filament to tissue. Diathermy should only be used
on arteries up to 1 mm in diameter and veins up to 2 mm in • Dilute chlorhexidine gluconate: A concentration of
diameter. Diathermy is helpful in most head, neck and 0.12% is recommended for rinsing the mucosal surfaces
thoracic surgeries because it produces a blood-free field, of the oral cavity and oropharynx. Higher concentrations
which provides optimal visibility for accurate dissection and are to be avoided as they may cause epithelial
reduces surgical time. However, excessive or indiscriminate desquamation and wound healing complications.
use of diathermy prolongs wound healing. Wound break- • Povidone–iodine: This may be applied with a swab to
down is of particular concern if electrosurgical equipment intact oral mucosal surfaces at a 10% concentration
is used for incisions or for control of haemorrhage in (diluted 10-fold if the mucosa is not intact) (Terpak and
tissues at sutured incision edges. Use of diathermy in the Verstraete, 2012).
oral cavity and oropharynx is not recommended unless it • Phosphate-buffered saline and lactated Ringer’s
is absolutely necessary. Monopolar or bipolar diathermy is solution: These solutions were found to induce no
available (Figure 1.16) and can be activated by either a hand significant fibroblast injury in an in vitro model (Buffa
or a foot switch. et al., 1997). In comparison, normal saline was found to
have cytotoxic effects on canine fibroblasts.
• Hank’s balanced salt solution: A commercial tissue
Monopolar diathermy: The current flows from the hand-
piece through the animal to a ground plate. The small culture medium for temporary storage of avulsed teeth
surface area of the handpiece concentrates the current until they are reimplanted (Reiter, 2013).
density at the point of application to the tissue, resulting in
electrocoagulation. The handpiece is usually touched to Materials aiding in haemostasis
forceps that have been applied to the bleeding vessel. The • Cold lavage: Lactated Ringer’s solution placed in the
freezer and then removed before the freezing point is
reached may provide good haemostasis during
maxillectomy and other surgical procedures that
expose the nasal cavity.
• Aluminium chloride: This astringent produces tissue
shrinkage and reduces minor haemorrhage. It may be
added to cut surfaces following gingivoplasty or biopsy
of gingival masses.
• Bone wax: This sterile beeswax-based compound can
be used for haemostasis of cut bony surfaces following
maxillectomies and mandibulectomies and excessive
bleeding from, for instance, an alveolus, the mandibular
or infraorbital canal or the retroglenoid foramen.
• Oxidized regenerated cellulose: Absorbable sterile
mesh applied directly on to an area of bleeding.
• Absorbable gelatin sponges: These are derived from
gelatin and are available as sheets (which may be cut
into particles of appropriate size) or as a powder.
• Microporous polysaccharide spheres: Powder
derived from potato starch, which when applied
1.16 Diathermy equipment. 1 = monopolar; 2 = bipolar.
directly on to a bleeding site accelerates clot formation.

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