Complications in Equine Surgery. Группа авторов. Читать онлайн. Newlib. NEWLIB.NET

Автор: Группа авторов
Издательство: John Wiley & Sons Limited
Серия:
Жанр произведения: Биология
Год издания: 0
isbn: 9781119190158
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into three categories: incision/excision, ablation and coagulation of tissue. Which of these occurs depends upon power density and absorption length of the laser, which in turn influence the rate of heat generation in tissue (Figure 12.6) [8]. Incision/excision and ablation result in cell disruption and “vaporization” of tissue into smoke. Coagulation here refers to denaturing of tissue proteins, which grossly appears as blanching and tissue contraction [2].

Photo depicts absorption length of various wavelengths of surgical lasers in unpigmented skin. Wavelengths commonly used in veterinary medicine are in dark gray; wavelengths (nm) are stated beside the names. The far-infrared Ho:YAG and CO2 lasers are highly absorbed by water so penetrate minimally into skin, whereas the near-infrared Nd:YAG or GAA Diode lasers are absorbed more by the darker pigments of the deeper layers [8]. Photo depicts range of tissue changes from laser beam. With sufficient power density, a laser beam has a central area of tissue vaporization/ablation shown by the crater in this drawing. A layer of carbonization occurs when tissue that has been significantly heated cools to produce char. The area of thermal necrosis is where tissue is heated beyond physiological limits and sloughs later. The goal of incisive surgery is to use adequate power density to create as little carbonization and thermal necrosis as possible [10].

      Laser energy can be delivered to the tissue in a noncontact or contact manner. As the term implies, with noncontact delivery, nothing but the laser light touches the tissue, thus imparting a purely optical interaction. Carbon dioxide laser energy is reflected by mirrors or down a highly polished waveguide and delivered in noncontact fashion. Lasers delivered by quartz fibers (Nd:YAG and GAA diode lasers) can deliver energy either way.


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Laser Description Capacity Accessories Preference for skin incision Comments
GAA Diode Laser Quartz fiber delivery 25–50 W 600 and 1,000 micron quartz fibers Handpiece to hold fibers 1,000 micron fiber sculpted down to approximately 600 micron at the tip 25 W is insufficient for noncontact vaporization 600 micron fiber too fragile for general surgery. Excellent for endoscopic surgery Sterilize fibers for aseptic procedures.
Nd:YAG Laser