Surgery of Exotic Animals. Группа авторов

and diminished depth of focus, technological advances in loupe magnification and use of carefully obtained measurements to guide customization of loupes have diminished the impact of these limitations (Ross et al. 2003; Jarrett 2004; Hart and Hall 2007; Chang 2014b). Loupes are also significantly less expensive than operating microscopes (Pieptu and Luchian 2003; Jarrett 2004; Stanbury and Elfar 2011).

      Illumination

      Properly adjusted and color‐balanced illumination increases apparent resolution, enhancing the surgeon's ability to discern tissue color, depth, and dimension and more readily distinguish anatomic structures in the patient (Carr and Castellucci 2010). Standard overhead surgical lights, including LED lights, are often too far to provide adequate illumination of structures in small or deep body cavities of exotic animals. Both operating microscopes and surgical loupes are equipped with coaxial light sources that illuminate a path parallel to the line of sight and reduce the potential for shadows and other visual obstructions (Carr and Castellucci 2010; Cordero 2014). Both the xenon light source of an operating microscope and the LED lights of surgical loupes illuminate without the risk of added warmth and tissue desiccation (Carr and Castellucci 2010; Cordero 2014) (Figure 3.10).

Instrumentation

      Fine, delicate instruments are of great utility when operating on small exotic animals. Such instruments are designed to exert minimal pressure while maintaining a firm hold on tissues. Microsurgical forceps and needle holders eliminate or discourage wide, erratic, or irregular movements when opening and closing the instrument. Observation of such movements is greatly exaggerated with magnification and damage to delicate tissues may be substantial.

      Microsurgical Instrumentation

Along with basic instrumentation required for soft tissue procedures, exotic animal surgeons benefit from using a number of additional microsurgical instruments (Bennett 2000b; Hernandez‐Divers 2008; Alworth et al. 2011; Capello 2011) (Figure 3.11). A fine‐pointed, diamond‐jawed needle holder, vascular forceps such as DeBakey forceps, curved and straight microsurgical dissecting scissors, adventitia scissors and small Metzenbaum scissors, atraumatic vascular clamps, and a right‐angled dissecting forceps such as a small, blunt‐tipped mixter are recommended.

Many microsurgical instruments are manufactured with ergonomic qualities that offer advantages in delicate procedures (Bennett 2000b; Hart and Hall 2007). Nearly all instruments are manufactured in a variety of lengths to accommodate a range of hand sizes. Lengths of 4–6 in. are used most commonly. Detailed operations in small spaces benefit from fine and smooth movements, and precise movements are most readily accomplished by rolling the instrument (Bennett 2000b). Choose needle holders and tissue forceps with rounded handles to permit rolling between the thumb and index finger. Another quality of microsurgical instruments that enables smooth and precise movements is counterbalancing. Counterbalanced instruments are notched and weighted at the nonoperative end to encourage stability of the instrument in the groove between the surgeon's thumb and index finger (Bennett 2000b) (Figure 3.12). Finally, choose microsurgical instruments without locking mechanisms. A needle holder that automatically locks or ratchets closed requires added exertion and excessive force to open. Such force may cause irreparable and unnecessary damage to tissues.

Figure 3.11 Small collection of microsurgical instruments. From right to left: microsurgical clamp applier, vessel dilator, straight microvascular scissor, curved jeweler's forceps, straight jeweler's forceps, and single and double Acland microvascular clamps mounted on a frame.

Castroviejo and Vannas needle holders maintain a precise and fine grip on tiny needles. The author prefers small, curved, or straight jeweler’s forceps with 0.2–0.3 mm tips for use as needle holders, and frequently maintains a jeweler’s forceps in each hand when suturing. One jeweler’s forceps acts as a needle holder, and the other is used to manipulate tissue or suture ends when knot tying. A curved jeweler’s forceps as a needle holder can be used to readily grasp a suture tag by lightly turning in any direction and is preferred by some microsurgeons. The author, however, prefers a straight jeweler’s forceps with a tying platform as a needle holder and a fine jeweler’s forceps or vessel dilator for tissue manipulation. A tying platform extends the grasping area of the forceps, and a vessel dilator has fine tips (0.1–0.2 mm) for grasping very thin or delicate tissue. Take care when using a vessel dilator as tissue forceps as the tips, though accurate, are thinner than the tips of jeweler’s forceps and may cause trauma.

Figure 3.12 A stable hand position with fingers stacked on one another holding a round‐handled, counterbalanced jeweler's forceps. Counterbalanced instruments are notched and weighted at the nonoperative end to encourage stability of the instrument in the groove between the surgeon's thumb and index finger.

Atraumatic vascular clamps, such as Satinsky, Cooley, and Codman clamps, come in a variety of sizes and configurations, and pediatric sizes are available for vascular use in small exotic animals, as in adrenalectomy in ferrets. Acland‐style microvascular approximating clamps are very helpful as atraumatic gastrointestinal clamps, serving as Doyen clamps would to prevent accidental spillage of ingesta during enterotomy and resection and anastomosis procedures (Jenkins 2000a). Acland microvascular clamps come in arterial and venous patterns and several sizes, designed to exert specific degrees of closing pressure on vessels in a range of sizes. The clamps exert a pressure of 5 g/mm² when used on the largest structure in the size range, and 15 g/mm² when used on the smallest structure in the recommended size range (Jenkins 2000a). The approximating frame facilitates sliding of the clamps closer together or further apart as needed to maintain approximation of vessel or intestinal ends. U‐shaped hooks at each end of the approximating frame are meant for tethering of stay sutures that facilitate maintenance of tension on the anastomotic line, improving visualization, and suture placement (Figure 3.13).

Figure 3.13 Double Acland microvascular clamps on an approximating frame. The frame facilitates sliding of the clamps closer together or further apart as needed to maintain approximation of vessel or intestinal ends. Note the U‐shaped hooks at each end meant for tethering of stay sutures.

      Care and Handling of Instruments

      Microsurgical instruments are highly refined to permit accurate and precise use, and are very fragile and prone to damage. Storage trays for microsurgical instruments are lined with rubber pads with finger‐like projections