Small Animal Laparoscopy and Thoracoscopy. Группа авторов

Figure 2.17 The “needle dance” for needle positioning. (A). The needle is touching a serosal surface. (B). The instrument is rotated along the axis, and/or pivoted as needed to rotate the needle. (C). The needle has rotated to the correct position. (D). The needle driver grasps the needle.

After obtaining an appropriate needle position as described earlier, the ratchet is engaged with a firm grasp of the needle as the bite is initiated.

Knot Tying Using a Vertical Plane: The “Rosser Technique” (Figure 2.18, Video 2.3)

      With this method, the right‐hand instrument (needle driver) is always creating the throws around the left‐hand instrument. When maximal driving along the arc of the needle has occurred, the right‐hand needle driver is used to grasp the tip of the needle to disengage it from the tissue. The same instrument can then hold the needle without repositioning throughout the tying.

      This tying technique lends itself best if a short suture (15 cm or less) and is quick. Disadvantages include tightening of the second throw with crossed instruments. Holding on to the needle instead of the suture material close to the knot also increases the risk for an inadequately tightened knot. Both instruments are located in the vertical plane above the suture site. A common novice mistake is to move the instrument tips from the suture site closer toward the surgeon, which will make knot tying harder.

      For braided suture, the knot is complete with a double and two single throws. However, for monofilament suture, two or three more single throws are required for knot security.

Paying attention to in which direction one is wrapping the suture material around the instrument needs to become second nature. Alternating between clockwise and counterclockwise wrappings (Figure 2.19) ensures that square knots are formed.

Knot Tying with Horizontal C‐Loops as Described by Szabo et al. [15, 16](Figure 2.20, Video 2.4)

      This technique entails several transfers of the needle between instruments. It is therefore slightly slower than the Rosser technique described above. However, benefits include tightening of the knot without crossing instruments. Needle transfer also encourages regrasping close to the knot for tightening. These features minimize the risk of inadvertently applying inadequate tension on the knot. In fact, the authors prefer this technique for ligation purpose or for sutures placed in tissues under tension. This technique also differs from the earlier one in that the throws are wrapped around the ipsilateral instrument (i.e., the throws are alternately made around the left and the right instrument). Traditionally, this suturing is performed with two needle drivers, with a right and a left curved jaw, respectively.

      Continuous Suture Patterns

      Introduction of barbed sutures has made continuous MIS suturing easy, fast, and safe. The novice MIS surgeon should not attempt continuous suturing with smooth suture in these authors' opinion. For suturing with barbed sutures, it is important to follow the manufacturer's instructions on strength and how to anchor the start of the running suture.

Extracorporeal Suturing

      Indications

Extracorporeal knot tying is indicated when the maneuvring space is insufficient for intracorporeal suturing. Another indication is if the tension on the defect exceeds what an intracorporeal surgeon's throw can withstand because a high‐strength jamming knot tied extracorporeally is stronger. In contrast to using a ligature loop, extracorporeal knot tying is also useful for placing ligatures without the need to divide the structure before ligation. The concept of extracorporeal knot tying is depicted in Figure 2.21.

      Technique

In extracorporeal suturing, a long suture is required, with 75 cm (30 in.) the minimum and 90 cm (36 in.) being ideal in a large breed dog. A knot pusher is also required (Figure 2.22) The needle is introduced into the body cavity, while the end of the suture is secured outside the cannula. If the valves cannot hinder CO₂ leak with the suture in place, an introducer is necessary. Needle introduction, suture bite, and needle removal are performed as described in intracorporeal suturing. Importantly, the needle end of the suture is exteriorized through the same cannula as it was introduced through (Figure 2.21). When both ends of the suture are available at equal length, a slip knot is tied by hand. The knot is cinched down using a knot pusher (Figure 2.22), while the surgeon maintains tension on one or both ends of the suture, depending on knot type. Knot pushers are available with either a slotted (“open”) end or a closed end. The disadvantage with a slotted design is that they may disengage from the suture during cinching. Closed end designs need to be threaded onto the post suture, which can be a disadvantage.

The knot type used depends on the indication for using an extracorporeal knot. If paucity of intracorporeal space is the main reason, regular square throws can be tied extracorporeally, with each throw being cinched with a knot pusher while both suture ends are secured outside the body. These throws should be applied with proper one‐handed technique to avoid that identical half hitches are placed, resulting in granny knots. However, if a stronger starting knot is needed to overcome tension, a more complex slip knot is needed. With few exceptions, these slip knots need additional throws for security if they are to be placed in tissues under tension.