Small Animal Laparoscopy and Thoracoscopy. Группа авторов

4.18), inflatable flanges to help with retention, and optical trocars (Figure 4.19). Optical trocars have a transparent plastic sleeve, into which the laparoscope may be fitted before insertion of the trocar, enabling the surgeon to monitor the passage of the instrument through the layers of the abdominal wall. The internal surface of the sleeve must be nonreflective to avoid light from the laparoscope interfering with the surgeon's view.

Nondisposable Trocar Assemblies

Reusable trocar assemblies are the most common type used in veterinary medicine. These include smooth and threaded, a.k.a. Ternamian, stainless steel trocars (Figures 4.20 and 4.21). These have the advantages of being easy to clean and sterilize with a long shelf life. The plastic valves that attach to these trocars are also autoclavable, but they eventually wear or crack over time. The threaded cannulas can be used without an obturator as the distal end is shaped to penetrate the body wall and screw into place, avoiding the need for retention sutures. These may be difficult to place through very thick tissue planes without appropriate insufflation pressures or without an appropriately sized skin incision.

Figure 4.18 Disposable bladeless cannula with a safety shield.

Figure 4.19 Disposable optical view cannula–trocar with an internal flange and balloon for improved retention.

Figure 4.20 Different sizes of smooth stainless steel reusable cannulas.

      Source: © 2014 Photo courtesy of KARL STORZ SE & CO, KG.

Figure 4.21 A Ternamian (i.e., threaded) EndoTIP stainless steel reusable cannula.

      Source: © 2014 Photo courtesy of KARL STORZ SE & CO, KG.

Figure 4.22 Multiple types of plastic reusable thoracic ports.

      Source: © 2014 Photo courtesy of KARL STORZ SE & CO, KG.

Flexible ports or plastic cannulas have been used to gain access to the abdomen or chest (Figure 4.22). Specialized Thoracoports (Covidien, Mansfield, MA) are plastic cannulas with plastic blunt trocars used for atraumatic entrance into the thoracic cavity to decrease the chance of iatrogenic damage to intercostal vessels or underlying structures (e.g., heart, esophagus, trachea) (Figure 4.23). There are also many multiport systems available to veterinary surgeons today, which allow for a telescope and up to three instruments to be passed into a body cavity simultaneously through one incision. These ports are discussed elsewhere in detail. They have different advantages and disadvantages, including cost, resterilization ability, flexibility of instrument handling after the cannulas are engaged, and so on.

Figure 4.23 Reusable Thoracoport.

      Source: Photo courtesy of Dr. Philipp Mayhew.

Trocar Assembly‐Related Complications

      Most insertional complications can be avoided with special attention to detail and do not usually require the need for conversion to an open procedure. Complications associated with trocar placement and insufflation include damage to intraabdominal organs, vascular injury, subcutaneous insufflation (emphysema), fatal air embolism, and insufflation of falciform fat [15]. Insertion of the Veress needle via the intercostal technique in one article was associated with 35% grade 1 complications (subcutaneous emphysema, omental or falciform injuries), 10.7% grade 2 complications (liver of splenic injuries), and 1.7% grade 3 complications (pneumothorax) [16]. Insertion of the Veress needle and primary trocar for initial entry remains the most hazardous part of laparoscopy, accounting for 40% of all laparoscopic complications and the majority of the fatalities [17]. Despite decades of research and development to find safer methods for initial laparoscopic entry, major vessel injuries have been reported using virtually all types of trocar insertion methods. The overall morbidity and mortality rates related to laparoscopic access are low. The life‐threatening complications include injury to the bowel, bladder, and major abdominal vessels. A recent Cochrane review included 17 randomized controlled trials concerning 3040 individuals undergoing laparoscopy. Overall, there was no evidence of advantage using any single abdominal access technique in terms of preventing major complications [18].

Vascular Injury

      Vascular injury can occur regardless of the method of access, and most vascular injuries (up to 80%) occur at the initial access. Recent studies have suggested that the incidence of major vascular injury is slightly higher with the closed technique (Veress and direct trocar insertion) as opposed to the open (Hasson) technique. Molloy et al. [4] suggest that the open technique decreased the rate of vascular injury to 0.01% compared with a rate of 0.04% associated with closed techniques using a Veress needle. Although the incidence of major vascular injuries is low, the mortality rate arising from these lesions reportedly ranges between 8 and 17%. Vessel injuries attributable to trocars are usually more obvious and catastrophic than injuries related to Veress needle insertion. An expanding retroperitoneal hematoma, hemodynamic instability in the face of active bleeding, and active intraabdominal hemorrhage that cannot be managed laparoscopically are all indications for conversion to laparotomy and exploration or vascular repair.

Visceral Injury

      Although studies have suggested that the open technique of initial trocar placement may be associated with a lower incidence of major vascular injuries, the same cannot be said for visceral injuries [14]. The incidence of this complication is about 0.05% of all open access procedures [19]. The main difference between bowel injuries occurring during the open technique compared with the closed technique is that with the open procedure, it is more likely that the injury will be immediately obvious and repaired without delay. Veress needle injuries to the large and small bowel may be associated with a higher incidence of peritonitis and other complications than injuries to the stomach, which can often be managed conservatively.

Figure