Figure 23.22 Dispersive electrode burns. If the dispersive electrode becomes partially detached, the current density may increase to the point that a skin burn results.
electrode could result in a thermal injury because reducing the surface area of the electrode in contact with the skin raises the current density (Fig. 23.22).
Because a few ground-referenced machines without such safeguards may still be in use, it is important to know the type of electrosurgical unit used in the operating room. If the electrosurgical generator is ground referenced and if the dispersive electrode becomes detached, unplugged, or otherwise ineffective, the current seeks any grounded conductor, such as electrocardiograph patch electrodes or the conductive metal components of the operating table (Fig. 23.23). If the conductor has a small surface area, the current or power density may become high enough to cause thermal injury (Fig. 23.24).
The most dangerous hemorrhagic complications are injuries to the great vessels, including the aorta and the vena cava, the common iliac vessels and their branches, and the internal and external iliac arteries and veins. The most catastrophic injuries occur secondary to insertion of an insufﬂation needle or the tip of the obturator (trocar) used to position the primary or ancillary cannulas. The vessels most frequently damaged are the aorta and the right common iliac artery as it branches from the aorta in the midline. The anatomically more posterior location of the vena cava and the iliac veins provides relative protection, but not immunity, from injury (116). After vascular injury, patients usually develop profound hypotension with or without hemoperitoneum. In some instances, blood is aspirated through the insufﬂation needle before the introduction of the distending gas. In such instances, the needle should be left in place while immediate preparations are made to obtain blood products and perform laparotomy.
The bleeding frequently will be contained in the retroperitoneal space, which usually delays the diagnosis; consequently, hypovolemic shock may develop. To avoid late recognition, the course of each great vessel must be identified before completing the procedure. Because it is difficult to assess the volume of blood filling the retroperitoneal space, immediate laparotomy is indicated if retroperitoneal bleeding is suspected. A midline incision should be made to allow access to the great vessels. Upon entry into the peritoneal cavity, the aorta and vena cava should immediately be compressed just below the level of the renal vessels to gain at least temporary control of blood loss. The most appropriate course of action depends on the site and extent of injury. Vascular or general surgery consultation may be necessary to evaluate and repair significant vascular injuries. Although most of these injuries are small and amenable to repair with suture, some are larger and require the insertion of a vascular graft. Deaths have occurred as a result of these injuries.
Figure 23.23 Risk of ground-referenced generators. Current diversion along alternate pathways is a risk associated with ground-referenced electrosurgical generators, particularly if the dispersive electrode is detached. In the example depicted, the relatively high current density at the electrocardiogram electrode site may result in a skin burn.
The abdominal wall vessels most commonly injured during laparoscopy are the superficial inferior epigastric vessels as they branch from the femoral artery and vein and course cephalad in each lower quadrant. They are invariably damaged by the initial passage of an ancillary trocar-cannula system or by the introduction of a wider device later in the procedure. The problem may be recognized immediately by the observation of blood dripping along the cannula or out through the incision. However, the bleeding may be obstructed by the cannula until it is withdrawn at the end of the operation.