Techniques of Liver Parenchyma Dissection
Mickaël Lesurtel, Pierre-Alain Clavien
Parenchyma dissection of the liver may cause complications including blood loss, hematoma, infection, bile leakage and liver failure. Various surgical techniques have been developed for careful and safe dissection of the liver parenchyma to prevent intraoperative and postoperative complications.
The aim of this chapter is to give an overview of the techniques and devices frequently used to perform parenchyma dissection of the liver, including:
■
Kelly clamp and bipolar forceps
■
Water jet dissection
■
Ultrasonic dissection
■
Ultrasound cutting
■
Dissecting sealer
Preparation of Parenchyma Dissection
The liver capsule is incised with diathermy on the resection line. For a better exposure, two stay sutures (2-0 silk) can be placed at the inferior margin of the liver, one on each side of the resection line. These stay sutures are used to lift up the liver and the resection line. Care should be taken not to pull and tear the liver parenchyma, leading to bleeding.
To prevent unnecessary liver ischemia, the Pringle maneuver for continuous or inter-
mittent inflow occlusion is applied individually depending on the intraoperative surgical
situation. Indeed, except for the Kelly clamp, the other techniques were developed to
avoid use of the Pringle maneuver and to minimize risk of liver ischemia.
Kelly Clamp and Bipolar Forceps
A small clamp (Kelly) is used to crush parenchyma between its blades in order to isolate vessels and bile ducts (A-1, A-2). Fine branches of Glisson’s tree or tiny tributaries of hepatic veins (<3mm) are coagulated using a bipolar forceps and are cut by scissors (A-3). Bipolar forceps cautery is equipped with a channel for water dripping, which prevents adhesion of debris to the cautery blades. Bigger identified vessels or bile ducts (>3mm) are ligated or clipped on the remnant liver slice before cutting. The alternative is to use clips only to secure vessels and bile ducts.
A-1
Water Jet Dissection (Helix Hydro-Jet, Erbe)
With this device the liver parenchyma is dissected by a jet of water (A-1). Saline is pres- surized by high pressure pump and is conducted by a high pressure hose to the nozzle.
Here the pressure is converted into kinetic energy. For liver parenchyma, pressures of 30–50bar should be used. The soft liver tissue is washed off the more resistant vessels and bile ducts (A-2). The applicator should be used in direct contact with the tissue and moved like a paintbrush. It can be used in combination with suction and with an elec- trosurgical unit. Vessels and bile ducts are isolated and can be secured using bipolar forceps, clips or ligatures as with the Kelly clamp. They can then be transected under controlled conditions.
A-1
A-2
Ultrasonic Dissection
(Cavitron Ultrasonic Surgical Aspirator; Dissectron, Integra NeuroSciences) The principle of ultrasonic dissection is a cavitational effect which occurs at the tip of the vibrating rod of the device. The handpiece delivers ultrasonic vibration and provides simultaneous aspiration and irrigation (A-1). The ultrasonic probe divides parenchymal cells (because of their high water content) by the cavitational effect with less injury to structures with a high content of fibrous tissue, e.g., bile ducts and blood vessels (A-2).
Once skeletonized by the probe, these elements are then clipped, ligated or coagulated as with the other techniques. Additional electrocoagulation functions are optionally available. The ultrasonic and high frequency currents can be activated simultaneously to divide and coagulate vessels, ducts and nerves.
A-1
Ultrasound Cutting (Ultracision, Ethicon Endo-Surgery)
The ultrasound cutting system includes an ultrasound generator with a foot switch, a reusable handle for the scalpel, and the cutting device with scissors. The electrical energy provided by the generator is converted into mechanical energy by the handpiece through a piezoelectric crystal system. The blade or tip of the instrument being used vibrates axially with a constant frequency of 55,500Hz (A-1, A-2). The longitudinal extension of the vibration can be varied between 25 and 100 mm in five levels, by adjusting the power setting of the generator. The cutting derives from a saw mechanism in the direction of the vibrating high-frequency blade. The intracellular generation of vacuoles (cavitation) brings about the correct dissection of the liver parenchyma.
Blood vessels up to 2–3mm in diameter are coagulated on contact of the tissue with the vibrating metal. For coagulation of larger vessels, exertion of pressure between blades for 3–5s is required. Especially in the periphery, the harmonic scalpel allows the liver parenchyma to be divided without causing bleeding, bile leakage or trauma. It is especially used for laparoscopic dissection because of its speed of action and ease of use.
However, its use in the depth of the liver may lead to vascular injury, especially to hepatic veins. That is the reason why, in depth, larger vessels should be secured with clips or sutures.
A-1
A-2
Dissecting Sealer (TissueLink)
The TissueLink dissecting sealer uses proprietary technology to coagulate and seal tissue to provide hemostasis before and after transection. It delivers radiofrequency (RF) energy through a conductive fluid (saline) to coagulate and seal tissue (A-1, A-2).
The saline couples the RF energy into tissue and cools the tissue so that the temperature never exceeds 100°C. The result is hemostasis via collagen shrinking without the tissue desiccation, smoking, arcing, and char of conventional electrosurgery. The dissecting sealer can be connected to the same standard RF generator that is used for standard electrocautery. The dissecting sealer is applied directly to the target tissue. It is impor- tant to maintain constant contact with the liver and move the device in a “painting”
motion to ensure effective application of energy. Vessels less than 5mm in diameter encountered through skeletonization can be completely coagulated within 10s and can thereafter be transected. Larger vessels should be secured by clips or sutures.
A-1
Tricks of the Senior Surgeon
■
The different devices can be used in the same intervention as they may offer different and cumulative advantages.
■
During laparoscopic liver resection, the harmonic scalpel is useful because it can coagulate and divide the hepatic parenchyma during the same application, avoiding changing instruments.
■
During parenchyma dissection, whatever the techniques used, central venous pressure must be kept low to minimize blood loss.
■
