clavien_atlas_of_upper_gastrointestinal_and_hepato-pancreato-biliary_surgery2007-10-01_3540200045_springer
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322 SECTION 3 Liver
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
A-2
Techniques of Liver Parenchyma Dissection |
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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 100mm 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
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SECTION 3 |
Liver |
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Dissecting Sealer (TissueLink) |
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The TissueLink dissecting sealer uses proprietary technology to coagulate and seal |
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tissue to provide hemostasis before and after transection. It delivers radiofrequency |
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(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 important 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
A-2
Techniques of Liver Parenchyma Dissection |
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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.
■Regardless of the device used, inflow occlusion should be used loosely in case of significant bleeding during transection.
Techniques of Vascular Exclusion and Caval Resection
Felix Dahm, Pierre-Alain Clavien
Vascular exclusion techniques in liver surgery include continuous inflow occlusion (Fig. 1A) (first described by J.H. Pringle in 1908), intermittent inflow occlusion (Fig. 1B) (first described by M. Makuuchi in the late 1970s), and ischemic preconditioning
(Fig. 1C) and (continuous) total vascular exclusion. The use of inflow occlusion varies considerably among centers – some use it routinely, while others use it only exceptionally. When using inflow occlusion, a low central venous pressure (CVP) (<3 mm Hg) needs to be maintained to reduce bleeding. The effect of a low CVP associated with a Pringle maneuver can be equivalent to total vascular exclusion. Total vascular exclusion, on the other hand, can lead to cardiovascular instability by reduced cardiac preload, and adequate volume loading with a high CVP (>10 mm Hg) needs to be maintained. A venovenous bypass is sometimes used in this setting.
Table1. Maximum safe duration (min) of hepatic inflow occlusion with different techniques
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Normal liver |
Cirrhotic liver |
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Continuous inflow occlusion |
60 |
30 |
Ischemic preconditioning |
75 |
? |
Intermittent clamping |
>90 |
>60 |
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Figure1. Ischemia periods are drawn in black, reperfusion in white
Indications and Contraindications
Indications |
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Reduction of blood loss during parenchymal dissection |
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Dissection in proximity of major vascular structures |
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Tumor invading vena cava or all hepatic veins, central hepatectomy |
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(for total vascular exclusion) |
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Technical reasons (adhesions, etc.) |
Contraindications |
■ |
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Cardiac failure (for total vascular exclusion) |
Intraoperative Complications
■Splenic rupture (exceptional) – remove clamps and attempt conservative management of splenic rupture. If not possible, proceed with splenectomy.
■Cardiovascular instability (in total vascular exclusion) – ensure adequate fluid loading, open clamps, consider venovenous bypass.
328 SECTION 3 Liver
Procedures
Pringle Maneuver ( = Inflow Occlusion)
A right-angle clamp is passed under the hepatoduodenal ligament to allow a Mersilene band to be placed around it (A). A red rubber catheter is passed over the band. It is then pushed downwards as a tourniquet to occlude the ligament, and clamped in place (B).
The time of inflow occlusion should now be noted. An alternative technique is to place a vessel clamp on the hepatoduodenal ligament (C). We prefer the tourniquet because it is mobile and does not get in the way when performing the hepatectomy. Another alternative is to selectively clamp portal venous and arterial branches when a dissection
of the structures in the hepatoduodenal ligament has been performed, e.g., for cholangiocarcinoma.
Total Vascular Exclusion
Before total vascular exclusion can be performed, the liver needs to be completely mobilized as for a liver transplantation (see chapter “Orthotopic Liver Transplantation”).
A
B
C
Techniques of Vascular Exclusion and Caval Resection |
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STEP 1
The hepatoduodenal ligament is dissected and the tourniquet is placed around it without closing, as described for inflow occlusion.
STEP 2
The infrahepatic vena cava is prepared on its right and left side for 2–3cm. The right adrenal vein needs to be identified and transected through ligatures (A).
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SECTION 3 |
Liver |
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STEP 2 (continued)
A finger is passed under the cava from the right to the left, and the connective tissue is dissected on the finger with electrocautery (B-1). A large right angle is then passed under the infrahepatic vena cava (B-2), and isolated with a Mersilene band (B-3), which is then pulled through a catheter as when performing inflow occlusion (tourniquet technique as in the Pringle maneuver, see above).
Techniques of Vascular Exclusion and Caval Resection |
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STEP 3
Mobilize the retrohepatic and suprahepatic vena cava up to the diaphragm. This is accomplished by passing a finger behind the vena cava and cauterizing the connective tissue. There are no venous branches in this area.
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SECTION 3 |
Liver |
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STEP 4
Occlude the infrahepatic cava with the corresponding tourniquet. If this is not tolerated, total vascular exclusion cannot be performed. If it is tolerated, lift up the left hepatic hemiliver and place a large curved vascular clamp from left to right on the suprahepatic cava as high as possible. Check if it can be closed, then occlude hepatic inflow by closing the tourniquet on the hepatoduodenal ligament. Clamp the suprahepatic vena cava including a little bit of diaphragm (if possible) (A). The liver is now in total vascular exclusion (B). We do not routinely use venovenous bypass in this setting (see section on venovenous bypass in the chapter “Orthotopic Liver Transplantation”).