Chapter 45 expertly describes the preoperative evaluation, patient selection, integration of chemotherapy, and results of resection for colorectal cancer (CRC) metastatic to the liver. Below are comments about the technique of resection.
Most liver resections can be done with a right subcostal incision extended vertically in the midline to the xyphoid process. Patients prefer this incision to the rooftop or “Chevron” incision that rarely is needed. Inspection and palpation should exclude extrahepatic disease and assess intrahepatic disease. At this point, intraoperative ultrasound (IOUS) should be performed to determine the size and location of all tumor nodules. IOUS can help plan the resection to maximize the chance of obtaining a negative margin. With no contraindication to resection, the appropriate resection can be performed. Resections depend on the segments that need to be removed. A diagram of Couinaud's segments is in Fig. 46B-1.
The nomenclature for resections depends on the segments removed as summarized in Table 46B-1. Right hepatectomy is the most common major liver resection and it is described in detail below.
The right side of the liver is mobilized by dividing the right triangular ligament and the anterior and posterior leaflets of the right coronary ligament. The inferior vena cava (IVC) is exposed and small branches from the liver to the IVC are ligated and divided to facilitate exposure and avoid tearing. At this point, attention is focused on the porta hepatis for the hepatoduodenal dissection.
The gallbladder is removed and the bile duct is traced to the liver. The hepatic artery is identified and the right hepatic artery (RHA) isolated, usually anterior to the hepatic duct but occasionally posterior to the hepatic duct. The RHA is ligated and divided, carefully protecting the main and left hepatic arteries. The right hepatic duct is divided and the hepatic duct can be lifted anteriorly to the left to expose the portal vein (Fig. 46B-2). The junction of left and right portal vein (RPV) is exposed cautiously and a vessel loop is placed around the RPV. It is preferable to ligate and divide the RPV with sutures or a vascular stapler that ligates and cuts. At this point, inflow control is achieved and the liver will quickly demarcate such that the right liver will discolor. It now is reasonable to maximize outflow control.
An alternative method to achieve inflow control is to isolate and ligate the right portal pedicle intrahepatically. This can be done by incising the capsule in segments four and six and placing a finger around the pedicle in the liver. IOUS can monitor this technique. A vascular stapler can be applied to control the inflow.
The liver is rotated anteriorly and to the left. Small veins emptying directly from the liver into the IVC are ligated and divided. This might require suture ligation of the veins at the IVC as these branches are quite short. The surgeon should work from caudad to cephalad to secure these branches; usually there are about four pairs. A broad fibrous band of tissue extends from the IVC to the liver just caudad to the right hepatic vein (RHV). This tissue has small veins in it or next to it. There can be a larger accessory RHV in or next to this tissue. This band needs to be divided to expose the RHV (Fig. 46B-3).
A and B. Retrohepatic dissection to achieve control of hepatic veins.
Careful sharp and blunt dissection usually can isolate the RHV outside the liver such that it can be divided with clamps or a vascular stapler. The vascular stapler with 2.5-mm staples works well; clamps and Prolene sutures occasionally slip or tear producing significant bleeding. With inflow and outflow control, the parenchyma is transected to obtain a 1-cm margin. If the central venous pressure (CVP) is kept low, then backbleeding will be minimized. To minimize the risk of air embolism when the CVP is low during transection, the patient should be kept in a Trendelenberg position. There are several methods for parenchymal transection. The standard technique is “finger fracture” that requires fracturing the parenchyma with the index finger and thumb to define vessels and bile ducts. The vessels and ducts are ligated or clipped and the liver is expeditiously transected (Fig. 46B-4). Variations of the finger fracture technique use a Kelly clamp, closed scissors, or a metal suction device. The key is to use a method that works well for the surgical team such that one surgeon can do the fracturing while another surgeon secures the vessels. During this maneuver, bleeding can be minimized by occluding inflow at the porta hepatis as a Pringle maneuver with clamping for 10–15 minutes with 2–5 minutes of unclamping. This maneuver can be repeated until the liver has been divided. A normal liver without steatohepatitis should tolerate 45 minutes of normothermic ischemia.
Finger fracture technique. Posterosuperior intraparenchymal dissection of the RHV.
Other devices have been designed to divide the parenchyma. These include the ultrasonic dissector, the water jet dissector, the saline-linked radiofrequency (RF) dissecting sealer, the bipolar vessel sealing device, and the harmonic scalpel. Each device has its proponents. Some use these devices to meticulously and slowly divide the complete parenchyma of the liver, suturing, tying, or clipping vessels or ducts. Others use these devices to divide a portion of the parenchyma; when they are deep in the parenchyma and when the margin is not an issue, these surgeons switch to a finger fracture technique to finish the dissection. To expedite deep parenchymal division, many will use vascular staplers. Vascular staplers control vessels efficiently and they can be used for parenchymal transection. To perform transection of the right liver can require over 15 vascular stapler cartridges. The parenchymal transection can be performed in less than 10 minutes without the need for a Pringle maneuver. The staplers can rip vessels if not guided appropriately. The firm metal blade of the stapler should be introduced carefully; there should be no force required to introduce the stapler. The obvious argument against staplers is cost. If the stapler companies would reduce the costs of the staplers, many surgeons would use multiple loads of the vascular stapler to divide the liver. If two experienced surgeons use finger fracture, the cost of transection is small and the resection can be performed with little blood loss. If a liver surgeon performs finger fracture with an inexperienced resident, the time for transection and the blood loss can be considerable. The RF resection device (such as the Habib) ablates liver tissue that then can be cut with a knife or a bipolar cautery device. The problem with these devices are twofold: (1) cost—one RF resection device can cost as much as 30 or more stapler cartridges; and (2) vessels less than 5 mm in diameter can be ablated but larger vessels can bleed significantly from the holes of the electrodes. The RF resection devices are very effective for peripheral nonanatomic wedge resections and left lateral liver resections. Theoretically, the radiofrequency ablation (RFA) can treat microscopic tumor cells at the margin. The first laparoscopic liver resection with a RF resection device was done at the Brigham and Women's Hospital (BWH),1 but now most laparoscopic liver resections at the BWH are done with the staplers or a variation of the finger fracture method.
The above operation can be performed with a laparoscope either as a complete laparoscopic procedure or as a hand-assisted laparoscopic liver resection.2,3 Multiple methods of parenchymal transection can be performed laparoscopically. The vascular staplers work well with the use of a handport. A reason to use staplers to transect the liver during open liver resection is to become familiar with this technique for laparoscopic resection. The intra-abdominal pressure with pneumoperitoneum can tamponade some of the smaller venous bleeding. This nuisance bleeding can be controlled with the Argon Beam Coagulator, topical sealants, or with sutures as necessary. The Argon Beam Coagulator should be used with caution as a venous embolus with Argon does not dissipate as quickly as carbon dioxide. Draining the right upper quadrant usually is done for several days if there is concern about a possible bile leak.
Patients should be discharged in 4–5 days. Blood transfusions should be avoided, if possible, as the survival rate decreases after liver resection if transfusion is used.
Left hepatectomy essentially is the mirror image to right hepatectomy. A hilar dissection controls inflow (Fig. 46B-5). If the caudate lobe needs to be removed, it can be freed from the IVC facilitating isolation of the left hepatic vein (LHV). A stapler can be used to divide it. Alternatively, the parenchyma can be divided and the LHV can be secured during the parenchymal dissection (Fig. 46B-6).
Hilar dissection in left hepatectomy. A. Division of cystic duct and left hepatic duct; B. Division of left hepatic artery; C. Exposure of left portal vein; D. Division of left portal vein.
Completed transection of the parenchyma in left hepatectomy.