Plate 172

See Plate 171.

The patient's ability to tolerate a portacaval shunt procedure depends primarily upon the state of liver function at the time of the procedure. In general, every effort should be made to improve the patient's general nutrition and hepatic state before surgery. Several weeks of careful medical management of diet, diuretics, and activity are often necessary. After a careful history and physical examination, hepatic function studies and hepatosplanchnic hemodynamic determinations are obtained.

If the patient is bleeding, the acute phase of the hemorrhage from the gastrointestinal tract requires prompt control with sclerotherapy or with an intraesophageal pressure balloon. Vasopressin may be administered as a continuous intravenous infusion (20 to 40 units per hour) or as a selective intraarterial infusion (superior mesenteric artery at 0.1 to 0.4 unit per minute). In addition to vasopressin's efficiency in reducing portal pressure, it helps evacuate blood and fecal residue from the alimentary tract. If vasopressin is not administered, it is essential to remove old blood by means of colonic irrigation. This simplifies exposure and reduces the risk of ammonia intoxication. Nonabsorbable antibacterial agents are used to control nitrogen-splitting bacteria in the gastrointestinal tract. Blood volume should be restored preoperatively by careful use of blood, albumin, and lactated Ringer's solution. Fresh whole blood products, platelet transfusion, and vitamin K are sometimes indicated, depending upon the results of coagulation studies.

Liver function must be evaluated using a combination of clinical factors and laboratory studies. A history of jaundice or ascites indicates an increased surgical risk. Serum albumin should be above 3 g/dL and prothrombin time less than 1.5 times normal. The partial thromboplastin time and platelet count should be within normal limits. If there are any deviations from these values, correction should be attempted with vitamin K and parenteral administration of albumin, fresh frozen plasma, or whole blood. Diuretic therapy may be necessary in those patients with ascites. Appropriate steps must be taken to control electrolyte and acid-base balance, especially hypokalemic alkalosis. Coagulation deficits other than those associated with prothrombin may be corrected with fresh frozen plasma and platelet concentrate. At the time of surgery, 10 to 12 units of whole blood should be available.

Esophagoscopy and gastroscopy should be obtained routinely along with appropriate barium studies of the esophagus and stomach. Hepatosplanchnic hemodynamics can be determined by estimation of total hepatic blood flow, liver scan, hepatic vein catheterization, splenoportography, indirect portography, and visceral angiography. Total hepatic blood flow can be estimated using radionuclide scanning. Using hepatic vein catheterization, it is possible to determine the degree of portal hypertension and the amount of hepatopetal portal blood flow. Splenoportography is usually the single best source of estimating portal hemodynamics. Prerequisites for this study are that prothrombin time be less than 1.5 times normal and the operating room be available, should trouble from hemorrhage develop. This study will reveal the degree of portal hypertension, and according to the degree of opacification of the portal vein, it can give valuable information concerning the degree of compromise of portal blood flow to the liver. Information obtained from these hemodynamic studies may influence the choice of shunt to be performed.

A general anesthetic is required. The major hazards during anesthesia are hypoxia and hypotension. These hazards are more significant than the effect of any particular anesthetic agent commonly employed today. However, there is sufficient reason to suspect the possible danger of using halogenated compounds in patients with impaired liver function, and therefore these agents should not be used during the operation. The other commonly employed general anesthetic agents and the muscle relaxants appear to have no adverse effect on liver function. Provision should be made for the rapid administration of blood and fluids in adequate amounts.

Elevation of the right side to a 30-degree angle aids in extension of the right subcostal incision into the flank and provides additional exposure for this procedure. If the choice between the portacaval and splenorenal shunt has not been made before operation, the patient should be left in the supine position so that either procedure may be carried out merely by extending the initial central incision in the appropriate direction.

The skin is cleansed higher than the nipples and well down to the symphysis. Likewise, the chest, particularly on the left side, should be prepared, since an extension of the incision into the thorax may be necessary.

Along the right subcostal margin, an incision is made crossing the left rectus muscle and extending well into the flank (Figure 1A). Satisfactory exposure may also be obtained with a large midline incision that extends to the xyphoid (Figure 1B).

The routine exploration is carried out after the peritoneal cavity is opened. The diagnosis of portal hypertension is confirmed by catheterization of an omental vein (Figure 2), preferably toward the stomach. This is useful even if splenic pulp pressure has been measured preoperatively, since measurement at this time will permit a more valid comparison of preshunt and postshunt pressures. The pressure usually will measure 30 cm of saline or higher above the portal vein level. Considerably lower pressures would not indicate the necessity or desirability of a shunting procedure. If a previous splenoportogram has shown the presence of a satisfactory portal vein, dissection is begun by mobilizing the duodenum. If the presence of a suitable portal vein for shunting is in doubt, this vein should be isolated and surveyed with a portal venogram before exposure of the vena cava. Collateral venous networks are usually enlarged considerably over the posterior peritoneum and subject to increased pressure. Therefore, this normally avascular area may be quite the opposite, and dissection during the Kocher maneuver should progress by clamping and ligating the peritoneal surfaces, rather than by making the usual simple incision lateral to the descending portion of the duodenum (Figure 3). This precaution applies to all dissection during this procedure in the retroperitoneal space and in the hepatoduodenal ligament. The inferior vena cava ordinarily is exposed without great difficulty (Figure 4). A required additional exposure may be obtained in the presence of an enlarged caudate lobe of the liver by resecting a portion of that lobe. Through-and-through mattress sutures of 00 silk are placed to control the bleeding before the liver is divided. The caudate lobe is freed from the vena cava, and the veins encountered are ligated (Figures 5 and 6). Argon-beam electrocoagulation may be useful.

Next >