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 ...