© 2004 WebMD, Inc. All rights reserved.                                                           ACS Surgery: Principles ...
© 2004 WebMD, Inc. All rights reserved.                                                                   ACS Surgery: Pri...
© 2004 WebMD, Inc. All rights reserved.                                                                                ACS...
© 2004 WebMD, Inc. All rights reserved.                                                   ACS Surgery: Principles and Prac...
© 2004 WebMD, Inc. All rights reserved.                                                   ACS Surgery: Principles and Prac...
© 2004 WebMD, Inc. All rights reserved.                                                                  ACS Surgery: Prin...
© 2004 WebMD, Inc. All rights reserved.                                                        ACS Surgery: Principles and...
© 2004 WebMD, Inc. All rights reserved.                                                        ACS Surgery: Principles and...
© 2004 WebMD, Inc. All rights reserved.                                                       ACS Surgery: Principles and ...
© 2004 WebMD, Inc. All rights reserved.                                                    ACS Surgery: Principles and Pra...
© 2004 WebMD, Inc. All rights reserved.                                                    ACS Surgery: Principles and Pra...
© 2004 WebMD, Inc. All rights reserved.                                                                            ACS Sur...
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Acs0510 Portal Hypertension 2004

  1. 1. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 5 GASTROINTESTINAL TRACT AND ABDOMEN 10 PORTAL HYPERTENSION — 1 10 PORTAL HYPERTENSION Clifford S. Cho, M.D., and Layton F Rikkers, M.D., F.A.C.S. . Clinical strategies for managing portal hypertension have under- cellular necrosis results in marked elevations in serum amino- gone significant refinements over the past half-century. This evo- transferases that are readily observed in patients with chronic lution has been driven by advances in our understanding of the active viral or alcoholic hepatitis. An alanine aminotransferase physiology of both the disease and the therapies employed against (ALT)–aspartate aminotransferase (AST) ratio of 2 or higher is it. Today, clinical management of the portal hypertensive patient often seen in patients with alcoholic liver disease. is a truly multidisciplinary endeavor, requiring the coordinated The Child-Pugh scoring system is a useful tool for quantifying efforts of skilled intensivists, gastroenterologists, hepatologists, hepatic functional reserve [see Table 2].1 Based on total bilirubin interventional radiologists, and surgeons. Nevertheless, portal and albumin levels, PT (INR), and the clinical severity of ascites hypertension and its manifold complications remain some of the and hepatic encephalopathy, the Child-Pugh score predicts both most vexing problems encountered in modern medicine and the likelihood of variceal hemorrhage and its anticipated mortali- surgery. ty. A newer assessment tool, the Model for End-Stage Liver In this chapter, we briefly review portal venous anatomy and Disease (MELD) scoring system, which takes the degree of renal the pathophysiology of portal hypertension [see Sidebar Portal impairment and the cause of hepatic dysfunction into account, Hypertension: Anatomic and Physiologic Considerations]; how- has also been used to predict outcomes in cirrhotic patients.2 ever, our main focus is on current practical approaches to man- aging portal hypertension and its associated sequelae (variceal bleeding, ascites, and hepatic encephalopathy). Of particular rele- Management of Variceal Bleeding vance to surgeons is that the role of surgical therapy has shifted The prognosis of variceal hemorrhage depends on the presence significantly. Operative treatment now occupies only the final or absence of underlying cirrhosis. In noncirrhotic patients, the steps in modern treatment protocols for portal hypertension— mortality associated with a first episode of variceal hemorrhage that is, it serves as a form of salvage for intractable cases that are ranges from 5% to 10%; in cirrhotic patients, the range is from refractory to other forms of therapy. 40% to 70%. Esophagogastric varices ultimately develop in approximately one half of cirrhotic patients, and bleeding epi- sodes occur in approximately one third of cirrhotic patients with Clinical Evaluation varices. If the initial hemorrhagic episode resolves spontaneously, The ultimate aims of diagnostic evaluation in a patient with 30% of patients experience rebleeding within 6 weeks, and 70% portal hypertension are (1) to determine the cause of portal hy- experience rebleeding within 1 year. It is noteworthy that overall pertension [see Table 1], (2) to estimate hepatic functional reserve, mortality in patients who survive 6 weeks after an episode of (3) to define the portal venous anatomy and assess hemodynam- variceal bleeding is statistically indistinguishable from that in per- ic status, and (4) to identify the site of GI hemorrhage (if present). sons who have never experienced such an episode. Any history of chronic alcohol abuse, hepatitis, or exposure to hepatotoxins raises the suspicion of cirrhotic liver disease. Confir- matory evidence of chronic liver disease on physical examination Table 1 Causes of Portal Hypertension may be found in the form of jaundice, chest wall spider angioma- ta, palmar erythema, Dupuytren contractures, testicular atrophy, Extrahepatic or gynecomastia. Ascites, splenomegaly, caput medusae, encepha- Portal vein thrombosis lopathic alterations in mental status, and asterixis are all sugges- Splenic vein thrombosis tive of portal hypertension. Intrahepatic Presinusoidal obstruction Congenital hepatic fibrosis Primary biliary cirrhosis Investigative Studies Sarcoidosis Laboratory studies can also provide indicators of hepatic dys- Schistosomiasis function.The hypersplenism that often accompanies cirrhosis can Steatohepatitis produce mild to moderate pancytopenia. Anemia may also reflect Sinusoidal obstruction Wilson disease variceal hemorrhage, hemolysis, or simply the chronic malnutri- tion or bone-marrow suppression associated with chronic alco- Extrahepatic Budd-Chiari syndrome holism. Associated hyperaldosteronism, emesis, or diarrhea may Right heart failure give rise to electrolyte derangements, including hyponatremia, Intrahepatic hypokalemia, metabolic alkalosis, and prerenal azotemia. Coagu- Postsinusoidal obstruction Hemochromatosis lopathy is usually attributable to chronic deficiencies in clotting Laennec (alcoholic) cirrhosis factors that are normally synthesized by the liver; thus, elevation Secondary biliary cirrhosis of the prothrombin time (PT) or the international normalized Posthepatitic cirrhosis ratio (INR) often reflects the degree of chronic hepatic impair- Arteriovenous fistula ment. Similarly, the degree of hyperbilirubinemia can be a mea- High-flow states Massive splenomegaly sure of both acute and chronic hepatic dysfunction. Hepato-
  2. 2. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 5 GASTROINTESTINAL TRACT AND ABDOMEN 10 PORTAL HYPERTENSION — 2 Portal Hypertension: Anatomic and Physiologic Considerations Anatomy of Portal Venous System and fibrosis causing hepatic venule compression; however, the demonstration of collagen deposition within Disse’s space in cirrhotic The 6 to 8 cm portal vein is formed by the confluence of the splenic livers suggests the presence of a concurrent sinusoidal locus as well. vein and the superior mesenteric vein behind the pancreatic neck and is the most posterior component of the portal triad in the hepatoduo- Similarly, the extrahepatic postsinusoidal Budd-Chiari syndrome often denal ligament. The inferior mesenteric vein, though prone to anatom- produces cirrhotic changes that create a secondary intrahepatic sinu- ic variation, typically enters the splenic vein at or near its confluence soidal cause of portal hypertension. with the superior mesenteric vein. The left gastric vein drains the less- Normal portal vein pressures range from 3 to 6 mm Hg, with daily er curvature of the stomach and typically enters the portal vein near circadian variation. Transient pressure elevations are commonly de- its origin. tected after eating, exercise, and Valsalva maneuvers. Sustained ele- The unique dual blood supply of the liver, consisting of the portal vations in portal vein pressure to levels higher than 10 mm Hg can re- vein and the hepatic artery, is coordinated by a compensatory regula- sult in gradual shunting of blood from the portal circulation into the tory system. Total hepatic blood flow, which averages 1.5 L/min, ac- adjacent low-pressure systemic circulation via certain collateral ves- counts for about one quarter of cardiac output. The portal circulation sels. Formation and expansion of these collaterals are thought to typically accounts for two thirds of this hepatic blood flow but provides progress by means of active angiogenesis. The most clinically signifi- only one third of hepatic oxygen content. Portal blood flow is an indi- cant of these vessels are the left gastric vein and the short gastric rect function of splanchnic arterial vasoconstriction and vasodilatation; veins, which decompress hypertensive portal flow into the azygous in contrast, hepatic arterial flow is directly regulated by sympathetic in- vein via esophageal and gastric submucosal veins, respectively. Col- nervation and circulatory catecholamines. As a result, changes in por- tal blood flow resulting from splanchnic circulatory changes can be lateral filling from the left portal vein to the epigastric veins through re- compensated for by hepatic arteriolar dilatation or constriction. In this canalization of the obliterated umbilical vein can result in the caput manner, hepatic arterial autoregulatory vasodilatation can preserve medusae pattern of dilated abdominal wall veins that is readily appre- normal hepatic blood flow even in the setting of significant decreases ciated on physical examination. Portosystemic shunting also takes in portal flow resulting from shock, hypovolemia, splanchnic vasocon- place via retroperitoneal and anorectal collateral vessels. striction, or portosystemic shunting. Although hepatic oxygenation Long-term shunting of high-pressure portal venous blood through may be preserved in this fashion, augmented hepatic arterial flow systemic venous vessels evolved for low-pressure capacitance can does not replace the essential regulators of hepatic metabolism and eventually result in variceal dilatation of the latter. Sustained portal growth (e.g., insulin) that are found in portal venous blood. As a con- pressures of 12 mm Hg or higher are necessary to produce sufficient sequence, prolonged restriction of portal perfusion, as is seen with distention of these thin-walled vessels to induce rupture. Variceal rup- portal hypertension–induced portosystemic collateralization or surgi- ture presents as GI hemorrhage. Although varices can form through- cally created portosystemic shunts, results in deprivation of these he- out the entire length of the alimentary canal, the majority of portal hy- patotrophic factors, which can ultimately contribute to hepatic atrophy pertensive bleeding is from esophagogastric varices. Unfortunately, and failure. prediction of variceal hemorrhage can be difficult; only one third to Pathophysiology of Portal Hypertension one half of patients with portal pressures exceeding 12 mm Hg will Traditionally, the various causes of portal hypertension have been cat- experience bleeding episodes. On the basis of Laplace’s law, one egorized according to the anatomic locus of increased resistance to can expect variceal size, intraluminal variceal pressure, and overlying portal flow. In reality, this categorization is an oversimplification, in that epithelial wall thickness to be predictive of the likelihood of variceal individual causes have been shown to exert their inciting effects at rupture. Clinically, variceal size and the presence and severity of red- multiple levels. For example, portal hypertension arising from alcoholic wale markings on upper GI endoscopy (a marker of epithelial thick- cirrhosis has classically been considered an intrahepatic postsinu- ness) can be used in conjunction with the Child-Pugh score to predict soidal obstructive process resulting from regenerative hepatic nodules the likelihood of variceal hemorrhage.54 Further risk stratification is based on the extent of hepatic disease often necessitates vigorous replacement of circulatory vol- decompensation. The mortality associated with variceal hemor- ume and coagulation factors, often involving infusion of colloids rhage is 5% for patients with Child class A cirrhosis, 25% for and transfusion of fresh frozen plasma and packed red blood cells. those with Child class B cirrhosis, and over 50% for those with Antibiotic prophylaxis therapy is recommended because of the Child class C cirrhosis.The likelihood of recurrent hemorrhage is propensity of bacterial infections to develop in patients with 28% for patients with Child class A cirrhosis, 48% for those with chronic liver disease after bleeding episodes. Child class B cirrhosis, and 68% for those with Child class C cir- rhosis.3 Pharmacologic Therapy First-line pharmacotherapy for acute variceal bleeding relies TREATMENT OF ACUTE VARICEAL HEMORRHAGE on the long-acting somatostatin analogue octreotide, which has Management of acute variceal hemorrhage [see Figure 1] begins been shown to decrease splanchnic blood flow and portal venous with the establishment of adequate airway protection. The risk of pressure. Octreotide is administered in a 250 µg I.V. bolus, fol- aspiration and consequent respiratory deterioration is particular- lowed by infusion of 25 to 50 µg/hr for 2 to 4 days.4 In addition, ly high among patients with hepatic encephalopathy and those vasopressin, a strong splanchnic vasoconstrictor, has been shown undergoing endoscopic therapy. Accordingly, the threshold for to control approximately 50% of acute variceal bleeding early endotracheal intubation should be low, particularly if episodes.4,5 Vasopressin is typically administered in a 20 U I.V. endosopic therapy is considered. As with all cases of brisk hemor- bolus over 20 minutes, followed by infusion of 0.2 to 0.4 U/min. rhage, adequate venous access is mandatory; placement of a cen- The therapeutic benefits of octreotide and vasopressin appear to tral venous catheter for accurate volume assessment is particular- be similar, though the side-effect profile of octreotide appears to ly useful in cases of major bleeding.The presence of chronic liver be much lower than that of vasopressin monotherapy.4 Adjunctive
  3. 3. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 5 GASTROINTESTINAL TRACT AND ABDOMEN 10 PORTAL HYPERTENSION — 3 use of nitroglycerin at an initial rate of 50 µg/min (titrated accord- Patient has acute variceal hemorrhage ing to blood pressure tolerance) effectively reduces the cardiac complications of vasopressin and thereby facilitates its adminis- Protect airway. tration.6 The long-acting vasopressin analogue terlipressin has Initiate resuscitation. been shown to be approximately as effective as octreotide.7 Obtain I.V. access. Administer prophylactic antibiotics. Endoscopic Therapy Endoscopic treatment, in the form of sclerosant injection or band ligation, has become a standard form of therapy for acute Give octreotide (250 µg bolus, then 25–50 µg/hr variceal hemorrhage. Experienced endoscopists achieve initial con- for 2–4 days). trol of hemorrhage in 74% to 95% of cases; however, rebleeding Alternatively, give vasopressin (20 U bolus, then rates ranging from 20% to 50% are typically observed. 0.2–0.4 µg/min) plus nitroglycerin (initially 50 µg/min, titrated to BP). In endoscopic sclerotherapy, a sclerosant—typically either 5% sodium morrhuate (more common in the United States) or 5% ethanolamine oleate (more common in Europe and Japan)—is injected either intravariceally to obliterate the varix or para- Hemorrhage Hemorrhage is not controlled variceally to induce submucosal fibrosis and thereby prevent is controlled variceal rupture. Three prospective, randomized, controlled trials Perform endoscopic variceal demonstrated that endoscopic sclerotherapy, compared with tra- ligation or endoscopic sclerotherapy. ditional balloon tamponade, achieved better initial hemorrhage control, resulted in fewer episodes of rebleeding, and, in selected cohorts of patients, led to improved long-term survival.8-10 Fur- thermore, routine use of balloon tamponade after sclerotherapy Hemorrhage is not controlled Hemorrhage is controlled appeared not to confer any additional therapeutic benefit.8 There are, however, significant risks associated with the use of endo- Consider TIPS. scopic sclerotherapy, including pulmonary complications, tran- sient chest pain, esophageal stricture formation with recurrent sclerotherapy, iatrogenic portal vein thrombosis, hemorrhagic esophageal ulceration, bacteremia, and esophageal perforation.11 TIPS is available TIPS is unavailable or Partially in response to the potential complications of endo- and successful unsuccessful scopic sclerotherapy, endoscopic variceal band ligation has been Perform balloon tamponade. advocated as a sclerosant-free therapeutic alternative.The limited data comparing the two approaches suggest a trend toward fewer rebleeding episodes, fewer endoscopic interventions, and signifi- cantly lower procedure-related morbidity and overall mortality Hemorrhage is not Hemorrhage after variceal ligation.12 controlled is controlled Pharmacologic versus Endoscopic Therapy Two meta-analyses compared medical pharmacotherapy with emergency sclerotherapy as first-line treatment of acute variceal Assess patient's candidacy hemorrhage.13,14 No significant differences between the two ap- for transplantation. proaches were demonstrated with respect to initial hemorrhage Patient is future Patient is not future Table 2 Child-Pugh System for Classifying transplant candidate transplant candidate Cirrhosis Construct mesocaval Score* interposition shunt or DSRS. Parameter 1 2 3 Ascites is intractable Ascites is absent Total bilirubin (mg/dl) 1–2 2.1–3 ≥ 3.1 or manageable Construct side-to-side Albumin (g/dl) ≥ 3.5 2.8–3.5 ≤ 2.7 portosystemic shunt. Construct end-to-side INR < 1.7 ≥ 2.4 portacaval shunt. 1.8–2.3 or PT (sec) 1–4 4.1–6 ≥ 6.1 Figure 1 Algorithm outlines treatment of acute variceal bleeding. Ascites None Mild Moderate control or mortality, though treatment-related complications ap- Hepatic encephalopathy None Mild Advanced peared to be significantly more common after sclerotherapy. On *Class of cirrhosis is determined on the basis of total points scored: 5 to 6 points, class A; the basis of these studies, it has been suggested that endoscopic 7 to 9 points, class B; 10 to 15 points, class C. treatment should be reserved for cases of pharmacotherapeutic INR—international normalized ratio PT—prothrombin time failure or that pharmacologic therapy should be initiated in situa-
  4. 4. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 5 GASTROINTESTINAL TRACT AND ABDOMEN 10 PORTAL HYPERTENSION — 4 tions where endoscopy is not immediately available. At present, however, it is more common for the two forms of treatment to be employed concurrently. Pharmacotherapy is often initiated in prep- aration for endoscopy; early mitigation or control of variceal hem- orrhage can make endoscopic visualization and intervention easi- er, safer, and more effective. Indeed, administration of somato- statin before and after endoscopic sclerotherapy has been shown to improve treatment efficacy and decrease transfusion require- ments in comparison with endoscopic sclerotherapy alone.15,16 Balloon Tamponade Although the devices used for balloon tamponade have evolved through numerous different forms over the years, all of them rely on the same basic principle—application of direct upward pres- sure against varices at the esophagogastric junction. Patients for whom balloon tamponade is considered should be intubated endotracheally to prevent airway occlusion and aspiration. The tube is inserted into the stomach, and the gastric balloon is par- tially inflated with 40 to 50 ml of air [see Figure 2]. An abdominal radiograph is obtained to ensure that the gastric balloon is cor- rectly positioned within the stomach and below the diaphragm. This balloon is then further inflated until it holds 300 ml of air, and the tube is pulled upward with external traction. If hemor- rhage is not controlled at this point, the esophageal balloon is Figure 2 The Sengstaken-Blakemore tube permits tamponade inflated to a pressure of 35 to 40 mm Hg. Suction drainage is of both the distal esophagus and the gastric fundus. An accesso- applied to both the esophageal port and the gastric port to mini- ry nasogastric tube permits aspiration of secretions from above mize aspiration risk and monitor for recurrent hemorrhage. the esophageal balloon. When properly applied, direct tamponade therapy is 90% effec- tive in controlling acute hemorrhage. The primary limitation of such therapy is that bleeding resumes in as many as 50% of Given the relative paucity of data on the use of TIPS as first- patients after takedown and removal of the balloon. Furthermore, line therapy for acute variceal hemorrhage, it is logical to recom- serious potential complications (e.g., gastric or esophageal perfo- mend that TIPS be employed in cases of pharmacotherapeutic ration, aspiration, and airway obstruction) result in treatment- and endoscopic failure; the efficacy of TIPS as salvage therapy in related mortalities as high as 20%.17,18 Nevertheless, in cases of this setting is well documented.22 Contraindications to TIPS in- brisk variceal hemorrhage refractory to pharmacologic and endo- clude right heart failure and polycystic liver disease. Portal vein scopic therapy, balloon tamponade may have a role to play as a thrombosis is a relative contraindication. bridge therapy to more definitive forms of treatment, such as trans- Surgical Therapy jugular intrahepatic portosystemic shunting (TIPS) (see below) or operative intervention. The role of surgical management in the treatment of acute variceal bleeding has changed considerably over the past 50 years. Transjugular Intrahepatic Portosystemic Shunting At present, operative intervention is reserved for cases that have A nonoperative technique for creating an intrahepatic por- proved refractory to pharmacotherapy, endoscopy, balloon tam- tosystemic fistula for decompression of portal hypertension was ponade, and TIPS. Numerous operations have been developed, proposed in 196919 and first performed in 1982.20 As currently each with its own merits and flaws. practiced, TIPS is performed by (1) cannulating a hepatic vein Esophageal transection with an end-to-end anastomosis (EEA) (usually the right hepatic vein) via the internal jugular vein, (2) stapler has been employed as a means of interrupting blood flow passing a needle from the hepatic vein through the liver parenchy- into bleeding esophageal varices. In this technique, the esophagus ma and into a portal vein branch, (3) passing a guide wire through is mobilized, and the EEA stapler is passed into the distal esoph- the needle, (4) dilating the needle tract with a balloon passed over agus through a gastrotomy.With care taken not to injure the vagus the guide wire, and (5) stenting the tract to a desired diameter, nerves and the external periesophageal veins that may be provid- thus effectively constructing a nonselective side-to-side portosys- ing collateral venous drainage, a full-thickness segment of the temic shunt [see Figure 3]. esophagus is transected.When this technique is used on an emer- Experience with TIPS in the setting of acute variceal hemor- gency basis in a patient with acutely bleeding varices, operative rhage is limited. However, one meta-analysis of studies comparing mortality is as high as 76%, and the rate of operative complica- the efficacy of conventional endoscopic therapy (with or without tions (e.g., esophageal perforation, stricture, esophagitis, and in- pharmacotherapy) with that of TIPS in treating acute hemor- fection) is approximately 26%.23 Accordingly, esophageal transec- rhagic episodes demonstrated a significant improvement in hem- tion is not commonly advocated as a useful form of surgical ther- orrhage control with TIPS.21 Unfortunately, this improvement apy for acutely bleeding esophageal varices. came at the cost of increased rates of hepatic encephalopathy as a In contrast, portosystemic shunting operations have been wide- consequence of the nonselective shunting of portal venous flow ly used to treat acute variceal hemorrhage.The largest single body into the systemic venous circulation. Furthermore, the meta- of data on this practice comes from Orloff and associates,24 who analysis failed to demonstrate a significant improvement in over- reported remarkable outcomes—71% survival at 10 years—in all mortality with TIPS.21 400 consecutive patients undergoing emergency portacaval shunt
  5. 5. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 5 GASTROINTESTINAL TRACT AND ABDOMEN 10 PORTAL HYPERTENSION — 5 operations (mostly side-to-side) over a 28-year period. Unfortu- PREVENTION OF RECURRENT VARICEAL HEMORRHAGE nately, these investigators’ experience stands in stark contrast to that of most other groups, who uniformly reported operative mor- Pharmacotherapy talities of about 40% and 5-year survival rates of about 30%. Without further treatment, the likelihood that hemorrhage will Another potential drawback to urgent operative shunting is the recur within 1 year after control of an acute episode of variceal manipulation and dissection that are often necessary in the region bleeding is approximately 70%.26 The pharmacologic maneuver of the porta hepatis: these measures can result in adhesions and that has been used most extensively to prevent recurrent variceal scarring, which can complicate future orthotopic liver transplan- bleeding [see Figure 4] is nonselective beta-adrenergic blockade, tation. For this reason, some surgeons have advocated using the most commonly with propranolol. Although beta blockade has mesocaval interposition shunt [see Prevention of Recurrent Vari- been shown to lower portal pressure and hepatic vein wedge pres- ceal Hemorrhage, Surgical Therapy, Portosystemic Shunts, Non- sure, its ability to induce this effect is variable and unpre- selective Shunts, below] in the emergency setting because of its dictable.27 Nevertheless, a meta-analysis of multiple trials study- ability to lower portal pressure without complicating the hilar dis- ing the effectiveness of nonselective beta blockade demonstrated section that will be necessary if transplantation is carried out a significant decline in recurrent bleeding and a trend toward later.25 In addition, surgeons familiar with the distal splenorenal improved overall survival.4 Patients with decompensated hepatic shunt (DSRS) can employ this selective shunt in some cases of function appear to derive less benefit from beta blockade, possi- acute variceal hemorrhage unaccompanied by refractory ascites. bly because of the downregulation of beta-adrenergic receptors a b Hepatic Vein Portal Vein c d Figure 3 Depicted is the procedure for performing TIPS. (a) A needle is passed under radio- logic guidance from a hepatic vein into a major portal venous branch, and a guide wire is advanced through this needle. (b) A balloon is passed over the guide wire, creating a tract in the hepatic parenchyma. (c) An expandable stent is placed though this tract. (d) The effective result is a nonselective portosystemic shunt.
  6. 6. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 5 GASTROINTESTINAL TRACT AND ABDOMEN 10 PORTAL HYPERTENSION — 6 Patient is at risk for recurrent variceal hemorrhage Assess patient's candidacy for transplantation. Patient is future transplant candidate Patient is not future transplant candidate Give propranolol, with or without ISMN. Give propranolol, with or without ISMN. Patient has Child class A or Patient has more severe Child Tertiary care is readily Tertiary care is not mild Child class B cirrhosis class B or Child class C cirrhosis accessible readily accessible Perform liver transplantation. Provide long-term Consider TIPS as bridge therapy. endoscopic therapy. Tertiary care is readily Tertiary care is not Hemorrhage Hemorrhage recurs accessible readily accessible does not recur Provide long-term Construct DSRS. endoscopic therapy. Assess patient's candidacy for operative intervention. Hemorrhage Hemorrhage recurs does not recur Patient is good operative candidate Patient is poor Assess status of disease. operative candidate Assess status of disease. Perform TIPS. Cirrhosis is Cirrhosis progresses Cirrhosis is Ascites is Ascites is Splanchnic vein stable stable intractable controlled thrombosis rules out Perform liver transplantation. shunt procedure Construct DSRS. Construct Construct DSRS. Consider TIPS as bridge nonselective shunt. therapy. Perform esophagogastric devascularization. Figure 4 Algorithm outlines prevention of recurrent variceal bleeding. associated with cirrhosis.28 Adjunctive use of the long-acting Transjugular Intrahepatic Portosystemic Shunting vasodilator isosorbide 5-mononitrate (ISMN) appears to potenti- TIPS [see Figure 3] has been employed to prevent recurrent ate the efficacy of propranolol therapy.29 episodes of variceal hemorrhage, particularly as a form of bridge Endoscopic Therapy therapy for patients awaiting orthotopic liver transplantation. The potential advantage TIPS has over surgical portosystemic shunting Repeated endoscopic therapy with sclerosant injection or is the ability to decompress the portal system without the risks asso- band ligation has been advocated as a means of completely erad- ciated with general anesthesia and without postoperative complica- icating esophageal varices. Once the varices are eliminated, rou- tions.The major limitation of TIPS is the shunt stenosis (caused by tine endoscopy is performed at 6- to 12-month intervals to pre- neointimal hyperplasia or thrombosis) that occurs in as many as vent recurrent hemorrhage. Compared with medical treatment, 50% of patients in the first year after the procedure. Fortunately, long-term endoscopic therapy results in fewer rebleeding epi- most such episodes of stenosis are amenable to balloon dilatation sodes.4 Nevertheless, approximately one half of endoscopically or secondary shunt insertion; however, 10% to 15% of TIPS recip- treated patients eventually experience recurrent hemorrhage, ients experience total shunt occlusion that cannot be reversed. usually within the first year. Approximately one third of patients Furthermore, TIPS functions as a nonselective shunt, leading to treated with repeated endoscopy ultimately must be converted to hepatic encephalopathy in approximately one third of patients.32 another form of therapy because of unrelenting major bleed- Meta-analytic comparison of TIPS with endoscopic therapy ing.30,31 For this reason, such extended endoscopic surveillance indicates that rebleeding episodes are markedly reduced in pa- and treatment should be reserved for compliant patients who live tients treated with TIPS, but at the cost of a higher incidence of in proximity to tertiary medical care and should be administered encephalopathy and a shunt malfunction rate of at least 50%.That with the understanding that conversion to a more definitive form the efficacy of TIPS is relatively short-lived makes this modality an of therapy may be necessary if endoscopy fails. ideal form of bridge therapy for patients who are awaiting ortho-
  7. 7. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 5 GASTROINTESTINAL TRACT AND ABDOMEN 10 PORTAL HYPERTENSION — 7 topic liver transplantation or those who have severe hepatic blood flow into the liver. Consequently, the encephalopathy rates decompensation and thus are unlikely to live long enough to expe- are no different from those observed after end-to-side portacaval rience failure of TIPS. TIPS can reduce the number of bleeding shunting. Side-to-side portacaval shunting does offer the benefit episodes for patients on the transplant waiting list. In addition, the of decompressing the hepatic sinusoidal pressure via reversed significant reduction in portal pressure produced by TIPS techni- (i.e., hepatofugal) flow of blood from the liver into the portal vein. cally facilitates future liver transplantation. Finally, unlike surgical Because transudation of interstitial fluid from both the liver and shunts,TIPS is completely removed at the time of recipient native the intestines is thought to contribute to ascites formation, better hepatectomy. control of ascites is achieved with a side-to-side portacaval shunt, which effectively decompresses both the splanchnic veins and the Surgical Therapy intrahepatic sinusoids, than with an end-to-side portosystemic Surgical therapy is the most effective method of controlling shunt, which decompresses only the splanchnic veins.The side-to- portal hypertension and preventing recurrent variceal hemor- side portacaval shunt is therefore also recommended for patients rhage. The operative procedures available to the surgeon have with Budd-Chiari syndrome, in whom an end-to-side portacaval undergone numerous modifications and become more effective shunt would not relieve intrahepatic congestion resulting from over the years. Review of the surgical experience reveals that with hepatic venous outflow occlusion. Otherwise, no significant out- the onset of alternative modalities (e.g., TIPS and transplanta- come differences between end-to-side and side-to-side portacaval tion), the risk status of patients undergoing surgical therapy (as shunts have been documented.The end-to-side variant is, howev- predicted by Child’s classification) and the frequency of emer- er, technically easier to construct. gency operations have steadily declined. As a result, the incidence Placement of an interposition mesocaval shunt [see Figure 5c] of postoperative hepatic encephalopathy has gradually fallen and composed of prosthetic or autogenous vein grafts offers the tech- overall survival has gradually improved.33 Surgical options for the nical advantages of avoiding hilar dissection (thereby making fu- prevention of recurrent variceal hemorrhage in patients with por- ture liver transplantation less complicated) and permitting inten- tal hypertension may be divided into three categories: (1) por- tional shunt ligation in the event of refractory postoperative en- tosystemic shunt procedures, (2) esophagogastric devasculariza- cephalopathy. Like the side-to-side portacaval shunt, the interpo- tion, and (3) orthotopic liver transplantation. sition shunt functions physiologically as a nonselective shunt because of the hepatofugal portal venous blood flow. The major Portosystemic shunts Surgical portosystemic shunting pro- drawback to the interposition shunt is shunt thrombosis, which vides a means of decompressing the hypertensive portal venous may develop in as many as 35% of cases. system into the low-pressure systemic venous circulation. The conventional (proximal) splenorenal shunt [see Figure 5d] Diversion of portal blood flow from the liver also deprives the liver was initially advocated as a means of decompressing portal venous of important hepatotrophic hormones that are present in portal flow while retaining hepatopedal hepatic portal perfusion. This venous blood while routing cerebral toxins normally metabolized shunt is constructed by performing a splenectomy and anasto- by the liver directly into the systemic circulation. As a result, the mosing the proximal splenic vein to the left renal vein. Physiologic primary complications of surgical portosystemic shunting are ac- testing of patent conventional splenorenal shunts suggests that celerated hepatic dysfunction and hepatic encephalopathy. they eventually divert all portal flow into the renal vein and there- Primarily in an attempt to minimize these adverse sequelae, vari- fore effectively function as nonselective shunts. Indeed, long-term ous forms of portosystemic shunting operations have evolved, rates of hepatic encephalopathy appear to be no lower after con- which may be classified as nonselective shunts, selective shunts, or ventional splenorenal shunting than after portacaval shunting.38 partial shunts. Shunt occlusion develops in about 18% of cases.39 In short, nonselective portosystemic shunts are an effective Nonselective shunts. The classic nonselective portosystemic means of controlling variceal hemorrhage in cases that are refrac- shunt is the end-to-side portacaval shunt (the so-called Eck fistu- tory to other therapeutic approaches. Given the absence of any la) [see Figure 5a].This is the only nonselective shunt that has been major differences in the rate of encephalopathic complications rigorously compared with conventional nonoperative therapy. Sev- after the various nonselective shunts, the choice of a nonselective eral randomized, controlled trials demonstrated superior control of shunting procedure should be based on the surgeon’s technical bleeding after operative shunting: 9% to 25% of patients experi- familiarity with the operations and on the patient’s candidacy for enced rebleeding after portacaval shunting (mostly related to non- future transplantation. The end-to-side portacaval shunt can be variceal hemorrhage or shunt thrombosis), whereas 65% to 98% constructed relatively quickly but should be avoided in patients of patients experienced rebleeding after medical therapy.34-37 who have intractable ascites or Budd-Chiari syndrome and those Markedly higher rates of spontaneous posttreatment encephalopa- who may subsequently undergo liver transplantation.The side-to- thy were reported in the operative shunt groups; however, the side portacaval shunt may provide better control of ascites but is overall rates of encephalopathy did not differ between the opera- technically more challenging to construct and should also be tive groups and the medical groups, because the encephalopathy avoided if future transplantation is an option. The interposition seen in the medically treated patients (mainly attributable to hem- mesocaval shunt is relatively easy to construct and avoids hepatic orrhage and infection) eventually became equivalent to that seen hilar dissection but is associated with a relatively high rate of shunt in the surgically treated patients. There were trends toward im- occlusion when a nonautogenous conduit is used. The conven- proved overall survival in the surgical groups, but these trends did tional splenorenal shunt also avoids hilar dissection but is associ- not attain statistical significance. ated with a high shunt occlusion rate and is technically challeng- The side-to-side portacaval shunt [see Figure 5b] maintains the ing to construct. anatomic continuity of the portal vein as it passes into the liver. However, the high sinusoidal resistance typically present in the Selective shunts. In response to the postoperative complications setting of cirrhosis effectively renders this shunt a nonselective seen after nonselective portosystemic shunting (hepatic en- one, with no measurable antegrade (i.e., hepatopedal) portal cephalopathy and hepatic failure), Warren and colleagues intro-
  8. 8. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 5 GASTROINTESTINAL TRACT AND ABDOMEN 10 PORTAL HYPERTENSION — 8 a b c d Splenectomy 1 3 2 Figure 5 Nonselective portosystemic shunts either immediately or eventually divert all portal blood flow from the liver into the systemic venous circulation. Shown are the four main variants: (a) end-to-side portacaval shunt, (b) side-to-side portacaval shunt, (c) interposition shunt (por- tacaval [1], mesocaval [2], and mesorenal [3]), and (d) conventional (proximal) splenorenal shunt. duced the distal splenorenal shunt in 1967.40 The DSRS has be- Unfortunately, perfusion studies indicate that approximately come the prototypical selective shunt, in that it selectively decom- one half of patients lose hepatopedal flow within 1 year after a presses the esophagogastric veins while maintaining hepatopedal DSRS procedure. This is a particular problem in patients with flow from the mesenteric veins. It is performed by anastomosing alcoholic cirrhosis.The loss of shunt selectivity is believed to result the distal splenic vein to the left renal vein and interrupting venous from progressive collateral diversion of portal flow into the splenic collaterals (e.g., the left gastric and right gastroepiploic veins) [see vein via a network of pancreatic and peripancreatic veins (the so- Figure 6]. As a result, the DSRS effectively separates the portal sys- called pancreatic siphon effect). Extensive skeletonization of the tem into two components: (1) a decompressed esophagogastric ve- splenic vein off the pancreas (so-called splenopancreatic discon- nous circuit and (2) a persistently hypertensive mesenteric venous nection) has been proposed as a means of minimizing this circuit that continues to provide hepatopedal portal flow.Thus, the unwanted collateralization,41 but at present, the evidence is insuf- DSRS does not address the mesenteric and sinusoidal hyperten- ficient to support routine employment of this measure. sion that is responsible for ascites formation. Indeed, it is believed The complications of DSRS procedures are well described. that the extensive retroperitoneal dissection required to construct Depending on patient selection, postoperative ascites formation is this shunt may actually contribute to ascites formation through seen in 7% to 98% of cases; however, in only 0% to 14% of cases inadvertent disruption of retroperitoneal lymphatic vessels. The is ascites clinically significant and refractory to dietary sodium DSRS is contraindicated in patients who have refractory ascites or restriction and diuresis.23 Hepatic encephalopathy is reported in splenic vein thrombosis, those who have previously undergone 0% to 32% of cases; several clinical trials comparing DSRS with splenectomy, and those with an excessively small (< 7 mm) splenic nonselective shunting demonstrated significantly lower rates of vein diameter. encephalopathy after DSRS, whereas other trials found no statis-
  9. 9. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 5 GASTROINTESTINAL TRACT AND ABDOMEN 10 PORTAL HYPERTENSION — 9 tically significant difference. With respect to overall survival and thy rate was lower, and shunt occlusion was reduced, but the inci- hemorrhage control, DSRS and nonselective shunts appear to be dence of postoperative ascites was higher.43 A National Institutes equivalent.42 of Health–sponsored randomized comparison between DSRS Comparison of DSRS construction with endoscopic therapy and TIPS is currently under way at multiple centers. has yielded interesting results. Two controlled trials comparing The other main form of selective portosystemic shunt is the endoscopic therapy and salvage DSRS with early DSRS alone coronary-caval shunt, initially described in Japan in 1984.44 This demonstrated superior hemorrhage control with early DSRS.30,31 shunt is constructed by anastomosing an interposition graft to the Rates of hepatic encephalopathy did not differ between the two left gastric (coronary) vein on one end and the inferior vena cava groups. One of the trials, conducted in an urban-suburban area on the other. To date, the applicability of this procedure has been where 85% of sclerotherapy failures could be rescued with salvage limited, and most surgeons have relatively little experience with it. DSRS, found survival to be improved in patients treated with endoscopic therapy and salvage DSRS, compared with survival in Partial shunts. Various small-diameter interposition portosys- patients treated with early DSRS alone.30 The other, performed in temic shunts have been proposed as partial shunts, designed to a less densely populated region where only 31% of sclerotherapy achieve partial decompression of the entire portal venous system failures could be rescued with salvage DSRS, found survival to be while maintaining a degree of hepatopedal portal flow to the liver. improved in the early DSRS group.31 These data suggest that early The most successful of these partial shunts has been the small- definitive surgical intervention may be preferable for patients who diameter portacaval interposition shunt. The use of a 10 mm or are too far from a tertiary medical center to be able to reach one smaller interposition shunt, combined with extensive disruption expeditiously in the event of uncontrollable hemorrhage. of portosystemic collateral venous circuits, serves to maintain Attention is now being turned toward comparisons between some degree of hepatic portal perfusion. Early experience with the the DSRS and TIPS. One uncontrolled comparative study found 8 mm ringed polytetrafluoroethylene graft suggests that hepatic that with DSRS, hemorrhage control was better, the encephalopa- encephalopathy rates are lower with this shunt than with nonse- Umbilical Vein Left Gastric (Coronary) Vein Splenic Vein Inferior Mesenteric Vein Renal Vein Inferior Mesenteric Vein Superior Right Mesenteric Gastroepiploic Vein Vein Figure 6 The distal splenorenal shunt diverts portal flow from the spleen and short gastric veins into the left renal vein. The DSRS provides selective shunting by preserving portal flow from the mesenteric circulation. Potential sites of collateralization (e.g., the left gastric vein, the gastroepiploic vein, and the umbilical vein) are routinely interrupted to preserve hepatopedal portal flow.
  10. 10. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 5 GASTROINTESTINAL TRACT AND ABDOMEN 10 PORTAL HYPERTENSION — 10 lective 16 mm grafts and that use of the smaller shunt yields com- endoscopic examination have been shown to predict the likelihood parable long-term survival.45 An early comparison of the small- of rupture: evidence of variceal wall thinning (cherry-red spots, diameter portacaval shunt with TIPS demonstrated lower rates of red wales), variceal tortuosity, superimposition of varices on other shunt occlusion and treatment failure in the operative therapy varices, and the presence of gastric varices all appear to be corre- group.46 lated with a higher likelihood of hemorrhage.54 At present, pharmacologic therapy is the only measure that Esophagogastric devascularization The most effective provides effective prophylaxis against variceal hemorrhage. nonshunt operation for preventing recurrent variceal hemorrhage Nonselective beta-adrenergic blockade, either with propranolol or is esophagogastric devascularization with esophageal transection the long-acting agent nadolol, reduces portal venous pressure by and splenectomy, as advocated by Sugiura and associates.47 Unlike decreasing cardiac output and favoring splanchnic vasoconstric- simple esophageal transection, which has been used with limited tion. Clinical trials examining the efficacy of propranolol therapy success in the setting of acute hemorrhage, the Sugiura procedure demonstrated lowered rates of initial variceal bleeding, though the and its subsequent modifications [see Figure 7] involve ligation of ultimate influence of beta blockade on patient survival was venous branches entering the distal esophagus and the proximal mixed.55-57 stomach from the level of the inferior pulmonary vein, combined Endoscopic sclerotherapy has not been consistently effective in with selective vagotomy and pyloroplasty [see 5:20 Gastric and Duo- preventing initial variceal bleeding. In fact, several trials found sur- denal Dis.]. A key point is that the left gastric (coronary) vein and vival to be poorer in patients treated with prophylactic sclerother- the paraesophageal collateral veins are preserved to permit por- apy than in those managed with prophylactic pharmacotherapy.4,58 toazygous collateralization, which inhibits future varix formation. This difference is probably attributable to the well-documented Initial reports from Japan cited a 5.2% operative mortality and a complications associated with endoscopic sclerotherapy. 6.3% rate of recurrent hemorrhage (most often from nonvariceal The flaws of prophylactic endoscopic sclerotherapy have led causes).47,48 Unfortunately, these successes have not been easily some authorities to advocate endoscopic variceal band ligation as replicated in the United States, where operative mortality with this a more effective form of prophylaxis. One trial demonstrated that procedure has exceeded 20%, with bleeding recurring in 35% to variceal band ligation achieved better prophylaxis of initial variceal 55% of patients.49,50 Nevertheless, modifications of the Sugiura bleeding than propranolol therapy did.59 Clearly, this observation procedure continue to be performed in patients who are unable to warrants further investigation. undergo shunting procedures because of extensive splanchnic vein Early trials comparing prophylactic portosystemic shunting thrombosis. with medical prophylaxis definitively showed that early operative intervention conferred no significant benefit. In fact, the signifi- Orthotopic liver transplantation Orthotopic liver trans- cant morbidity associated with surgical shunting and the substan- plantation is the most definitive form of therapy for complications tial risk of accelerated hepatic dysfunction and encephalopathy of portal hypertension.The cost of cadaveric and living-donor liver led to lower survival rates in patients treated with prophylactic transplantation and its attendant immunosuppression, as well as surgical procedures.6,60 At present, the data are insufficient to rec- the paucity of available allografts, make liver replacement an ommend the use of prophylactic TIPS to prevent acute variceal option for only a select minority of patients presenting with portal hemorrhage. hypertensive sequelae. Accordingly, careful analysis of the out- comes of transplantation procedures in comparison with those of nontransplantation procedures is necessary for optimal allocation Management of Ascites of this limited resource. The presence of ascites in a patient with portal hypertension is For patients whose portal hypertension has become refractory typically an ominous finding that is of significant prognostic to nonoperative management strategies, the decision whether to importance: 1-year mortalities as high as 50% have been reported employ transplantation or nontransplantation operative therapy in cirrhotic patients with new-onset ascites, whereas baseline 1- can be based on the level of hepatic functional reserve. Patients year mortalities in cirrhotic patients without ascites are in the with Child class A or mild class B cirrhosis appear to do well with range of 10%.61 The pathogenesis of ascites formation appears to nontransplantation therapy as first-line operative treatment, with be related to the relative hypovolemia and the primary avidity of the understanding that liver transplantation may remain an option renal sodium retention that develop in patients with cirrhosis. for salvage therapy in the event of future hepatic functional dete- Hypovolemia induces renin-angiotensin activation and salt and rioration. In contrast, patients with more advanced Child class B water reabsorption, which, in the setting of chronic liver dysfunc- or Child class C cirrhosis appear to benefit from early transplan- tion, results in excessive transudation of fluid out of the liver and tation, with nonoperative strategies employed strictly as bridge the intestines and into the peritoneal cavity. The major complica- therapy for maintenance during the time spent on the allograft tions of this process are spontaneous bacterial peritonitis (SBP) waiting list.51,52 and hepatorenal syndrome (HRS) [see Complications, below], which account for the bulk of the morbidity and mortality associ- PROPHYLAXIS OF INITIAL VARICEAL HEMORRHAGE ated with ascites in patients with portal hypertension. The significant mortality associated with variceal hemorrhage NONSURGICAL THERAPY has prompted efforts to devise effective means of preventing the onset of initial variceal bleeding.The difficulty of identifying those By addressing the hyperavidity of sodium retention that drives 20% to 33% of cirrhotic patients who will experience bleeding much of ascites formation, restriction of dietary salt intake (to lev- episodes remains the primary challenge in the application of pro- els as low as 2 g of sodium a day) can resolve ascites in approxi- phylaxis for variceal hemorrhage. Patient characteristics that pre- mately 25% of cases. The hyperaldosteronemic state that exists dict an increased likelihood of variceal bleeding include alcoholic can be countered by initiating diuresis with spironolactone, which, cirrhosis, active alcohol consumption, and severe hepatic dysfunc- at dosages ranging from 100 to 400 mg/day, can relieve ascites in tion.53 Certain anatomic features of varices seen at the time of an additional 60% to 70% of patients. Although automatic addi-
  11. 11. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 5 GASTROINTESTINAL TRACT AND ABDOMEN 10 PORTAL HYPERTENSION — 11 Interior Pulmonary Vein Figure 7 Shown is the modified Sugiura procedure. By extensively devascularizing the esophagogas- tric junction, this procedure may provide a means of interrupting Esophageal Transection esophagogastric varices without and Reanastomosis portosystemic shunting. Selective Vagotomy Pyloroplasty Splenectomy Paraesophagogastric Devascularization tion of loop diuretics has not been proved to enhance the clinical sions.64 Long-term follow-up, however, indicates that shunt occlu- efficacy of spironolactone, augmentation of spironolactone thera- sion occurs in 47% of patients so treated and disseminated py with furosemide can be helpful for patients whose ascites is intravascular coagulation in as many as 35%. refractory to spironolactone monotherapy or who have hyper- The morbidity and mortality associated with operative therapy kalemia as a result of spironolactone treatment. Gradual diuresis make routine use of side-to-side portacaval shunts a poor option is necessary to prevent potential complications (e.g., prerenal for managing ascites.The exceptions to this general statement are azotemia and HRS).62 cases in which ascites proves refractory to medical and TIPS ther- In cases of ascites that is refractory to medical dietary restric- apy or in which concomitant refractory variceal hemorrhage is tion and diuretic therapy, large-volume paracentesis has been present. employed with some success. Albumin is typically infused at a COMPLICATIONS dose of 6 to 8 g per liter of ascitic fluid to prevent the hypotension that results from acute volume shifts. Patients in whom ascites SBP is the most common form of ascitic infection. It typically recurs after multiple rounds of large-volume paracentesis should is signaled by fever and abdominal tenderness and often is also be considered for TIPS. TIPS is particularly useful in patients accompanied by acute hepatic and renal deterioration. The diag- with ascites and a history of bleeding esophageal varices; it cor- nosis is generally made by analyzing ascitic fluid collected through rects as many as 80% of medically refractory cases of ascites.63 paracentesis and is defined by the presence of a positive bacterial However, the efficacy of TIPS is counterbalanced by its attendant culture and a neutrophil count higher than 250/mm3 in the risks (i.e., hepatic encephalopathy, shunt occlusion, and acceler- absence of an obvious intra-abdominal source of infection. Unlike ated hepatic failure), especially in patients with poor hepatic func- secondary peritonitis, SBP is typically monomicrobial, and the tional reserve. frequency with which enteric gram-negative rods are found with SBP suggests intestinal bacterial translocation as a potential cause. SURGICAL THERAPY SBP carries a mortality of 25% and should therefore be treated Operative intervention plays only a limited role in the manage- aggressively with I.V. antibiotic therapy. Given the 70% recurrence ment of ascites. Surgically inserted peritoneovenous shunts have rate after an initial episode of SBP, continuation of suppressive been compared with large-volume paracentesis in patients with antimicrobial therapy until ascites resolves is warranted.65 ascites refractory to medical therapy. No significant differences in HRS, a poorly understood state characterized by progressive early control of ascites have been detected, but patients treated and refractory renal impairment, typically occurs in the setting of with peritoneovenous shunting appear to benefit from faster tense ascites and hepatic disease. Management of HRS is strictly ascites resolution, longer palliation, and fewer hospital readmis- supportive, in that the syndrome often responds only to correc-
  12. 12. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 5 GASTROINTESTINAL TRACT AND ABDOMEN 10 PORTAL HYPERTENSION — 12 tion of the underlying liver dysfunction. Accordingly, the only mercaptans, and γ-aminobutyric acid) away from hepatic metab- proven therapy for HRS is liver transplantation. olism is what causes hepatic encephalopathy; however, the absolute level of circulating ammonia correlates poorly with the magnitude of encephalopathic symptoms. Management of Hepatic Encephalopathy Correction of the triggers that cause hepatic encephalopathy Hepatic encephalopathy is a complex of symptoms character- often reverses the psychoneurologic disturbances. In severe cases, ized by mental status changes ranging from impaired mentation patients should also receive neomycin (1.5 g every 6 hours), which to frank stupor.The classic neurologic finding associated with this covers enteric urease-positive bacteria, and lactulose (20 to 30 g symptom complex is asterixis. Typically, hepatic encephalopathy two to four times daily), a disaccharide GI cathartic. Both agents develops in the setting of significant portosystemic shunting or are believed to reduce intestinal levels of ammonia and inhibit its significant hepatic functional impairment. It is most commonly enteric absorption. Whereas neomycin has long-term side effects observed after the creation of a therapeutic nonselective portosys- (i.e., nephrotoxicity and ototoxicity), long-term lactulose therapy temic shunt. Its onset is usually precipitated by dehydration, GI is generally well tolerated. Dietary protein restriction should also hemorrhage, sepsis, or excessive protein intake; in fact, the spon- be employed for long-term suppression of hepatic encephalopa- taneous development of hepatic encephalopathy mandates work- thy. On occasion, refractory cases of shunt-induced hepatic en- up for these physiologic triggers. It has been speculated that the cephalopathy may be treated by means of intentional ligation or shunting of intestinally absorbed cerebral toxins (e.g., ammonia, occlusion of the portosystemic shunt. References 1. Pugh RN, Murray-Lyon IM, Dawson JL, et al: 14. D’Amico G, Pietrosi G, Tarantino I, et al: Emer- 26. Grace ND: A hepatologist’s view of variceal bleed- Transection of the oesophagus for bleeding oe- gency sclerotherapy versus vasoactive drugs for ing. Am J Surg 160:26, 1990 sophageal varices. Br J Surg 60:646, 1973 variceal bleeding in cirrhosis: a Cochrane meta- 27. Garcia-Tsao G, Grace ND, Groszmann RJ, et al: 2. 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