Advanced chronic renal failure Age >60 years Portal vein thrombosis Cholangiocarcinoma
Hypoxemia with intrapulmonary right-to-left shunts
Hepatitis: HBsAg and HBeAg positivity
Prior portocaval shunting procedure
Prior complex hepatobiliary surgery
Active alcohol and/or drug abuse
HIV positivity without clinical AIDS
Modified from Maddrey WC, Van Thiel DH: Liver transplantation: an overview, Hepatology 8:948,1988. AIDS, Acquired immunodeficiency syndrome; HIV, human immunodeficiency virus.
syndrome), hepatic disease may be overshadowed by the severity of the comorbid conditions. Prior abdominal surgeries and encephalopathy are important features to note, as are coagulation deficits (factor deficiencies and thrombocytopenia). The thromboelastogram (TEG) provides valuable insight into the patient's entire clotting process. The TEG graphs the viscoelastic properties of a clot from the formation of the first fibrin strands to the full hemostatic plug. Thus the TEG is a dynamic test showing the evolution of clot formation. Because the TEG examines multiple phases of clot formation within a single test, it reflects information that is otherwise available only in multiple tests. The TEG is the best laboratory assessment of qualitative platelet function.
Electrolyte abnormalities are common. Hypokalemia is commonly seen in earlier stages of liver disease since hepatic injury leads to hyperaldosteronism. Hyperkalemia may be caused by the use of potassium-sparing diuretics to treat ascites and hepatorenal syndrome. Hyponatremia may result from diuretic use, hyperaldosteronism, orvolume overload. Renal dysfunction should be assessed since intraoperative dialysis may be necessary. In fulminant hepatic failure, cerebral cytotoxic edema is a common complication, and there must be aggressive preoperative control of intracranial pressure to prevent brainstem herniation, a common cause of death. Patients with cerebral edema should have an intracranial pressure monitoring device.
Pulmonary hypertension associated with cirrhosis occurs in approximately 8% of patients and is a cause of significant intraoperative morbidity and mortality. Many liver failure patients are hypoxemic secondary to atelectasis and hepatopulmonary syndrome. All potential transplant candidates should undergo a screening transthoracic echocardiogram to assess pulmonary arterial pressures, left ventricular function, and intrapulmonary shunting. If pulmonary arterial pressures are elevated or right ventricular function is decreased, a right heart catheterization may be indicated.
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