Evaluation of patients with liver disease prior to surgery is crucial to estimating perioperative morbidity and mortality and to improving outcomes. The operative risk of liver disease can be related to the rapid changes in liver function that can occur in acute hepatitis or can be related to chronic complications of portal hypertension and parenchymal liver disease in patients with cirrhosis. Therefore, establishment of a risk profile should be based on the etiology of the underlying liver disease and the degree of hepatic decompensation associated with the presence of cirrhosis and portal hypertension. This chapter explains how to assess and prepare patients with liver disease for surgery and provides a framework for predicting operative morbidity and mortality.
Changes in Hepatic Blood Flow
The liver receives a dual blood supply from the portal vein and the hepatic artery. Unlike most other organs, the majority of hepatic oxygen supply in normal individuals is venous via the portal vein. Administration of anesthesia and surgery influences portal and hepatic blood flow. However, when flow through the portal vein is reduced, the hepatic artery vasodilates to increase oxygen supply to the liver. This compensatory vasodilatation appears to be reduced in response to a decrease in portal vein flow caused by changes in hepatic architecture as a result of fibrosis and nodular formation associated with cirrhosis. Due to intraoperative decreases in blood pressure and cardiac output, blood flow in patients with cirrhosis is further decreased in the portal vein and splanchnic vessels. Anesthetics in high doses reduce the hepatic artery's ability to vasodilate in response to these changes in portal blood flow.
These changes in hepatic blood flow may lead to hepatic ischemia and necrosis induced by hypotension when patients with cirrhosis undergo surgery or receive anesthetic agents. This phenomenon leads to the release of inflammatory mediators resulting in multiorgan system failure. In a study of 733 cirrhosis patients undergoing surgery, Ziser and colleagues found an 11.6% mortality rate. Intraoperative hypotension was among factors found to predict perioperative complications and decreased survival.
Postoperative morbidity and mortality in patients with cirrhosis are also influenced by the type of surgery.
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Postoperative morbidity and mortality in patients with liver disease are related to the etiology and severity of liver disease.
- Generally, patients with mild liver enzyme abnormalities without cirrhosis and most compensated Child-Pugh Class A patients can safely undergo surgery.
- For all other patients, a careful assessment of the benefits of surgical intervention must be weighed against the risk of hepatic decompensation and mortality. These risks should be enumerated as part of the informed consent process.