EVALUATION OF THE PATIENT WITH LIVER DISEASE

Patients with serious liver disease are at increased risk for perioperative morbidity and demise. Appropriate preoperative evaluation requires consideration of the effects of anesthesia and surgery on postoperative liver function and of the complications associated with anesthesia and surgery in patients with preexisting liver disease.

The Effects of Anesthesia & Surgery on Liver Function

Postoperative elevation of serum aminotransferase levels is a relatively common finding after major surgery. Most of these elevations are transient and not associated with hepatic dysfunction. General anesthetic agents may cause deterioration of hepatic function either via intraoperative reduction in hepatic blood flow leading to ischemic injury or, in the case of inhalational agents, direct hepatotoxicity. The latter effect, however, is rare with modern anesthetic agents such as desflurane and sevoflurane. Medications used for regional anesthesia produce similar reductions in hepatic blood flow and thus may be equally likely to lead to ischemic liver injury. Intraoperative hypotension, hemorrhage, and hypoxemia may also contribute to liver injury.

Risk Factors for Surgical Complications

Observational studies have found that surgery in patients with serious liver disease is associated with a variety of complications, including hemorrhage, infection, renal failure, and encephalopathy, and with a substantial mortality rate. A key limitation in interpreting these data is our inability to determine the contribution of the liver disease to the observed complications independent of the surgical procedure.

Acute hepatitis appears to increase surgical risk. In three small series of patients with acute viral hepatitis who underwent abdominal surgery, the mortality rate was roughly 10%. Similarly, patients with undiagnosed alcoholic hepatitis had high mortality rates when undergoing abdominal surgery. Thus, elective surgery in patients with acute viral or alcoholic hepatitis should be delayed until the acute episode has resolved. There are few data regarding the risks of surgery in patients with chronic hepatitis. In the absence of cirrhosis or synthetic dysfunction, chronic viral hepatitis is unlikely to increase risk significantly. A large cohort study of hepatitis C seropositive patients who underwent surgery found a mortality rate of less than 1%. Similarly, nonalcoholic fatty liver disease by itself probably does not pose a serious risk in surgical patients.

In patients with cirrhosis, postoperative complication rates correlate with the severity of liver dysfunction. Traditionally, severity of dysfunction has been assessed with the Child-Turcotte-Pugh score (see Chapter 16). Patients with Child-Turcotte-Pugh class C cirrhosis who underwent portosystemic shunt surgery, biliary surgery, or trauma surgery during the 1970s and 1980s had a 50–85% mortality rate. Patients with Child-Turcotte-Pugh class A or B cirrhosis who underwent abdominal surgery during the 1990s, however, had relatively low mortality rates (hepatectomy 0–8%, open cholecystectomy 0–1%, laparoscopic cholecystectomy 0–1%). A conservative approach would be to avoid elective surgery in patients with Child-Turcotte-Pugh class C cirrhosis and pursue it with great caution in class B patients. The Model for End-stage Liver Disease (MELD) score, based on bilirubin and creatinine levels, and the prothrombin time expressed as the International Normalized Ratio, also predicted surgical mortality and outperformed the Child-Turcotte-Pugh classification in some studies. A web-based risk assessment calculator incorporating age and MELD score can predict both perioperative and long-term mortality (mayoclinic.org/meld/mayomodel9.html).

In addition, when surgery is elective, it is prudent to attempt to reduce the severity of ascites, encephalopathy, and coagulopathy preoperatively. Ascites is a particular problem in abdominal operations, where it can lead to wound dehiscence or hernias. Great care should be taken when using
analgesics and sedatives, as this can worsen hepatic encephalopathy. In general, short-acting agents and lower doses should be used. Patients with coagulopathy should receive vitamin K and may need plasma transfusion at the time of surgery.