The liver has several physiologic functions, including drug metabolism, hemostasis, protein synthesis, and gluconeogenesis. Since these functions are critical during the perioperative period, anesthetizing animals with severe liver dysfunction is a challenge. Assessment of liver function requires several physical and laboratory studies. History and physical examination findings vary, depending on the type and duration of dysfunction. Indicators may include poor performance, weight loss, anorexia, vomiting, and diarrhea. Seizures after a high-protein meal may be reported. Hepatomegaly may be detected during abdominal palpation. Laboratory testing should include a complete blood count and biochemical profile. Erythrocyte morphologic characteristics of microcytosis, poikilocytosis, and acanthocytosis may indicate liver disease. Low blood urea nitrogen may indicate reduced biosynthesis by the liver. Increased alanine aminotransferase levels indicate parenchymal damage; however, these values may be normal or low in end-stage liver disease. Elevations in gamma-glutamyl transferase and alkaline phosphatase are primarily associated with biliary disorders. Bile acid analysis is useful in identifying abnormal blood flow to the liver and occult hepatobiliary disease. All patients with suspected liver disease should have coagulation testing. Imaging is also an important diagnostic method.

Anesthetic drugs that require extensive hepatic metabolism should be avoided in patients with liver disease. These agents include long-acting tranquilizers and oxybarbiturates. Opiates with available antagonistic drugs are some of the safest parenteral agents. Anticholinergics can be used if the heart rate falls below 70 beats per minute. The author prefers sevoflurane or isoflurane by facemask induction. Parenteral fluids should be given, including colloids, hetastarch, or fresh frozen plasma if the albumin level is below 2.0. Supplemental warming techniques should be used.

Anesthesia for severe liver dysfunction. Raffe MR. PROCEEDINGS 8TH ANNUAL IVECCS, 2002, 49-52.