CHAPTER 17 Anesthesia for Liver Diseases

Preoperative Evaluation of Liver Function

Evaluation should be directed at establishing the etiologic diagnosis, then grading or estimating how severe the disease is, and finally staging the disease. The severity or activity of the disease is assessed and graded accordingly as mild, moderate, or severe. Estimation of the point in the course of the natural history of the disease, early or late, precirrhotic, cirrhotic, or end-stage, is referred to as the stage of the disease.

History

The relevant history, including symptoms and signs, is summarized in Table 17.1.

Table 17.1 Symptoms and signs of liver disease

**Table 17.1** Symptoms and signs of liver disease
Symptoms	Signs
Fatigue, weakness, nausea, poor appetite, malaise Jaundice Light or clay-colored stools with high colored urine (suggestive of obstructive jaundice) Itching Abdominal pain History of fever: Fever with arthralgia at the onset of jaundice is indicative of viral hepatitis, fever with rigors could be due to cholangitis, low-grade fever over several days can be seen in neoplasm Bloating and dyspepsia History of multiple blood transfusion, vaccinations Drug intake: The history of ingestion of hepatotoxic drugs, e.g., antitubercular drugs Family history of diseases such as Wilson’s disease, alpha-antitrypsin deficiency, etc. History of substance abuse especially alcohol History of any previous surgery	Icterus Pallor due to anemia Tenderness in the abdomen: Murphy’s sign—seen in cholecystitis cholangitis Xanthoma due to hypercholesteremia Ecchymosis due to vitamin K deficiency Hepatosplenomegaly Pedal edema due to hypoproteinemia Ascites Distended and palpable gall bladder (Courvoisier’s sign) seen in malignant obstruction of common bile duct Encephalopathy

Investigations

Biochemical tests or liver function tests include the following:

Serum bilirubin: Normal value of 0.3 to 1.5 mg/dL for total bilirubin and 0.3 mg/dL for conjugated bilirubin. It forms the basis of grading the severity of the liver injury and is a critical component of scores like Child–Turcotte–Pugh (CTP) score or Child Criteria and model for end-stage liver disease or MELD score (Table 17.2).
Serum enzymes: The aminotransferases (transaminases) are sensitive indicators of liver cell injury. Aspartate aminotransferase (AST) is found in the liver, cardiac muscle, skeletal muscle, kidneys, brain, pancreas, lungs, leukocytes, and erythrocytes. Alanine transferase (ALT) is found mainly in the liver. The normal range is 10 to 40 IU/L. Modest elevations up to 300 IU/L are nonspecific, while elevations more than 1,000 IU/L are seen in viral hepatitis, ischemic liver injury (prolonged hypotension or acute heart failure), or toxin/drug-induced liver injury. AST:ALT ratio is typically < 1 in patients with chronic viral hepatitis and nonalcoholic fatty liver disease (NAFLD). As cirrhosis develops, ratio rises to > 1. AST:ALT ratio > 2:1 is suggestive, and > 3:1 is highly suggestive of alcoholic liver diseases. Alkaline phosphatase, 5′–nucleotidase, and gamma-glutamyl transpeptidase (GGT) are elevated in cholestatic jaundice.
Tests for biosynthetic functions:
- Serum albumin: Half-life of 18 to 20 days, with 4% degrade per day. Minimal changes are seen in acute events, but their levels are decreased (<3 g/dL) in chronic liver disease (CLD). In ascites, the level could be low due to an increased volume of distribution even with normal production.
- Serum globulins: A group of gamma globulins produced by B lymphocytes and primarily produced by hepatocytes. Diffuse polyclonal increase in IgG is seen in autoimmune hepatitis, while elevations in IgM levels are seen in primary biliary cirrhosis, and IgA levels are higher in alcoholic liver disease.
- Coagulation factors: Liver synthesizes all clotting factors except Factor VIII (it is synthesized by vascular endothelium). Vitamin k is required for posttranslational modification of factors II, VII, IX, and X. Their serum half-lives are much smaller than albumin, and hence the measurement of the clotting factors is not only the single best acute measure of synthetic hepatic function but also helpful in diagnosing and assessing the parenchymal function of the liver.
- Other tests: Other tests that may be needed in the specific patient are serum ammonia level, abdominal ultrasound, endoscopic retrograde cholangiopancreatography (ERCP), etc.