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Abstract
The liver is the largest gland in the body lies in the right upper quadrant of the abdominal cavity weighs 1.2 – 2 kgs. Under normal resting conditions in human, total hepatic blood flow is 1200 – 1400mL/min.
There are many sophisticated techniques for measurement of hepatic blood flow, which is regulated by either intrinsic or extrinsic factors.
Since the introduction of halothane into clinical practice, fluorinated volatile anesthetics have been associated with liver injury. Although the mechanism of the liver injury caused by fluorinated volatile anesthetics has not been established, evidence suggests it may be due to the oxidative metabolism of these drugs.
Disease can be clinically silent. High degree of suspicion is needed during the preoperative evaluation, and a detailed workup may be needed in patients with risk factors for liver disease, such as alcoholism, obesity, diabetes mellitus, drug abuse, blood transfusion, sexual promiscuity, or family history of liver disease. The presence of any abnormal liver test or otherwise unexplained reductions in hemoglobin, white blood cell count, or especially platelet count, should alert the clinician to the possibility of cirrhosis.
In acute hepatitis, surgery appears unwise, especially if the acute liver disease is severe enough to cause jaundice. Surgery in non-cirrhotic chronic liver disease appears relatively safe.
Patients with cirrhosis whose Child-Pugh scores are less than 8 appear to be reasonable candidates for most types of surgery, including cardio-thoracic surgery. In the MELD scoring system, the suggested cutoff value appears to be 14, though some studies suggest that lower values should be used.
Emergency surgery carries higher risk in general, but it may not be avoidable in life-threatening situations (e.g. dissecting aneurysm or bowel perforation).
We can classify the causes of post-operative hepatic dysfunction into:
1. Patient’s factors including hemolytic disorders, coagulopathy, etc.
2. Perioperative factors including bleeding, hypotension, blood transfusion.
3. Drugs as anesthetic agents.
Hepatocellular damage due to drugs may produce a broad spectrum of hepatic reactions, ranging from cholestasis to hepatitis. So discontinuing the implicating drug(s) is mandatory.
It should not be forgotten that when the liver fails there is often associated failure of kidneys, heart and lung; all of which need treatment to optimize best conditions in which the liver can recover.