The Postoperative Patient


6
The Postoperative Patient


Louise China and Douglas Thorburn


Royal Free London NHS Foundation Trust, London, UK


Introduction


Abnormality in liver function tests (LFTs) is a common situation encountered in patients who have recently undergone surgery. Many of these patients do not have primary liver disease, as most of the commonly performed markers labeled “LFTs” are not specific for the liver and are affected by many factors unrelated to the liver. Also, many of these tests (like liver enzyme levels) do not measure the function of the liver, but are markers of liver injury, which is broadly of two types: hepatocellular and cholestatic. A combination of a careful history and clinical examination, together with interpretation of pattern of liver test abnormalities, can often identify the type of liver injury or etiology of liver disease, allowing for focused investigation (Figure 6.1).


Most postoperative patients with abnormal LFTs will have no symptoms in relation to their liver. Most commonly the test abnormalities will be iatrogenic and caused by the surgery, its complications or the supportive care before or after surgery. Sometimes, patients manifest an underlying pre‐existing liver disease in the postoperative period. For example, a patient with compensated liver cirrhosis and previously normal blood tests may decompensate with ascites or hepatic encephalopathy in the postoperative period. Taking a careful history from the patient, their general practitioner, and reviewing preoperative blood tests may allow distinction between these problems.

Schematic illustration of common hepatic causes of abnormal liver function tests after surgery.

Figure 6.1 Common hepatic causes of abnormal liver function tests after surgery.


There should be a low threshold for discussing abnormal LFTs with the local gastroenterology or hepatology team after an initial history has been sought, with differentials considered.


Common Liver Problems Associated with the Postoperative Patient


Common Postoperative Causes of a Predominant Hepatocellular Injury


Common postoperative causes of a predominant hepatocellular injury will usually present with a predominant rise in alanine amino transferase (ALT) and aspartate amino transferase (AST). Depending on the severity of the injury the bilirubin and international normalized ratio (INR)/prothrombin time (PT) can also be deranged [1].


Drug‐Induced Liver Injury


DILI can be classified according to the pattern of liver tests observed (hepatocellular, cholestatic, or mixed) [2]. Amoxicillin–clavulanate is the most common drug implicated in DILI and is commonly used in the postoperative setting. Other drugs commonly responsible for DILI that are used in postoperative patients are listed in Table 6.1. Timing of onset of LFT abnormality varies and can occur within days or sometimes weeks post‐medication introduction.


Vascular Liver Injury


Ischemic hepatitis, caused by liver hypoperfusion, is most commonly caused by a systemic hypotensive episode with rapid onset of liver enzyme abnormalities after the event. There is usually a large rise in serum ALT and AST, which peaks at 25–250 times the upper limit of normal (ULN) within one to three days of the hypotensive event. Less frequently, raised serum bilirubin and alkaline phosphatase (ALP) are observed and to a much lesser extent (two to four time the ULN). In the absence of continuing hypotension, liver enzymes usually return to normal within 7–10 days, with AST falling first due to its shorter half‐life. Rarely, hepatic synthetic function is impaired.


Table 6.1 Common postoperative medications causing drug induced liver injury.



















Type of drug Common example
Antibiotics Co‐amoxiclav, flucloxacillin
Halogenated anesthetic agents Halothane (pediatrics)
Pain relief Paracetamol, non‐steroidal anti‐inflammatory drugs
Cardiac Amiodarone

Rarer forms of perfusional liver injury, which may be seen in the postoperative setting, are:



  • Hepatic infarction represents a focal ischemic injury to the liver and typically results from an occlusion of a single branch of the hepatic artery. Inadvertent ligation of the hepatic artery (usually right) has been described after laparoscopic cholecystectomy.
  • Prothrombotic vascular occlusion usually happens in patients who have a hypercoagulable state or in patients undergoing hepatic surgery.
  • Congestion due to cardiac failure: any cause of right‐sided heart failure can result in hepatic congestion and should be considered in patients with pre‐existing heart conditions that could deteriorate postoperatively or in those who are undergoing cardiac surgery.

Blood‐Transmitted Viral Infection


This is rare but it is possible for hepatitis viruses (A/B/C/E), cytomegalovirus, Epstein–Barr virus, and herpes viruses to cause a hepatocellular injury, and should be considered during discussions with the gastroenterology and virology team in unexplained cases.


Common Postoperative Causes of a Predominantly Cholestatic Injury


This category of liver problems will usually present with a predominant rise in ALP (with or without bilirubin). Depending on the severity of the injury, the bilirubin and INR/PT may also be elevated.


Intrahepatic Cholestatic Injury


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Dec 15, 2022 | Posted by in GASTROENTEROLOGY | Comments Off on The Postoperative Patient

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