Hepatic functional reserve in patients with obstructive jaundice: an assessment by the redox tolerance test

Bioelectrical impedance may predict cell viability during ischemia and reperfusion in rat liver

Ischemia and reperfusion (I/R) injury is a major cause of hepatic failure after liver surgery, but no method could monitor or predict it real-time during surgery. We measured bioelectrical impedance (BEI) and cell viability to assess the usefulness of BEI during I/R in rat liver. A 70% partial liver ischemia model was used. BEI was measured at various frequencies. Adenosine triphosphate (ATP) content, and palmitic acid oxidation rate were measured, and histological changes were observed in order to quantify liver cell viability. BEI changed significantly during ischemia at low frequency. In the ischemia group, BEI increased gradually during 60 min of ischemia and had a tendency to plateau thereafter. The ATP content decreased below 20% of the baseline level. In the I/R group, BEI recovered to near baseline level. After 24 hr of reperfusion, the ATP contents decreased to below 50% in 30, 60 and 120 min of ischemia and the palmitic acid metabolic rates decreased to 91%, 78%, and 74%, respectively, compared with normal liver. BEI may be a good tool for monitoring I/R during liver surgery. The liver is relatively tolerant to ischemia, however after reperfusion, liver cells may be damaged depending upon the duration of ischemia.

Quantitative assessment of hepatic function and its relevance to the liver surgeon

BACKGROUND

Standard evaluation of patients undergoing hepatic surgery has been through radiological and quantitative determination of liver function. As more complex and extensive surgery is now being performed, often in the presence of cirrhosis/fibrosis or following administration of chemotherapy, it is questioned whether additional assessment may be required prior to embarking on such surgery. The aim of this review was to determine the current knowledge base in relation to the performance of quantitative assessment of hepatic function both pre- and post-operatively in patients undergoing hepatic resectional surgery and liver transplantation.

METHODS

An electronic search was performed of the medical literature using the MEDLINE database to identify relevant articles with cross-referencing of all identified papers to ensure full literature capture.

RESULTS AND CONCLUSIONS

The review has identified a number of different methods of dynamically assessing hepatic function, the most frequently performed being through the use of indocyanine green clearance. With the recent and further anticipated developments in hepatic resectional surgery, it is likely that quantitative assessment will become more widely practiced in order to reduce post-operative hepatic failure and improve outcome.

How much liver resection is too much?

BACKGROUND

Hepatic failure occurring after liver resection carries a poor prognosis and is a complication dreaded by surgeons. Inadequate reserve in the remaining parenchyma leads to a steady decrease in liver function, inability to regenerate, and progression to liver failure. For this reason, many methods to quantify functional hepatic reserve have been developed.

METHODS

This article reviews the main methods used in the assessment of hepatic reserve in patients undergoing hepatectomy and their use in operative decision making.

RESULTS

A range of methods to categorically quantify the functional reserve of the liver have been developed, ranging from scoring systems (such as the Child-Pugh classification) to tests assessing complex hepatic metabolic pathways to radiological methods to assess functional reserve. However, no one method has or is ever likely to emerge as a single measure with which to dictate safe limits of resectability.

CONCLUSIONS

In the future, the role of residual liver function assessment may be of most benefit in the routine stratification of risk, thus enabling both patient consent to be obtained and surgical procedure to be performed, with full information and facts regarding operative risks. However, there is no one single test that remains conclusively superior.

Impaired ketogenesis is a major mechanism for disturbed hepatic fatty acid metabolism in rats with long-term cholestasis and after relief of biliary obstruction

BACKGROUND/AIMS

Rats with long-term cholestasis have reduced ketosis of unknown origin.

METHODS

Fatty acid metabolism was studied in starved rats with biliary obstruction for 4 weeks (bile duct ligated rats = BDL rats), and 3, 7, 14, 28 and 84 days after reversal of biliary obstruction by Roux-en-Y anastomosis (RY rats), and in sham-operated control rats.

RESULTS

BDL rats had reduced beta-hydroxybutyrate concentrations in plasma (0.25 +/- 0.10 vs. 0.75 +/- 0.20 mmol/l) and liver (2.57 +/- 0.20 vs. 4.63 +/- 0.61 micromol/g) which increased after restoring bile flow. Hepatic expression and activity of carnitine palmitoyltransferase I (CPT I) or CPT II were unaffected or decreased in BDL rats, respectively, and increased after restoring bile flow. Oxidative metabolism of different substrates by isolated liver mitochondria and activation of palmitate were reduced in BDL rats and recovered 7-14 days after restoring bile flow. Ketogenesis was decreased in mitochondria from BDL rats and recovered 3 months after restoring bile flow. Both mRNA and protein expression of hydroxymethylglutaryl-coenzyme A synthase (HMG-CoA synthase), the rate-limiting enzyme of ketogenesis, was reduced in livers of BDL rats and increased after reversing biliary obstruction.

CONCLUSIONS

In BDL rats, impairment of hepatic fatty acid metabolism is multifactorial. After reversing biliary obstruction, reduced activity of HMG-CoA synthase is the major factor.

Effect of preoperative biliary drainage on surgical outcome after pancreatoduodenectomy

BACKGROUND

The role of preoperative biliary drainage in patients with biliary obstruction undergoing pancreatoduodenectomy remains controversial. Several authors failed to show any effect of preoperative biliary drainage, whereas others even reported an increased morbidity following pancreatoduodenectomy.

METHODS

Retrospective analysis was performed in a consecutive series of 257 patients undergoing pancreatoduodenectomy between November 1993 and November 1999.

RESULTS

Ninety-nine patients (38%) underwent preoperative biliary drainage for a median time period of 10 days (range 1 to 41) prior to resection. Cumulative postoperative morbidity was 47% (120 patients), the reoperation rate was 4.3% (11 patients), and mortality was 2.3% (6 patients). There was no difference in total morbidity, infectious complications, reoperation rate, mortality, or long-term survival between patients with or without preoperative biliary drainage.

CONCLUSIONS

Preoperative biliary instrumentation and biliary drainage do not affect early or late outcome in patients undergoing pancreatoduodenectomy.

Xenobiotic-induced hepatotoxicity: mechanisms of liver injury and methods of monitoring hepatic function

Xenobiotic-induced liver injury is a clinically important etiology of hepatic disease that, if not recognized, can lead to hepatic failure. In this article we discuss the mechanisms of xenobiotic-induced liver injury, various factors that can alter the risk and severity of injury, the clinical and laboratory manifestations of injury, and the methods used to detect the presence of injury and (or) functioning liver mass.