Ischemic preconditioning for major liver resection under vascular exclusion of the liver preserving the caval flow: a randomized prospective study

Complex Hepatectomy Under Total Vascular Exclusion of the Liver Preserving the Caval Flow with Portal Hypothermic Perfusion and Temporary Portacaval Shunt: A Proof of Concept

BACKGROUND

Hypothermic liver perfusion decreases ischemia/reperfusion injury during hepatectomy under standard total vascular exclusion (TVE) of the liver. This surgery needs venovenous bypass and is hampered by high morbi-mortality. TVE preserving the inferior vena cava (IVC) flow is hemodynamically well tolerated but remains limited in duration when performed under liver normothermia. The objective of this study was to report the results of TVE preserving the caval flow, modified to allow hypothermic liver perfusion and obviate splanchnic congestion.

PATIENTS AND METHODS

The technique, indicated for tumors abutting large tributaries of the hepatic veins but sparing their roots in IVC and the latter, was applied when TVE was anticipated to last for ≥ 60 min. It combines continuous TVE preserving the IVC flow with hypothermic liver perfusion and temporary portacaval shunt (PCS). Results are given as median (range).

RESULTS

Vascular control was achieved in 13 patients with excellent hemodynamical tolerance. PCS was direct or via an interposed synthetic graft (five and eight cases, respectively). Liver temperature dropped to 16.5 (6-24) °C under perfusion of 2 (2-4) L of cold perfusate. TVE lasted 67 (54-125) min and 4.5 (0-8) blood units were transfused. Resection was major in nine cases and was complete in all cases. Five complications occurred in four patients, and the 90-day mortality rate was zero.

CONCLUSIONS

This technique maintains stable hemodynamics and combines the advantages of in situ or ex situ standard TVE with hypothermic liver perfusion, without their inherent prolongation of ischemia time and need for venovenous bypass.

Post-hepatectomy liver failure: A timeline centered review

BACKGROUND

Post-hepatectomy liver failure (PHLF) is a leading cause of postoperative mortality after liver surgery. Due to its significant impact, it is imperative to understand the risk stratification and preventative strategies for PHLF. The main objective of this review is to highlight the role of these strategies in a timeline centered way around curative resection.

DATA SOURCES

This review includes studies on both humans and animals, where they addressed PHLF. A literature search was conducted across the Cochrane Library, Embase, MEDLINE/PubMed, and Web of Knowledge electronic databases for English language studies published between July 1997 and June 2020. Studies presented in other languages were equally considered. The quality of included publications was assessed using Downs and Black's checklist. The results were presented in qualitative summaries owing to the lack of studies qualifying for quantitative analysis.

RESULTS

This systematic review with 245 studies, provides insight into the current prediction, prevention, diagnosis, and management options for PHLF. This review highlighted that liver volume manipulation is the most frequently studied preventive measure against PHLF in clinical practice, with modest improvement in the treatment strategies over the past decade.

CONCLUSIONS

Remnant liver volume manipulation is the most consistent preventive measure against PHLF.

Impacts of ischemic preconditioning in liver resection: systematic review with meta-analysis

OBJECTIVE

To assess the beneficial effects of ischemic preconditioning (IPC) in liver resection and evaluate its applicability in clinical practice.

SUMMARY BACKGROUND DATA

Liver surgeries are usually associated with intentional transient ischemia for hemostatic control. IPC is a surgical step that intends to reduce the effects of ischemia-reperfusion; however, there is no strong evidence about the real impact of the IPC, and it is necessary to effectively clarify what its effects are.

METHODS

Randomized clinical trials were selected, comparing IPC with no preconditioning in patients undergoing liver resection. Data were extracted by three independent researchers according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, Supplemental Digital Content 1, http://links.lww.com/JS9/A79 . Several outcomes were evaluated, including postoperative peaks of transaminases and bilirubin, mortality, length of hospital stay, length of stay in the ICU, bleeding, and transfusion of blood products, among others. Bias risks were assessed using the Cochrane collaboration tool.

RESULTS

Seventeen articles were selected, with a total of 1052 patients. IPC did not change the surgical time of the liver resections while these patients bled less (Mean Difference: -49.97 ml; 95% CI: -86.32 to -13.6; I2 : 64%), needed less blood products [relative risk (RR): 0.71; 95% CI: 0.53-0.96; I2 =0%], and had a lower risk of postoperative ascites (RR: 0.40; 95% CI: 0.17-0.93; I2 =0%). The other outcomes had no statistical differences or could not have their meta-analyses conducted due to high heterogeneity.

CONCLUSIONS

IPC is applicable in clinical practice, and it has some beneficial effects. However, there is not enough evidence to encourage its routine use.

Direct, remote and combined ischemic conditioning in liver surgery

Liver ischemia-reperfusion injury is a major cause of postoperative liver dysfunction, morbidity and mortality following liver resection and transplantation. Ischemic conditioning has been shown to ameliorate ischemia-reperfusion injury in small animal models. It can be applied directly or remotely when cycles of ischemia and reperfusion are applied to a distant site or organ. Considering timing of the procedure, different protocols are available. Ischemic preconditioning refers to that performed before the duration of ischemia of the target organ. Ischemic perconditioning is performed over the duration of ischemia of the target organ. Ischemic postconditioning applies brief episodes of ischemia at the onset of reperfusion following a prolonged ischemia. Animal studies pointed towards suppressing cytokine release, enhancing the production of hepatoprotective adenosine and reducing liver apoptotic response as the potential mechanisms responsible for the protective effect of direct tissue conditioning. Interactions between neural, humoral and systemic pathways all lead to the protective effect of remote ischemic preconditioning. Despite promising animal studies, none of the aforementioned protocols proved to be clinically effective in liver surgery with the exception of morbidity reduction in cirrhotic patients undergoing liver resection. Further human clinical trials with application of novel conditioning protocols and combination of methods are warranted before implementation of ischemic conditioning in day-to-day clinical practice.

Effect of remote ischemic preconditioning on hepatic ischemia-reperfusion injury in patients undergoing liver resection: a randomized controlled trial

BACKGROUND

Studies in animal models have shown that remote ischemic preconditioning (RIPC) could protect the liver from hepatic ischemia-reperfusion injury (HIRI). The aim of this study was to examine whether RIPC could reduce HIRI in patients undergoing liver resection.

METHODS

A total of 120 patients were randomly assigned to three groups: a control group receiving no conditioning, an ischemic preconditioning (IPC) group, and an RIPC group. In the IPC group, the hepatoduodenal ligament was blocked for 10 min followed by 10 min of reperfusion prior to hepatic resection. Patients in the RIPC group received three cycles of 5-min ischemia followed by 5-min reperfusion to the right arm. Alanine transaminase (ALT), aspartate transaminase (AST), and tumor necrosis factor-like weak inducer of apoptosis (TWEAK) were examined before and after surgery.

RESULTS

A total of 105 patients completed the trial: 39 in the control group, 32 in the IPC group, and 34 in the RIPC group. In comparison to the control, serum ALT and AST levels significantly decreased in the IPC (ALT: 507.0±401.3 vs. 1040.7±649.5 IU/L, P<0.001; AST: 495.8±369.4 vs. 935.9±640.7 IU/L, P=0.001) and RIPC (ALT: 680.8±291.5 vs. 1040.7±649.5 IU/L, P=0.002; AST: 661.7±290.6 vs. 935.9±640.7 IU/L, P=0.014) groups on the first postoperative day. In comparison to the control, TWEAK significantly decreased in the IPC group (IPC 57.99±17.8 vs. control 76.13±12.4 ng/L, P=0.025) after surgery. TWEAK did not differ between the RIPC and IPC groups (RIPC 64.84±14.2 vs. IPC 57.99±17.8 ng/L, P=0.385).

CONCLUSIONS

RIPC could reduce hepatic ischemia-reperfusion injury after liver resection.

Effect of Remote Ischemic Preconditioning in Patients Undergoing Hepatectomy With Portal Triad Clamping: A Randomized Controlled Trial

BACKGROUND

Remote ischemic preconditioning (RIPC) is reported to reduce liver injury in patients undergoing hepatectomy for colorectal liver metastasis, but its role is unclear in hepatocellular carcinoma patients with portal triad clamping during hepatectomy.

METHODS

In this prospective, randomized trial, 140 patients with hepatocellular carcinoma undergoing liver resection requiring portal triad clamping were randomized to a RIPC group or a control group. Patients in the RIPC group received RIPC (3 cycles of 5-minute ischemia and 5-minute reperfusion in right upper limb with cuff pressure at 30 kPa [225 mm Hg]) approximately 10 minutes after induction of anesthesia. In the control group, patients received sham RIPC (the cuff was not inflated). The primary outcome was the postoperative peak level of total bilirubin (TBIL) and was analyzed with the independent t test. Secondary outcomes were liver function test at postoperative days 1, 3, and 5; postoperative morbidity and mortality during the first month; and the length of postoperative hospital stay.

RESULTS

Data from 136 patients (69 in the RIPC group and 67 in the control group) were analyzed. The RIPC group had on average a 5.9 μmol lower peak level of TBIL than the control group; the mean difference is -5.9, and the 95% confidence interval (CI) reverses to -17.9 to 6.1. There were no significant differences between the 2 groups in liver function test at postoperative days 1, 3, and 5; postoperative morbidity and mortality during the first month; and the length of postoperative hospital stay.

CONCLUSIONS

We found no evidence that RIPC can reduce postoperative liver injury after hepatectomy.

Regional Ischemic Preconditioning Has Clinical Value in Cirrhotic HCC Through MAPK Pathways

BACKGROUND

This study assessed the clinical value of regional ischemic preconditioning (RIP) and the role of the mitogen-activated protein kinase (MAPK) pathways in the protective mechanism of RIP in cirrhotic hepatocellular carcinoma (HCC) patients undergoing hepatectomy.

METHODS

Liver resection was performed with hemi-hepatic vascular inflow occlusion (HHV) under RIP (RIP group) or with HHV alone (HHV group). Clinical data, surgical outcomes, and the levels of phosphorylated MAPKs before occlusion and 30 min after reperfusion were estimated.

RESULTS

HHV under RIP was associated with less intraoperative blood loss (300 vs. 400 ml; P = 0.042), postoperative plasma transfused (400 vs. 800 ml; P = 0.019), and a higher level of prothrombin activity at postoperative days 3, 5, and 7 compared to HHV alone. The level of phosphorylated ERK protein was significantly increased and the levels of phosphorylated p38 and JNK proteins were significantly decreased 30 min after reperfusion compared to HHV group in the RIP group.

CONCLUSIONS

HHV under RIP may have clinical value in cirrhotic HCC patients requiring resection and the protective mechanism of RIP may be associated with changes in the protein phosphorylation level of MAPK pathways.

Interaction between anesthetic conditioning and ischemic preconditioning on metabolic function after hepatic ischemia-reperfusion in rabbits

BACKGROUND

Both anesthetic-induced and ischemic preconditioning are protective against hepatic ischemia-reperfusion injury. However, the effects of these preventive methods on the metabolic function remain to be elucidated. We investigated the anesthetic conditioning and ischemic preconditioning on the metabolic function of the rabbit model of hepatic ischemia-reperfusion.

METHODS

After approval by the institutional animal care and use committee, 36 Japanese White rabbits underwent partial hepatic ischemia for 90 min either under sevoflurane or propofol anesthesia. All the rabbits underwent 90 min of hepatic ischemia, and half of the rabbits in each group underwent additional 10-min ischemia and 10-min reperfusion before index ischemia. Hepatic microvascular blood flow was intermittently measured during reperfusion period, and galactose clearance, serum aminotransferase activities, and lactate concentrations were determined 180 min after reperfusion.

RESULTS

Neither anesthetic conditioning with sevoflurane nor ischemic preconditioning altered hepatic microvascular blood flow during reperfusion and serum transaminase activities after reperfusion. However, galactose clearance of reperfused liver was significantly higher under sevoflurane anesthesia than propofol (0.016 ± 0.005/min vs. 0.011 ± 0.004/min). Statistically significant interaction between anesthetic choice and application of ischemic preconditioning suggests that the ischemic preconditioning is selectively protective under propofol anesthesia. Increase of blood lactate concentration was significantly suppressed under sevoflurane anesthesia compared to propofol (1.5 ± 0.8 vs. 3.9 ± 1.4 mmol/l) without any statistically significant interaction with the application of ischemic preconditioning.

CONCLUSION

Sevoflurane attenuated the decrease of galactose clearance and increase of the blood lactate after reperfusion compared to propofol. Application of ischemic preconditioning was significantly protective under propofol anesthesia.

Comparison of hepatoprotective effect from ischemia-reperfusion injury of remote ischemic preconditioning of the liver vs local ischemic preconditioning of the liver during human liver resections

AIM

To compare and evaluate the hepatoprotective effect of remote ischemic preconditioning (RIPC) with local ischemic preconditioning (LIPC) of the liver during human liver resections.

METHODS

A prospective, single-centre, randomised control trial was conducted in the Clinical Hospital "***" from April 2017 to January 2018. A total of 60 patients, who underwent liver resection due to colorectal cancer liver metastasis, were randomised to one of three study arms: 1) a RIPC group, 2) an LIPC group and 3) a control group (CG) in which no ischemic preconditioning was done before liver resection. The hepatoprotective effect was evaluated by comparing serum transaminase levels, bilirubin levels, albumin, and protein levels, coagulograms and through pathohistological analysis. The trial was registered on ClinicalTrials.gov (NCT****).

RESULTS

Significant differences were found in serum levels of liver transaminases and bilirubin levels between thegroups, the highest level in the CG and the lowest level in the LIPC group. Levels of cholinesterase were also significantly higher in the LIPC group. Pathohistological findings graded by the Rodriguez score showed favourable changes in the LIPC and RIPC groups versus the CG.

CONCLUSION

Strong evidence supports the hepatoprotective effect of RIPC and LIPC preconditioning from an ischemia-reperfusion injury of the liver. Better synthetic liver function preservation in these two groups supports this conclusion.

Meta-analysis of ischemic preconditioning (IP) on postoperative outcomes after liver resections

BACKGROUND

The protective role (decrease ischemia-reperfusion injury) of ischemic preconditioning (IP) before continuous vascular occlusion in liver resection is controversial. This meta-analysis aimed to compare the advantages and any potential disadvantages of IP maneuver.

METHODS

A systematic search in the Embase, Medline, PubMed databases, and the Cochrane Library was performed using both medical subject headings (MeSH) and truncated word searches to identify all randomized controlled trials (RCTs) published on this topic. The primary outcomes were postoperative morbidity, mortality, postoperative aspartate aminotransferase (AST) level, alanine aminotransferase (ALT) level, and total bilirubin (TB) level. Pooled odds ratios (ORs) and weighted mean differences (WMDs) with 95% confidence intervals (95% CIs) were calculated using either the random effects model or fixed effects model.

RESULTS

Thirteen RCTs involving 918 patients were analyzed to achieve a summated outcome. The patients have been divided into IP group (n = 455) and no IP group (n = 463) before continuous vascular occlusion. No significant difference was found in postoperative mortality between both groups (P = .30). Subgroup analysis revealed that the postoperative morbidity in the cirrhosis subgroup was significantly less for the IP group compared with the control group (P = .01). In the cirrhosis subgroup, the result was stable (P = .04), without heterogeneity (P = .59; I = 0%). Meta-analysis of AST level on postoperative day (POD) 1 indicated lower postoperative AST level in the IP group (P = .04). The analysis of ALT level showed lower ALT level in the IP group versus control group (P = .02). However, there was no difference in postoperative AST and ALT level after excluding 1 study with statistical heterogeneity (all P > .05). With respect to postoperative TB level, there was no significant difference between 2 groups.

CONCLUSION

IP cannot decrease the hospital mortality for patients undergoing hepatectomy. IP may be beneficial for patients with cirrhosis due to less morbidity in patients with liver cirrhosis. However, we cannot conclude that IP can decrease ischemia-reperfusion injury because it did not significantly decrease postoperative AST, ALT, and TB levels.

Hypothermia is better than ischemic preconditioning for preventing early hepatic ischemia/reperfusion in rats

BACKGROUND

Topical hypothermia (TH) and ischemic preconditioning (IPC) are used to decrease I/R injury. The efficacy of isolated or combined use of TH and IPC in the liver regarding inflammation and cytoprotection in early ischemia/reperfusion (I/R) injury needs to be evaluated.

MATERIAL AND METHODS

Wistar rats underwent 70% liver ischemia for 90 min followed by 120 min of reperfusion. Livers of animals allocated in the sham, normothermic ischemia (NI), IPC, TH, and TH+IPC groups were collected for molecular analyses by ELISA and Western blot, aiming to compare proinflammatory, anti-inflammatory, and antioxidant profiles.

RESULTS

Compared with NI, TH presented decreased tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-12 concentrations and increased IL-10 levels. TH animals displayed lower inducible nitric oxide synthase (iNOS) and higher endothelial nitric oxide synthase (eNOS) expressions. NAD(P)H-quinone oxidoreductase-1(NQO1) expression was also lower with TH. Isolated IPC and NI were similar regarding all these markers. TH+IPC was associated with decreased IL-12 concentration and reduced iNOS and NQO1 expressions, similarly to isolated TH. Expression of Kelch-like ECH-associated protein (Keap)-1 was increased and expression of nuclear and cytosolic nuclear erythroid 2-related factor 2 (Nrf2) was decreased with TH+IPC vs. NI.

CONCLUSION

TH was the most effective method of protection against early I/R injury. Isolated IPC entailed triggering of second-line antioxidant defense enzymes. Combined TH+IPC seemed to confer no additional advantage over isolated TH in relation to the inflammatory process, but had the advantage of completely avoid second-line antioxidant defense enzymes.

How much ischemia can the liver tolerate during resection?

The use of vascular inflow occlusion (VIO, also known as the Pringle maneuver) during liver surgery prevents severe blood loss and the need for blood transfusion. The most commonly used technique for VIO entails clamping of the portal triad, which simultaneously occludes the proper hepatic artery and portal vein. Although VIO is an effective technique to reduce intraoperative blood loss, it also inevitably inflicts hepatic ischemia/reperfusion (I/R) injury as a side effect. I/R injury induces formation of reactive oxygen species that cause oxidative stress and cell death, ultimately leading to a sterile inflammatory response that causes hepatocellular damage and liver dysfunction that can result in acute liver failure in most severe cases. Since the duration of ischemia correlates positively with the severity of liver injury, there is a need to find the balance between preventing severe blood loss and inducing liver damage through the use of VIO. Although research on the maximum duration of hepatic ischemia has intensified since the beginning of the 1980s, there still is no consensus on the tolerable upper limit. Based on the available literature, it is concluded that intermittent and continuous VIO can both be used safely when ischemia times do not exceed 120 min. However, intermittent VIO should be the preferred technique in cases that require >120 min duration of ischemia.

Conditioning With Sevoflurane in Liver Transplantation: Results of a Multicenter Randomized Controlled Trial

BACKGROUND

During times of organ scarcity and extended use of liver grafts, protective strategies in transplantation are gaining importance. We demonstrated in the past that volatile anesthetics such as sevoflurane attenuate ischemia-reperfusion injury during liver resection. In this randomized study, we examined if volatile anesthetics have an effect on acute graft injury and clinical outcomes after liver transplantation.

METHODS

Cadaveric liver transplant recipients were enrolled from January 2009 to September 2012 at 3 University Centers (Zurich/Sao Paulo/Ghent). Recipients were randomly assigned to propofol (control group) or sevoflurane anesthesia. Postoperative peak of aspartate transaminase was defined as primary endpoint, secondary endpoints were early allograft dysfunction, in-hospital complications, intensive care unit, and hospital stay.

RESULTS

Ninety-eight recipients were randomized to propofol (n = 48) or sevoflurane (n = 50). Median peak aspartate transaminase after transplantation was 925 (interquartile range, 512-3274) in the propofol and 1097 (interquartile range, 540-2633) in the sevoflurane group. In the propofol arm, 11 patients (23%) experienced early allograft dysfunction, 7 (14%) in the sevoflurane one (odds ratio, 0.64 (0.20 to 2.02, P = 0.45). There were 4 mortalities (8.3%) in the propofol and 2 (4.0%) in the sevoflurane group. Overall and major complication rates were not different. An effect on clinical outcomes was observed favoring the sevoflurane group (less severe complications), but without significance.

CONCLUSIONS

This first multicenter trial comparing propofol with sevoflurane anesthesia in liver transplantation shows no difference in biochemical markers of acute organ injury and clinical outcomes between the 2 regimens. Sevoflurane has no significant added beneficial effect on ischemia-reperfusion injury compared to propofol.

Molecular Mechanisms of Renal Ischemic Conditioning Strategies

Ischemia-reperfusion injury is the leading cause of acute kidney injury in a variety of clinical settings such as renal transplantation and hypovolemic and/or septic shock. Strategies to reduce ischemia-reperfusion injury are obviously clinically relevant. Ischemic conditioning is an inherent part of the renal defense mechanism against ischemia and can be triggered by short periods of intermittent ischemia and reperfusion. Understanding the signaling transduction pathways of renal ischemic conditioning can promote further clinical translation and pharmacological advancements in this era. This review summarizes research on the molecular mechanisms underlying both local and remote ischemic pre-, per- and postconditioning of the kidney. The different types of conditioning strategies in the kidney recruit similar powerful pro-survival mechanisms. Likewise, renal ischemic conditioning mobilizes many of the same protective signaling pathways as in other organs, but differences are recognized.

Comparative Effects of Ischemic Preconditioning and Iron Chelation in Hepatectomy

PURPOSE/AIM

Major hepatectomies can result in severe ischemia/reperfusion (I/R) injury of the liver. The aim of this survey is to comparatively evaluate the effects of a surgical and a pharmacological hepatoprotective modality on the liver remnant in a porcine model of hepatectomy.

MATERIAL AND METHODS

Twenty-one Landrace pigs were randomly divided into three groups: a control group (CON) (n = 7), an Ischemic Preconditioning (PRE) group (n = 7) and a Desferoxamine (DFX) treated one (n = 7). Animals were subjected to 120 min of liver ischemia with subsequent 75% hepatectomy followed by 24-hr reperfusion. In all animals, continuous intracranial pressure (ICP) monitoring was employed. Blood samples were collected at t0, t6, t12, and t24 hrs after reperfusion. Liver remnant specimens were excised for histological examination.

RESULTS

In the PRE group, ICP was statistically lower at t6 time point compared to CON group and in comparison with t0. In addition, ICP was significantly lower at all-time points after reperfusion in the DFX group. Finally, with regard to DFX and PRE group correlation, ICP was significantly lower at t0, t12, and t24 time points after reperfusion in the DFX group. In the PRE group, NH3 levels were significantly lower at t12 after reperfusion compared to CON and DFX groups. Histological evaluation elucidated significantly less hepatocellular necrosis, apoptosis, and degeneration in the PRE and DFX groups correlated to CON group.

CONCLUSIONS

Both hepatoprotective modalities including PRE and DFX administration are associated with lower ICP levels and correlated with attenuated liver remnant injury.

Impact of ischemic preconditioning on outcome in clinical liver surgery: a systematic review

Background. Ischemia-reperfusion injury is a major cause of post-liver-surgery complications. Ischemic preconditioning (IPC) has been demonstrated to protect against ischemia-reperfusion injury. Clinical studies have examined IPC in liver surgery but with conflicting results. This systematic review aimed to evaluate the effects of IPC on outcome in clinical liver surgery. Methods. An electronic search of OVID Medline and Embase databases was performed to identify studies that reported outcomes in patients undergoing liver surgery subjected to IPC. Basic descriptive statistics were used to summarise data from individual clinical studies. Results. 1093 articles were identified, of which 24 met the inclusion criteria. Seven topics were selected and analysed by subgroup. There were 10 studies in cadaveric liver transplantation, 2 in living-related liver transplantation, and 12 in liver resection. IPC decreases hepatocellular damage in liver surgery as determined by transaminases but does not translate to any significant clinical benefit in orthotopic liver transplant or liver resection. Conclusions. Available clinical evidence does not support routine use of IPC in liver surgery as it does not offer any apparent benefit in perioperative outcome. Further clinical studies will need to be carried out to determine the subset of patients that will benefit from IPC.

Impact of ischaemic preconditioning on experimental steatotic livers following hepatic ischaemia-reperfusion injury: a systematic review

BACKGROUND

Steatotic livers are vulnerable to the deleterious effects of ischaemia-reperfusion injury (IRI) that occur after hepatic surgery. Ischaemic preconditioning (IPC) has been shown to abrogate the effects of IRI in patients undergoing hepatic surgery. Experimental studies have suggested that IPC may be beneficial in steatotic livers subjected to IRI.

OBJECTIVE

The aim of this systematic review was to evaluate the effects of IPC on steatotic livers following hepatic IRI in experimental models.

METHODS

An electronic search of the OVID Medline and EMBASE databases was performed to identify studies that reported clinically relevant outcomes in animal models of hepatic steatosis subjected to IPC and IRI.

RESULTS

A total of 1093 articles were identified, of which 18 met the inclusion criteria. There was considerable heterogeneity in the type of animal model, and duration and type of IRI. Increased macrovesicular steatosis (> 30%) was associated with a poor outcome following IRI. Ischaemic preconditioning was found to be beneficial in > 30% steatotic livers and provided for decreased histological damage, improved liver function findings and increased survival.

CONCLUSIONS

Experimental evidence supports the use of IPC in steatotic livers undergoing IRI. These findings may be applicable to patients undergoing liver surgery. However, clinical studies are required to validate the efficacy of IPC in this setting.

Complications following hepatectomy

As the number of liver resections in the United States has increased, operations are more commonly performed on older patients with multiple comorbidities. The advent of effective chemotherapy and techniques such as portal vein embolization, have compounded the number of increasingly complex resections taking up to 75% of healthy livers. Four potentially devastating complications of liver resection include postoperative hemorrhage, venous thromboembolism, bile leak, and post-hepatectomy liver failure. The risk factors and management of these complications are herein explored, stressing the importance of identifying preoperative factors that can decrease the risk for these potentially fatal complications.

Ischemic preconditioning provides no additive clinical value in liver resection of cirrhotic and non-cirrhotic patients under portal triad clamping: a prospective randomized controlled trial

BACKGROUND AND OBJECTIVE

The clinical value of ischemic preconditioning (IP) on patients undergoing hepatectomy under portal triad clamping (PTC) is uncertain, especially for patients with liver cirrhosis. Hence, we conducted a prospective randomized controlled trial to test whether IP could protect liver against ischemic reperfusion (IR) injury after hepatectomy under PTC.

METHOD

One hundred patients, including 67 with cirrhosis, undergoing hepatectomy with PTC were randomly divided into IP and control groups. Liver function tests at postoperative days 1, 3, and 7 as well as postoperative morbidity, mortality, and duration of hospitalization were compared between the two groups.

RESULTS

The general clinical characteristics between both groups were comparable. The duration of the operation, the amount of intraoperative blood loss, and the need and amount of perioperative blood transfusion were similar in both groups. The postoperative levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, and albumin were not statistically different between the two groups. In addition, the morbidity and mortality rates and the duration of hospitalization were similar in both groups.

CONCLUSIONS

IP did not improve liver tolerance to IR injury after hepatectomy under PTC. Therefore, the clinical use of IP cannot be recommended as a standard procedure before PTC.

Ischaemic conditioning strategies for the nephrologist: a promise lost in translation?

Over the last quarter of a century, a huge effort has been made to develop interventions that can minimise ischaemia reperfusion injury. The most potent of these are the ischaemic conditioning strategies, which comprise ischaemic preconditioning, remote ischaemic preconditioning and ischaemic postconditioning. While much of the focus for these interventions has been on protecting the myocardium, other organs including the kidney can be similarly protected. However, translation of these beneficial effects from animal models into routine clinical practice has been less straightforward than expected. In this review, we examine the role of ischaemic conditioning strategies in reducing tissue injury from the 'bench to the bedside' and discuss the barriers to their greater translation.

Redox therapeutics in hepatic ischemia reperfusion injury

Ischemia-reperfusion plays a major role in the injury experienced by the liver during transplantation. Much work has been done recently investigating the role of redox species in hepatic ischemia-reperfusion. As animal models are better characterized and developed, and more insights are gained into the pathophysiology of hepatic ischemia reperfusion injury in humans the questions into exactly how oxidants participate in this injury are becoming more refined. These questions include effects of cellular location, timing of injury, and ability of therapeutics to access this site are increasing our appreciation of the complexity of ischemia reperfusion and improving attempts to ameliorate its effects. In this review, we aim to discuss the various methods to alter redox chemistry during ischemia reperfusion injury and future prospects for preventing organ injury during hepatic ischemia reperfusion.

Hepatic colorectal metastases involving infra-hepatic inferior vena cava in high risk patients for extended resection: an alternative method for achieving radical resection in patient with borderline liver remnant

Resection is the only chance of cure for isolated liver metastases from colorectal cancer. In the case of extended parenchymal resections, one crucial point is the ischemic damage to the remnant liver. We report an alternative technique for extremely extended liver resections without total hilar clamping for borderline liver remnants. Two patients presented with invasion of the infrahepatic vena cava, both with an estimated live remnant ≤20 %. The crucial point of the technique is the absence of a portal triad clamping in under beating heart-extracorporeal circulation. In both patients resection margins were free of disease. No signs of liver insufficiency were noted. Survival was more than 2 years in both cases. We believe that aggressive treatment of liver colorectal metastases should be given to all suitable patients. This operation may be added to the techniques that can be offered to these patients.

Meta-analysis of ischaemic preconditioning for liver resections

BACKGROUND

Vascular clamping reduces blood loss during liver resection but leads to ischaemia-reperfusion injury. Ischaemic preconditioning (IP) may reduce this. This study aimed to evaluate IP in liver resection under clamping.

METHODS

This was a systematic review and meta-analysis of randomized clinical trials (RCTs) evaluating IP in adults undergoing liver resection under either continuous clamping (CC) or intermittent clamping (IC). Primary outcomes were mortality, liver failure and morbidity. Secondary outcomes included duration of operation, blood loss, length of hospital stay, length of intensive therapy unit stay, transfusion requirements, prothrombin time, and bilirubin and aminotransferase levels. Weighted mean differences were calculated for continuous data, and pooled odds ratios (ORs) for dichotomous data. Results were produced with a random-effects model with 95 per cent confidence intervals (c.i.).

RESULTS

A total of 2960 records were identified and 11 RCTs included 669 patients (IP 331, control 338). No significant difference in mortality (6 RCTs; IP 186, control 190; OR 1·36, 95 per cent c.i. 0·13 to 13·68; P = 0·80) or morbidity (6 RCTs; IP 186, control 190; OR 0·58, 0·31 to 1·07; P = 0·08) was found for IP plus CC versus CC. Nor was there a significant difference in mortality (4 RCTs; IP 122, control 121; OR 1·33, 0·24 to 7·32; P = 0·74) or morbidity (4 RCTs; IP 122, control 121; OR 0·87, 0·52 to 1·47; P = 0·61) for IP plus (CC or IC) versus IC. No significant differences were found for secondary outcome measures.

CONCLUSION

This meta-analysis failed to find a significant benefit of IP in liver resection.

Minimizing blood loss during hepatectomy: a literature review

There are numerous techniques surgeons employ to reduce blood loss during partial hepatectomy. In this literature review, prospective studies from the last 20 years are examined to determine the techniques that are best supported by the literature. Some of the techniques include vascular control, multiple parenchymal transection techniques, various hemostatic agents, low central venous pressure, and hemodilution. The strategies supported most convincingly by the literature include low CVP and total hepatic inflow occlusion.

Perioperative ischaemia-induced liver injury and protection strategies: An expanding horizon for anaesthesiologists

Liver resection is an effective modality of treatment in patients with primary liver tumour, metastases from colorectal cancers and selected benign hepatic diseases. Its aim is to resect the grossly visible tumour with clear margins and to ensure that the remnant liver mass has sufficient function which is adequate for survival. With the advent of better preoperative imaging, surgical techniques and perioperative management, there is an improvement in the outcome with decreased mortality. This decline in postoperative mortality after hepatic resection has encouraged surgeons for more radical liver resections, leaving behind smaller liver remnants in a bid to achieve curative surgeries. But despite advances in diagnostic, imaging and surgical techniques, postoperative liver dysfunction of varied severity including death due to liver failure is still a serious problem in such patients. Different surgical and non-surgical techniques like reducing perioperative blood loss and consequent decreased transfusions, vascular occlusion techniques (intermittent portal triad clamping and ischaemic preconditioning), administration of pharmacological agents (dextrose, intraoperative use of methylprednisolone, trimetazidine, ulinastatin and lignocaine) and inhaled anaesthetic agents (sevoflurane) and opioids (remifentanil) have demonstrated the potential benefit and minimised the adverse effects of surgery. In this article, the authors reviewed the surgical and non-surgical measures that could be adopted to minimise the risk of postoperative liver failure following liver surgeries with special emphasis on ischaemic and pharmacological preconditioning which can be easily adapted clinically.

Surrogate endpoints in liver surgery related trials: a systematic review of the literature

BACKGROUND

Although the safety of liver surgery has improved enormously, hepatic surgery continues to face challenging complications. Therefore, improvements supported by evidence-based guidelines are still required. The conduct of randomized controlled trials in liver surgery using dichotomous outcomes requires a large sample size. The use of surrogate endpoints (SEPs) reduces sample size but SEPs should be validated before use.

AIM

The aim of this review was to summarize the SEPs used in hepatic surgery related trials, their definitions and recapitulating the evidence validating their use.

METHOD

A systematic computerized literature search in the biomedical database PubMed using the MeSH terms 'hepatectomy' or 'liver resection' or 'liver transection' was conducted. Search was limited to papers written in the English language and published between 1 January 2000 and 1 January 2010.

RESULTS

A total of 593 articles met the search terms and 49 articles were included in the final selection. Standard biochemical liver functions tests were the most frequently used SEP (32 of 49 the studies). The used definitions of SEPs varied greatly among the studies. Most studies referred to earlier published material to justify their choice of SEP. However, no validating studies were found.

CONCLUSION

Many SEPs are used in liver surgery trials however there is little evidence validating them.

Protection of pharmacological postconditioning in liver surgery: results of a prospective randomized controlled trial

OBJECTIVES

: To elucidate the possible organ-protective effect of pharmacological postconditioning in patients undergoing liver resection with inflow occlusion.

BACKGROUND

: Inflow occlusion reduces blood loss during liver transection in selected patients but is potentially harmful due to ischemia-reperfusion injury. Preventive strategies include the use of repetitive short periods of ischemia interrupted by a reperfusion phase (intermittent clamping), application of a short period of ischemia before transection (ischemic preconditioning), or pharmacological preconditioning before transection. Whether intervention after resection (postconditioning) may confer protection is unknown.

METHODS

: A 3 arm, prospective, randomized trial was designed for patients undergoing liver resection with inflow occlusion to compare the effects of pharmacological postconditioning with the volatile anesthetic agent sevoflurane (n = 48), intermittent clamping (n = 50), or no protective intervention (continuous inflow occlusion, n = 17). Endpoints included peak serum aspartate transaminase level, postoperative complications, and hospital stay. All patients were intravenously anesthetized with propofol. In patients with postconditioning, propofol infusion was stopped upon reperfusion and replaced with sevoflurane for 10 minutes.

RESULTS

: Compared with the control group, both postconditioning (P = 0.044) and intermittent clamping (P = 0.015) significantly reduced aspartate transaminase levels. The risk of complications was significantly decreased by postconditioning, odds ratio, 0.08 [95% confidence interval (CI), 0.02-0.36; P = 0.001]) and intermittent clamping, odds ratio, 0.50 [95% CI, 0.26-0.96; P = 0.038], compared with controls. Both interventions reduced length of hospital stay, postconditioning -4 days [95% CI, -6 to -1; P = 0.009], and intermittent clamping -2 days, [95% CI, -4 to 0; P = 0.019].

CONCLUSIONS

: Pharmacological postconditioning reduces organ injury and postoperative complications. This easily applicable strategy should be used in patients with prolonged continuous inflow occlusion.

Right hepatectomy with extra-hepatic vascular division prior to transection: intention-to-treat analysis of a standardized policy

BACKGROUND

Right hepatectomy (RH) is the most common type of major hepatectomy and can be achieved without portal triad clamping (PTC) in non-cirrhotic liver. The present study reviews our standardized policy of performing RH without systematic PTC.

METHODS

One hundred and eighty-one consecutive RH were performed in non-cirrhotic patients, with division of the right afferent and efferent blood vessels prior to transection, without systematically using PTC. Prospectively collected data were analysed, focusing on the following endpoints: need for salvage PTC, ischaemic time, blood loss and post-operative outcome.

RESULTS

Extra-hepatic division of the right hepatic vessels was feasible in all patients, but was ineffective in 48 patients (26.5%) who required salvage PTC during transection. In those patients, the median ischaemic time was 20 min. The median blood loss was 500 ml (50-3000). Six patients (3.3%) experienced post-operative liver failure. Overall morbidity, severe morbidity and mortality were 42%, 12.1% and 1.6%, respectively, with peri-operative transfusion rate (16.6%) being the only factor associated with morbidity.

DISCUSSION

By performing RH with extra-hepatic vascular division prior to transection, PTC can be safely avoided in the majority of patients.

Topical hepatic hypothermia plus ischemic preconditioning: analysis of bile flow and ischemic injuries after initial reperfusion in rats

PURPOSE

To evaluate the effects of the topical liver hypothermia and IPC combination against I/R injury after initial reperfusion.

METHODS

In 32 Wistar rats, partial liver ischemia was induced for 90 minutes in normothermia (IN), ischemic preconditioning (IPC), 26ºC topical hypothermia (H) and 26ºC topical hypothermia plus IPC (H+IPC). MAP, body temperature and bile flow were recorded each 15 minutes. Plasmatic injury markers and tissue antioxidant defenses were assessed after 120 minutes of reperfusion.

RESULTS

MAP and body temperature remained constant during all experiment. Bile flow returned to levels similar to controls after 45 minutes of reperfusion in the H and H+IPC groups and increased significantly in comparison to the NI and IPC groups after 105 and 120 minutes. AST and ALT increased significantly in the normothermic groups in comparison to controls. TBARS levels decreased significantly in the H+IPC group in comparison to the other groups whereas Catalase levels increased significantly in the IPC group. SOD levels were significantly higher in the H group in comparison to all groups.

CONCLUSION

The induction of 26ºC topical hypothermia associated or not to IPC protected the ischemic liver against ischemia/reperfusion injuries and allowed an early recovery of the hepatic function.

Portal triad clamping versus other methods of vascular control in liver resection: a systematic review and meta-analysis

BACKGROUND

Portal triad clamping (PTC) is the most commonly used method of achieving vascular control during liver resection. However, the efficacy and safety of PTC, compared with those of other methods of vascular control, are uncertain.

METHODS

A systematic review was conducted to identify randomized controlled trials (RCTs) comparing PTC with other methods of vascular control during liver resection. Endpoints included in-hospital mortality, need for transfusion, number of complications and length of hospital stay. Meta-analyses were performed using a random-effects model.

RESULTS

Ten RCTs were identified; these included a total of 820 patients. No statistically significant differences between PTC and other forms of vascular control in liver resection were demonstrated.

CONCLUSIONS

There is no evidence, on the basis of this meta-analysis of RCTs, of any difference between PTC and other forms of vascular control in liver resection.

Avaliação da regeneração hepática com modulação pelo pré-condicionamento isquêmico após isquemia e reperfusão e hepatectomia parcial

OBJETIVO: Avaliar a regeneração hepática com modulação pelo pré-condicionamento isquêmico após isquemia, reperfusão e hepatectomia parcial. MÉTODOS: Foram usadas 24 ratas Wistar, de 12 semanas de idade, distribuídas randomicamente em quatro grupos: Grupo Controle (SHAM), Grupo Hepatectomia (HEP), Grupo Isquemia e Reperfusão (GIR) e Grupo Pré-condicionamento Isquêmico (PRE). Foi feita a análise das enzimas hepáticas ALT e AST, avaliação da regeneração através dos pesos inicial e final do fígado e da proliferação dos hepatócitos pela análise imunoistoquímica com o Proliferating Cell Nuclear Antigen (PCNA). RESULTADOS: Em todos os grupos ocorreu regeneração do fígado, não havendo significância estatística entre eles. Houve diferenças significativas em relação a ALT e AST entre os grupos HEP-SHAM, GIR-PRE, GIR-SHAM E PRE-SHAM (p< 0,05). Também houve diferença significativa em relação à marcação de PCNA do grupo SHAM quando comparado aos demais grupos (p< 0,05). CONCLUSÃO: O pré-condicionamento isquêmico diminuiu a lesão hepática, mas não influenciou na regeneração até 48 horas.

The Current Knowledge of the Role of PPAR in Hepatic Ischemia-Reperfusion Injury

Strategies to improve the viability of steatotic livers could reduce the risk of dysfunction after surgery and increase the number of organs suitable for transplantation. Peroxisome proliferator-activated receptors (PPARs) are major regulators of lipid metabolism and inflammation. In this paper, we review the PPAR signaling pathways and present some of their lesser-known functions in liver regeneration. Potential therapies based on PPAR regulation will be discussed. The data suggest that further investigations are required to elucidate whether PPAR could be a potential therapeutic target in liver surgery and to determine the most effective therapies that selectively regulate PPAR with minor side effects.

Recent advances in liver preconditioning: Thyroid hormone, n-3 long-chain polyunsaturated fatty acids and iron

Liver preconditioning (PC), defined as an enhanced tolerance to injuring stimuli induced by previous specific maneuvers triggering beneficial functional and molecular changes, is of crucial importance in human liver transplantation and major hepatic resection. For these reasons, numerous PC strategies have been evaluated in experimental models of ischemia-reperfusion liver injury, which have not been transferred to clinical application due to side effects, toxicity and difficulties in implementation, with the exception of the controversial ischemic PC. In recent years, our group has undertaken the assessment of alternate experimental liver PC protocols that might have application in the clinical setting. These include thyroid hormone (T(3)), n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA), or iron, which suppressed liver damage due to the 1 h ischemia-20 h reperfusion protocol. T(3), n-3 LCPUFA and iron are hormetic agents that trigger biologically beneficial effects in the low-dose range, whose multifactorial mechanisms of action are discussed in the work.

Metabolic syndrome and hepatic resection: improving outcome

OBJECTIVE

A review of the peri-operative risk associated with hepatic resection in patients with metabolic syndrome (MetS) and identification of measures for the improvement of cardiometabolic disturbances and liver-related mortality.

BACKGROUND

MetS and its hepatic manifestation non-alcoholic fatty liver disease (NAFLD) are associated with an increased operative mortality in spite of a significant improvement in peri-operative outcome after hepatic resection.

METHODS

A review of the English literature on MetS, liver resection and steatosis was performed from 1980 to 2011 using the MEDLINE and PubMed databases.

RESULTS

MetS is a predictor of NAFLD and patients with multiple metabolic risk factors may harbour non-alcoholic steatohepatitis (NASH) predictive of operative and cardiovascular mortality. Pre-operative diagnosis of unsuspected NASH with the selective use of a liver biopsy can modify the operative strategy by limiting the extent of hepatic resection, avoiding or altering the pre-operative chemotherapy regimen and the utilization of portal vein embolization. Thiazolidinediones are therapeutic for MetS and NASH and Vitamin E for active NASH; however, their utility in improving the peri-operative outcome after hepatic resection is unknown. A short-term regimen for weight loss improves post-operative patient and liver-related outcomes in patients with >30% steatosis. Cardiovascular disease associated with MetS or NAFLD should be managed aggressively. Peri-operative measures to minimize thrombotic events and acute renal injury secondary to the pro-inflammatory, prothrombotic state of MetS may further improve the outcome.

CONCLUSION

Potential candidates for hepatic resection should be screened for MetS as the pre-operative identification of NASH, short-term treatment of significant steatosis, cardiovascular risk assessment and optimization of each component of MetS may improve the peri-operative outcome in this high-risk subset of patients.

Preconditioning, postconditioning, and remote conditioning in solid organ transplantation: basic mechanisms and translational applications

Ischemia and reperfusion (I/Rp) injury is inherent to solid organ transplantation and can result in primary nonfunction or delayed function of grafts, which is associated with a significant morbidity and mortality posttransplantation. It is also a major obstacle for the use of marginal grafts to increase the donor pool, as these grafts are prone to a higher degree of I/Rp injury. Pre-, post-, and remote conditioning are protective strategies against I/Rp injury, which can be applied in the transplant setting. These strategies hold the potential to reduce graft injury and to safely expand the donor pool. However, despite convincing experimental data, the protective effects of the "conditioning" protocols remain unclear, and only few have translated to clinical practice. This review summarizes pre-, post-, and remote conditioning strategies in clinical use in solid organ transplantation and discusses an overview of the mechanistic pathways involved in each strategy.

Impact of reversible cardiac arrest in the brain-dead organ donor on the outcome of adult liver transplantation

Several donor and graft characteristics are associated with higher failure rates for deceased donor liver transplantation (LT). The influence of reversible cardiac arrest in the donor on these failure rates is unclear because of scarce and inconsistent data. The aim of this study was to determine whether reversible cardiac arrest in the donor could affect the early postoperative outcome of LT. From January 2008 to February 2010, 165 patients underwent LT, and they were retrospectively divided into 2 groups: a cardiac arrest group (34 patients who received grafts from donors who had experienced reversible cardiac arrest before organ procurement) and a control group (131 patients who received grafts from donors without a history of reversible cardiac arrest). The postoperative complications and the graft and recipient outcomes were prospectively recorded for all the patients. Graft failure was defined as death or the need for retransplantation within 90 days of LT. Donors in the cardiac arrest group displayed higher serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels than donors in the control group [AST: 104 (19-756) versus 42 IU/L (10-225 IU/L), P < 0.001; ALT: 73 (13-869) versus 29 IU/L (6-549 IU/L), P < 0.001]. However, no difference in the graft failure rates was found between the 2 groups (11.8% versus 8.4%, P = 0.51). The biological parameters 5 and 7 days after LT and the peak AST/ALT levels were similar for the 2 groups. Furthermore, the 2 groups had similar graft and patient survival rates at the 6-month mark (87% and 88%, respectively). In conclusion, our study shows that brief and reversible cardiac arrest in organ donors does not affect post-LT allograft survival and function, even though liver function test values are higher for these donors. However, the risk of using these grafts needs to be balanced against the potential benefits for the recipients.

Post-hepatectomy haemorrhage: a definition and grading by the International Study Group of Liver Surgery (ISGLS)

BACKGROUND

A standardized definition of post-hepatectomy haemorrhage (PHH) has not yet been established.

METHODS

An international study group of hepatobiliary surgeons from high-volume centres was convened and a definition of PHH was developed together with a grading of severity considering the impact on patients' clinical management.

RESULTS

The definition of PHH varies strongly within the hepatic surgery literature. PHH is defined as a drop in haemoglobin level > 3 g/dl post-operatively compared with the post-operative baseline level and/or any post-operative transfusion of packed red blood cells (PRBC) for a falling haemoglobin and/or the need for radiological intervention (such as embolization) and/or re-laparotomy to stop bleeding. Evidence of intra-abdominal bleeding should be obtained by imaging or blood loss via the abdominal drains if present. Transfusion of up to two units of PRBC is considered as being Grade A PHH. Grade B PHH requires transfusion of more than two units of PRBC, whereas the need for invasive re-intervention such as embolization and/ or re-laparotomy defines Grade C PHH.

CONCLUSION

The proposed definition and grading of severity of PHH enables valid comparisons of results from different studies. It is easily applicable in clinical routine and should be applied in future trials to standardize reporting of complications.

How to protect liver graft with nitric oxide

Organ preservation and ischemia reperfusion injury associated with liver transplantation play an important role in the induction of graft injury. One of the earliest events associated with the reperfusion injury is endothelial cell dysfunction. It is generally accepted that endothelial nitric oxide synthase (e-NOS) is cell-protective by mediating vasodilatation, whereas inducible nitric oxide synthase mediates liver graft injury after transplantation. We conducted a critical review of the literature evaluating the potential applications of regulating and promoting e-NOS activity in liver preservation and transplantation, showing the most current evidence to support the concept that enhanced bioavailability of NO derived from e-NOS is detrimental to ameliorate graft liver preservation, as well as preventing subsequent graft reperfusion injury. This review deals mainly with the beneficial effects of promoting “endogenous” pathways for NO generation, via e-NOS inducer drugs in cold preservation solution, surgical strategies such as ischemic preconditioning, and alternative “exogenous” pathways that focus on the enrichment of cold storage liquid with NO donors. Finally, we also provide a basic bench-to-bed side summary of the liver physiology and cell signalling mechanisms that account for explaining the e-NOS protective effects in liver preservation and transplantation.

Ischemia/reperfusion injury in liver resection: a review of preconditioning methods

Ischemic preconditioning is one of the therapeutic interventions aiming at preventing ischemia/reperfusion-related injury. Numerous experimental studies and a few clinical series have shown that during liver resections, ischemic preconditioning is a promising strategy for optimizing the postoperative outcome. Moreover, various types of pharmacological intervention as well as different types of preconditioning, such as remote preconditioning, the use of heat shock, and hyperbaric oxygen, have been developed to attenuate the functional impairment accompanying ischemia/reperfusion injury. This review summarizes the various forms of preconditioning, thus suggesting that close cooperation between surgeons and anesthesiologists paves the way to apply novel strategies to improve the outcome of liver resection.

Ischemic preconditioning induces autophagy and limits necrosis in human recipients of fatty liver grafts, decreasing the incidence of rejection episodes

Whether ischemic preconditioning (IP) reduces ischemia/reperfusion (I/R) injury in human normal and fatty livers remains controversial. We compared two independent groups of liver donor transplants with versus without steatosis to evaluate IP consequences. Liver donors with (n=22) or without (n=28) steatosis either did or did not undergo IP before graft retrieval. Clinical data from the recipients, as well as histological and immunohistological characteristics of post-reperfusion biopsies were analyzed. Incidence of post-reperfusion necrosis was increased (10/10 versus 9/14, respectively; P<0.05) and the clinical outcome of recipients was worse for non-IP steatotic liver grafts compared with non-IP non-steatotic grafts. IP significantly lowered the transaminase values only in patients receiving a non-steatotic liver. An increased expression of beclin-1 and LC3, two pro-autophagic proteins, tended to decrease the incidence of necrosis (P=0.067) in IP steatotic livers compared with non-IP steatotic group. IP decreased the incidence of acute and chronic rejection episodes in steatotic livers (2/12 versus 6/10; P=0.07 and 2/12 versus 7/10; P<0.05, respectively), but not in non-steatotic livers. Thus, IP may induce autophagy in human steatotic liver grafts and reduce rejection in their recipients.

Molecular mechanisms of liver preconditioning

Ischemia/reperfusion (I/R) injury still represents an important cause of morbidity following hepatic surgery and limits the use of marginal livers in hepatic transplantation. Transient blood flow interruption followed by reperfusion protects tissues against damage induced by subsequent I/R. This process known as ischemic preconditioning (IP) depends upon intrinsic cytoprotective systems whose activation can inhibit the progression of irreversible tissue damage. Compared to other organs, liver IP has additional features as it reduces inflammation and promotes hepatic regeneration. Our present understanding of the molecular mechanisms involved in liver IP is still largely incomplete. Experimental studies have shown that the protective effects of liver IP are triggered by the release of adenosine and nitric oxide and the subsequent activation of signal networks involving protein kinases such as phosphatidylinositol 3-kinase, protein kinase C δ/ε and p38 MAP kinase, and transcription factors such as signal transducer and activator of transcription 3, nuclear factor-κB and hypoxia-inducible factor 1. This article offers an overview of the molecular events underlying the preconditioning effects in the liver and points to the possibility of developing pharmacological approaches aimed at activating the intrinsic protective systems in patients undergoing liver surgery.