The "kidney-liver" multiorgan ex vivo perfused model improves the circuit's biochemical milieu during perfusion compared to the "liver-kidney" counterpart.

The multiorgan ex vivo perfused liver-kidney model allows studying the hepatic pathophysiology and purifying waste products. We tested if the addition of the kidney first followed by the liver (KL circuit) produces better results compared to the classic liver-first approach (LK). Intact livers and kidneys were obtained post mortem from ten female domestic white pigs, five experiments were conducted with the KL circuit and five with the LK. Bile, urine production, arterial blood gases, glucose, renal and liver tests were collected hourly during the perfusions. The KL circuit had values more close to physiological ranges, more stable over time and showed less variability compared to the LK circuit for urine production, glucose, PH, anion gap, lactate, urea, sodium, potassium and Alanine Transaminase (ANOVA test for repeated measures p < 0.05). The KL circuit produced a more physiological and reliable biochemical milieu.

History, ethics, advantages and limitations of experimental models for hepatic ablation.

Numerous techniques developed in medicine require careful evaluation to determine their indications, limitations and potential side effects prior to their clinical use. At present this generally involves the use of animal models which is undesirable from an ethical standpoint, requires complex and time-consuming authorization, and is very expensive. This process is exemplified in the development of hepatic ablation techniques, starting experiments on explanted livers and progressing to safety and efficacy studies in living animals prior to clinical studies. The two main approaches used are ex vivo isolated non-perfused liver models and in vivo animal models. Ex vivo non perfused models are less expensive, easier to obtain but not suitable to study the heat sink effect or experiments requiring several hours. In vivo animal models closely resemble clinical subjects but often are expensive and have small sample sizes due to ethical guidelines. Isolated perfused ex vivo liver models have been used to study drug toxicity, liver failure, organ transplantation and hepatic ablation and combine advantages of both previous models.

Steps for the autologous ex vivo perfused porcine liver-kidney experiment.

The use of ex vivo perfused models can mimic the physiological conditions of the liver for short periods, but to maintain normal homeostasis for an extended perfusion period is challenging. We have added the kidney to our previous ex vivo perfused liver experiment model to reproduce a more accurate physiological state for prolonged experiments without using live animals. Five intact livers and kidneys were retrieved post-mortem from sacrificed pigs on different days and perfused for a minimum of 6 hr. Hourly arterial blood gases were obtained to analyze pH, lactate, glucose and renal parameters. The primary endpoint was to investigate the effect of adding one kidney to the model on the acid base balance, glucose, and electrolyte levels. The result of this liver-kidney experiment was compared to the results of five previous liver only perfusion models. In summary, with the addition of one kidney to the ex vivo liver circuit, hyperglycemia and metabolic acidosis were improved. In addition this model reproduces the physiological and metabolic responses of the liver sufficiently accurately to obviate the need for the use of live animals. The ex vivo liver-kidney perfusion model can be used as an alternative method in organ specific studies. It provides a disconnection from numerous systemic influences and allows specific and accurate adjustments of arterial and venous pressures and flow.

Histological changes during extracorporeal perfusions of the porcine liver: implications for temporary support during acute liver failures.

Ex vivo perfused porcine livers have been used for temporary support during acute liver failure. The aim of this study was to assess both the histological changes and temporal pattern of the changes that occur during extracorporeal liver perfusions and to correlate these with factors that may influence them. Five porcine livers were harvested, preserved in cold ice and reperfused for 6 h in an extracorporeal circuit using autologous normothermic blood. Tissue biopsies were collected hourly. The Ishak score was used to quantify hepatic necrosis, and immunohistochemistry was used to evaluate apoptosis and regeneration. Liver weight, perfusion parameters, arterial blood gases and blood samples were also collected. The Ishak score peaked immediately before and 4 h after the start of reperfusion. Scattered necrosis, microvesicular steatotic vacuolization, sinusoidal dilatation and red cell extravasation were present. Anion gap acidosis was associated with the Ishak score. An inverse correlation was present between liver regeneration and necrosis, and between liver weight and regeneration. No changes were observed for apoptosis. Among the inflammatory cytokines evaluated, interleukin-6 and -8 levels increased significantly during the perfusions. Hepatic necrosis was always present during the extracorporeal perfusions, followed a definite pattern and was inversely correlated with regeneration. Apoptosis did not increase over baseline levels. The meaning of these findings and their correlation with clinical outcomes during acute hepatic failures deserve further investigation.

The autologous normothermic ex vivo perfused porcine liver-kidney model: improving the circuit's biochemical and acid-base environment.

BACKGROUND: The ex vivo porcine liver perfused model isolates the organ from extrinsic regulatory mechanisms, facilitating an improved understanding of the organ physiology and reaction to various conditions. We have assessed the influence of the addition of a porcine kidney to the circuit. METHODS: Eight livers were harvested and perfused for 6 hours. In 5 additional experiments a kidney also was connected in parallel. Hourly arterial blood gases were collected to analyze glucose, acid base, and renal parameters. The primary end point was an evaluation of the influence of the kidney on glucose, pH, and electrolyte levels. RESULTS: In the combined porcine liver-kidney circuit all the parameters significantly improved compared with the liver circuit alone. This was particularly evident for glucose values because normoglycemia was reached by the end of the perfusion, and for pH and electrolyte values that were maintained at initial levels. CONCLUSIONS: The addition of a porcine kidney to the perfusion circuit improves the biochemical milieu. This might produce more consistent and reliable results, particularly during studies requiring a steady-state environment.

Patterns of histological changes following hepatic electrolytic ablation in an ex-vivo perfused model.

Electrolytic ablation (EA) destroys the liver by releasing toxic radicles and producing modifications in the local pH without increasing the tissue temperature. We assessed the histological changes produced by EA using an ex-vivo perfused model. Five porcine livers were harvested, preserved in ice and reperfused for six hours in an extracorporeal circuit using autologous normothermic blood. One hour after reperfusion EA was performed and liver biopsies collected at the end of the experiments. The main necrotic zone consisted of coagulative necrosis, sinusoidal dilatation and haemorrhage with an unusual morphological pattern. The coagulative necrosis and haemorrhage affected mainly the peripheral area of the lobule with relative sparing of the area surrounding the centrilobular vein. Contrasting with this sinusoidal dilatation appeared to be more prominent in the centrilobular area. EA produces patterns of tissue destruction that have not been observed with the more commonly used thermal techniques. Further studies should obtain more information about the influence of adjacent biliary and vascular structures so that appropriate clinical trials can be designed.

Addition of a kidney to the normothermic ex vivo perfused porcine liver model does not increase cytokine response.

The addition of a kidney to the ex vivo liver perfused model may facilitate the circuit homeostatic balance of important biochemical parameters (i.e. pH changes, urea and creatinine, or glucose levels) but might also increase the inflammatory reaction produced. In this study, we compared the production of various cytokines between liver-kidney and liver-alone circuits. Seven livers were harvested from female pigs and perfused for 6 h. In five additional experiments, a kidney was also harvested and connected in parallel. Blood samples for interleukins (IL) 1, 2, 4, 6, 8, 10, and 12, interferon (IFN)-γ and tumor necrosis factor (TNF)-α were collected before perfusion and at hours 1, 2, 4 and 6 postperfusion. In the combined liver-kidney circuit, a significant increase was present only for IL-6 and IL-8, but this did not differ significantly from those recorded in the liver-alone circuit. All other cytokines were not modified from baseline levels. The addition of a kidney to the perfusion circuit does not stimulate a greater inflammatory reaction than that of the liver alone and therefore further confirms the safety of the experimental setups in view of more delicate experiments requiring strict homeostatic conditions.

Mechanisms of reducing postoperative pain, nausea and vomiting: a systematic review of current techniques.

BACKGROUND: Multimodal recovery programmes decrease hospital stay. The objective of this systematic review was to assess how single-modality evidence-based care principles, regarding postoperative analgesia and postoperative nausea and vomiting (PONV) prophylaxis, combine to achieve this. METHODS: A systematic review of randomised controlled trials was performed. Relevant trials compared postoperative epidural analgesia/parenteral opioid analgesia/paracetamol/non-steroidal anti-inflammatory drugs (NSAIDs) and postoperative antiemetics. The effect on recovery was evaluated in terms of length of hospital stay, pain intensity, duration of gastrointestinal dysfunction and incidence of PONV. RESULTS: Twenty-three trials were included. Epidural anaesthesia failed to reduce length of stay or the incidence of PONV when compared to controls. Pain intensity and time to first bowel movement were reduced (p<0.05). Paracetamol did not reduce the incidence of PONV. NSAIDs reduced postoperative opioid consumption and the incidence of PONV (p<0.05). Dexamethasone and 5-HT3 antagonists reduced the incidence of PONV compared to controls. CONCLUSIONS: Epidural anaesthesia appears to not reduce length of hospital stay or incidence of PONV despite reducing pain intensity and ileus. NSAIDs are more effective than paracetamol in reducing postoperative opioid consumption and PONV, while dexamethasone and 5-HT3 antagonists are both effective in reducing PONV.

Changes in acid-base balance during electrolytic ablation in an ex vivo perfused liver model.

BACKGROUND: Electrolytic ablation (EA) destroys tissues through extreme pH changes in the local microenvironment. An ex vivo perfused liver model was used to assess the systemic effects of EA on the acid-base balance without the influence of compensatory organs (lungs and kidneys). METHODS: Eleven pigs were perfused extracorporeally at 39°C with autologous blood; 4 also underwent EA after 1 hour of reperfusion. Arterial blood samples were obtained hourly. RESULTS: pH and CO(2) levels did not change throughout the experiments. A significant increase of HCO(3)-, anion gap, base excess, and lactate was present after the third hour. No differences were observed between EA experiments and controls. CONCLUSIONS: EA does not alter the acid-base balance even when the confounding influence of compensatory organs is removed. Such findings should be considered when planning ablations in patients with renal failure or respiratory diseases in which EA could avoid undesirable metabolic changes.

Use of the recanalised umbilical vein for islet autotransplantation following total pancreatectomy.

INTRODUCTION: Islet autotransplantation requires access to the portal vein or tributaries. We originally infused islets into the liver via the middle or right colic veins, but since 2005 we have used the recanalised umbilical vein. Here, we describe the technique, the advantages and the early results achieved. MATERIALS AND METHODS: After removal of the pancreas and restoration of the biliary and enteric continuity, the ligamentum teres is transected. The obliterated umbilical vein is identified and recanalised with Bakes dilators giving access to the left portal vein. A Vygon® Nutricath 'S' 11-Fr catheter is inserted and used for the islet infusion. If the ligamentum teres is to be exteriorised for postoperative measurements or subsequent access, it is pulled through a 10-mm laparoscopic port in the epigastrium, sutured to the skin and covered with a dressing. RESULTS: We have used this approach in 17 patients and exteriorised the falciform ligament in 4. There have been no intra- or postoperative complications. CONCLUSIONS: The recanalised umbilical approach is safe and allows for venous sampling and postoperative measurements of the portal pressure. Under local anaesthetic, the umbilical vein can be approached above the umbilicus and exteriorised if repeated transplants are required for allograft patients. and IAP.

The porcine hepatic arterial supply, its variations and their influence on the extracorporeal perfusion of the liver.

BACKGROUND: Variations in the porcine hepatic vasculature may contribute to the outcome of experiments based on liver perfusion models. We studied the hepatic artery (HA), variations of its branches, and the correlation with the resultant perfusion. MATERIALS AND METHODS: Nineteen animals were used. After 6 h of perfusion, dissection of the HA and its branches was conducted up to the insertion in the liver parenchyma. Data about the macroscopic appearance of lobes and the pattern of branching were recorded. RESULTS: In all cases, the HA bifurcated into two constant branches, one for the LL/LM lobes (further divided in two vessels for each lobe) and one for the RM lobe. Five main patterns were identified involving vessels for the RL and the CL lobes. Two variations produced complete and uniform perfusion of the entire liver in all cases, while in the remaining cases, only part of them were completely perfused. CONCLUSIONS: Some variants of the porcine HA and its branches are associated with the risk of incomplete perfusion if the perfusion cannula placement does not take the individual hepatic arterial anatomy into account. Understanding of the hepatic arteries branching patterns is essential when ex vivo perfusion models are being established.

Bile changes after liver surgery: experimental and clinical lessons for future applications.

INTRODUCTION: The aim of this review is to summarize the available evidence for changes in bile composition following liver surgery and assess their use in predicting post-operative complications. MATERIALS AND METHODS: A literature search was undertaken for all studies focusing on bile composition, bile volume and analysis. Articles were selected from MEDLINE, Embase and the Cochrane Central Register of Controlled Trials databases up to May 2009. RESULTS: Low values of pre-operative bilirubin diglucuronide predict reduced post-operative liver function and the occurrence of jaundice. Low concentrations of hepatocyte growth factor and interleukin-6 in bile following surgery are associated with the subsequent development of liver failure and are probably surrogate markers for situations where the resultant hepatic regeneration is inadequate. CONCLUSIONS: Analysis of the composition and quality of bile is probably underused as a tool for the pre-operative screening and early post-operative monitoring of patients at high risk of developing liver failure following major hepatobiliary procedures.

Cytokine response of electrolytic ablation in an ex vivo perfused liver model.

BACKGROUND: The inflammatory response following hepatic ablation depends on different factors including the method used, the duration and intensity of the treatment and the presence or absence of ischemia. Debate continues about the use of different modalities and whether some aspects of the response may be advantageous by releasing immunological active substances. Little data have been published concerning the cytokine response elicited by hepatic electrolytic ablation (EA). Study of an ex vivo liver model could allow for the evaluation of this response without the influence of confounding systemic factors. METHODS: Livers explanted from 11 pigs were perfused extracorporeally with normothermic autologous blood. Four of them underwent EA after 1 h of reperfusion. Serum samples were obtained up to 6 h after the reperfusion and assayed for IL-1 beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IFN-gamma, TNF-alpha. RESULTS: Significant changes in the control group were observed for IL-6 after the second hour and IL-8 after the first hour compared with baseline levels (P < 0.001). In the EA group, IL-6 and IL-12 were raised after the second hour and IL-8 and IL-10 after the first hour (P < 0.001). The comparison between groups showed significant differences for IL-2, IL-4 (decreased in the EA group compared with controls), IL-10 and TNF-alpha (EA group increased compared with controls; P < 0.001). CONCLUSIONS: The ex vivo perfused liver model demonstrated changes in levels of IL-2, IL-4, IL-10 and TNF-alpha following hepatic EA.

Caveat reporting in ultrasound interpretation of surgical pathology: a comparison of sonographer versus radiologist.

BACKGROUND: Radiology reports provide specialist interpretation of images and relate these findings to the patient's symptoms and signs. This study compared ultrasound (USS) reports generated by radiologists and sonographers to determine if any significant or clinically relevant differences existed. METHODS: A retrospective analysis of 624 consecutive USS reports was carried out. The reports were assessed for the presence of a 'disclaimer' or 'caveat' pertaining to the quality of the images and were analysed with respect to the clarity of their wording and ability to answer the clinical request. RESULTS: The majority of sonographer USS reports contained a disclaimer regarding the quality of the USS images (57.1%) compared with a smaller proportion of radiologist scans (9.9%) (P < 0.001). Overall, radiologists performed significantly better in providing a clear negative or positive diagnosis to the clinical question on the request form, when compared with sonographers (88.5% vs. 65.4%, P < 0.001). CONCLUSION: 'Disclaimer' comments and 'hedging' must be avoided in radiology reporting. While feedback as to the accuracy of the radiology images is important, overuse of such terms undermines the validity of the radiology report.

Effects of hypoxia due to isovolemic hemodilution on an ex vivo normothermic perfused liver model.

BACKGROUND: The liver has a complex hormonal and nervous control mechanism leading to difficulty in the interpretations of its responses to chronic hypoxia. Theoretically an ex vivo perfused model of the liver should, by dissociating the organ from the extrinsic regulatory mechanisms, allow a better and unequivocal analysis of changes obtained. MATERIALS AND METHODS: Twelve livers were harvested from female pigs and perfused for 6 h. Hypoxia was produced by means of isovolemic hemodilution with hemoglobin and hematocrit reduced to 40% of the baseline value. The extracorporeal circuit included a centrifugal pump, heat exchanger, and oxygenator. Every hour, physiological parameters (arterial/portal venous pressures and flows) were measured and blood samples were collected for the analysis of hemoglobin, red blood cells, hematocrit, lactate, glucose, albumin, alanine aminotransferase, alkaline phosphatase, and total bilirubin, arterial and venous blood gases. The arterio-venous oxygen and carbon dioxide differences, and the hepatic metabolic rate for oxygen, were also calculated. Primary endpoint of the study was the glucose response of the liver to acute hypoxia. Secondary endpoints were eventual changes of markers for hepatic viability and functionality. RESULTS: Most parameters showed significant variability during the first h of perfusion but subsequently normalized and remained stable at baseline values for the following 5 h. A strong and significant hyperglycemic response was present throughout the experiment (P < 0.001). Lactate rose steadily throughout the study period and after 6 h of perfusion there was a significant deviation from initial values (P < 0.05). Albumin did not change significantly throughout the study although a trend towards decreasing values was observed (Friedman test, P = NS). After an initial rise in levels of alanine transaminase and alkaline phosphatase following perfusion (P < 0.01), values remained constant without any further increase. CONCLUSIONS: Following reperfusion in an ex vivo model, the liver reacts to low oxygen concentrations mobilizing glycogen deposits. This mechanism depends on an intrinsic sensibility of hepatocytes to hypoxia, as demonstrated by the ex vivo liver perfusion. These findings improve our knowledge in organ preservation for liver transplantation.

Preoperative biliary drainage for distal obstruction: the case against revisited.

OBJECTIVES: No conclusive evidence exists confirming the role of preoperative biliary drainage (PBD) in reversing the physiological disturbances resulting from biliary obstruction to improve outcome. This review examined the impact of PBD and the outcomes after surgery. METHODS: A PubMed literature search was undertaken using the keywords preoperative, biliary, and drainage. The primary end points were the effect of PBD on mortality, morbidity, and bile cultures. The secondary outcome measures were PBD and pancreatic leakage, intra-abdominal abscess, sepsis/infectious complications, wound infection, hemorrhage, and bile leak rates. The impact of bile cultures positive for bacteria and the outcomes after surgery were also examined. RESULTS: Preoperative biliary drainage significantly increases wound and bile infection rates on meta-analysis (P < 0.0005) using a fixed and random effect model, but no adverse effect on mortality and morbidity was found. A bile culture positive for bacteria negatively impacts on both mortality and morbidity (P < 0.005) after surgery. CONCLUSIONS: Preoperative biliary drainage significantly increases the rates of bile culture positive for bacteria and the probability of wound infection. Bile cultures positive for bacteria adversely impact mortality and morbidity after surgery in jaundiced patients. Although no evidence has been found by this review that PBD directly increases mortality and morbidity, it is possible that in certain patients, PBD may deleteriously affect outcome by bacterial contamination of the bile.

The current role of PET-CT in the characterization of hepatobiliary malignancies.

BACKGROUND: Surgery has become heavily dependent on accurate imaging in the assessment and treatment of suspected or confirmed intra-abdominal malignancy. Positron emission tomography-computed tomography (PET-CT) fuses uptake of a radiotracer combined with CT images to assess both functional tissue activity and anatomical detail. Since its introduction it has offered new ways of treating gastrointestinal cancers. METHODS: The review analyses the present literature regarding the use of PET-CT in the assessment, diagnosis, staging and treatment of hepatobiliary malignancies. RESULTS: PET-CT is widely used in pre-operative tumours staging for colorectal liver metastases. There is convincing data that it may also be applicable for neuroendocrine tumours, assessment of indeterminate pancreas lesions and clinical drug trials. PET-CT is of limited value in hepatocellular cancers, although new techniques in dual-tracer PET-CT may change this. CONCLUSION: Knowledge of the strengths and limitations of PET-CT is important for all surgeons managing cancer of the hepatobiliary system. More clinical data are required on PET-CT, particularly its effect on long-term survival in PET-CT-staged patients undergoing resection.

Efficacy and safety of microwave ablation for primary and secondary liver malignancies: a systematic review.

This article reviews the therapeutic efficacy and complications of microwave ablation (MWA) in the treatment of primary and secondary liver malignancies. A PubMed search using keywords 'microwave', 'liver', 'malignancy', 'cancer' and 'tumour' was performed to identify articles related to MWA of liver malignancies published in English from 1975 to February 2008. MWA is an effective treatment options for both primary and secondary liver malignancies with survivals comparable with those of liver resections. Local recurrences can be managed with further ablation. Small tumour size, well-differentiated tumour and a reduced number of lesions are factors associated with good prognosis. Temporary occlusion of the portal venous and hepatic arterial flow may increase the size of ablation but the safety aspect requires further validation. MWA is a minimally invasive technique that has broadened the therapeutic option for patients with conventionally unresectable liver tumours with promising survival data. Future advances in the applicator design and treatment monitoring may further improve its efficacy and widen the indications.