Liver manipulation during liver surgery in humans is associated with hepatocellular damage and hepatic inflammation

BACKGROUND

Manipulation of the liver during liver surgery results in profound hepatocellular damage. Experimental data show that mobilization-induced hepatocellular damage is related to hepatic inflammation. To date, information on this link in humans is lacking. As it is possible to modulate inflammation, it is clinically relevant to unravel this relationship.

AIM

This observational study aimed to establish the association between liver mobilization and hepatic inflammation in humans.

METHODS

Consecutive patients requiring mobilization of the right hemi-liver during liver surgery were studied. Plasma samples and liver biopsies were collected prior to and directly after mobilization and after transection of the liver. Hepatocellular damage was assayed by liver fatty acid-binding protein (L-FABP) and aminotransferase levels. Hepatic inflammation was determined by (a) immunohistochemical identification of myeloperoxidase (MPO) and CD68- positive cells and (b) hepatic gene expression of inflammatory and cell adhesion molecules (IL-1β, IL-6, IL-8, VCAM-1 and ICAM-1).

RESULTS

A total of 25 patients were included. L-FABP levels increased significantly during mobilization (301 ± 94 ng/ml to 1599 ± 362 ng/ml, P = 0.008), as did ALAT levels (36 ± 5 IU/L to 167 ± 21 IU/L, P < 0.001). A significant increase in MPO (P = 0.001) and CD68 (P = 0.002) positive cells was noticed in the liver after mobilization. The number of MPO-positive cells correlated with the duration of mobilization (Pearson correlation=0.505, P = 0.033). Hepatic gene expression of pro-inflammatory cytokines IL-1β and IL-6, chemo-attractant IL-8 and adhesion molecule ICAM-1 increased significantly during liver manipulation.

CONCLUSIONS

Liver mobilization is associated with hepatocellular damage and liver inflammation, as shown by infiltration of inflammatory cells and upregulation of genes involved in acute inflammation.

Guided treatment improves outcome of patients with enterocutaneous fistulas

BACKGROUND

The present study was designed to evaluate the effects of guided treatment of patients with an enterocutaneous fistula and to evaluate the effect of prolonged period of convalescence on outcome.

METHODS

All consecutive patients with an enterocutaneous fistula treated between 2006 and 2010 were included in this study. Patient information was gathered prospectively. Treatment of patients focused on sepsis control, optimization of nutritional status, wound care, establishing the anatomy of the fistula, timing of surgery, and surgical principles. Outcome included spontaneous and surgical closure, mortality, and postoperative recurrence. The relationship between period of convalescence and recurrence rate was determined by combining the present prospective cohort with a historical cohort from our group.

RESULTS

Between 2006 and 2010, 79 patients underwent focused treatment for enterocutaneous fistula. Cox regression analysis showed that period of convalescence related significantly with recurrence of the fistula (hazard ratio 0.99; 95 % confidence interval 0.98-0.999; p = 0.04). Spontaneous closure occurred in 23 (29 %) patients after a median period of convalescence of 39 (range 7-163) days. Forty-nine patients underwent operative repair after median period of 101 (range 7-374) days and achieved closure in 47 (96 %). Overall, eight patients (10 %) died.

CONCLUSIONS

Prolonging period of convalescence for patients with enterocutaneous fistulas improves spontaneous closure and reduces recurrence rate.

Hyaluronic acid as a marker of hepatic sinusoidal obstruction syndrome secondary to oxaliplatin-based chemotherapy in patients with colorectal liver metastases

BACKGROUND

A considerable number of patients develop sinusoidal obstruction syndrome (SOS) after oxaliplatin-based chemotherapy for colorectal liver metastases (CLMs). SOS is associated with adverse outcomes after major hepatectomy. Hyaluronic acid (HA) is a marker of hepatic sinusoidal endothelial cell function and may serve as an accurate marker of SOS. This study aimed to assess the value of systemic HA levels and fractional extraction (FE) of HA by the splanchnic area and liver as markers of SOS after oxaliplatin-based chemotherapy for CLMs.

METHODS

Forty patients were studied. The presence of SOS was assessed histopathologically. Blood samples from the radial artery and portal and hepatic veins were collected. HA levels were determined by ELISA and the FE of HA was estimated.

RESULTS

SOS was present in 23 patients, 11 of whom demonstrated moderate or severe SOS. Preoperative HA levels were significantly higher in patients with moderate or severe SOS (group B, n = 11) compared to patients with no or mild SOS (group A, n = 29) (51.6 ± 10.2 ng/mL vs. 32.1 ± 3.5 ng/mL, p = 0.030). A cutoff HA level of 44.1 ng/mL yielded a sensitivity of 67 % and specificity of 83 % for detection of SOS. The positive predictive value was 50 % and the negative predictive value 91 %. Both groups exhibited a similar FE of HA by the splanchnic area (-7.9 ± 8.5 % in Group A vs. 7.3 ± 3.6 % in Group B, p = 0.422) and liver (-10.7 ± 6.2 % in Group A vs. 4.6 ± 2.3 % in Group B, p = 0.265).

CONCLUSIONS

Systemic HA levels can be used to detect patients at risk of SOS after oxaliplatin-based chemotherapy for CLMs. Additional investigations into the presence of SOS are indicated in patients with elevated HA levels.

Sarcopenia negatively affects preoperative total functional liver volume in patients undergoing liver resection

OBJECTIVES

Sarcopenia may negatively affect short-term outcomes after liver resection. The present study aimed to explore whether total functional liver volume (TFLV) is related to sarcopenia in patients undergoing partial liver resection.

METHODS

Analysis of total liver volume and tumour volume and measurements of muscle surface were performed in patients undergoing liver resection using OsiriX(®) and preoperative computed tomography. The ratio of TFLV to bodyweight was calculated as: [TFLV (ml)/bodyweight (g)]*100%. The L3 muscle index (cm(2) /m(2) ) was then calculated by normalizing muscle areas (at the third lumbar vertebral level) for height.

RESULTS

Of 40 patients, 27 (67.5%) were classified as sarcopenic. There was a significant correlation between the L3 skeletal muscle index and TFLV (r= 0.64, P < 0.001). Median TFLV was significantly lower in the sarcopenia group than in the non-sarcopenia group [1396 ml (range: 1129-2625 ml) and 1840 ml (range: 867-2404 ml), respectively; P < 0.05]. Median TFLV : bodyweight ratio was significantly lower in the sarcopenia group than in the non-sarcopenia group [2.0% (range: 1.4-2.5%) and 2.3% (range: 1.5-2.5%), respectively; P < 0.05].

CONCLUSIONS

Sarcopenic patients had a disproportionally small preoperative TFLV compared with non-sarcopenic patients undergoing liver resection. The preoperative hepatic physiologic reserve may therefore be smaller in sarcopenic patients.

Total parenteral nutrition induces a shift in the Firmicutes to Bacteroidetes ratio in association with Paneth cell activation in rats

The use of total parenteral nutrition (TPN) in the treatment of critically ill patients has been the subject of debate because it has been associated with disturbances in intestinal homeostasis. Important factors in maintaining intestinal homeostasis are the intestinal microbiota and Paneth cells, which exist in a mutually amendable relationship. We hypothesized that the disturbed intestinal homeostasis in TPN-fed individuals results from an interplay between a shift in microbiota composition and alterations in Paneth cells. We studied the microbiota composition and expression of Paneth cell antimicrobial proteins in rats receiving TPN or a control diet for 3, 7, or 14 d. qPCR analysis of DNA extracts from small intestinal luminal contents of TPN-fed rats showed a shift in the Firmicutes:Bacteroidetes ratio in favor of Bacteroidetes after 14 d (P < 0.05) compared with the control group. This finding coincided with greater staining intensity for lysozyme and significantly greater mRNA expression of the Paneth cell antimicrobial proteins lysozyme (P < 0.05), rat α-defensin 5 (P < 0.01), and rat α-defensin 8 (P < 0.01). Finally, 14 d of TPN resulted in greater circulating ileal lipid-binding protein concentrations (P < 0.05) and greater leakage of horseradish peroxidase (P < 0.01), which is indicative of enterocyte damage and a breached intestinal barrier. Our findings show a shift in intestinal microbiota in TPN-fed rats that correlated with changes in Paneth cell lysozyme expression (r(s) = -0.75, P < 0.01). Further studies that include interventions with microbiota or nutrients that modulate them may yield information on the involvement of the microbiota and Paneth cells in TPN-associated intestinal compromise.

A survey in the hepatopancreatobiliary community on ways to enhance patient recovery

OBJECTIVES

Both laparoscopic techniques and multimodal enhanced recovery programmes have been shown to improve recovery and reduce length of hospital stay. Interestingly, evidence-based care programmes are not widely implemented, whereas new, minimally invasive surgical procedures are often adopted with very little evidence to support their effectiveness. The present survey aimed to shed light on experiences of the adoption of both methods of optimizing recovery.

METHODS

An international, web-based, 18-question, electronic survey was composed in 2010. The survey was sent out to 673 hepatopancreatobiliary (HPB) centres worldwide in June 2010 to investigate international experiences with laparoscopic liver surgery, fast-track recovery programmes and surgery-related equipoise in open and laparoscopic techniques and to assess opinions on strategies for adopting laparoscopic liver surgery in HPB surgical practice.

RESULTS

A total of 507 centres responded (response rate: 75.3%), 161 of which finished the survey completely. All units reported performing open liver resections, 24.2% performed open living donor resections, 39.1% carried out orthotopic liver transplantations, 87.6% had experience with laparoscopic resections and 2.5% performed laparoscopic living donor resections. A median of 50 (range: 2-560) open and 9.5 (range: 1-80) laparoscopic liver resections per surgical unit were performed in 2009. Patients stayed in hospital for a median of 7 days (range: 2-15 days) after uncomplicated open liver resection and a median of 4 days (range: 1-10 days) after uncomplicated laparoscopic liver resection. Only 28.0% of centres reported having experience with fast-track programmes in liver surgery. The majority considered the instigation of a randomized controlled trial or a prospective register comparing the outcomes of open and laparoscopic techniques to be necessary.

CONCLUSIONS

Worldwide dissemination of laparoscopic liver resection is substantial, although laparoscopic volumes are low in the majority of HPB centres. The adoption of enhanced recovery programmes in liver surgery is limited and should be given greater attention.

Systematic review of ophthalmate as a novel biomarker of hepatic glutathione depletion

BACKGROUND

Sustainability of hepatic glutathione (GSH) homeostasis is an important cellular defense against oxidative stress. Therefore, knowledge of liver GSH status is important. However, measurement of plasma GSH and tissue is difficult due to its instability. Alternatively, ophthalmate (OPH), an endogenous tripeptide analog of GSH, has been suggested as a potential indicator to assess GSH depletion.

AIM

To provide an overview of present knowledge with respect to the usefulness of OPH as a biomarker for oxidative stress and hepatic GSH homeostasis.

METHODS

A systematic, computerized search combined with a cross-reference search of the literature described in PubMed (January 1975 to January 2012) was conducted, key words: 'ophthalmate' and 'ophthalmic acid'.

RESULTS

Twenty-two articles were included. Hepatic OPH levels increase inversely proportional to a drop in hepatic GSH in mice with paracetamol (PCM) induced hepatotoxicity. Little is known about the stability of OPH in human plasma. To measure the very low physiological concentrations of plasma OPH, liquid chromatography-mass spectrometry techniques can be employed. OPH synthesis can be measured in humans, using stable isotope labeling with a deuterated water ((2)H2O) load.

CONCLUSION

OPH may be a promising biomarker to indicate hepatic glutathione depletion, but the suggested biological pathways need further unraveling.

Pyruvate kinase M2 is a novel diagnostic marker and predicts tumor progression in human biliary tract cancer

BACKGROUND

The early diagnosis of biliary tract cancer (BTC) remains challenging, and there are few effective therapies. This study investigated whether the M2 isotype of pyruvate kinase (M2-PK), which serves as the key regulator of cellular energy metabolism in proliferating cells, could play a role in the diagnosis and therapy of BTC.

METHODS

Plasma and bile M2-PK concentrations were measured by enzyme-linked immunosorbent assay in 88 patients with BTC, 79 with benign biliary diseases, and 17 healthy controls. M2-PK expression was assayed in a BTC tissue array by immunohistochemistry. The role of M2-PK in tumor growth, invasion, and angiogenesis was evaluated in BTC cell lines by retrovirus-mediated M2-PK transfection and short hairpin RNA silencing techniques.

RESULTS

Sensitivity (90.3%) and specificity (84.3%) of bile M2-PK for malignancy were significantly higher than those for plasma M2-PK and serum carbohydrate antigen 19-9. M2-PK expression was specific for cancer cells and correlated with microvessel density. M2-PK positivity was a significant independent prognostic factor by multivariable analysis. Transfection of M2-PK in a negatively expressed cell line (HuCCT-1 cells) increased cell invasion, whereas silencing in an M2-PK-positive cell line (TFK cells) decreased tumor nodule formation and cellular invasion. A significant increase in endothelial tube formation was noted when supernatants from M2-PK-transfected cells were added to an in vitro angiogenesis assay, whereas supernatants from silenced cells negated endothelial tube formation.

CONCLUSIONS

Bile M2-PK is a novel tumor marker for BTC and correlates with tumor aggressiveness and poor outcome. Short hairpin RNA-mediated inhibition of M2-PK indicates the potential of M2-PK as a therapeutic target.

Ophthalmate detection in human plasma with LC-MS-MS

Based on animal experimentations, ophthalmate (OPH) has recently been suggested as a potential plasma biomarker to probe hepatic GSH homeostasis. Up until now, the inability to accurately determine OPH concentrations in human plasma prohibited further studies of OPH metabolism in humans. This study therefore aimed to study the influence of delayed sample preparation on OPH concentrations using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Venous plasma samples from 5 healthy human volunteers were incubated for varying times (5, 30, 60 and 120 min) at temperatures of 4 °C and 37 °C to investigate potential enzymatic degradation. At 37 °C, the decrease in OPH reached significance after 120 min (74.6% (range: 56.2-100.0%; p<0.0001)). At 4 °C, the same trend was observed but did not reach significance. These findings indicate ongoing enzymatic activity, stressing the need for immediate sample deproteinization to obtain reliable plasma concentrations. To investigate the feasibility of the here developed method, baseline arterial plasma values of 21 patients scheduled for partial liver resection were determined to be 0.06±0.03 μmol/l (mean±s.d.). In addition, in pooled samples from 3 patients, an OPH calibration curve was spiked to arterial plasma, arterial whole blood and liver biopsy material, resulting in a linear calibration curve in all cases. Individual measurements of baseline samples revealed that both arterial whole blood and liver biopsy material contained significant levels of endogenous OPH, namely 16.1 (11.8-16.4) μmol/l and 80.0 (191.8-349.2) μmol/kg, respectively. In conclusion, the present LC-MS/MS assay enables the accurate measurement of OPH in human plasma, whole blood and liver biopsies. Freshly prepared samples and immediate deproteinization are mandatory to block enzymatic degradation.

Hepatic sinusoidal obstruction syndrome (SOS) reduces the effect of oxaliplatin in colorectal liver metastases

AIMS

Oxaliplatin is an important chemotherapeutic agent used to reduce hepatic colorectal metastases, resulting in tumour reduction and permitting surgical resection. This treatment has significant side effects, as oxaliplatin can induce sinusoidal obstruction syndrome (SOS) in the non-tumour-bearing liver, resulting in increased morbidity. We hypothesized that SOS might impede hepatic perfusion, thereby interfering with the tumour environment and attenuate the response to the chemotherapy.

METHODS AND RESULTS

From the prospective database of the Maastricht University Medical Centre we collected 50 patients with hepatic colorectal carcinoma metastases. All patients received neo-adjuvant oxaliplatin followed by partial hepatectomy. Metastases and non-tumour-bearing liver were studied histopathologically. Thirty-two of 50 (64%) patients showed SOS lesions, classified as mild (26%) and moderate-severe (38%). The response to treatment, as expressed in the tumour regression grade (TRG), was grade 1 (10%); grade 2 (14%); grade 3 (28%); grade 4 (32%) and grade 5 (16%). Statistical analysis showed that a higher grade of SOS was associated with a higher grade of TRG (P = 0.016).

CONCLUSION

Developing SOS is associated with a lower tumour response to neo-adjuvant oxaliplatin treatment. Hepatic hypoperfusion due to sinusoidal obstruction syndrome might induce hepatic hypoxia, diminishing the response to chemotherapy.

Open versus laparoscopic left lateral hepatic sectionectomy within an enhanced recovery ERAS® programme (ORANGE II-trial): study protocol for a randomised controlled trial

Background

The use of lLaparoscopic liver resection in terms of time to functional recovery, length of hospital stay (LOS), long-term abdominal wall hernias, costs and quality of life (QOL) has never been studied in a randomised controlled trial. Therefore, this is the subject of the international multicentre randomised controlled ORANGE II trial.

Methods

Patients eligible for left lateral sectionectomy (LLS) of the liver will be recruited and randomised at the outpatient clinic. All randomised patients will undergo surgery in the setting of an ERAS programme. The experimental design produces two randomised arms (open and laparoscopic LLS) and a prospective registry. The prospective registry will be based on patients that cannot be randomised because of the explicit treatment preference of the patient or surgeon, or because of ineligibility (not meeting the in- and exclusion criteria) for randomisation in this trial. Therefore, all non-randomised patients undergoing LLS will be approached to participate in the prospective registry, thereby allowing acquisition of an uninterrupted prospective series of patients. The primary endpoint of the ORANGE II trial is time to functional recovery. Secondary endpoints are postoperative LOS, percentage readmission, (liver-specific) morbidity, QOL, body image and cosmetic result, hospital and societal costs over 1 year, and long-term incidence of incisional hernias. It will be assumed that in patients undergoing laparoscopic LLS, length of hospital stay can be reduced by two days. A sample size of 55 patients in each randomisation arm has been calculated to detect a 2-day reduction in LOS (90% power and α = 0.05 (two-tailed)).

The ORANGE II trial is a multicenter randomised controlled trial that will provide evidence on the merits of laparoscopic surgery in patients undergoing LLS within an enhanced recovery ERAS programme.

Trial registration

ClinicalTrials.gov NCT00874224.

Prevention of acute kidney injury in a rodent model of cirrhosis following selective gut decontamination is associated with reduced renal TLR4 expression

BACKGROUND & AIMS

Superimposed infection and/or inflammation precipitate renal failure in cirrhosis. This study aimed at testing the hypothesis that increased gut bacterial translocation in cirrhosis primes the kidney to the effect of superimposed inflammation by upregulating expression of Toll-like receptor 4 (TLR4), NFκB, and cytokines. A well-characterized bile-duct ligated (BDL) model of cirrhosis, which develops renal failure following superimposed inflammatory insult with lipopolysaccharide (LPS), was used and selective gut decontamination was performed using norfloxacin.

METHODS

Sprague-Dawley rats were studied: Sham, Sham+LPS; BDL, BDL+LPS; an additional BDL and BDL+LPS groups were selectively decontaminated with norfloxacin. Plasma biochemistry, plasma renin activity (PRA) and cytokines and, protein expression of TLR4, NFκB, and cytokines were measured in the kidney homogenate. The kidneys were stained for TLR4, TLR2, and caspase-3. Endotoxemia was measured using neutrophil burst and Limulus amoebocyte lysate (LAL) assays.

RESULTS

The groups treated with norfloxacin showed significant attenuation of the increase in plasma creatinine, plasma and renal TNF-α and renal tubular injury on histology. The increased renal protein expression of TLR4, NFκB, and caspase-3 in the untreated animals was significantly attenuated in the norfloxacin treated animals. PRA was reduced in the treated animals and severity of endotoxemia was also reduced.

CONCLUSIONS

The results show for the first time that kidneys in cirrhosis show an increased expression of TLR4, NFκB, and the pro-inflammatory cytokine TNF-α, which makes them susceptible to a further inflammatory insult. This increased susceptibility to LPS can be prevented with selective decontamination, providing novel insights into the pathophysiology of renal failure in cirrhosis.

Laparoscopic liver resection in the Netherlands: how far are we?

BACKGROUND

The objective of this study was to provide a systematic review on the introduction of laparoscopic liver surgery in the Netherlands, to investigate the initial experience with laparoscopic liver resections and to report on the current status of laparoscopic liver surgery in the Netherlands.

METHODS

A systematic literature search of laparoscopic liver resections in the Netherlands was conducted using PubMed/MEDLINE. Analysis of initial experience with laparoscopic liver surgery was performed by case-control comparison of patients undergoing laparoscopic left lateral sectionectomy matched with patients undergoing the open procedure in the Netherlands between the years 2000 and 2008. Furthermore, a nationwide survey was conducted in 2011 on the current status of laparoscopic liver surgery.

RESULTS

The systematic review revealed only 6 Dutch reports on actual laparoscopic liver surgery. Matched case-control comparison showed significant differences in the length of hospital stay, blood loss and operation time. Complications did not differ significantly between the two groups (26 vs. 21%). The 2011 survey showed that 21 centers in the Netherlands performed formal liver resections and that 49 (5% of total) laparoscopic liver resections were performed in 2010.

CONCLUSION

The systematic review revealed that very few laparoscopic liver resections were performed in the Netherlands in the previous millennium. The matched case-control comparison of laparoscopic and open left lateral resection showed a reduction in hospital length of stay with comparable morbidity. The laparoscopic technique has been slowly adopted in the Netherlands, but its popularity seems to increase in recent years.

Total intermittent Pringle maneuver during liver resection can induce intestinal epithelial cell damage and endotoxemia

OBJECTIVES

The intermittent Pringle maneuver (IPM) is frequently applied to minimize blood loss during liver transection. Clamping the hepatoduodenal ligament blocks the hepatic inflow, which leads to a non circulating (hepato)splanchnic outflow. Also, IPM blocks the mesenteric venous drainage (as well as the splenic drainage) with raising pressure in the microvascular network of the intestinal structures. It is unknown whether the IPM is harmful to the gut. The aim was to investigate intestinal epithelial cell damage reflected by circulating intestinal fatty acid binding protein levels (I-FABP) in patients undergoing liver resection with IPM.

METHODS

Patients who underwent liver surgery received total IPM (total-IPM) or selective IPM (sel-IPM). A selective IPM was performed by selectively clamping the right portal pedicle. Patients without IPM served as controls (no-IPM). Arterial blood samples were taken immediately after incision, ischemia and reperfusion of the liver, transection, 8 hours after start of surgery and on the first post-operative day.

RESULTS

24 patients (13 males) were included. 7 patients received cycles of 15 minutes and 5 patients received cycles of 30 minutes of hepatic inflow occlusion. 6 patients received cycles of 15 minutes selective hepatic occlusion and 6 patients underwent surgery without inflow occlusion. Application of total-IPM resulted in a significant increase in I-FABP 8 hours after start of surgery compared to baseline (p<0.005). In the no-IPM group and sel-IPM group no significant increase in I-FABP at any time point compared to baseline was observed.

CONCLUSION

Total-IPM in patients undergoing liver resection is associated with a substantial increase in arterial I-FABP, pointing to intestinal epithelial injury during liver surgery.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01099475.

[Malnutrition in patients with cancer: is eating enough really enough?]

The new practice guideline 'Malnutrition in patients with cancer' provides a good framework for the practical treatment of patients with impending cancer cachexia. Because the pathophysiology of cancer cachexia is multifactorial, its treatment requires a multimodal approach. Such multimodal treatment should probably consist of nutritional support in combination with physical exercise, anti-inflammatory medication and an anabolic or anticatabolic intervention. The aim is to control undesired loss of muscle and fat mass. Unfortunately, the data currently available are limited and do not allow evidence-based advice beyond the paradigm of treating malnutrition by feeding patients appropriately.

The use of nasojejunal nutrition in patients with chronic pancreatitis

CONTEXT

Abdominal pain, malabsorption and diabetes all contribute to a negative impact upon nutritional status in chronic pancreatitis and no validated standard for the nutritional management of patients exists.

OBJECTIVE

To assess the effect of nasojejunal nutrition in chronic pancreatitis patients.

DESIGN

All consecutive chronic pancreatitis patients fed via the nasojejunal route between January 2004 and December 2007 were included in the study. Patients were assessed via retrospective review of case notes.

RESULTS

Fifty-eight chronic pancreatitis patients (35 males, 23 females; median age 46 years) were included. Patients were discharged after a median of 14 days and nasojejunal nutrition continued for a median of 47 days. Forty-six patients (79.3%) reported resolution of their abdominal pain and cessation of opioid analgesia intake over the study period and median weight gain at 6 weeks following nutritional cessation was +1 kg (range -24 to +27 kg; P=0.454). Twelve (20.7%) patients reported recurrence of their pain during the follow-up period and complications were both minor and infrequent. Significant improvements were noted in most blood parameters measured, including: sodium (from 134.8 to 138.1 mEq/L; P<0.001); urea (from 3.4 to 5.1 mmol/L; P<0.001); creatinine (from 58.3 to 60.3 µmol/L; P<0.001); corrected calcium (from 2.24 to 2.35 mmol/L; P=0.018); albumin (from 34.5 to 38.7 g/L; P=0.002); CRP (from 73.0 to 25.5 mg/L; P=0.006); and haemoglobin (from 11.8 to 12.4 g/dL; P=0.036).

CONCLUSION

Nasojejunal nutrition, commenced in hospital and continued at home, is safe, efficacious and well tolerated in patients with severe chronic pancreatitis and is effective in helping to relieve pain and diminish analgesic requirements.

Urinary ammonia excretion increases acutely during living donor liver transplantation

INTRODUCTION

Arterial ammonia concentrations increase acutely during the anhepatic phase of a liver transplantation (LTx) and return to baseline within 1 h after reperfusion of a functioning liver graft. So far, this return to baseline has solely been attributed to hepatic ammonia clearance. No data exist on the potential contribution of altered renal ammonia handling to peritransplantation ammonia homoeostasis.

AIM

The present study investigated the consequences of a hepatectomy and subsequent implantation of a partial liver graft on arterial ammonia concentrations and urinary ammonia excretion during a living donor liver transplantation (LDLTx).

METHODS

Patients with end-stage liver disease undergoing LDLTx were selected. Samples of arterial blood and urine were taken before, during and 2 h after the anhepatic phase. Differences were tested using Wilcoxon's test. Results are given as median and range.

RESULTS

Eleven adult patients undergoing an LDLTx were included. Before hepatectomy, arterial ammonia concentrations were 89 μM (40-156 μM), increasing to 146 μM (102-229 μM) (P<0.001) during the anhepatic phase and returning to 79 μM (46-111 μM) (P<0.01) after reperfusion. Urinary ammonia excretion was initially 1.06 mmol/h (0.02-6.00 mmol/h), increasing to 3.81 mmol/h (0.32-12.55 mmol/h) (P=0.004) during the anhepatic phase and further increasing to 4.00 mmol/h (0.79-9.51 mmol/h) (P=0.013) after reperfusion.

CONCLUSION

The kidney significantly increased urinary ammonia excretion during the anhepatic phase, which was sustained after reperfusion, contributing to the rapid decrease of ammonia concentrations. Accordingly, the plasma ammonia concentrations measured directly after LTx cannot simply be used as a read-out of initial liver graft function.

Randomized controlled trial analyzing the effect of 15 or 30 min intermittent Pringle maneuver on hepatocellular damage during liver surgery

BACKGROUND & AIMS

Aminotransferases are commonly used to determine the optimal duration of ischemic intervals during intermittent Pringle maneuver (IPM). However, they might not be responsive enough to detect small differences in hepatocellular damage. Liver fatty acid-binding protein (L-FABP) has been suggested as a more sensitive marker. This randomized trial aimed to compare hepatocellular injury reflected by L-FABP in patients undergoing liver resection with IPM using 15 or 30 min ischemic intervals.

METHODS

Twenty patients undergoing liver surgery were randomly assigned to IPM with 15 (15IPM) or 30 (30IPM) minutes ischemic intervals. Ten patients not requiring IPM (noIPM) served as controls. Primary endpoint was hepatocellular injury during liver surgery reflected by systemic L-FABP plasma levels. Between group comparisons were performed using area under the curve and repeated measures two-way ANOVA.

RESULTS

The IPM groups had similar characteristics. Aminotransferases did not differ significantly between 15IPM and 30IPM at any time point. L-FABP levels rose up to 1853±708 ng/ml in the 15IPM and 3662±1355 ng/ml in the 30IPM group after finishing liver transection and decreased rapidly thereafter. There were no significant differences between 15IPM and 30IPM in cumulative L-FABP level (p=0.378) or L-FABP level at any time point (p=0.149). Blood loss, remnant liver function and morbidity were comparable.

CONCLUSIONS

IPM with 15 or 30 min ischemic intervals induced similar hepatocellular injury measured by the sensitive marker L-FABP. The present study confirms the results of earlier trials, suggesting that IPM with 30 min ischemic intervals may be used.

Use of hepatocyte and stem cells for treatment of post-resectional liver failure: are we there yet?

Post-operative liver failure following extensive resections for liver tumours is a rare but significant complication. The only effective treatment is liver transplantation (LT); however, there is a debate about its use given the high mortality compared with the outcomes of LT for chronic liver diseases. Cell therapy has emerged as a possible alternative to LT especially as endogenous hepatocyte proliferation is likely inhibited in the setting of prior chemo/radiotherapy. Both hepatocyte and stem cell transplantations have shown promising results in the experimental setting; however, there are few reports on their clinical application. This review identifies the potential stem cell sources in the body, and highlights the triggering factors that lead to their mobilization and integration in liver regeneration following major liver resections.

Radical surgery in the presence of biliary metallic stents: revising the palliative scenario

BACKGROUND

The application of endobiliary self-expandable metallic stents (SEMS) is considered the palliative treatment of choice in patients with biliary obstruction in the setting of inoperable malignancies. In the presence of SEMS, however, radical surgery is the only curative option when the resectability status is revised in case of malignancies or for overcoming complications arising from their application in benign conditions that masquerade as inoperable tumours. The aim of our study was to report our surgical experience with patients who underwent an operation due to revision of the initial palliative approach, whilst they had already been treated with biliary SEMS exceeding the hilar bifurcation.

METHODS

Three patients with hilar cholangiocarcinoma that was considered inoperable and one patient with IgG4 autoimmune cholangio-pancreatopathy mimicking pancreatic cancer underwent radical resections in the presence of biliary SEMS.

RESULTS

After a detailed preoperative workup, two right trisectionectomies, one left extended hepatectomy and a radical extrahepatic biliary resection were performed. All cases demanded resection and reconstruction of the portal vein. R0 resection was achieved in all the malignant cases. Two patients required multiple biliodigestive anastomoses entailing three and seven bile ducts respectively. There was one perioperative death due to postoperative portal vein and hepatic artery thrombosis, whilst two patients developed grade III complications. At follow-up, one patient died at 13 months due to disease recurrence, whilst the remaining two are free of disease or symptoms at 21 and 12 months, respectively.

CONCLUSIONS

Revising the initial palliative approach and operating in the setting of biliary metallic stents is extremely demanding and carries significant mortality and morbidity. Radical resection is the only option for offering cure in such complex cases, and this should only be attempted in advanced hepatopancreaticobiliary centres with active involvement in liver transplantation.

Interorgan ammonia metabolism in liver failure: the basis of current and future therapies

Hepatic encephalopathy complicates the course of both acute and chronic liver disease and its treatment remains an unmet clinical need. Ammonia is thought to be central in its pathogenesis and remains an important target of current and future therapeutic approaches. In liver failure, the main detoxification pathway of ammonia metabolism is compromised leading to hyperammonaemia. In this situation, the other ammonia-regulating pathways in multiple organs assume important significance. The present review focuses upon interorgan ammonia metabolism in health and disease describing the role of the key enzymes, glutamine synthase and glutaminase. Better understanding of these alternative pathways are leading to the development of new therapeutic approaches.

Procalcitonin as a prognostic marker for infectious complications in liver transplant recipients in an intensive care unit

Clinically significant infections (CSIs) are life-threatening but difficult to diagnose after liver transplantation (LTx). This study investigates the value of procalcitonin (PCT) in addition to c-reactive protein (CRP) and the leukocyte count (LC) as a prognostic marker for CSIs in LTx recipients. The clinical course of 135 LTx recipients was prospectively studied. CSIs were defined as pulmonary, bloodstream, or intra-abdominal infections. Independent risk factors for CSIs were determined by Cox proportional hazard analysis. The concordance statistics (c-statistics) were used to assess the discrimination effect of PCT. Thirty recipients (22%) experienced a CSI. They had significantly higher peak PCT (27.2 versus 12.7 ng/mL, P = 0.014) and peak CRP (13.7 versus 9.9 mg/dL, P < 0.001) and a tendency toward a higher peak LC (19.3 versus 14.2 cells/nL, P = 0.051) in comparison with recipients without CSIs. Independent risk factors for CSIs were male sex [hazard ratio (HR) = 6.4], a body mass index (BMI) < 20 kg/m(2) (versus a BMI > 25 kg/m(2), HR = 13.8), acute liver failure as an indication for LTx (HR = 7.1), a cold ischemic time > 420 minutes (HR = 3.5), and peak CRP (HR = 1.1) but not peak PCT. The addition of peak PCT marginally improved the c-statistic from 0.815 to 0.827. In conclusion, although peak PCT differed significantly between recipients with and without CSIs, it was not an independent risk factor for CSIs and added little prognostic accuracy. Interestingly, the parameters peak CRP, male sex, low BMI, acute liver failure, and long cold ischemic time were independent risk factors for CSIs. They could serve as risk stratifiers directing medical therapy in clinical practice.

Is positive end-expiratory pressure suitable for liver recipients with a rescue organ offer?

PURPOSE

Rescue organ offers may help to overcome the organ shortage. However, because of initial poor liver function, the recipient may develop a severe lung injury with the requirement for higher positive end-expiratory pressure (PEEP) levels to achieve adequate oxygenation. Positive end-expiratory pressure has been associated with perfusion impairment in the hepatosplanchnic area. We assessed the effects of increased PEEP levels on systemic hemodynamic and liver perfusion in liver transplantation (LT) patients with a rescue organ.

METHODS

Twenty-four LT recipients of a rescue organ offer were enrolled. All patients were postoperatively mechanically ventilated with biphasic positive airway pressure, and 3 different PEEP levels (0, 5, 10 mbar) were randomly set within 4 hours after admission at the intensive care unit. Systemic hemodynamic parameters were recorded using a pulmonary artery catheter; and flow velocities of the hepatic artery, portal vein, and right hepatic vein were measured using Doppler.

RESULTS

Positive end-expiratory pressure of 10 mbar did not impair the systemic hemodynamic. Flow velocities in the right hepatic vein, the portal vein, and the hepatic artery were not influenced by PEEP.

CONCLUSION

Our study demonstrates that PEEP up to 10 mbar did not impair the liver outflow in recipients with a rescue organ offer.

Short chain fatty acids exchange: Is the cirrhotic, dysfunctional liver still able to clear them?

BACKGROUND & AIMS

Prebiotics are increasingly used to improve gut integrity. A presumed mechanism of their beneficial action is the synthesis of short chain fatty acids (SCFA: acetate, propionate and butyrate). High systemic concentrations of propionate and butyrate are toxic and can adversely affect the patient. In physiological situations the liver uses propionate and butyrate for energy metabolism. The aim of the present study was to investigate to which extent patients with liver cirrhosis are still able to metabolize portal derived SCFA in the liver.

METHODS

Twelve patients with liver cirrhosis and an intrahepatic portosystemic shunt (TIPSS) were studied. Blood was sampled from the femoral artery, portal and hepatic vein. Organ plasma flow was measured. Net release or uptake was calculated by multiplying the arteriovenous differences by plasma flow. SCFA plasma concentrations were measured using LC-MS.

RESULTS

Arterial concentrations were 124+/-12, 8+/-1 and 10+/-1micromol/l for acetate, propionate and butyrate, respectively. The gut produced 32.5+/-13.0, 4.8+/-1.3 and 6.2+/-2.1micromolkgbw(-1)h(-1) of acetate, propionate and butyrate, respectively. Assuming 70% portosystemic shunting, hepatic uptake of propionate and butyrate was 3.1+/-0.9 and 5.2+/-1.4micromolkgbw(-1)h(-1). Hepatic uptake of acetate was non significant (12.1+/-12.3micromolkgbw(-1)min(-1)). As a consequence of shunting, part of total acetate escaped from the splanchnic bed, which equalled 34.9+/-14.7micromolkgbw(-1)h(-1).

CONCLUSION

The liver of patients with stable cirrhosis is able to use butyrate and propionate, most likely preventing increased systemic concentrations. This suggests that prebiotics can be administered safely, but monitoring butyrate levels may be advisable in patients with diminished liver function.

Neurologic complications in adult living donor liver transplant patients: an underestimated factor?

Liver transplantation is the only curative treatment in patients with end-stage liver disease. Neurological complications (NC) are increasingly reported to occur in patients after cadaveric liver transplantation. This retrospective cohort study aims to evaluate the incidence and causes of NC in living donor liver transplant (LDLT) patients in our transplant center. Between August 1998 and December 2005, 121 adult LDLT patients were recruited into our study. 17% of patients experienced NC, and it occurred significantly more frequently in patients with alcoholic cirrhosis (42%) and autoimmune hepatitis (43%) as compared with patients with hepatitis B or C (9/10%, P = 0.013). The most common NC was encephalopathy (47.6%) followed by seizures (9.5%). The choice of immunosuppression by calcineurin inhibitor (Tacrolimus or Cyclosporin A) showed no significant difference in the incidence of NC (19 vs. 17%). The occurrence of NC did not influence the clinical outcome, since mortality rate, median ICU stay and length of hospital stay were similar between the two groups. Most patients who survived showed a nearly complete recovery of their NC. NCs occur in approximately 1 in 6 patients after LDLT and seem to be predominantly transient in nature, without major impact on clinical outcome.

Development of hypertriglyceridemia in patients with enterocutaneous fistulas

BACKGROUND & AIMS

Hypertriglyceridemia is commonly observed in patients with enterocutaneous fistulas, compromising their health status. In this study potential causes for hypertriglyceridemia in patients with an enterocutaneous fistula are explored and treatment options discussed accordingly.

METHODS

A database was created consisting of all consecutively treated patients with an enterocutaneous fistula from 1991 until 2007. Two successive measures of serum triglyceride concentrations of more than 3.0 mmol/L (266 mg/dL) were regarded as hypertriglyceridemia. The relation between fistula specific characteristics and hypertriglyceridemia was analyzed using a multivariable Cox proportional hazard model with time-dependent covariates.

RESULTS

A total 102 patients were eligible for this study of whom 25 had hypertriglyceridemia. Multivariable analysis showed that sepsis (HR 4.503, CI 1.778-11.401, P=0.002), high output small bowel fistula (HR 3.534, CI 1.260-9.916, P=0.016), parenteral nutrition (HR 5.689, CI 1.234-26.216, P=0.026) and inflammatory diseases (inflammatory bowel disease vs. malignancy HR 6.211, CI 1.081-35.696, P=0.041) were independent predictors of hypertriglyceridemia.

CONCLUSIONS

High triglyceride concentrations in patients with an enterocutaneous fistula were mainly associated with sepsis, a high output small bowel fistula, nutrition by the parenteral route and primary diseases with inflammatory aetiology. This should direct a treatment strategy that focuses on these aspects.

Interorgan ammonia trafficking in liver disease

Patients with liver disease have reduced urea synthesis capacity resulting in reduced capacity to detoxify ammonia in the liver. The contribution of the gut to the hyperammonemic state observed during liver failure is mainly due to portacaval shunting and not the result of changes in the metabolism of ammonia in the gut. Small intestinal synthesis of ammonia is related to amino acid breakdown, predominantly glutamine, whereas large bowel ammonia production is caused by bacterial breakdown of amino acids and urea. The kidneys produce ammonia but adapt to liver failure in experimental portacaval shunting by reducing ammonia release into the systemic circulation. The kidneys have the ability to switch from net ammonia production to net ammonia excretion. Data from recent studies in patients with cirrhosis of the liver show that the kidneys have a major role in post upper gastrointestinal bleeding hyperammonemia. During hyperammonemia muscle takes up ammonia and plays a major role in (temporarily) detoxifying ammonia to glutamine. Net uptake of ammonia by the brain occurs in patients and experimental animals with acute and chronic liver failure. Insight will be given in recent developments on ammonia lowering therapies which are based on the information of interorgan ammonia trafficking.

The gut does not contribute to systemic ammonia release in humans without portosystemic shunting

The gut is classically seen as the main source of circulating ammonia. However, the contribution of the intestines to systemic ammonia production may be limited by hepatic extraction of portal-derived ammonia. Recent data suggest that the kidney may be more important than the gut for systemic ammonia production. The aim of this study was to quantify the role of the kidney, intestines, and liver in interorgan ammonia trafficking in humans with normal liver function. In addition, we studied changes in interorgan nitrogen metabolism caused by major hepatectomy. From 21 patients undergoing surgery, blood was sampled from the portal, hepatic, and renal veins to assess intestinal, hepatic, and renal ammonia metabolism. In seven cases, blood sampling was repeated after major hepatectomy. At steady state during surgery, intestinal ammonia release was equaled by hepatic ammonia uptake, precluding significant systemic release of intestinal-derived ammonia. In contrast, the kidneys released ammonia to the systemic circulation. Major hepatectomy led to increased concentrations of ammonia and amino acids in the systemic circulation. However, transsplanchnic concentration gradients after major hepatectomy were similar to baseline values, indicating the rapid institution of a new metabolic equilibrium. In conclusion, since hepatic ammonia uptake exactly equals intestinal ammonia release, the splanchnic area, and hence the gut, probably does not contribute significantly to systemic ammonia release. After major hepatectomy, hepatic ammonia clearance is well preserved, probably related to higher circulating ammonia concentrations.

Liver failure after partial hepatic resection: definition, pathophysiology, risk factors and treatment

Liver failure is a dreaded and often fatal complication that sometimes follows a partial hepatic resection. This article reviews the definition, incidence, pathogenesis, risk factors, risk assessment, prevention, clinical features and treatment of post-resectional liver failure (PLF). A systematic, computerized search was performed using key words related to 'partial hepatic resection' and 'liver failure' to review most relevant literature about PLF published in the last 20 years. The reported incidence of PLF ranges between 0.7 and 9.1%. An inadequate quantity or quality of residual liver mass are key events in its pathogenesis. Major risk factors are the presence of comorbid conditions, pre-existent liver disease and small remnant liver volume (RLV). It is essential to identify these risk factors during the pre-operative assessment that includes evaluation of liver volume, anatomy and function. Preventive measures should be applied whenever possible as curative treatment options for PLF are limited. These preventive measures intend to increase RLV and protect remnant liver function. Management principles focus on support of end-organ and liver function. Further research is needed to elucidate the exact pathogenesis of PLF and to develop and validate adequate treatment options.

Brain cytokine flux in acute liver failure and its relationship with intracranial hypertension

BACKGROUND

In acute liver failure (ALF), it is unclear whether the systemic inflammatory response associated with intracranial hypertension is related to brain cytokine production.

AIM

To determine the relationship of brain cytokine production with severity of intracranial hypertension in ALF patients.

METHOD

We studied 16 patients with ALF. All patients were mechanically ventilated and cerebral blood flow measured using the Kety-Schmidt technique and intracranial pressure (ICP) measured with a Camino subdural catheter. We sampled blood from an artery and a reverse jugular catheter to measure proinflammatory cytokines (TNF-alpha, IL-6 and IL-1beta) and ammonia. Additionally, in 3 patients, serial samples were obtained over a 72 h period.

RESULTS

In ALF patients a good correlation between arterial pro-inflammatory cytokines and ICP (r (2) = 0.34, 0.50 and 0.52; for IL-6, IL-1beta and TNF-alpha respectively) was observed. There was a positive cerebral cytokine 'flux' (production), in ALF patients with uncontrolled ICP. Plasma ammonia between groups was not statistically significant. In the ALF patients studied longitudinally, brain proinflammatory cytokine production was associated with uncontrolled ICP.

CONCLUSION

Our results provide novel data supporting brain production of cytokines in patients with uncontrolled intracranial hypertension indicating activation of the inflammatory cascade in the brain. Also, the appearance of these cytokines in the jugular bulb catheter may indicate a compromised blood brain barrier at this late stage.

Aromatic amino acid metabolism during liver failure

Liver failure is associated with hepatic encephalopathy (HE). An imbalance in plasma levels of aromatic amino acids (AAA) phenylalanine, tyrosine, and tryptophan and branched chain amino acids (BCAA) and their BCAA/AAA ratio has been suggested to play a causal role in HE by enhanced brain AAA uptake and subsequently disturbed neurotransmission. Until recently, data on this subject and the role of the liver and splanchnic bed were scarce, particularly in humans, due to inaccessibility of portal and hepatic veins. Here, we discuss, against a background of relevant literature, data obtained in patients undergoing liver resection or with a transjugular intrahepatic portasystemic stent shunt (TIPSS), where these veins are accessible. The BCAA/AAA ratio remained unchanged after major liver resection, but plasma AAA levels were inversely correlated (P < 0.001) with residual liver volume, in keeping with the observed hepatic AAA uptake. In patients with stable cirrhosis and a TIPSS, the plasma BCAA/AAA ratio was lower than in controls (1.19 +/- 0.09 vs. controls: 3.63 +/- 0.34). Gastrointestinal bleeding in cirrhotics with a TIPSS induced disturbances in BCAA levels and the BCAA/AAA ratio and induced catabolism, which could partly be corrected by isoleucine administration. AAA may be important in the pathogenesis of HE, but it is unlikely that they are the sole factors. HE most likely is a syndrome with multifactorial pathogenesis, where hyperammonemia, AAA/BCAA imbalances, inflammation, brain edema, and neurotransmitter changes interact. Novel therapies to normalize AAA levels in patients with liver failure (such as the molecular adsorbent recirculating system dialysis device) should probably be combined with supplementation of e.g. isoleucine and enhancing ammonia excretion by the kidneys.

Isoleucine infusion during "simulated" upper gastrointestinal bleeding improves liver and muscle protein synthesis in cirrhotic patients

Upper gastrointestinal (GI) bleeding in cirrhotic patients has a high incidence of mortality and morbidity. Postbleeding catabolism has been hypothesized to be partly due to the low biological value of hemoglobin, which lacks the essential amino acid isoleucine. The aims were to study the metabolic consequences of a "simulated" upper GI bleed in patients with cirrhosis of the liver and the effects of intravenous infusion of isoleucine. Portal drained viscera, liver, muscle, and kidney protein kinetics were quantified using a multicatheterization technique during routine portography. Sixteen overnight-fasted, metabolically stable patients who received an intragastric infusion of an amino acid solution mimicking hemoglobin every 4 hours were randomized to saline or isoleucine infusion and received a mixture of stable isotopes (L-[ring-2H5]phenylalanine, L-[ring-2H4]tyrosine, and L-[ring-2H2]tyrosine) to determine organ protein kinetics. This simulated bleed resulted in hypoisoleucinemia that was attenuated by isoleucine infusion. Isoleucine infusion during the bleed resulted in a positive net balance of phenylalanine across liver and muscle, whereas renal and portal drained viscera protein kinetics were unaffected. In the control group, no significant effect was shown.

CONCLUSION

The present study investigated hepatic and portal drained viscera protein metabolism selectively in humans. The data show that hepatic and muscle protein synthesis is stimulated by improving the amino acid composition of the upper GI bleed by simultaneous intravenous isoleucine administration.

Portopulmonary Hypertension in the Early Phase Following Liver Transplantation

BACKGROUND

Portopulmonary hypertension (PPH) is a severe complication of liver cirrhosis, which poses a high risk for postliver transplantation (LT) mortality. In most liver transplant centers, severe PPH is viewed as an absolute contraindication for LT, but recent reports challenge this. The purpose of our study was to determine the incidence of PPH, its influence on the 30-day mortality rate following LT and to determine the sensitivity and specificity of Doppler echocardiography and electrocardiography as noninvasive tools to determine PPH.

METHODS

We studied 74 consecutive patients that underwent LT between February 2004 and November 2005. Pulmonary arterial pressure and cardiac index were repeatedly determined during surgery and postoperatively. PPH was defined as mild (mean pulmonary arterial pressure (MPAP) 25-35 mm Hg), moderate (MPAP of 35-45 mm Hg) and as severe (MPAP >45 mm Hg).

RESULTS

The total incidence of PPH was 31% (16 mild, 5 moderate, and 2 severe). There was a tendency towards increased 30-day mortality rate in patients with PPH compared to controls (22% vs. 12%, P=0.1). However, the two patients with the most severe PPH survived. The duration of ventilation and total stay at the intensive care unit did not differ significantly between groups. The positive predictive value of Doppler echocardiography for PPH was 39% and the negative predictive value 90%.

CONCLUSIONS

Mild pulmonary hypertension is common in patients with liver failure, whereas moderate and severe hypertension is not. Severe PPH should not be considered as absolute contraindication for LT.

Kidney plays a major role in ammonia homeostasis after portasystemic shunting in patients with cirrhosis

The kidney plays an important role in ammonia metabolism. In this study the hypothesis was tested that the kidney can acutely diminish ammonia release after portacaval shunting. Thirteen patients with cirrhosis (6 female/7 male, age 54.4 +/- 3.3 yr) were studied. Blood was sampled prior to and 1 h after transjugular intrahepatic stent-shunt (TIPSS) insertion from the portal vein, a hepatic vein, the right renal vein, and the femoral vein, and renal and liver plasma flow were measured. Prior to TIPSS, renal ammonia release was significantly higher than ammonia release from the splanchnic region, which was not significantly different from zero. TIPSS insertion did not change arterial ammonia concentration or ammonia release from the splanchnic region but reduced renal ammonia release into the circulation (P < 0.05) to values that were not different from zero. TIPSS resulted in a tendency toward increased venous-arterial ammonia concentration differences across leg muscle. Post-TIPSS ammonia efflux via portasystemic shunts was estimated to be seven times higher than renal efflux. Kidneys have the ability to acutely diminish systemic ammonia release after portacaval shunting. Diminished renal ammonia release and enhanced muscle ammonia uptake are important mechanisms by which the cirrhotic patient maintains ammonia homeostasis after portasystemic shunting.

Moderate hypothermia in patients with acute liver failure and uncontrolled intracranial hypertension

BACKGROUND AND AIMS

About 20% of patients with acute liver failure (ALF) die from increased intracranial pressure (ICP) while awaiting transplantation. This study evaluates the clinical effects and pathophysiologic basis of hypothermia in patients with ALF and intracranial hypertension that is unresponsive to standard medical therapy.

METHODS

Fourteen patients with ALF who were awaiting orthotopic liver transplantation (OLT) and had increased ICP that was unresponsive to standard medical therapy were studied. Core temperature was reduced to 32 degrees C-33 degrees C using cooling blankets.

RESULTS

Thirteen patients were successfully bridged to OLT with a median of 32 hours (range, 10-118 hours) of cooling. They underwent OLT with no significant complications related to cooling either before or after OLT and had complete neurologic recovery. ICP before cooling was 36.5 +/- 2.7 mm Hg and was reduced to 16.3 +/- .7 mm Hg at 4 hours, which was sustained at 24 hours (16.8 +/- 1.5 mm Hg) ( P < .0001). Mean arterial pressure and cerebral perfusion pressure increased significantly, and the requirement for inotropes was reduced significantly. Hypothermia produced sustained and significant reduction in arterial ammonia concentration and its brain metabolism, cerebral blood flow, brain cytokine production, and markers of oxidative stress.

CONCLUSIONS

Moderate hypothermia is an effective and safe bridge to OLT in patients with ALF who have increased ICP that is resistant to standard medical therapy. Hypothermia reduces ICP by impacting on multiple pathophysiologic mechanisms that are believed to be important in its pathogenesis. A large multicenter trial of hypothermia in ALF is justified.

Pathogenesis of intracranial hypertension in acute liver failure: inflammation, ammonia and cerebral blood flow

BACKGROUND/AIMS

The study aims were to determine the role of inflammation in the pathogenesis of increased intracranial pressure (ICP) in patients with acute liver failure (ALF) and its interplay with cerebral blood flow (CBF) and ammonia.

METHODS

Twenty-one patients with ALF were studied from the time they were ventilated for grade 4 encephalopathy until receiving specific treatment for increased ICP. Depending upon the ICP, the patients were divided into two groups; those that required specific treatment (ICP>20 mmHg, group 1: n=8, ICP: 32 (28-54) mmHg); and those that did not (ICP< or =20 mmHg, group 2: n=13, ICP: 15 (10-20) mmHg).

RESULTS

Inflammatory markers, arterial ammonia and CBF were significantly higher in the group 1 patients. TNFalpha levels correlated with CBF (r=0.80). Four patients from group 2 developed surges of increased ICP (32 (15-112) hours from enrolment). These were associated increases in markers of inflammation and TNFalpha, and an increase in CBF. There was no change in these inflammatory markers, CBF or ICP in the other 9 group 2 patients.

CONCLUSIONS

The results of this study suggest that inflammation plays an important synergistic role in the pathogenesis of increased ICP possibly through its effects on CBF.

Moderate hypothermia prevents cerebral hyperemia and increase in intracranial pressure in patients undergoing liver transplantation for acute liver failure

BACKGROUND

During orthotopic liver transplantation (OLT) for acute liver failure (ALF), some patients develop acute increases in intracranial pressure (ICP). The authors tested the hypothesis that increases in ICP during OLT for ALF can be prevented by moderate hypothermia.

METHODS

Sixteen patients with ALF undergoing OLT were studied. Depending on the measured ICP before OLT, the patients were divided into three groups as follows: group I (n=6), did not require treatment for increased ICP (ICP <15 mm Hg); group II (n=5), had episodes of increased ICP that were controlled by conventional treatment (group I and group II patients were maintained normothermic during OLT); and group III (n=5), had uncontrolled increased ICP before OLT for which they had been cooled and underwent OLT with the median core temperature of 33.4 degrees C (92.1 degrees F) (range, 31.9 degrees -33.8 degrees C [89.4 degrees -92.8 degrees F])

RESULTS

There was a significant increase in ICP during the dissection and reperfusion phases in the patients in groups I and II (P=0.004 and P=0.006, respectively). Patients in group III had no significant increase in ICP during the OLT. The increase in ICP in groups I and II was associated with an increase in cerebral blood flow, which was not observed in group III. The increase in ICP was corrected during the anhepatic phase of the operation. There was no difference in the requirement of transfusions or incidence of postoperative infection between the groups.

CONCLUSIONS

Moderate hypothermia is safe and successfully prevents increases in ICP during OLT for ALF.

The kidney plays a major role in the hyperammonemia seen after simulated or actual GI bleeding in patients with cirrhosis

Upper gastrointestinal (UGI) bleeding in cirrhosis is associated with enhanced ammoniagenesis, the site of which is thought to be the colon. The aims of this study were to evaluate interorgan metabolism of ammonia following an UGI bleed in patients with cirrhosis. Study 1: UGI bleed was simulated in 8 patients with cirrhosis and a transjugular intrahepatic portasystemic stent-shunt (TIPSS) by intragastric infusion of an amino acid solution that mimics the hemoglobin molecule. We sampled blood from the femoral artery and a femoral, renal, portal, and hepatic vein for 4 hours during the simulated bleed and measured plasma flows across these organs. Study 2: In 9 cirrhotic patients with an acute UGI bleed that underwent TIPSS insertion, blood was sampled from an artery and a hepatic, renal, and portal vein, and plasma flows were measured. Study 1: During the simulated bleed, arterial concentrations of ammonia increased significantly (P =.002). There was no change in ammonia production from the portal drained viscera, but renal ammonia production increased 6-fold (P =.008). In contrast to an unchanged ammonia removal by the liver, a significant increase in muscle ammonia removal was observed. Study 2: In patients with an acute UGI bleed, ammonia was only produced by the kidneys (572 [184] nmol/kg bw/min) and not by the splanchnic area (-121 [87] nmol/kg bw/min). In conclusion, enhanced renal ammonia release has an important role in the hyperammonemia that follows an UGI bleed in patients with cirrhosis. During this hyperammonemic state, muscle is the major site of ammonia removal.

Induced hyperammonemia alters neuropsychology, brain MR spectroscopy and magnetization transfer in cirrhosis

Hyperammonemia is a universal finding after gastrointestinal hemorrhage in cirrhosis. We administered an oral amino acid solution mimicking the hemoglobin molecule to examine neuropsychological changes, brain glutamine levels, and brain magnetization transfer ratio (MTR). Forty-eight metabolically stable patients with cirrhosis and no evidence of "overt" hepatic encephalopathy (HE) were randomized to receive 75 g of amino acid solution or placebo; measurements were performed before and 4 hours after administration. Neuropsychological tests included the Trails B Test, Digit Symbol Substitution Test, memory subtest of the Randt battery, and reaction time. Plasma was collected for ammonia and amino acid measurements, and brain metabolism was studied using proton magnetic resonance (MR) spectroscopy in the first 16 randomized patients. In 7 other patients, MTR was measured. A significant increase in ammonia levels was observed in the amino acid group (amino acid group, 76 +/- 7.3 to 121 +/- 6.4 micromol/L; placebo, 83 +/- 3.3 to 78 +/- 2.9 micromol/L; P <.001). Neuropsychological function improved significantly in the placebo group, but no significant change in neuropsychological function was observed in the amino acid group. Brain glutamate/glutamine (Glx)/creatine (Cr) ratio increased significantly in the amino acid group. MTR decreased significantly from 30 +/-2.9 to 23 +/- 4 (P <.01) after administration of the amino acid solution. In conclusion, an improvement in neuropsychological test results followed placebo, which was not observed in patients administered the amino acid solution. Induced hyperammonemia resulted in an increase in brain Glx/Cr ratio and a decrease in MTR, which may indicate an increase in brain water as the operative mechanism.

Oral amino acid load mimicking hemoglobin results in reduced regional cerebral perfusion and deterioration in memory tests in patients with cirrhosis of the liver

This study tests the hypothesis that administration of an oral amino acid load mimicking hemoglobin in patients with cirrhosis of the liver causes deterioration in neuropsychological function and a reduction in regional cerebral perfusion. Eight overnight fasted, metabolically stable cirrhotic patients with no evidence of overt hepatic encephalopathy were studied prior to and 4 h after simulating an upper gastrointestinal bleed by oral administration of 75 g of a solution mimicking the amino acid composition of hemoglobin. Neuropsychological function was measured using a test battery. Peripheral venous blood was collected for the measurement of ammonia and amino acid concentrations. Regional cerebral perfusion was measured using a head SPECT scanner following intravenous administration of technetium-99m hexamethyl propylamineoxime. The amino acid solution resulted in significant deterioration in the immediate and delayed story recall tests. Ammonia concentration increased from a median of 87 (range 67-94) micromol/L to 105 (98-112) micromol/L at 4 h after the simulated bleed (p < 0.01). The concentration of almost all amino acids increased; only isoleucine levels decreased following the upper gastrointestinal bleed. SPECT analysis showed a significant reduction in cerebral perfusion after the simulated bleed in both temporal lobes, left superior frontal gyrus, and right parietal and cingulate gyrus. An oral amino acid load mimicking hemoglobin in cirrhotic patients produces hyperammonemia and hypoisoleucinemia and causes a significant deterioration in memory tests, probably due to a reduction in regional cerebral perfusion. The model of simulating the metabolic effects of an upper gastrointestinal bleed in patients with cirrhosis of the liver seems to be useful in studying the metabolism of hepatic encephalopathy.

Hypothermia for the management of intracranial hypertension in acute liver failure

Increased intracranial pressure in patients with acute liver failure (ALF) remains a major immediate cause of mortality. Several studies in animal models of ALF set the stage for the clinical application of moderate hypothermia in man. Studies in patients with ALF and increased intracranial hypertension have shown that temperatures as low as 32 degrees C are safe and effectively reduce increased intracranial pressure unresponsive to other medical therapies, and can be used as a successful bridge to liver transplantation. Data from studies in patients undergoing liver transplantation for ALF suggest that increases in intracranial pressure can be prevented during the dissection and reperfusion phases of the operation if the patients are maintained hypothermic during surgery. The present review focuses upon the clinical aspects of using hypothermia as a treatment of increased intracranial pressure in patients with ALF.

Interorgan ammonia and amino acid metabolism in metabolically stable patients with cirrhosis and a TIPSS

Ammonia is central to the pathogenesis of hepatic encephalopathy. This study was designed to determine the quantitative dynamics of ammonia metabolism in patients with cirrhosis and previous treatment with a transjugular intrahepatic portosystemic stent shunt (TIPSS). We studied 24 patients with cirrhosis who underwent TIPSS portography. Blood was sampled and blood flows were measured across portal drained viscera, leg, kidney, and liver, and arteriovenous differences across the spleen and the inferior and superior mesenteric veins. The highest amount of ammonia was produced by the portal drained viscera. The kidneys also produced ammonia in amounts that equaled total hepatosplanchnic area production. Skeletal muscle removed more ammonia than the cirrhotic liver. The amount of nitrogen that was taken up by muscle in the form of ammonia was less than the glutamine that was released. The portal drained viscera consumed glutamine and produced ammonia, alanine, and citrulline. Urea was released in the splenic and superior mesenteric vein, contributing to whole-body ureagenesis in these cirrhotic patients. In conclusion, hyperammonemia in metabolically stable, overnight-fasted patients with cirrhosis of the liver and a TIPSS results from portosystemic shunting and renal ammonia production. Skeletal muscle removes more ammonia from the circulation than the cirrhotic liver. Muscle releases excessive amounts of the nontoxic nitrogen carrier glutamine, which can lead to ammonia production in the portal drained viscera (PDV) and kidneys. Urinary ammonia excretion and urea synthesis appear to be the only way to remove ammonia from the body.

Interorgan ammonia metabolism in liver failure

In the post-absorptive state, ammonia is produced in equal amounts in the small and large bowel. Small intestinal synthesis of ammonia is related to amino acid breakdown, whereas large bowel ammonia production is caused by bacterial breakdown of amino acids and urea. The contribution of the gut to the hyperammonemic state observed during liver failure is mainly due to portacaval shunting and not the result of changes in the metabolism of ammonia in the gut. Patients with liver disease have reduced urea synthesis capacity and reduced peri-venous glutamine synthesis capacity, resulting in reduced capacity to detoxify ammonia in the liver. The kidneys produce ammonia but adapt to liver failure in experimental portacaval shunting by reducing ammonia release into the systemic circulation. The kidneys have the ability to switch from net ammonia production to net ammonia excretion, which is beneficial for the hyperammonemic patient. Data in experimental animals suggest that the kidneys could have a major role in post-feeding and post-haemorrhagic hyperammonemia.During hyperammonemia, muscle takes up ammonia and plays a major role in (temporarily) detoxifying ammonia to glutamine. Net uptake of ammonia by the brain occurs in patients and experimental animals with acute and chronic liver failure. Concomitant release of glutamine has been demonstrated in experimental animals, together with large increases of the cerebral cortex ammonia and glutamine concentrations. In this review we will discuss interorgan trafficking of ammonia during acute and chronic liver failure. Interorgan glutamine metabolism is also briefly discussed, since glutamine synthesis from glutamate and ammonia is an important alternative pathway of ammonia detoxification. The main ammonia producing organs are the intestines and the kidneys, whereas the major ammonia consuming organs are the liver and the muscle.