Decreased splanchnic oxygen uptake and increased systemic oxygen uptake in cirrhosis are normalized after liver transplantation

Comparison of central and mixed venous saturation during liver transplantation in cirrhotic patients: a pilot study

BACKGROUND AND OBJECTIVE

Liver transplantation is associated with important haemodynamic variations requiring cardiac output and oximetric data monitoring. The mixed venous saturation (SvO2) integrates parameters combining information about oxygen consumption, cardiac output and haemoglobin concentration. Central venous saturation (ScvO2) can be directly measured from blood drawn in the superior venous system via a central venous catheter. ScvO2 has been proposed as an alternative to SvO2 for intraoperative haemodynamic monitoring. The aim of the present study was to examine the level of agreement between SvO2 and ScvO2 during the preanhepatic and the neohepatic stage of liver transplantation in cirrhotic patients.

MATERIALS AND METHODS

After agreement from the regulatory authorities for medical research and having obtained informed consent, 30 patients with cirrhosis undergoing liver transplantation were prospectively included. Blood gas samples were simultaneously drawn from the arterial line, the right atrium port and the pulmonary artery port of the catheter: during the preanhepatic stage (two times) and two times 30-40 min after graft revascularization. Arterial saturation (SaO2), haemoglobin concentration, cardiac index, SvO2, ScvO2 and oxygen consumption, delivery and extraction (VO2, DO2 and EO2, respectively) were measured. A Bland-Altman test was used to determine bias and limits of agreement between SvO2 and ScvO2. Both parameters were considered to be equivalent if limits of agreement were within +/-5%.

RESULTS

Bland-Altman analysis revealed a bias (limit of agreement) of -1.2% (-9.1 to 6.6%), -0.3% (-4.8 to 4%) and -2.1% (-12 to 7.8%) for the overall measurements and preanhepatic and postgraft reperfusion measurements, respectively. SvO2 decreased significantly between hepatectomy and reperfusion, whereas cardiac index, VO2, DO2 and EO2 showed significantly higher values after reperfusion. ScvO2 and SaO2 levels did not display different values between the two periods.

DISCUSSION

Measurements of SvO2 and ScvO2 showed a good level of agreement during the preanhepatic stage, whereas the level of agreement was low after liver graft reperfusion. The increase of VO2 associated with the decrease of SvO2 and the stability of ScvO2 between the two periods suggest an incomplete mixing of splanchnic venous blood into the right atrium. In addition, our samples were taken from the right atrium, which is not possible using a conventional central venous catheter, as the tip must lie in the superior vena cava and not in the right atrium. ScvO2 cannot be considered equivalent to SvO2 for the haemodynamic monitoring of patients with cirrhosis undergoing liver transplantation.

Plasma bile acids are not associated with energy metabolism in humans

Bile acids (BA) have recently been shown to increase energy expenditure in mice, but this concept has not been tested in humans. Therefore, we investigated the relationship between plasma BA levels and energy expenditure in humans. Type 2 diabetic (T2DM) patients (n = 12) and gender, age and BMI-matched healthy controls (n = 12) were studied before and after 8 weeks of treatment with a BA sequestrant. In addition, patients with liver cirrhosis (n = 46) were investigated, since these display elevated plasma BA together with increased energy expenditure. This group was compared to gender-, age- and BMI-matched healthy controls (n = 20). Fasting plasma levels of total BA and individual BA species as well as resting energy expenditure were determined. In response to treatment with the BA sequestrant, plasma deoxycholic acid (DCA) levels decreased in controls (-60%, p < 0.05) and T2DM (-32%, p < 0.05), while chenodeoxycholic acid (CDCA) decreased in controls only (-33%, p < 0.05). Energy expenditure did not differ between T2DM and controls at baseline and, in contrast to plasma BA levels, was unaffected by treatment with the BA sequestrant. Total BA as well as individual BA species did not correlate with energy expenditure at any time throughout the study. Patients with cirrhosis displayed on average an increase in energy expenditure of 18% compared to values predicted by the Harris-Benedict equation, and plasma levels of total BA (up to 12-fold) and individual BA (up to 20-fold) were increased over a wide range. However, neither total nor individual plasma BA levels correlated with energy expenditure. In addition, energy expenditure was identical in patients with a cholestatic versus a non-cholestatic origin of liver disease while plasma total BA levels differed four-fold between the groups. In conclusion, in the various (patho)physiological conditions studied, plasma BA levels were not associated with changes in energy expenditure. Therefore, our data do not support an important role of circulating BA in the control of human energy metabolism.

Plasma levels of PBEF/Nampt/visfatin are decreased in patients with liver cirrhosis

Liver cirrhosis is a catabolic disease associated with a high incidence of insulin resistance and diabetes mellitus. Pre-B cell colony-enhancing factor/ nicotinamide phosphoribosyltransferase/visfatin has been characterized as a novel adipokine with a potential role in glucose metabolism and nicotinamide dinucleotide (NAD) generation. We studied plasma levels and metabolic relevance of visfatin in 19 patients with cirrhosis and 19 body mass index-, age-, and sex-matched controls. In addition, hepatic mRNA expression was assessed by qPCR in livers of seven patients with cirrhosis and four controls. Circulating visfatin was 78% lower in cirrhotics (P < 0.001) and decreased with worsening of the clinical stage of liver disease. Hepatic visfatin secretion decreased with clinical stage (P < 0.05) and reduced liver function (P = 0.01). Consistent with these data, hepatic visfatin mRNA expression was significantly lower in cirrhotic livers (P < 0.05). Circulating visfatin in cirrhosis was correlated with body cell mass (r = 0.72, P < 0.01) as well as with body fat mass (r = 0.53, P < 0.05) but not with plasma glucose, insulin, the degree of insulin resistance, or whole body glucose oxidation rates. Higher visfatin levels were associated with higher hepatic glucose production (r = 0.53, P < 0.05) and also with a higher arterial ketone body ratio (KBR) (r = 0.48, P < 0.05), an indicator of increased hepatic NAD generation. In conclusion, circulating visfatin levels are significantly decreased in liver cirrhosis, presumably attributable to decreased hepatic expression and production. Plasma visfatin in cirrhosis is not associated with insulin resistance but correlates with hepatic glucose production and the arterial KBR, indicating a potential link between the NAD-generating properties of visfatin and metabolism.

Decreased hepatic RBP4 secretion is correlated with reduced hepatic glucose production but is not associated with insulin resistance in patients with liver cirrhosis

OBJECTIVE

Patients with liver cirrhosis have a high incidence of insulin resistance and diabetes. This study was designed to determine circulating levels and hepatic production of retinol-binding protein 4 (RBP4) in relation to parameters of hepatic and systemic metabolism in patients with liver cirrhosis.

DESIGN AND METHOD

Circulating RBP4 levels were measured in 19 patients with liver cirrhosis at different clinical stages of the disease and in 20 age-, sex- and body mass index (BMI)-matched controls. Hepatic production rates of RBP4 and glucose were assessed by measuring the arterial hepatic venous concentration difference together with hepatic blood flow. Insulin resistance was determined by the Quantitative Insulin Sensitivity Check Index (QUICKI) and the homeostasis model assessment of insulin resistance (HOMA-IR), energy expenditure by indirect calorimetry and body composition by bioelectrical impedance analysis (BIA).

RESULTS

Compared with controls, RBP4 levels in cirrhosis were decreased (8.1 +/- 1.8 vs. 22.6 +/- 2.4 mg/l, P < 0.001) due to decreased hepatic production (P < 0.05). RBP4 correlated with hepatic protein synthesis capacity (P < 0.01), but not with insulin resistance, energy expenditure, BMI or body fat mass. Plasma RBP4 correlated with hepatic glucose production (P < 0.05).

CONCLUSIONS

These data demonstrate that RBP4 in cirrhosis (i) is decreased due to reduced hepatic production, (ii) is not associated with insulin resistance, and (iii) might have a beneficial role by decreasing hepatic glucose production and could thus also be regarded as a hepatokine.

Distinct roles of free leptin, bound leptin and soluble leptin receptor during the metabolic-inflammatory response in patients with liver cirrhosis

BACKGROUND

Alteration of the leptin system appears to play a role in the inflammatory-metabolic response in catabolic diseases such as chronic liver diseases.

AIM

To investigate the association between leptin components, inflammatory markers and hepatic energy and substrate metabolism.

METHODS

We investigated in vivo hepatic substrate and leptin metabolism in 40 patients employing a combination of arterial and hepatic vein catheterization techniques and hepatic blood flow measurements. In addition to metabolic, inflammatory and neuroendocrine parameters, circulating levels of free leptin, bound leptin and soluble leptin receptor were determined.

RESULTS

Compared with controls, bound leptin and soluble leptin receptor levels were significantly elevated in cirrhosis, while free leptin did not increase. In cirrhosis bound leptin was correlated with soluble leptin receptor (r = 0.70, P < 0.001). Free leptin was positively correlated with metabolic parameters such as energy storage (body fat mass; r = 0.36, P < 0.05), insulin and insulin resistance (r = 0.48; r = 0.46, P < 0.01) as well as with hepatic glucose and energy release (r = 0.35 and r = 0.40, P < 0.05). In contrast, bound leptin and soluble leptin receptor were linked to proinflammatory cytokines and sympathetic activity (r = 0.61 and r = 0.56, P < 0.01).

CONCLUSION

The components of the leptin system (free leptin, bound leptin and soluble leptin receptor) have distinct roles in metabolic and inflammatory processes in patients with liver cirrhosis. The better understanding of this metabolic and inflammatory tissue-repair response may lead to innovative new therapeutic strategies in liver disease as well as in various other catabolic diseases.

Elevated resistin levels in cirrhosis are associated with the proinflammatory state and altered hepatic glucose metabolism but not with insulin resistance

The adipokine resistin has been implicated in obesity and insulin resistance. Liver cirrhosis is associated with decreased body fat mass and insulin resistance. We determined plasma resistin levels in 57 patients with cirrhosis, 13 after liver transplantation, and 30 controls and correlated these with hemodynamic as well as hepatic and systemic metabolic parameters. Patients with cirrhosis had, dependent on the clinical stage, an overall 86% increase in resistin levels (P < 0.001) with hepatic venous resistin being higher than arterial levels (P < 0.001). Circulating resistin was significantly correlated with plasma TNF-alpha levels (r = 0.62, P < 0.001). No correlation was observed between resistin and hepatic hemodynamics, body fat mass, systemic energy metabolism, and the degree of insulin resistance. However, plasma resistin in cirrhosis was negatively associated with hepatic glucose production (r = -0.47, P < 0.01) and positively with circulating free fatty acids (FFA; r = 0.40, P < 0.01) and ketone bodies (r = 0.48, P < 0.001) as well as hepatic ketone body production (r = 0.40, P < 0.01). After liver transplantation, plasma resistin levels remained unchanged, whereas insulin resistance was significantly improved (P < 0.01). These data provide novel insights into the role of resistin in the pathophysiological background of a catabolic disease in humans and also indicate that resistin inhibition may not represent a suitable therapeutic strategy for the treatment of insulin resistance and diabetes in patients with liver cirrhosis.

Effect of meal and propranolol on whole body and splanchnic oxygen consumption in patients with cirrhosis

Our aim was to measure whole body energy expenditure after a mixed liquid meal, with and without simultaneous propranolol infusion, in patients with cirrhosis. We also wanted to investigate the effect of propranolol on substrate fluxes and oxygen uptake in the tissues drained by the hepatic vein and azygos vein in the postprandial period in these patients. Whole-body oxygen uptake, hepatic blood flow, hepatic venous pressure gradient and net-hepatic fluxes of oxygen, lactate, glucose, glycerol, and free fatty acids (FFA) were measured in 12 patients with alcoholic cirrhosis before and for 2 h after ingestion of a mixed liquid meal (700 kcal). Half of the patients (n = 6) were randomized to a treatment group receiving intravenous infusion of propranolol in combination with the meal. The meal-induced energy expenditure was significantly lower in patients given propranolol [15.0 +/- 18.9 vs. 67.0 +/- 26.1 kJ/120 min (means +/- SD), P < 0.01]. Meal-induced whole body oxygen uptake was lower in patients receiving propranolol (19.2 +/- 38 vs. 135.7 +/- 61 mmol/120 min, P < 0.01), and the meal-induced increase in splanchnic oxygen uptake was nonexistent when propranolol was administered in combination (-13.2 +/- 34.8 vs. 110.4 +/- 34.8 mmol/120 min, P = 0.04). Postprandially, the propranolol group had a tendency toward a reduced splanchnic glucose output, and the FFA uptake was significantly reduced. Propranolol reduces meal-induced whole body oxygen uptake and energy expenditure as well as splanchnic oxygen uptake. The splanchnic reduction in oxygen consumption can explain almost the entire reduction in whole body oxygen consumption.

The isolated perfused liver response to a 'second hit' of portal endotoxin during severe acute pancreatitis

BACKGROUND/AIM

During severe acute pancreatitis (AP), the liver may show an exaggerated response to the inflammatory products of gut injury transported in the portal vein. Our aim was to explore liver proinflammatory mediator production after a 'second hit' of portal lipopolysaccharide (LPS) during AP.

METHODS

Twenty-four rats underwent one of three 'first-hit' scenarios: (1) severe AP induced by intraductal glycodeoxycholic acid injection and intravenous caerulein infusion, (2) sham laparotomy, or (3) no first intervention. Eighteen hours later, all animals received a 'second hit' of portal LPS in an isolated liver perfusion system. Tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, and IL-6 concentrations were measured in portal and systemic serum, and in the perfusate 30 and 90 min after the 'second hit'. Neutrophil activation by the perfusate was assayed using dihydrorhodamine-123 fluorescence.

RESULTS

We observed a six-fold increase in IL-6 concentration across the liver during AP. All livers produced TNF-alpha after the portal LPS challenge, but this was not exaggerated by AP. No differential neutrophil activation by the perfusate was seen.

CONCLUSION

TNF-alpha, IL-1beta, IL-6 and neutrophil activator production by the isolated perfused liver, in response to a 'second hit' of portal LPS, does not appear to be enhanced during AP.

Blockade of intrahepatic adenosine receptors improves urine excretion in cirrhotic rats induced by thioacetamide

BACKGROUND/AIMS

In healthy rats, we recently showed that reduced intrahepatic portal blood flow leads to activation of hepatic adenosine receptors and a nerve-induced decrease in urine production. We hypothesize that the impaired urine excretion in liver cirrhosis is related to an increase in intrahepatic adenosine.

METHODS

Anesthetized normal and thioacetamide-induced cirrhotic rats were instrumented for the measurement of urine flow, hepatic portal venous blood flow, and renal arterial blood flow. 8-Phenyltheophylline was used to block adenosine receptors.

RESULTS

Compared to normal rats, cirrhotic rats had a lower baseline urine flow (P<0.05). In both normal and cirrhotic rats, intraportal but not intravenous administration of 8-phenyltheophylline increased urine flow. Saline overload in normal rats increased urine flow (from 6.8+/-0.6 to 42.2+/-4.6 microlmin(-1)) and this ability was impaired in cirrhotic rats (from 3.9+/-0.4 to 6.2+/-0.9 microlmin(-1)). Intraportal, but not intravenous, administration of 8-phenyltheophylline partially restored the renal ability to excrete the saline load.

CONCLUSIONS

Impaired renal ability to excrete urine in liver cirrhosis is related to the activation of intrahepatic adenosine receptors, and this is consistent with our previous data showing renal regulation through a hepatorenal neural mechanism activated by intrahepatic adenosine.

Elevated circulating adiponectin levels in liver cirrhosis are associated with reduced liver function and altered hepatic hemodynamics

Adiponectin is a novel adipocytokine negatively correlated with parameters of the metabolic syndrome, such as body mass index (BMI), body fat mass (BFM), and circulating insulin levels. Furthermore, metabolic actions directly on the liver have been described. The aim of the present study was to characterize circulating adiponectin levels, hepatic turnover, and the association of adiponectin with key parameters of hepatic as well as systemic metabolism in cirrhosis, a catabolic disease. Circulating adiponectin levels and hepatic turnover were investigated in 20 patients with advanced cirrhosis. Hepatic hemodynamics [portal pressure, liver blood flow, hepatic vascular resistance, indocyanine green (ICG) half-life], body composition, resting energy expenditure, hepatic free fatty acids (FFA) and glucose turnover, and circulating levels of hormones (catecholamines, insulin, glucagon) and proinflammatory cytokines (IL-1beta, TNF-alpha, IL-6) were also assessed. Circulating adiponectin increased dependently on the clinical stage in cirrhosis compared with controls (15.2 +/- 1.7 vs. 8.2 +/- 1.1 microg/ml, respectively, P < 0.01), whereas hepatic extraction decreased. Adiponectin was negatively correlated with parameters of hepatic protein synthesis (prothrombin time: r = -0.62, P = 0.003; albumin: r = -0.72, P < 0.001) but not with transaminases or parameters of lipid metabolism. In addition, circulating adiponectin increased with portal pressure (r = 0.67, P = 0.003), hepatic vascular resistance (r = 0.60, P = 0.008), and effective hepatic blood flow (ICG half-life: r = 0.69, P = 0.001). Adiponectin in cirrhosis was not correlated with BMI, BFM, parameters of energy metabolism, insulin levels, hepatic FFA and glucose turnover, and circulating proinflammatory cytokines. These results demonstrate that 1) adiponectin plasma levels in cirrhosis are significantly elevated, 2) the liver is a major source of adiponectin extraction, and 3) adiponectin levels in cirrhosis do not correlate with parameters of body composition or metabolism but exclusively with reduced liver function and altered hepatic hemodynamics.