Potential role of increased sympathetic activity in impaired sodium and water excretion in cirrhosis

Cellular and Molecular Mechanisms Underlying Altered Excitability of Cardiac Efferent Neurons in Cirrhotic Rats

Patients with cirrhosis often exhibit cardiac autonomic dysfunction (CAD), characterized by enhanced cardiac sympathetic activity and diminished cardiac vagal tone, leading to increased morbidity and mortality. This study delineates the cellular and molecular mechanisms associated with altered neuronal activities causing cirrhosis-induced CAD. Biliary and nonbiliary cirrhotic rats were produced by common bile duct ligation (CBDL) and intraperitoneal injections of thioacetamide (TAA), respectively. Three weeks after CBDL or TAA injection, the assessment of heart rate variability revealed autonomic imbalance in cirrhotic rats. We observed increased excitability in stellate ganglion (SG) neurons and decreased excitability in intracardiac ganglion (ICG) neurons in cirrhotic rats compared to sham-operated controls. Additionally, threshold, rheobase, and action potential duration exhibited opposite alterations in SG and ICG neurons, along with changes in afterhyperpolarization duration. A- and M-type K⁺ channels were significantly downregulated in SG neurons, while M-type K⁺ channels were upregulated, with downregulation of the N- and L-type Ca2⁺ channels in the ICG neurons of cirrhotic rats, both in transcript expression and functional activity. Collectively, these findings suggest that cirrhosis induces an imbalance between cardiac sympathetic and parasympathetic neuronal activities via the differential regulation of K+ and Ca2+ channels. Thus, cirrhosis-induced CAD may be associated with impaired autonomic efferent functions within the homeostatic reflex arc that regulates cardiac functions.

Pathophysiology of Hepatorenal Syndrome

Hepatorenal syndrome type 1 (HRS-1) is a unique form of acute kidney injury that affects individuals with decompensated cirrhosis with ascites. The primary mechanism leading to reduction of kidney function in HRS-1 is hemodynamic in nature. Cumulative evidence points to a cascade of events that led to a profound reduction in kidney perfusion. A state of increased intrahepatic vascular resistance characteristic of advanced cirrhosis and portal hypertension is accompanied by maladaptive peripheral arterial vasodilation and reduction in systemic vascular resistance and mean arterial pressure. As a result of a fall in effective arterial blood volume, there is a compensatory activation of the sympathetic nervous system and the renin-angiotensin system, local renal vasoconstriction, loss of renal autoregulation, decrease in renal blood flow, and ultimately a fall in glomerular filtration rate. Systemic release of nitric oxide stimulated by the fibrotic liver, bacterial translocation, and inflammation constitute key components of the pathogenesis. While angiotensin II and noradrenaline remain the critical mediators of renal arterial and arteriolar vasoconstriction, other novel molecules have been recently implicated. Although the above-described mechanistic pathway remains the backbone of the pathogenesis of HRS-1, other noxious elements may be present in advanced cirrhosis and likely contribute to the renal impairment. Direct liver-kidney crosstalk via the hepatorenal sympathetic reflex can further reduce renal blood flow independently of the systemic derangements. Tense ascites may lead to intraabdominal hypertension and abdominal compartment syndrome. Cardio-hemodynamic processes have also been increasingly recognized. Porto-pulmonary hypertension, cirrhotic cardiomyopathy, and abdominal compartment syndrome may lead to renal congestion and complicate the course of HRS-1. In addition, a degree of ischemic or toxic (cholemic) tubular injury may overlap with the underlying circulatory dysfunction and further exacerbate the course of acute kidney injury. Improving our understanding of the pathogenesis of HRS-1 may lead to improvements in therapeutic options for this seriously ill population.

The Effects of SGLT2 Inhibitors on Liver Cirrhosis Patients with Refractory Ascites: A Literature Review

Decompensated liver cirrhosis is often complicated by refractory ascites, and intractable ascites are a predictor of poor prognosis in patients with liver cirrhosis. The treatment of ascites in patients with cirrhosis is based on the use of aldosterone blockers and loop diuretics, and occasionally vasopressin receptor antagonists are also used. Recent reports suggest that sodium–glucose cotransporter 2 (SGLT2) inhibitors may be a new treatment for refractory ascites with a different mechanism with respect to conventional agents. The main mechanisms of ascites reduction with SGLT2 inhibitors appear to be natriuresis and osmotic diuresis. However, other mechanisms, including improvements in glucose metabolism and nutritional status, hepatoprotection by ketone bodies and adiponectin, amelioration of the sympathetic nervous system, and inhibition of the renin–angiotensin–aldosterone system, may also contribute to the reduction of ascites. This literature review describes previously reported cases in which SGLT2 inhibitors were used to effectively treat ascites caused by liver cirrhosis. The discussion of the mechanisms involved is expected to contribute to establishing SGLT2 therapy for ascites in the future.

Beta-blockers in patients with liver cirrhosis: Pragmatism or perfection?

With increasing decompensation, hyperdynamic circulatory disturbance occurs in liver cirrhosis despite activation of vasoconstrictors. Here, the concept of a therapy with non-selective beta-blockers was established decades ago. They lower elevated portal pressure, protect against variceal hemorrhage, and may also have pleiotropic immunomodulatory effects. Recently, the beneficial effect of carvedilol, which blocks alpha and beta receptors, has been highlighted. Carvedilol leads to "biased-signaling" via recruitment of beta-arrestin. This effect and its consequences have not been sufficiently investigated in patients with liver cirrhosis. Also, a number of questions remain open regarding the expression of beta-receptors and its intracellular signaling and the respective consequences in the intra- and extrahepatic tissue compartments. Despite the undisputed role of non-selective beta-blockers in the treatment of liver cirrhosis, we still can improve the knowledge as to when and how beta-blockers should be used in which patients.

Fractional Excretion of Sodium and Urea in Differentiating Acute Kidney Injury Phenotypes in Decompensated Cirrhosis

BACKGROUND

Prerenal acute kidney injury (prerenal AKI), hepatorenal syndrome (HRS-AKI), and acute tubular necrosis (ATN-AKI) are the various phenotypes of acute kidney injury, which are described in decompensated cirrhosis. It has therapeutic and prognostic implications. We aimed to evaluate the diagnostic utility of fractional excretion of sodium and urea (FENa and FEUrea) for differentiating AKI phenotypes.

METHODS

A prospective analysis was performed in 200 patients with decompensated cirrhosis with AKI to derive receiver operating curve, optimal cut-off, sensitivity, and specificity. These findings were validated in an independent cohort (n = 50) to differentiate ATN-AKI, HRS-AKI, and prerenal AKI.

RESULTS

The incidence of prerenal AKI, HRS-AKI, and ATN-AKI were 37.5%, 34%, and 28.5% in the derivation cohort and 28%, 38%, and 34% in the validation cohort respectively. The median FENa was significantly different in various phenotypes of AKI in the derivation and validation cohort (P 0.001); FEUrea was significantly different in the derivation cohort (P 0.0001), not in the validation cohort (P 0.106). The AUC for FENa (cut-off, sensitivity/specificity) was 86.6% (0.567, 89/71) and for FEUrea was 60.3% (34.73, 70/58) for ATN-AKI vs. non-ATN-AKI. The area under the curve for FENa to differentiate between HRS-AKI vs. non-HRS-AKI was 74.5%. FEUrea could not differentiate HRS-AKI vs. non-HRS-AKI (AUC 60.4%) satisfactorily. FENa and FEUrea were unable to differentiate between prerenal AKI and HRS-AKI (AUC <70%).

CONCLUSION

Among cirrhotics FENa at admission is a simple, commonly available clinical tool that can be used to differentiate structural AKI from prerenal AKI and HRS-AKI. The newly derived lowered cut-off value of FENa makes the diagnosis of ATN-AKI easier, faster and thus obviates the need for extensive workup in a significant proportion of patients. FENa appears better than FEUrea in decompensated cirrhosis with AKI.

Reappraising the spectrum of AKI and hepatorenal syndrome in patients with cirrhosis

The occurrence of acute kidney injury (AKI) in patients with end-stage liver disease constitutes one of the most challenging clinical scenarios in in-hospital and critical care medicine. Hepatorenal syndrome type 1 (HRS-1), which is a specific type of AKI that occurs in the context of advanced cirrhosis and portal hypertension, is associated with particularly high mortality. The pathogenesis of HRS-1 is largely viewed as a functional derangement that ultimately affects renal vasculature tone. However, new insights suggest that non-haemodynamic tubulo-toxic factors, such as endotoxins and bile acids, might mediate parenchymal renal injury in patients with cirrhosis, suggesting that concurrent mechanisms, including those traditionally associated with HRS-1 and non-traditional factors, might contribute to the development of AKI in patients with cirrhosis. Moreover, histological evidence of morphological abnormalities in the kidneys of patients with cirrhosis and renal dysfunction has prompted the functional nature of HRS-1 to be re-examined. From a clinical perspective, a diagnosis of HRS-1 guides utilization of vasoconstrictive therapy and decisions regarding renal replacement therapy. Patients with cirrhosis are at risk of AKI owing to a wide range of factors. However, the tools currently available to ascertain the diagnosis of HRS-1 and guide therapy are suboptimal. Short of liver transplantation, goal-directed haemodynamically targeted pharmacotherapy remains the cornerstone of treatment for this condition; improved understanding of the underlying pathogenic mechanisms might lead to better clinical outcomes. Here, we examine our current understanding of the pathophysiology of HRS-1 and existing challenges in its diagnosis and treatment.

Is Exaggerated Release of Arginine Vasopressin an Endocrine Disorder? Pathophysiology and Treatment

Exaggerated release of arginine vasopressin (AVP) is profoundly involved in impaired water excretion and related hyponatremia. Such disorders underlie syndromes of inappropriate secretion of antidiuretic hormone (SIADH) and edematous diseases, such as congestive heart failure and decompensated liver cirrhosis. All the causes are fundamentally from non-endocrine diseases. AVP-induced water retention could produce hyponatremia, and further accelerate poor long-term outcome of edematous diseases. Administration of AVP V₂ receptor antagonists verifies how much AVP is involved in the pathogenesis of the impaired water excretion. The present paper demonstrated that exaggerated release of AVP plays a crucial role as an accessory endocrine disorder in pathological states of water retention and dilutional hyponatremia in non-endocrine disorders.

Left ventricular systolic function is associated with sympathetic nervous activity and markers of inflammation in cirrhosis

An accurate evaluation of cardiac function in patients with cirrhosis remains a challenge. We used robust echocardiographic indices to characterize left ventricular (LV) systolic function and its relationship to activation of the sympathetic nervous system and inflammation in 59 patients with cirrhosis and 59 age-matched controls. Additionally, in 11 patients we withdrew beta-blockers and diuretics and used phenylephrine and albumin infusion to evaluate the response to acute afterload and preload changes (interventional substudy). Measures of systolic LV function such as the ejection intraventricular pressure difference (EIVPD) and the systolic strain rate were higher in patients with cirrhosis than in controls (median [1st-3rd quartile], 4.0 [3.1-5.1] versus 2.9 [2.4-3.6] mm Hg and -1.3 [-1.6 to -1.1] versus -1.2 [-1.6 to -1.1)] s^-1 , respectively; P < 0.05 for both). EIVPD was related to the severity of liver disease (Model for End-Stage Liver Disease, rho = 0.45, P < 0.001), the degree of sympathetic nervous system activation (noradrenaline, rho = 0.26, P = 0.05; heart rate variability, rho = -0.43, P = 0.003), and treatment with beta-blockers (P = 0.001). In the interventional substudy, EIVPD was higher in patients with ascites (6.5 [5.4-8.5] versus 4.0 [3.9-5.1] mm Hg, P = 0.045). The decrease in EIVPD induced by phenylephrine was inversely related to baseline systolic function (P < 0.05) and associated with markers of systemic vasodilatation (nitric oxide, rho = -0.66, P = 0.06; diastolic blood pressure, rho = 0.68, P = 0.04) and inflammation (interleukin-1beta, rho = -0.80, P = 0.009).

CONCLUSION

LV systolic function is enhanced in cirrhosis due to augmented adrenergic tone and modulated by treatment with beta-blockers; acute afterload stress induces a deeper impairment of systolic function in patients with more advanced degrees of vasodilatation and inflammation; these changes in LV function related to cirrhosis can be assessed using robust echocardiographic methods. (Hepatology 2017;65:2019-2030).

Effects of alfapump™ system on kidney and circulatory function in patients with cirrhosis and refractory ascites

The alfapump system has been proposed as a new treatment for the management of refractory ascites. The system removes ascites from the peritoneal cavity to urinary bladder, producing a continuous low-volume paracentesis. The aim of the study is to investigate the effects of treatment with the alfapump™ system on kidney and circulatory function in patients with cirrhosis and refractory ascites. This was a prospective study including 10 patients with cirrhosis and refractory ascites. Primary outcomes were changes in glomerular filtration rate (GFR), as assessed by isotopic techniques, and changes in circulatory function assessed by arterial pressure, cardiac output, and activity of vasoconstrictor systems. Secondary outcomes were the need for large-volume paracentesis and adverse events. Follow-up was 1 year. GFR decreased significantly from 67 mL/minute/1.73 m² (41-90 mL/minute/1.73 m² ) at baseline to 45 mL/minute/1.73 m² (36-74 mL/minute/1.73 m² ) at month 6 (P = 0.04). Mean arterial pressure and cardiac output did not change significantly; however, there was a marked increase in plasma renin activity and norepinephrine concentration (median percent increase with respect to baseline +191% and 59%, respectively). There were 68 episodes of complications of cirrhosis in 8 patients during follow-up, the most frequent being acute kidney injury. In conclusion, treatment with alfapump™ system was associated with marked activation of endogenous vasoconstrictor systems and impairment of kidney function. The chronological relationship observed between kidney impairment and vasoconstrictor systems activation after device insertion suggests a cause-effect relationship, raising the possibility that treatment with alfapump impairs effective arterial blood volume mimicking a postparacentesis circulatory dysfunction syndrome. In this context, the potential role of albumin in counteracting these effects should be investigated in future studies. Liver Transplantation 23 583-593 2017 AASLD.

Fractional excretion of sodium in hepatorenal syndrome: Clinical and pathological correlation

AIM

To determine the accuracy of fractional excretion of sodium (FeNa) in the diagnosis of hepatorenal syndrome (HRS).

METHODS

Eighty-eight liver transplantation candidates with renal dysfunction and/or proteinuria were included in the study sample. The baseline characteristics of the patients were obtained. All the 88 patients underwent iothalamate glomerular filtration rate testing, 24-h urine collection for urinary sodium and protein excretions, random urine for sodium and creatinine testing, and percutaneous kidney biopsy. FeNa was calculated using the equation [(urine sodium × serum creatinine)/(serum sodium × urine creatinine)] × 100%. Diuretic use was recorded among the participants. Patients on renal replacement therapy were not included in the original sample.

RESULTS

Seventy-seven (87%) of the 88 patients had FeNa < 1%. FeNa < 1% was present in 10/10, 10/12, 11/13, 12/15 and 34/38 in patients with HRS, acute tubular necrosis, membranoproliferative glomerulonephritis, minimal histological findings (≤ 30%) and advanced (≥ 30%-40%) interstitial fibrosis and/or glomerulosclerosis, respectively (P = 0.4). FeNa < 1% was 100% sensitive and 14% specific in diagnosing HRS. Receiver operating characteristic curve confirmed the poor accuracy of FeNa < 1% in diagnosing HRS (area under the curve = 0.58, P = 0.47). Calculated positive predictive value and negative predictive value for FeNa < 1% in HRS diagnosis were 46% and 100%, respectively. When used as a continuous variable, FeNa did not correlate with kidney biopsy findings (P = 0.41).

CONCLUSION

FeNa < 1% was common in cirrhotic patients with renal dysfunction and it did not differentiate between HRS and other causes of renal pathologies. HRS diagnosis should be avoided in patients with FeNa > 1%.

Updates on Hepato-Renal Syndrome

Hepato-renal syndrome (HRS) is one of the most detrimental conditions in patients with end stage liver failure. Historically, HRS was considered a terminal disease associated with cirrhosis and was termed "liver-death syndrome". Furthermore, despite the improved understanding of pathophysiology and the reversibility of renal dysfunction in HRS, mortality remains extremely high especially for type 1 HRS. This review summarizes the recent advances in the pathophysiology, diagnosis and management of HRS and also provides an evolving area of research in the pathophysiologic mechanisms of HRS, which may open the door for new therapeutic approaches.

Ascites

Ascites is the pathologic accumulation of fluid in the peritoneum. It is the most common complication of cirrhosis, with a prevalence of approximately 10%. Over a 10-year period, 50% of patients with previously compensated cirrhosis are expected to develop ascites. As a marker of hepatic decompensation, ascites is associated with a poor prognosis, with only a 56% survival 3 years after onset. In addition, morbidity is increased because of the risk of additional complications, such as spontaneous bacterial peritonitis and hepatorenal syndrome. Understanding the pathophysiology of ascites is essential for its proper management.

Arginine vasopressin (AVP) and treatment with arginine vasopressin receptor antagonists (vaptans) in congestive heart failure, liver cirrhosis and syndrome of inappropriate antidiuretic hormone secretion (SIADH)

Arginine vasopressin (AVP) is the major physiological regulator of renal water excretion and blood volume. The AVP pathways of V(1a)R-mediated vasoconstriction and V(2)R-induced water retention represent a potentially attractive target of therapy for edematous diseases. Experimental and clinical evidence suggests beneficial effects of AVP receptor antagonists by increasing free water excretion and serum sodium levels. This review provides an update on the therapeutic implication of newly developed AVP receptor antagonists in respective disorders, such as chronic heart failure, liver cirrhosis and syndrome of inappropriate antidiuretic hormone secretion.

Terlipressin in hepatorenal syndrome: Evidence for present indications

Hepatorenal syndrome (HRS) is the most frequent life threatening complication of advanced liver failure and cirrhosis. HRS results from a functional renal dysfunction due to circulatory disturbances in patients with advanced liver disease and portal hypertension. Reduction in the effective circulating blood volume and hence hypoperfusion of the kidney is the basic underlying common pathogenetic mechanism for the development of hepatorenal syndrome. The prognosis for HRS remains very poor with types 1 and 2-both having an expected survival time of 2 weeks and 6 months, respectively. Although the available data are derived from studies including a limited number of patients mainly affected by type 1 HRS, vasoconstrictor drugs, in particular the vasopressin analog Terlipressin, seem to be the most effective approach for the management of HRS. Associated with albumin infusion, these drugs have been shown to lead to reduced mortality and improved renal function in HRS. Terlipressin administration significantly increases mean arterial pressure and systemic vascular resistance; while the heart rate, cardiac output, HVPG and portal venous blood flow decrease significantly. This decrease correlates well with the decrease in plasma renin activity. Thus the vasoconstrictor effect of Terlipressin reverses the basic pathology of HRS by reducing the plasma renin activity. The improvement in hemodynamics with Terlipressin is associated with an increase in glomerular filtration rate and deactivation of the vasoconstrictor and sodium-conserving hormones with reduced activity of the RAAS resulting in increased natriuresis. Terlipressin thus reverses HRS and is useful in bridging the patient to liver transplantation and may hence indirectly improve survival. Patients with HRS who show an improvement in renal function with Terlipressin and albumin seem to have an excellent post-transplantation outcome similar to that of patients without HRS. Thus, the use of Terlipressin has been shown to be safe, with minimal side effects that usually disappear after dose reduction, and results in an improved outcome in patients with HRS.

Effects of terlipressin on water excretion after oral water load test in nonazotemic cirrhotic patients with ascites without hyponatremia

OBJECTIVE

Impaired water excretion is a major prognostic factor in decompensated cirrhotic patients. We investigated if terlipressin improves water excretion after a water load test in nonazotemic cirrhotic patients with ascites without hyponatremia.

METHODS

Fifteen patients (Child-Pugh B/C: 6/9) were studied after an oral water intake of 20 ml/kg within 40 min and water excretion over 5 h was measured at baseline: day 1, and after a bolus infusion (2 mg) of terlipressin: day 3. Mean arterial pressure (MAP) before and after water loading on day 1, and MAP, cardiac output (CO), and systemic vascular resistance (SVR) before and 1 h after terlipressin infusion on day 3, were evaluated. The 5-h creatinine clearance (ClCre), diuresis, and sodium excretion were also evaluated in each study day.

RESULTS

The water load excreted on day 1 was significantly correlated with Child-Pugh score, ClCre, sodium excretion, and SVR. The water load excreted and diuresis increased significantly after terlipressin infusion in the 12 patients that completed the study (48.3±3.3% vs. 39.5±4.9%; p=0.001 and 2.51±0.21 vs. 2.06±0.29 ml/min; p=0.001, respectively); significant increases in ClCre and sodium excretion, a significant decrease in CO and significant increases in MAP and SVR were also noted. The changes in the percentage of water load excreted were significantly correlated with the changes in SVR and ClCre.

CONCLUSIONS

Terlipressin increases water excretion during a water load test in nonazotemic cirrhotic patients without hyponatremia, suggesting that the administration of arterial vasoconstrictors could influence the prognosis of these patients.

Impaired free water excretion in child C cirrhosis and ascites: relations to distal tubular function and the vasopressin system

BACKGROUND

Water retention in advanced cirrhosis and ascites may involve disturbances in renal distal tubular function and in the vasopressin system.

METHODS

Twelve patients with Child B cirrhosis and ascites were compared with 11 patients with Child C cirrhosis and ascites. The subjects were studied during a 400 ml/h oral water load.

RESULTS

Child C patients had a lower baseline glomerular filtration rate (32 vs 63 ml/min, P<0.001) and a lower urinary flow rate (V(u)) (0.86 vs 1.95 ml/min, P<0.001) than the Child B patients. However, the free water clearance (C(H2O)) did not differ (-0.60 vs -0.21 ml/min, P=0.20). After the water loading, plasma vasopressin (AVP) decreased significantly in both the groups (P<0.05). The Child B patients had increased V(u) (1.95-3.24 ml/min, P<0.001) and C(H2O) (-0.21-1.21 ml/min, P<0.01) and distal fractional water excretion (10.5 vs 0% in Child C, P=0.01) and aquaporin-2 (AQP2) (P<0.058) after water loading. In contrast, the Child C patients did not have increased V(u) and C(H2O) in response to the water and the decrease in AVP. Furthermore, the markers of distal tubular water regulation, AQP2 excretion and distal fractional water excretion, were unaltered.

CONCLUSION

In Child C cirrhosis, ascites and mild hyponatraemia, there is an impaired ability to excrete solute-free water. The patients are characterised by a low glomerular filtration rate, a low distal tubular flow and an inability to increase free water clearance during water loading. This may be related to a vasopressin-independent production of AQP2.

Renal failure in patients with hepatocellular carcinoma and ascites undergoing transarterial chemoembolization

BACKGROUND

Ascites is often present in patients with hepatocellular carcinoma (HCC) with cirrhosis. Advanced cirrhosis may predispose to renal dysfunction. Acute renal failure (ARF) may occur after transarterial chemoembolization (TACE) for HCC because of radiocontrast agents. This study aimed to investigate the incidence and risk factors of ARF and prognostic predictors in HCC patients with ascites undergoing TACE.

METHODS

A total of 591 HCC patients receiving TACE were enrolled.

RESULTS

In a mean follow-up duration of 19+/-17 months, 239 (40.4%) patients undergoing TACE died. Ascites, which was present in 91 (15.4%) patients at entry, independently predicted a poor prognosis in the Cox proportional hazard model [risk ratio (RR): 1.71, P=0.002]. Of these, 11 (12.6%) of 87 patients with complete follow-up developed ARF after TACE. Serum albumin level <3.3 g/dl (odds ratio: 7.3, P=0.009) was the only independent risk factor associated with ARF in the logistic regression analysis. ARF (RR: 2.17, P=0.036), alpha-fetoprotein >400 ng/ml (RR: 1.84, P=0.04), multiple tumours (RR: 2.11, P=0.013), tumour size > or = 5 cm (RR: 2.32, P=0.006) and serum sodium level <139 mmol/L (RR: 2.4, P=0.005) were independent poor prognostic predictors for HCC patients with ascites receiving TACE.

CONCLUSIONS

Pre-existing ascites is associated with increased mortality in HCC patients receiving TACE. In HCC patients with ascites, hypoalbuminaemia is associated with the occurrence of post-TACE ARF. Post-TACE ARF is a poor prognostic predictor in this subset of HCC patients.

Effect of hyponatraemia on outcomes following orthotopic liver transplantation

BACKGROUND

Hyponatraemia increases risk of adverse outcomes following orthotopic liver transplantation (OLT), but it is unclear whether improvement of pretransplant hyponatraemia ameliorates post-transplant complications.

AIMS

To assess impact of pretransplant hyponatraemia on post-transplant outcomes.

METHODS

We performed a retrospective analysis of 213 patients with cirrhosis who underwent liver transplantation. Patients with serum sodium <or=130 mEq/L immediately before transplantation ('hyponatraemia at OLT'; n=34) were compared with those who had experienced hyponatraemia but subsequently improved to a serum sodium >130 mEq/L at transplantation ('resolved hyponatraemia'; n=56) and to those without history of hyponatraemia before transplantation ('never hyponatraemic'; n=123). Primary endpoint was survival at 180 days post-OLT. Secondary outcomes included time until discharge alive, complications during hospitalization, length of time ventilated and length of post-transplant intensive care unit stay.

RESULTS

There was no survival difference at 180 days post-OLT between groups. After transplantation, patients with either hyponatraemia at OLT or resolved hyponatraemia had longer time until discharge alive and had higher rates of delirium, acute renal failure, acute cellular rejection and infection than those who were never hyponatraemic. As compared with patients with hyponatraemia at OLT, those with resolved hyponatraemia were more likely to be discharged alive within 3 weeks, but other outcomes, including survival, did not differ significantly.

CONCLUSIONS

We conclude that hyponatraemia at any time before liver transplantation is associated with adverse post-transplant outcome, even when hyponatraemia has resolved.

Sodium Retention in Heart Failure and Cirrhosis

Patients with cirrhosis and heart failure (HF) share the pathophysiology of decreased effective arterial blood volume because of splanchnic vasodilatation in cirrhosis and decreased cardiac output in HF, with resultant stimulation of the renin-angiotensin-aldosterone system. Hyperaldosteronism plays a major role in the pathogenesis of ascites and contributes to resistance to loop diuretics. Therefore, the use of high doses of aldosterone antagonist (spironolactone up to 400 mg/day) is the main therapy to produce a negative sodium balance in cirrhotic patients with ascites. Hyperaldosteronism also has increasingly been recognized as a risk factor for myocardial and vascular fibrosis. Therefore, low-dose aldosterone antagonists are being used in patients with HF for cardioprotective action. However, the doses (25 to 50 mg/day) at which they are being used in cardiac patients as reported in the Randomized Aldactone Evaluation Study are not natriuretic. It is likely, therefore, that the mortality benefit relates primarily from their effect on cardiac and vascular fibrosis. Resistance to commonly used loop diuretics is frequently present in patients with advanced HF. In patients with decompensated HF with volume overload who are loop diuretic resistant, ultrafiltration may be the only available option. This is, however, an invasive procedure. For these patients, natriuretic doses of aldosterone antagonists (spironolactone >50 mg/day) may be a potential option. The competitive natriuretic response of aldosterone antagonists is related to activity of the renin-angiotensin-aldosterone system: the higher the renin-angiotensin-aldosterone system activity, the higher the dose of aldosterone antagonist required to produce natriuresis. This article will discuss the potential use of natriuretic doses of aldosterone antagonists in patients with HF, including the potential side effect of hyperkalemia.

Renal failure in patients with cirrhosis

Renal failure in cirrhosis poses unique diagnostic and therapeutic challenges. Laboratory values and predictive equations grossly overestimate renal function in patients with cirrhosis. Development of renal failure connotes a worse prognosis; mortality is especially high with hepatorenal syndrome. Classification of the causes of renal failure in patients with cirrhosis is provided with more extensive discussion of selected causes. Finally, a suggested diagnostic approach to renal failure in cirrhosis is given.

Increased plasma nitric oxide, L-arginine, and arginase-1 in cirrhotic patients with progressive renal dysfunction

BACKGROUND AND AIMS

Increased levels of nitric oxide (NO) are hypothesized to contribute to renal dysfunction in patients with decompensated cirrhosis. In this study, we examined whether splanchnic and/or peripheral NO levels and L-arginine (L-Arg) correlate with progressive renal dysfunction in cirrhotics.

METHODS

Serum NO metabolites (NOx) and L-Arg were measured in: controls (n = 10); organ donors (n = 12); compensated cirrhotics (n = 17), cirrhotics with ascites (n = 25), refractory ascites (n = 11) or hepatorenal syndrome type II (HRS) (n = 11) and chronic renal failure patients (n = 18).

RESULTS

Plasma NOx and L-Arg levels rose progressively with worsening renal function in decompensated cirrhotics. Both NOx and L-Arg levels were highest in patients with HRS (P < 0.001 and P < 0.025, respectively). While there were no differences in NOx levels related to the site of sampling, L-Arg levels were lowest in hepatic venous blood. There were significant relationships of NOx and L-Arg with Model for End-Stage Liver Disease score and Child-Pugh scores (P < 0.04 and P < 0.01, respectively). Multivariate analysis showed a significant relationship between NOx, L-Arg and HRS.

CONCLUSION

Worsening renal function in decompensated cirrhosis is accompanied by progressive elevation in plasma NOx and L-Arg. These findings support the hypothesis that NO-mediated vasodilation is probably linked with the mechanism of progressive renal failure in decompensated cirrhotics.

Pathophysiologic basis for the medical management of portal hypertension

BACKGROUND

Portal hypertension is a potentially life-threatening complication of cirrhosis, resulting from increased intrahepatic resistance and portal inflow.

OBJECTIVE

Given the complex nature of this disorder, a more complete understanding of the pathophysiology of portal hypertension is necessary to develop new therapies that target specific pathways that regulate portal pressure.

METHODS

This review is based on a literature search of published articles and abstracts on the pathophysiology of portal hypertension, its complications and its treatment.

RESULTS/CONCLUSION

A number of therapies have been developed or are under investigation for the treatment of portal hypertension and its complications. These agents may reduce mortality and improve quality of life for patients with advanced liver disease.

Uncoupling of sympathetic nervous system and hypothalamic-pituitary-adrenal axis in cirrhosis

BACKGROUND AND AIM

The hypothalamic-autonomic nervous system (HANS) axis and the hypothalamic-pituitary-adrenal (HPA) axis are stimulated in parallel in response to stress factors under healthy conditions. This physiological synergism of the axes aims at optimizing anti-inflammatory actions. Therefore, we investigated whether this synergism is altered in patients with liver cirrhosis.

METHODS

As a typical marker of the HANS axis neuropeptide Y (NPY is a neurotransmitter of the sympathetic nerve terminal) and of the HPA axis, cortisol together with adrenocorticotropic hormone (ACTH) and cortisol-binding globulin (CBG), were measured in samples from control subjects and patients with liver cirrhosis.

RESULTS

Plasma NPY was found to be increased in cirrhotic patients compared to control subjects (P < 0.01). This increase was observed to be independent of the severity of liver disease (Child class). Serum cortisol was decreased in cirrhotics, particularly in patients with Child A cirrhosis. Plasma NPY was positively correlated with serum cortisol in control subjects (r = 0.32, P < 0.05) reflecting the parallel activation of both axes under the normal condition. However, serum cortisol was not correlated with plasma NPY in cirrhotic patients. For the subgroup of Child A patients, even a negative correlation between NPY and cortisol was observed (r = -0.43, P < 0.05). No significant change in serum levels of ACTH and its positive correlation with serum cortisol was observed in cirrhotic patients.

CONCLUSIONS

The present study demonstrates that the two stress axes seem to act in parallel fashion in control subjects but are uncoupled in liver cirrhosis. We discuss how uncoupling of the two anti-inflammatory axes can occur and may contribute to the increased susceptibility for infections and lethal complications in cirrhotic patients.

Terlipressin improves renal function in patients with cirrhosis and ascites without hepatorenal syndrome

Patients with advanced cirrhosis and ascites are characterized by circulatory dysfunction with splanchnic vasodilatation and renal vasoconstriction, which often lead to ascites. The vasoconstrictor terlipressin improves renal function in hepatorenal syndrome (HRS). The aim of this study was to evaluate if terlipressin also improves renal function in patients with ascites without HRS. Twenty-three patients with cirrhosis participated; 15 with nonrefractory ascites were randomized to either terlipressin (N group, n = 11) or a placebo (P group, n = 4), and 8 had refractory ascites and received terlipressin (R group). The glomerular filtration rate (GFR), sodium clearance (C(Na)), lithium clearance (C(Li)), osmolal clearance (C(Osm)), and urine sodium concentration (U(Na)) were assessed before and after the injection of 2 mg of terlipressin or the placebo. GFR increased in the N group (69 +/- 19 versus 92 +/- 25 mL/min, P < 0.005) and in the R group (31 +/- 19 versus 41 +/- 31 mL/min, P < 0.05) after terlipressin. In the N group, terlipressin induced an increase in C(Na) (0.89 +/- 0.21 versus 1.52 +/- 1.45 mL/min, P < 0.05), C(Li) (17.3 +/- 8.9 versus 21.5 +/- 11.6 mL/min, P < 0.05), and C(Osm) (2.10 +/- 0.81 versus 3.06 +/- 2.0 mL/min, P < 0.05). In the R group, terlipressin induced an increase in C(Na) (0.11 +/- 0.18 versus 0.35 +/- 0.40 mL/min, P < 0.05) and C(Li) (5.5 +/- 4.2 versus 9.5 +/- 8.55 mL/min, P < 0.05). U(Na) increased in both groups after terlipressin (P < 0.005). Plasma norepinephrine (P < 0.05) and renin (P < 0.05) decreased after terlipressin. All parameters remained unchanged after the placebo.

CONCLUSION

The vasopressin 1 receptor agonist terlipressin improves renal function and induces natriuresis in patients with cirrhosis and ascites without HRS. Vasoconstrictors may represent a novel future treatment modality for these patients.

Water and sodium retention in edematous disorders: role of vasopressin and aldosterone

This article discusses the pathophysiology of sodium and water retention in edematous disorders with a particular focus on cardiac failure, cirrhosis, and pregnancy. The body fluid volume hypothesis, which emphasizes the dominant role of arterial baroreceptors in renal sodium and water excretion, is reviewed. With arterial underfilling, either due to a decrease in cardiac output or peripheral arterial vasodilation, the normal central inhibition of the sympathetic nervous system activity and baroreceptor-mediated, nonosmotic arginine vasopressin (AVP) release is attenuated. The resultant increase in renal adrenergic activity stimulates the renin-angiotensin-aldosterone system. Although the resultant increase in systemic vascular resistance compensates for the primary arterial underfilling, this activation of the neurohumoral axis results in diminished sodium and water delivery to the renal collecting duct sites of aldosterone, AVP, and natriuretic peptide action. This diminished distal sodium and water delivery will be discussed as an important factor in the failure to escape from the sodium-retaining effects of aldosterone, the resistance to the natriuretic and diuretic effects of natriuretic peptides, and the diminished maximal solute-free water excretion in patients with edema. The role of the nonosmotic AVP release in water retention and hypo-osmolality/hyponatremia has been demonstrated in patients and experimental animals by administering nonpeptide, orally active vasopressin V2 receptor antagonists. These agents have been found to increase solute-free water excretion in patients with water-retaining, hyponatremic edema as well as in experimental animals.

The Oxyhemoglobin Dissociation Curve in Liver Cirrhosis

STUDY OBJECTIVES

To trace the entire oxyhemoglobin dissociation curve (ODC) in a cohort of cirrhotic patients in stable condition who were candidates for orthotopic liver transplantation (OLT).

DESIGN

Prospective cohort study.

SETTING

A large academic hospital.

PATIENTS AND METHODS

We traced the entire ODC in whole blood in standard conditions (pH 7.4; PCO2, 40 mm Hg; temperature, 37 degrees C) for 50 cirrhotic candidates for OLT (27 men and 23 women) and 50 age- and height-matched healthy subjects (27 men and 23 women). All subjects were nonsmokers or ex-smokers for at least 5 years. We also measured 2,3 diphosphoglycerate (2,3 DPG) in RBCs, plasma ions, and arterial blood gases in all subjects according to standard methods. Mixed venous blood was also obtained from the 50 cirrhotic patients.

RESULTS

Mean ODC was the same in the two groups. However, for the cirrhotic patients, the dispersion of the PO2 values of oxygen saturation percentage (SO2%) from 20 to 80% was significantly larger (p < 0.01 to p < 0.0001). In the cirrhotic patients, the mean PO2 for half-saturation of hemoglobin (P50) was 7.11 + 0.14 mEq/L chloride (p < 0.001) plus 0.36 mEq/L inorganic phosphate (p < 0.05) plus 0.25 micromol/gram of hemoglobin (gHb) 2,3 DPG (p < 0.00002) in absolute numerical values. Sodium, potassium, and calcium, three plasma ions disturbed in cirrhotic patients, did not contribute to determine the mean P50.

DISCUSSION

In patients with cirrhosis, increased dispersion of PO2 values for a given level of SO2% may be related to four factors: (1) an observed alteration of the enzymes controlling the phosphoglycerate shunt; (2) hypothyroidism, which may affect 7 to 20% of patients with primary biliary cirrhosis; (3) the type of ongoing treatment, eg, diuretics and/or propranolol; and (4) plasma ion disturbances.

CONCLUSIONS

We describe the ODC by three indexes: shape, position, and an index of dispersion of the PO2 values for a given level of SO2%. In addition, when the latter is increased, we suggest that other factors than pH, temperature, carbon dioxide, and inorganic phosphates are acting on the position of the ODC.

Management of cirrhotic ascites: physiological basis of diuretic action

Ascites is a significant complication of cirrhosis that occurs in approximately 50% of patients. The mortality rate is high in patients with cirrhosis and ascites. Conventional interventions rest with dietary sodium restriction, diuretic use, large-volume paracentesis, peritoneovenous shunts and transjugular intrahepatic portosystemic shunts. The mainstay of therapy, however, is the judicious use of diuretics. This article reviews the physiological basis of diuretic use in patients with cirrhosis and ascites, as well as recent concepts on the pathogenesis of ascites formation. Through a better understanding of the pathophysiology of ascites formation and the mechanism of action of diuretics, improved extracellular fluid balance can be achieved in these patients.

Effects of norepinephrine and acetylcholine on portal-systemic collaterals of common bile duct-ligated cirrhotic rat

BACKGROUND

Catecholamine exerts profound vascular effects on vascular smooth muscle, and serum norepinephrine (Nepi) and sympathetic nervous activity are increased in cirrhosis. The vascular response of Nepi and acetylcholine (Ach) in portal-systemic collaterals of cirrhotic rats is unknown. The purpose of the present study was to investigate the effects of Nepi and Ach on portal-systemic collaterals of common bile duct-ligated (BDL) cirrhotic rats.

METHODS

Perfusion studies were performed 6 weeks after BDL when hepatic cirrhosis was induced. Three series of experiments were performed in BDL rats: (i) the Nepi (10(-10) mol/L-10(-5) mol/L) vasoconstrictory responses with (n = 6) and without (n = 5) alpha1- (phentolamine, 5 x 10(-6) mol/L) or beta- (propranolol, 10(-5) mol/L) receptor antagonist (n = 6 and 5, respectively); (ii) the Ach (10(-8) mol/L-10(-5) mol/L) vasodilatory responses in Nepi- preconstricted portal-systemic collaterals in the absence (n = 7) or presence (n = 8) of N(pi)- L-nitro-arginine (NNA, 10(-4) mol/L); and (iii) the effect of indomethacin (10(-5) mol/L; n = 6) on Nepi responses. The collateral vascular responses were evaluated by the in situ collateral perfusion.

RESULTS

Norepinephrine significantly increased the perfusion pressure and was inhibited by phentolamine (P < 0.05). The constrictive responses of Nepi were not significantly modified in the presence of propranolol (P > 0.05). Acetylcholine produced >50% relaxation of the Nepi-preconstricted collateral vessels and was inhibited by NNA (P < 0.05). In addition, indomethacin significantly enhanced the constrictive response of Nepi (P < 0.05).

CONCLUSION

Norepinephrine has a vasoconstrictive effect on the portal-systemic collaterals of cirrhotic rats and this effect was mediated by alpha1-receptor. Both nitric oxide and prostaglandin are endogenous modulators in the collateral circulation of cirrhotic rats.

Le syndrome hépatorénal chez le patient cirrhotique

Hepatorenal syndrome is a particular form of functional renal failure which may develop in patients with liver cirrhosis. On a clinical standpoint, precise diagnostic criteria have been established to clearly define this entity, whereas recent advances in the understanding of the biology of vasoactive mediators and the physiology of microcirculation have allowed to better anticipate its pathophysiological mechanisms. During the course of cirrhosis, sinusoidal portal hypertension leads to splanchnic and systemic vasodilation, responsible for a reduction of effective arterial blood volume. As a result, a state of intense renal vasoconstriction develops, leading to renal failure in the absence of any organic renal disease. At this stage, liver transplantation is the only definitive therapy able to reverse renal dysfunction. In recent years, innovative therapies have shown promise to prolong survival in patients with hepatorenal syndrome, including the administration of analogs of vasopressin (mainly terlipressin), the insertion of transjugular intrahepatic portosystemic shunts and the use of novel techniques of dialysis. On a preventive viewpoint, several simple measures have been shown to reduce the risk of hepatorenal syndrome in cirrhotic patients, including the appropriate use of diuretics, the avoidance of nephrotoxic drugs, the prophylaxis of spontaneous bacterial peritonitis and optimal fluid management in patients undergoing large volume paracentesis.

Treatment of portal hypertension with NCX-1000, a liver-specific NO donor. A review of its current status

Portal hypertension, a life threatening complication of liver cirrhosis, results from increased intrahepatic resistance and increased portal blood inflow through a hyperdynamic splanchnic system. The increased intrahepatic vascular tone is the result of an enhanced activity of endogenous vasoconstrictors and a deficiency of nitric oxide (NO) release by sinusoidal endothelial cells. These pathophysiological events provide the rational basis for using NO-based therapies for the treatment of portal hypertension. Clinical studies have demonstrated that nitrate therapy results in a significant reduction of portal pressure as assessed by hepatic venous portal gradient but causes vasodilation in both systemic arterial and venous vascular beds, aggravating the progression of the vasodilatory syndrome of cirrhotic patients. For this reason, the ideal drug for the treatment of portal hypertension should act by decreasing intrahepatic vascular resistance, without worsening the splanchnic/systemic vasodilatation. NCX-1000 is the prototype of a family of NO-releasing derivatives of ursodeoxycholic acid (UDCA). These compounds are releasing selectively, from parenchymal and non-parenchymal hepatic cells, biologically active NO into the liver microcirculation with no detectable effect on systemic circulation. Preclinical studies have shown that long- and short-term administration of NCX-1000 to rodents with chronic liver injury protects against the development of portal hypertension and reduces the intrahepatic hyperreactivity to alpha1-adrenoceptor agonists. The finding of increased liver nitrite/nitrate content in NCX-1000-treated animals together with an increase in cGMP levels in their liver homogenates suggests that this nitro-compound behaves as a liver-selective NO donor. In contrast to conventional NO-donors such as isosorbide mono- and di-nitrate, which are also used for primary and secondary prevention of gastrointestinal bleeding, NCX-1000 has no effect on mean arterial pressure in either normal or cirrhotic animals indicating the absence of adverse systemic effect. In summary, these data suggest that NCX-1000 may provide a novel therapy for the treatment of patients with portal hypertension.

[Sympathetic overactivity and the kidney]

Hypertension is present in the majority of patients with chronic renal failure and constitutes a major risk factor for the very high cardiovascular morbidity and mortality in this patient population. Furthermore hypertension is known to be a substantial progression factor in renal disease. In the past, it had been presumed that hypertension in chronic renal failure is due to enhanced sodium retention, chronic hypervolemia and increased activity of the renin-angiotensin-aldosterone-system. Recent studies now provide evidence that sympathetic overactivity plays an additional important role and also promotes progression of renal failure. The treatment goal in renal patients is to delay or even prevent progression of renal failure and to reduce the cardiovascular risk. Recent studies have investigated the respective impact of sympatholytic drugs, e.g. inhibitors of the renin-angiotensin-aldosterone-system, beta-blockers or I1-Imidazolin-receptor-agonists in fulfilling these aims. The present report will review experimental and clinical studies on the role of sympathetic overactivity in hypertension and chronic renal failure and possible new therapeutic options.

Autonomic nervous dysfunction in patients with liver cirrhosis using 123I-metaiodobenzylguanidine myocardial scintigraphy and spectrum analysis of heart-rate variability

BACKGROUND

It has been reported that nitric oxide (NO) synthase is induced in patients with liver cirrhosis (LC), and that an excessive production of NO enhances sympathetic nervous function. The present report describes a study of the feasibility of evaluation of abnormalities of autonomic nervous function by 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy and heart-rate variability in patients with LC.

METHODS

Low-frequency (LF) power, high-frequency (HF) power, LF/HF, and 1/f fluctuations of heart rate variability were examined in 50 patients with LC (LC group), and 50 normal subjects (N group). Echocardiogram, urinary nitrite and nitrate, and cathecholamines were examined.

RESULTS

Fractional shortening was observed for the hyperdynamic state of patients in the LC group according to Child's A-C classification. Washout rate of MIBG, LF/HF, and blood levels of norepinephrine increased and HF power decreased with the progression of LC. However, the urinary secretion of nitrite and nitrate were significantly increased only in cirrhotic patients with Child C.

CONCLUSIONS

The present results indicate that autonomic abnormalities appear early in LC, and that these abnormalities can be detected by MIBG myocardial scintigraphy and analysis of heart-rate variability. We consider these methods to be clinically useful for the quantitative detection of hyperdynamic circulation of liver cirrhosis.

Review article: volume expansion in patients with cirrhosis

Adequate size and distribution of the circulating medium are important for cardiovascular function, tissue oxygenation, and fluid homoeostasis. Patients with cirrhosis have cardiovascular dysfunction with a hyperkinetic systemic circulation, abnormal distribution of the blood volume, vasodilation with low systemic vascular resistance, increased whole-body vascular compliance, and increased arterial compliance. The effectiveness and temporal relations of plasma/blood volume expansion depend highly on the type of load (water, saline, oncotic material, red blood cells). Patients with cirrhosis respond in some aspects differently from healthy subjects, owing to their disturbed circulatory function and neurohormonal activation. Thus the increase in cardiac output and suppression of the renin-angiotensin-aldosterone system and sympathetic nervous system during volume expansion may be somewhat blunted, and in advanced cirrhosis, especially the non-central parts of the circulation, including the splanchnic blood volume, are expanded by a volume load. Infusion of oncotic material (preferably albumin) is important in the prevention of post-paracentesis circulatory dysfunction. In conclusion, volume expansion in advanced cirrhosis is qualitatively and quantitatively different from that of healthy subjects, and in those with early cirrhosis. Timely handling is essential, but difficult as it is a balance between the risks of excess extravascular volume loading and further circulatory dysfunction in these patients with a hyperdynamic, but hyporeactive, circulation.

An alternative method to enhance vagal activities and suppress sympathetic activities in humans

Vagal withdrawal and/or sympathetic overactivity is always accompanied by various kinds of stress and is dangerous to the body. We proposed that mild acupuncture on the Sishencong points may effectively enhance vagal activities but suppress sympathetic regulations of the heart in humans. Experiments were carried out on nine healthy male volunteers, while they were lying in a quiet room during 2-4 P.M. Acupuncture was applied 2 mm deep into the skin using standard stainless acupuncture needles at the Sishencong points, which are located on the vertex of the head, each 1 cm away from Baihui (GV 20) in four directions. Four points around the temporal area were selected as control points. Forty minutes of precordial ECG signals before, during, and after acupuncture were recorded continuously. Frequency-domain analysis of the stationary RR intervals was performed to evaluate the total variance, high-frequency power (HF, 0.15-0.40 Hz) and low-frequency power (LF, 0.04-0.15 Hz) in normalized units (LF%). Acupuncture on the Sishencong points resulted in an increased HF but a decreased LF% compared with the before acupuncture stage. Such effects did not occur when manual acupuncture was applied to the control points. The differences in the heart rate dynamics between Sishencong and the control groups took place 10 min after initiation of acupuncture and persisted even after the removal of the needles. Based on these results, we concluded that manual acupuncture on the Sishencong points enhanced cardiac vagal and suppressed sympathetic activities in humans. The underlying mechanisms and potential applications warrant further investigations.

Update on ascites and hepatorenal syndrome

Ascites is the most common complication occurring during liver cirrhosis. Even if a significant decrease in renal clearance may be observed in the first step of chronic active liver disease, renal impairment, at times complicated by the typical signs of hepatorenal syndrome, occurs only in patients with ascites, especially when tense and refractory. Experimental and clinical data seem to suggest a primary sodium and water retention in the pathogenesis of ascites, in the presence of an intrahepatic increase of hydrostatic pressure, which, by itself, physiologically occurs during digestion. Abnormal sodium and water handling leads to plasma volume expansion, followed by decreased peripheral vascular resistance and increased cardiac output. This second step is in agreement with the peripheral arterial vasodilation hypothesis, depicted by an increase in total blood volume, but with a decreased effective arterial blood volume. This discrepancy leads to the activation of the sympathetic nervous and renin-angiotensin-aldosterone systems associated with the progressive activation of the renal autacoid systems, especially, that of the arachidonic acid. During advanced cirrhosis, renal impairment becomes more sustained and renal autacoid vasodilating substances are less available, possibly due to a progressive exhaustion of these systems. At the same time ascites becomes refractory inasmuch as it is no longer responsive to diuretic treatment. Various pathogenetic mechanisms leading to refractory ascites are mentioned. Finally, several treatment approaches to overcome the reduced effectiveness of diuretic therapy are cited. Paracentesis, together with simultaneous administration of human albumin or other plasma expanders is the main common approach to treat refractory ascites and to avoid a further decrease in renal failure. Other effective tools are: administration of terlipressin together with albumin, implantation of the Le Veen shunt, surgical porto-systemic shunting or transjugular intrahepatic portosystemic stent-shunt, or orthotopic liver transplantation, according to the conditions of the individual patient.

Rat renal function four days after bile-duct ligation: effects of indomethacin and vasoactive agents

The purpose of this study was to assess the effects of the cyclooxygenase inhibitor, indomethacin, and some vasoactive agents on the renal functional parameters during the early liver injury induced by four days bile duct ligation (BDL). Wistar rats with four days-BDL and control-sham operated were used. Renal function was measured in anesthetized rat treated with a single dose of indomethacin (control, 0.3, 1.0, 3.0 mg/kg b.w.; i.v.) one hour before clearance studies. Sulindac effects were also evaluated (5 mg/kg b.w., i.p). Isolated rat kidney preparations from control and BDL donor rats were used to study renal vascular response to noradrenaline, carbachol or sodium nitroprusside. The bile duct ligation promoted a diminished renal cortical plasma flow (RCPF) on the fourth day post surgery accompanied with a diminution in the glomerular filtration rate (GFR), increased filtration fraction and increased fractional excretion of water and sodium. Indomethacin 0.3 mg/kg induced an increase in GFR and RCPF, maintaining the high filtration fraction in BDL rats. The other doses did not alter these parameters as compared with bile duct ligated rats without treatment, but indomethacin 3 mg/kg caused a significant increase in filtration fraction. Indomethacin induced dose-dependent diminution in natriuresis in sham and BDL groups. Sulindac did not modify hemodynamic parameters, but induced antinatriuresis and antidiuresis in both experimental groups. Maximal vascular responses to noradrenaline measured in isolated rat kidneys were statistically diminished in BDL-rats as compared with controls (C, n=7; 35.0+/-2.3 mmHg ml(-1) min; BDL-rats, n=5; 23.8+/-0.7 mmHg ml(-1) min; p<0.02), without changes in EC15. Maximal relaxation induced by sodium nitroprusside in the phenylephrine (PHE)-pre-constricted renal vasculature in control preparations did not differ from that observed in BDL group (C: n=6; 49.5+/-2.3%). Values of EC50 were 1.26+/-0.07 microM (n=6) in control preparations and 0.34+/-0.03 microM (n=4) in kidneys from BDL-rats (p<0.001). Carbachol induced a biphasic relaxation of PHE-pre-constricted renal vasculature. No differences in maximal responses were found. EC50 value of the second phase in BDL group was significantly decreased compared to control preparations (C: n=6, 0.47+/-0.05 microM; BDL: n=6, 0.22+/-0.03 microM p<0.001). The present results show that the altered renal function after a short time post bile duct ligation is determined, at least in part, by increased release of arachidonic derivatives in vascular bed and tubular cells. At this stage of liver injury, the alteration in the renal vascular response to different vasoactive agents is remarkable.

Review article: spontaneous bacterial peritonitis--diagnosis, treatment and prevention

Spontaneous bacterial peritonitis is a serious complication of cirrhotic ascites, arising most frequently in those with advanced liver disease. Its development leads to a further reduction in the effective arterial blood volume, and it has a mortality rate equivalent to that of a variceal bleed. However, problems remain with regard to the identification and optimal treatment of spontaneous bacterial peritonitis. Several important studies and consensus documents on the condition have recently been published which aid in the identification of patients at risk and help to guide therapy. In this review, we discuss these publications and address the issues of diagnosis, treatment and both primary and secondary prophylaxis of spontaneous bacterial peritonitis in the light of recent data.

Nitric oxide and the liver

In recent years, the role of nitric oxide (NO) in the pathogenesis of liver disease and its complications has been extensively studied. There remain, however, many areas of controversy. In particular, the effect of NO on vascular function in the systemic circulation and the hepatic microcirculation has received the greatest attention. It has been proposed on the one hand that increased NO synthesis is responsible for the development of the hyperdynamic circulation in cirrhosis, while decreased production of NO within the hepatic microcirculation may be important in the development of parenchymal tissue damage and the onset of portal hypertension. The purpose of this review is to examine the available data concerning the role of NO in liver disease and to discuss some of the controversies and contradictions that surround it.

Close association of urinary excretion of aquaporin-2 with appropriate and inappropriate arginine vasopressin-dependent antidiuresis in hyponatremia in elderly subjects

The present study was undertaken to determine whether urinary excretion of aquaporin-2 (AQP-2) participates in the involvement of arginine vasopressin (AVP) in hyponatremia less than 130 mmol/L in 33 elderly subjects (> or =65 yr old) during the last 5-yr period. Subjects were separated into euvolemic hyponatremia groups: 13 with hypopituitarism, 8 with syndrome of inappropriate secretion of antidiuretic hormone (SIADH), 8 with mineralocorticoid-responsive hyponatremia of the elderly, and 4 with miscellaneous diseases. Approximately 40% of those with hyponatremia was derived from hypopituitarism, but severe hyponatremia was found in the patients with SIADH and mineralocorticoid-responsive hyponatremia of the elderly. Plasma AVP levels remained relatively high despite hypoosmolality and were tightly linked with exaggerated urinary excretion of AQP-2 and antidiuresis in the 3 groups of patients, except for one miscellaneous one. An acute water load test verified the impairment in water excretion, because the percent excretion of the water load was less than 42% and the minimal urinary osmolality was not sufficiently diluted. Also, plasma AVP and urinary excretion of AQP-2 were not reduced after the water load. The inappropriate secretion of AVP was evident in the patients with SIADH and hypopituitarism, and hydrocortisone replacement normalized urinary excretion of AQP-2 and renal water excretion in those with hypopituitarism. In contrast, the appropriate antidiuresis seemed to compensate loss of body fluid in the patients with mineralocorticoid-responsive hyponatremia of the elderly, who lost circulatory blood volume by 7.3% (mean). Fludrocortisone acetate increased renal sodium handling and body fluid, resulting in the reduction in AVP release and urinary excretion of AQP-2 in mineralocorticoid-responsive hyponatremia of the elderly. These findings indicate that urinary excretion of AQP-2 may be a more sensitive measure of AVP effect on renal collecting duct cells than are plasma AVP levels, and that increased urinary excretion of AQP-2 shows exaggerated AVP-induced antidiuresis in hyponatremic subjects in the elderly. In addition, mineralocorticoid-responsive hyponatremia of the elderly has to be carefully differentiated from SIADH in elderly subjects.

Hyperdynamic circulation in portal hypertension: a comparative model of arterio-venous fistula

Complications of portal hypertension remain perplexing physiologic phenomena in the understanding of shunt hemodynamics with multiple theories. Hyperdynamic circulation was also found in sepsis, chronic anemia and arterio-venous (A-V) fistula which relate to an increase in nitric oxide. We hypothesize that portosystemic collaterals may mimic an A-V fistula in which the high-pressure portal blood connects with the lower pressure systemic venous circulation. Although these collaterals decompress the portal circulation, a number of secondary hemodynamic phenomena occur which increase portal blood flow and tend to counteract the portal hypotensive effect of the portosystemic shunt. The consequent increases in cardiac output and portal blood flow perfuse the compromised liver. As portal blood flow increases, collateral flow increases and is nearly totally shunted in the systemic circulation. This shunt may eventually introduce a vicious cycle of hyperdynamic circulation into a compromised host. Ultimately, high-output cardiac failure occurs, leading to cirrhotic cardiomyopathy.

Water and electrolyte metabolism of the micropremie

There are five problem schemas presented in this article that indicate potential contradictions in therapeutic goals: (1) shock and edema presenting upon premature birth; (2) the hyperosmolar state, problematic in patients less than 750 g birth weight; (3) the respiratory distress syndrome and respiratory failure, often complicated by patent ductus arteriosus; (4) bronchopulmonary dysplasia, resulting from prematurity and mechanical ventilation; and (5) late onset of hyponatremia, sometimes accompanied by growth failure in the recovering premature. These five problems considered together comprise a developmental continuum of illness and recovery, where appropriate fluid management has recently been demonstrated to benefit outcomes greatly. Clinicians over the past decade have encountered all of the fluid and electrolyte nightmares. Although there are many different formulations for treating each of these scenarios, recommending one approach for all patients is likely to be incorrect much of the time.

Role of angiotensin II in regulation of basal and sympathetically stimulated vascular tone in early and advanced cirrhosis

BACKGROUND & AIMS

The renin-angiotensin and sympathetic nervous systems are activated in cirrhosis. This study aimed to establish the role of angiotensin II (ANG II) in the regulation of basal and sympathetically stimulated vascular tone in preascitic cirrhotic patients and patients with diuretic-refractory ascites compared with age- and sex-matched healthy controls.

METHODS

Forearm blood flow (FBF) responses to lower body negative pressure (LBNP) and to subsystemic, intrabrachial infusions of losartan, an angiotensin II type 1 (AT(1)) receptor antagonist, norepinephrine, and ANG II were measured using venous occlusion plethysmography.

RESULTS

In all groups, ANG II and norepinephrine caused dose-dependent reductions in FBF (P < 0.001); responses to norepinephrine were similar across the 3 groups but those to ANG II were less in both cirrhotic groups than in controls (P < 0.01). Losartan caused a dose-dependent increase in FBF only in patients with refractory ascites (P < 0.01). LBNP caused less reduction in FBF in refractory ascites patients than in both preascitic patients and controls (P < 0.01).

CONCLUSIONS

Despite hyporesponsiveness to exogenous ANG II in both early and advanced cirrhosis, endogenous ANG II contributes to the maintenance of basal vascular tone only in advanced cirrhosis. These findings suggest a role of ANG II in the pathogenesis of ascites. Attenuated LBNP responses occurred only in advanced cirrhosis, without apparent interaction with endogenous ANG II.