Interrelationship between cardiac output and vascular resistance as determinants of effective arterial blood volume in cirrhotic patients

Hyponatremia in the Context of Liver Disease

Hyponatremia is common in patients with liver disease and is associated with increased mortality, morbidity, and a reduced quality of life. In liver transplantation, the inclusion of hyponatremia in organ allocation scores has reduced waitlist mortality. Portal hypertension and the resulting lowering of the effective arterial blood volume are important pathogenetic factors, but in most patients with liver disease, hyponatremia is multifactorial. Treatment requires a multifaceted approach that tries to reduce electrolyte-free water intake, restore urinary dilution, and increase nonelectrolyte solute excretion. Albumin therapy for hyponatremia is a peculiarity of advanced liver disease. Its use appears to be increasing, while the vaptans are currently only given in selected cases. Osmotic demyelination is a special concern in patients with liver disease. Serial checks of serum sodium concentrations and urine volume monitoring are mandatory.

Management of renal failure in end-stage liver disease: A critical appraisal

Renal failure is a late consequence of end-stage liver disease (ESLD). Even with liver transplantation, pretransplant renal impairment remains a strong predictor of posttransplant mortality. This review seeks to summarize and critically appraise common therapies used in this setting, including pharmacologic agents, procedures (transjugular intrahepatic portosystemic shunt, renal replacement therapy), and simultaneous liver-kidney transplantation. More experimental extracorporal modalities, eg, albumin dialysis or bioartificial livers, will not be discussed. A brief discussion on the definition and pathophysiologic underpinnings of renal failure in ESLD will be held at the beginning to lay the groundwork for the main section. Liver Transplantation 22 1710-1719 2016 AASLD.

Role of albumin in diseases associated with severe systemic inflammation: Pathophysiologic and clinical evidence in sepsis and in decompensated cirrhosis

The metabolism of albumin in inflammatory states such as sepsis or major surgery is complex and still not well characterized. Nevertheless, in inflammatory states, albumin synthesis has been observed to increase. By contrast, in decompensated cirrhosis, a disease characterized by systemic inflammation, albumin synthesis by the liver may decrease to 30% to 50% of normal values. Furthermore, in these conditions, there are high capillary leakage and altered albumin kinetics. The discussion regarding the effect of exogenous albumin administration on intravascular volume in inflammatory states should therefore address albumin turnover. To add complexity to our understanding of the effects of albumin, there are many data indicating that the therapeutic action of albumin is mediated not only through the impact on plasma volume expansion but also through a modulatory effect on inflammation and oxidative stress. All these characteristics are relevant to diseases associated with systemic inflammation including sepsis and decompensated cirrhosis.

Human serum albumin, systemic inflammation, and cirrhosis

Human serum albumin (HSA) is one of the most frequent treatments in patients with decompensated cirrhosis. Prevention of paracentesis-induced circulatory dysfunction, prevention of type-1 HRS associated with bacterial infections, and treatment of type-1 hepatorenal syndrome are the main indications. In these indications treatment with HSA is associated with improvement in survival. Albumin is a stable and very flexible molecule with a heart shape, 585 residues, and three domains of similar size, each one containing two sub-domains. Many of the physiological functions of HSA rely on its ability to bind an extremely wide range of endogenous and exogenous ligands, to increase their solubility in plasma, to transport them to specific tissues and organs, or to dispose of them when they are toxic. The chemical structure of albumin can be altered by some specific processes (oxidation, glycation) leading to rapid clearance and catabolism. An outstanding feature of HSA is its capacity to bind lipopolysaccharide and other bacterial products (lipoteichoic acid and peptidoglycan), reactive oxygen species, nitric oxide and other nitrogen reactive species, and prostaglandins. Binding to NO and prostaglandins are reversible, so they can be transferred to other molecules at different sites from their synthesis. Through these functions, HSA modulates the inflammatory reaction. Decompensated cirrhosis is a disease associated systemic inflammation, which plays an important role in the pathogenesis of organ or system dysfunction/failure. Although, the beneficial effects of HAS have been traditionally attributed to plasma volume expansion, they could also relate to its effects modulating systemic and organ inflammation.

Effects of a 7-day treatment with midodrine in non-azotemic cirrhotic patients with and without ascites

BACKGROUND/AIMS

Splanchnic arterial vasodilatation has been causally related with hyperdynamic circulation and impaired natriuresis in advanced cirrhosis and has also been suggested to be responsible for the subtle sodium retention in pre-ascitic cirrhosis. This study evaluated the effects of a 7-day treatment with the alpha1-adrenergic agonist midodrine in non-azotemic cirrhotic patients with and without ascites.

METHODS

Thirty-nine cirrhotic patients were studied at baseline and 7 days after administration of oral midodrine 10mg, t.i.d. (11 without and 12 with ascites) or placebo (8 without and 8 with ascites).

RESULTS

A significant increase in urine sodium excretion was noted after midodrine administration in patients without and with ascites, in line with significant increases in mean arterial pressure and systemic vascular resistance, and significant decreases in cardiac output and heart rate. Significant increases in glomerular filtration rate, filtration fraction, and urine volume and significant decreases in plasma renin activity and aldosterone were observed in patients with ascites. Placebo had no effect in any study group.

CONCLUSIONS

The administration of midodrine for 7 days improves systemic haemodynamics and sodium excretion in non-azotemic cirrhotic patients without or with ascites. In patients with ascites, but not in those without ascites, these effects are associated with a suppression of the activity of the renin-angiotensin-aldosterone system, suggesting that the increase in natriuresis is related to the improvement in the effective arterial blood volume.

The hyperdynamic circulation of chronic liver diseases: from the patient to the molecule

The hyperdynamic circulatory syndrome observed in chronic liver diseases is a great example of research that originated from clinical observations and progressed in the last 50 years from the patient to the experimental laboratory. Our knowledge has evolved from the patient to the molecule, using experimental models that serve as a source for understanding the complex pathophysiological mechanisms that govern this complex syndrome. We now know that progressive vasodilatation is central to the detrimental effects observed in multiple organs. Although nitric oxide has been shown to be the primary vasodilator molecule in these effects, other molecules also participate in the complex mechanisms of vasodilatation. This review summarizes three major areas: first, clinical observation in patients; second, experimental models used to study the hyperdynamic circulatory syndrome; and third, the vasodilator molecules that play roles in vascular abnormalities observed in portal hypertension.

Loss of tubuloglomerular feedback in decompensated liver cirrhosis: physiopathological implications

In healthy subjects, arterial pressure reduction or renal ischemia produces renal artery dilatation through autoregulation and tubuloglomerular feedback (TuGF). Patients with decompensated cirrhosis have reduced kidney perfusion pressure but show renal vasoconstriction instead of autoregulation-mediated vasodilation. This study investigates the consequences of kidney autoregulation loss on renal perfusion, glomerular filtration rate, and tubular handling of electrolytes in both compensated and ascitic nonazotemic cirrhotic patients. Forty-two consecutive patients with diuretic-free liver cirrhosis (32 with preascitic and 10 with ascitic disease) and 10 controls were submitted to the following determinations: (a) basal plasma renin activity and aldosterone levels; (b) endogenous dopaminergic activity measured as incremental aldosterone responses during metoclopramide administration; and (c) renal clearances of sodium, potassium, inulin, para-aminohippurate and lithium. Compared with the other groups, ascitic patients showed lower renal plasma flow (P < 0.01) and lithium clearance (P < 0.05), a higher filtration fraction (P < 0.01), and secondary aldosteronism. Controls and preascitic patients displayed tubuloglomerular feedback (the mechanism increasing the glomerular filtration rate when a reduced sodium load reaches the distal tubule), as demonstrated by negative correlations between fractional excretion of lithium (an expression of fractional delivery of sodium to the distal nephron) and glomerular filtration rate (respectively, r = -0.73, P < 0.03, and r = -0.48, P < 0.01). Conversely, patients with ascites showed a positive correlation between lithium fractional excretion and glomerular filtration rate (r = 0.64, P < 0.05). Reduction in renal perfusion, increased filtration fraction, and TuGF derangement, as found in decompensated patients, are indicative of prevalent postglomerular arteriolar vasoconstriction, with ensuing stimulation of proximal tubular sodium reabsorption.

Circulating endogenous cannabinoid anandamide and portal, systemic and renal hemodynamics in cirrhosis

BACKGROUND

Endocannabinoids may participate in the homeostasis of arterial pressure. Recently, anandamide, the most extensively studied endocannabinoid, has been proposed as a key mediator in the peripheral arterial vasodilation of cirrhosis.

OBJECTIVES

To determine if circulating levels of anandamide are related to the extent of the peripheral arterial vasodilation, the severity of portal hypertension and the degree of liver and renal dysfunction of patients with cirrhosis.

METHODS

Plasma levels of anandamide and several systemic, portal and renal hemodynamic parameters were determined in 18 patients with cirrhosis and eight healthy subjects (control group).

RESULTS

Plasma levels of anandamide were elevated in patients compared to the control group (P<0.05), nevertheless, no differences between patients with ascites and well-compensated patients were found. There was no correlation between anandamide concentration and arterial pressure, cardiac output and systemic vascular resistance, Child-Pugh's score, portal pressure, renal vascular resistance, plasma renin activity or plasma aldosterone concentration.

CONCLUSIONS

Circulating levels of anandamide are increased in cirrhotic patients. However, this elevation was unrelated to the extent of arterial vasodilation, the severity of portal hypertension or the degree of hepatic and renal dysfunction. Although a local hormonal action cannot be excluded, our results do not support a relevant contribution of this system in the hemodynamic disturbance of cirrhosis.

Chronic nitric oxide synthase inhibition exacerbates renal dysfunction in cirrhotic rats

The present study investigated sodium balance and renal tubular function in cirrhotic rats with chronic blockade of the nitric oxide (NO) system. Rats were treated with the nonselective NO synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME) starting on the day of common bile duct ligation (CBL). Three weeks of daily sodium balance studies showed that CBL rats developed sodium retention compared with sham-operated rats and that l-NAME treatment dose dependently deteriorated cumulative sodium balance by reducing urinary sodium excretion. Five weeks after CBL, renal clearance studies were performed, followed by Western blotting of the electroneutral type 3 sodium/proton exchanger (NHE3) and the Na-K-ATPase present in proximal tubules. Untreated CBL rats showed a decreased proximal reabsorption with a concomitant reduction of NHE3 and Na-K-ATPase levels, indicating that tubular segments distal to the proximal tubules were responsible for the increased sodium reabsorption. l-NAME-treated CBL rats showed an increased proximal reabsorption measured by the lithium clearance method and showed a marked increase in NHE3 and Na-K-ATPase protein levels. Our results show that chronic l-NAME treatment exacerbates the sodium retention found in CBL rats by a significant increase in proximal tubular reabsorption.

Use of albumin in the management of patients with decompensated cirrhosis. An independent verdict

The use of intravenous albumin in cirrhosis has been reactivated during the last two decades. During this period several investigations have shown that albumin (1) prevents circulatory dysfunction in patients with massive ascites treated by paracentesis, (2) prevents circulatory dysfunction and type-1 HRS and increases survival in patients with SBP, and (3) in association with vasoconstrictors normalizes circulatory function and serum creatinine and increases survival in patients with type-1 HRS. Indications 2 and 3 are clear. There is discussion, however, regarding indication number 1. Although no significant differences in survival have been observed in trials comparing patients treated by paracentesis with and without albumin, in none of these studies was survival an end-point of the trial. In contrast, there is evidence that paracentesis-induced circulatory dysfunction is associated with a bad outcome. In consequence, although further studies on this indication are clearly required, with the current data it is advisable to use albumin as a plasma expander in patients with massive ascites treated by paracentesis.

Central and noncentral blood volumes in cirrhosis: relationship to anthropometrics and gender

The size of the central and arterial blood volume (CBV) is essential in the understanding of fluid retention in cirrhosis. Previously, it has been reported decreased, normal, or increased, but no reports have analyzed CBV with respect to gender and lean body mass. The aim of the present study was by means of an optimized technique to reassess it in a large group of patients with cirrhosis compared with healthy controls and matched controls in relationship to their body dimensions and gender. Eighty-three patients with cirrhosis (male/female, 60:23), 67 patients without liver disease (male/female, 22:45), and 14 young healthy controls (male/female, 6:8) underwent a hemodynamic investigation with determination of cardiac output, central circulation time, and CBV determined according to kinetic principles. Related to gender, CBV was lower in male cirrhotics (1.48 +/- 0.30 liter) than in matched and young controls (1.68 +/- 0.33 and 1.72 +/- 0.33 liter, respectively; P < 0.05-0.01). No significant differences in CBV were seen between female cirrhotics and controls. Absolute and adjusted CBVs were lower in the females than in men with cirrhosis (P < 0.001), and men with cirrhosis had lower absolute and body weight-adjusted CBVs than matched controls (P < 0.01). Normalized values of CBV (%total blood volume) were significantly lower in patients with cirrhosis (25 +/- 4%) than in matched controls (31 +/- 7%) and young controls (28 +/- 4%; P < 0.02). CBV correlated significantly with anthropometrics, including lean body mass (r = 0.68-0.82; P < 0.0001). In conclusion, the CBV of patients with cirrhosis was lower than that of controls when adjusted for body dimensions and gender. There are significant gender differences, and signs of underfilling are more pronounced in male than in female patients. The results emphasize the importance of adjustments of blood volumes for anthropometrics and gender.

Cirrhosis serum induces a nitric oxide-associated vascular hyporeactivity of aortic segments from healthy rats in vitro

OBJECTIVE

Arterial vasodilation with concomitant hyperdynamic circulation are common findings in liver cirrhosis. Nitric oxide acting at a local level has been suggested to be pathophysiologically relevant in this context. Several systemic factors in conjunction with nitric oxide might interfere with the observed phenomena.

DESIGN

The study has been designed to demonstrate the influence of cirrhotic serum on the nitric oxide system and vascular contractility.

METHODS

The contractile response of aortic segments from healthy rats was studied in vitro after incubation with serum of healthy and cirrhosis-induced rats (1 week, 2 weeks, 3 weeks and 4 weeks after bile duct ligation). A cumulative dose response curve to phenylephrine (10--10-4 mol) was established before and after incubation with nitric oxide synthesis blocker N(omega)-nitro-L-arginine, the more selective aminoguanidine (nitric oxide synthase [NOS]-2 inhibitor) and W7 (NOS-3 inhibitor). NOS-2 expression in incubated aortic rings was evaluated by Western blot analysis.

RESULTS

A 4-hour incubation with serum of cirrhosis-induced rats reduced the maximum contractile response to phenylephrine to 66.8 +/- 9.1% after 1 week, 50.4 +/- 7.8% after 2 weeks, 43.2 +/- 2.8% after 3 weeks and 35 +/- 5.2% after 4 weeks of bile duct ligation. This reduction in the contractility response to phenylephrine was completely reversed by blocking nitric oxide synthesis with N(omega)-nitro-L-arginine and aminoguanidine, but not after W7. Incubation with cirrhotic serum induced NOS-2 expression in aortic rings. In Western blot analysis, the most intensive signal for NOS-2 protein was obtained in rings incubated with serum from rats 3 weeks and 4 weeks after induction of cirrhosis.

CONCLUSIONS

Cirrhotic serum decreases the contractile response to phenylephrine even in an early stage of secondary cirrhosis. Reversibility of this effect after nitric oxide synthesis blockade suggests an induction of nitric oxide synthesis by systemic factors as a major point in vascular hyporeactivity to vasoconstrictors in cirrhosis.

Neuronal nitric oxide synthase and systemic vasodilation in rats with cirrhosis

Cirrhosis is typically associated with a hyperdynamic circulation consisting of low blood pressure, low systemic vascular resistance (SVR), and high cardiac output. We have recently reported that nonspecific inhibition of nitric oxide synthase (NOS) with nitro-L-arginine methyl ester reverses the hyperdynamic circulation in rats with advanced liver cirrhosis induced by carbon tetrachloride (CCl(4)). Although an important role for endothelial NOS (eNOS) is documented in cirrhosis, the role of neuronal NOS (nNOS) has not been investigated. The present study was carried out to specifically investigate the role of nNOS during liver cirrhosis. Specifically, physiological, biochemical, and molecular approaches were employed to evaluate the contribution of nNOS to the cirrhosis-related hyperdynamic circulation in CCl(4)-induced cirrhotic rats with ascites. Cirrhotic animals had a significant increase in water and sodium retention. In the aorta from cirrhotic animals, both nNOS protein expression and cGMP concentration were significantly elevated compared with control. Treatment of cirrhotic rats for 7 days with the specific nNOS inhibitor 7-nitroindazole (7-NI) normalized the low SVR and mean arterial pressure, elevated cardiac index, and reversed the positive sodium balance. Increased plasma arginine vasopressin concentrations in the cirrhotic animals were also repressed with 7-NI in association with diminished water retention. The circulatory changes were associated with a reduction in aortic nNOS expression and cGMP. However, 7-NI treatment did not restore renal function in cirrhotic rats (creatinine clearance: 0.76 +/- 0.03 ml. min(-1). 100 g body wt(-1) in cirrhotic rats vs. 0.79 +/- 0.05 ml. min(-1). 100 g body wt(-1) in cirrhotic rats+7-NI; P NS. ). Taken together, these results indicate that nNOS-derived NO contributes to the development of the hyperdynamic circulation and fluid retention in cirrhosis.

Complications of cirrhosis. II. Renal and circulatory dysfunction. Lights and shadows in an important clinical problem

The pathophysiology of circulatory and renal dysfunction in cirrhosis and the treatment of ascites and related conditions (hepatorenal syndrome and spontaneous bacterial peritonitis) have been research topics of major interest during the last two decades. However, many aspects of these problem remain unclear and will constitute major areas of investigation in the next millennium. The pathogenesis of sodium retention, the most prevalent renal function abnormality of cirrhosis, is only partially known. In approximately one third of patients with ascites, sodium retention occurs despite normal activity of the renin-aldosterone and sympathetic nervous systems and increased circulating plasma levels of natriuretic peptides and activity of the so-called natriuretic hormone. These patients present an impairment in circulatory function which, although less intense, is similar to that of patients with increased activity of the renin-aldosterone and sympathetic nervous systems, suggesting that antinatriuretic factors more sensitive to changes in circulatory function that these systems may be important in the pathogenesis of sodium retention in cirrhosis. The development of drugs that inhibit the tubular effect of antidiuretic hormone and increase renal water excretion without affecting urine solute excretion has opened a field of great interest for the management of water retention and dilutional hyponatremia in cirrhosis. Two families of drugs, the V2 vasopressin receptor antagonists and the kappa-opioid agonists, have been shown to improve free water clearance and correct dilutional hyponatremia in human and experimental cirrhosis with ascites. The first type of drugs blocks the tubular effect of antidiuretic hormone and the second inhibits antidiuretic hormone secretion by the neurohypophysis. On the other hand, two new treatments have also been proved to reverse hepatorenal syndrome in cirrhosis. The most interesting one is that based on the simultaneous administration of plasma volume expansion and vasoconstrictors. The second is transjugular intrahepatic porto-systemic shunt. The long-term administration (1-3 weeks) of analogs of vasopressin (ornipressin or terlipressin) or other vasoconstrictors together with plasma volume expansion with albumin is associated with a dramatic improvement in circulatory function and normalization of serum creatinine concentration in patients with severe hepatorenal syndrome. Of interest is the observation that in many of these patients, hepatorenal syndrome does not recur following discontinuation of the treatment, thus raising important questions about the mechanism by which hepatorenal syndrome follows a progressive course in most untreated cases. The pathogenesis of circulatory dysfunction in cirrhosis and the role of local mechanisms in the development of the splanchnic arteriolar vasodilation associated with portal hypertension will continue as important topics in clinical and basic research in Hepatology. Of special interest is the study of the mechanism by which circulatory function further deteriorates following complications such as severe bacterial infection or therapeutic interventions such as therapeutic paracentesis, and the adverse consequences of the impairment in circulatory function on renal and hepatic hemodynamics. Finally, although major advances have been made concerning the treatment and secondary prophylaxis of spontaneous bacterial peritonitis in cirrhosis, many aspects of the pathogenesis of this infection remain unclear. The mechanism of bacterial translocation and of the colonization of bacteria in the ascitic fluid are particularly important to design adequate measures for primary prophylaxis of this severe bacterial infection.

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.

Low-dose vasopressin restores diuresis both in patients with hepatorenal syndrome and in anuric patients with end-stage heart failure

OBJECTIVES

The purpose of this study was to confirm earlier reports that low-dose vasopressin (LDVP) analogues promote urine output in patients with hepatorenal syndrome (HRS) and to check whether this mode of therapy could also be effective in renal shutdown due to nonhepatic conditions.

DESIGN

A prospective, open, interventional study.

SETTING

An intermediate-level (step-down) medical intensive care unit within a general medical ward of a large university-affiliated hospital.

SUBJECTS

Eighteen successive hospitalized patients with HRS (mean age 65 +/- 13 years) and 11 patients with end-stage congestive heart failure (CHF) (mean age 81 +/- 5 years) who failed to restore urine output with conventional treatment (fluids, dopamine, and diuretics) given for at least 24 h.

INTERVENTIONS

The patients received LDVP (1 IU h-1) continuously in addition to the conventional treatment.

MAIN OUTCOME MEASURES

Urine output and creatinine clearance every 24 h.

RESULTS

In the HRS group, before treatment the urine output was 155 +/- 9 mL 24 -1h (mean +/- SD). After treatment with LDVP for 24, 48, and 72 h, urine output improved to 1067 +/- 87, 1020 +/- 501, and 1311 +/- 988 mL 24 -1h, respectively (P < 0.0001 for all measures; two-tailed paired t-test). In the CHF group, before treatment the urine output was 99 +/- 99 mL 24 -1h. After treatment with LDVP for 24, 48, and 72 h, this improved to 1125 +/- 994 mL 24 -1h (P = 0.0028), 1821 +/- 1300 mL 24 -1h (P = 0.004), and 2920 +/- 2423 mL 24 -1h (P = 0.0012), respectively. The improvement in urine output was not accompanied by a parallel improvement in creatinine clearance. The overall outcome did not change, and all patients except two in each group succumbed to their end-stage disease, due to nonrenal causes.

CONCLUSIONS

LDVP is effective in restoring urine output both in HRS and in CHF. This suggests that LDVP affects mechanisms not specifically related to liver disease. LDVP may be useful in critical patients with renal shutdown whilst awaiting liver or heart transplantation.

Acute effects of the oral administration of midodrine, an alpha-adrenergic agonist, on renal hemodynamics and renal function in cirrhotic patients with ascites

The effects of the acute administration of arterial vasoconstrictors on renal plasma flow (RPF) and urinary sodium excretion (UNaV) in cirrhotic patients with ascites with or without hepatorenal syndrome (HRS) are still controversial. As a consequence, vasoconstrictors are not actually used in the treatment of renal sodium retention or HRS in these patients, regardless of the several lines of evidence suggesting that these renal functional abnormalities are related to a marked arterial vasodilation. The lack of an orally available effective arterial vasoconstrictor probably represents a further reason for this omission. Consequently, the present study was made to evaluate the acute effects of the oral administration of midodrine, an orally available -mimetic drug, on systemic and renal hemodynamics and on UNaV in cirrhotic patients with ascites. Mean arterial pressure (MAP), heart rate (HR), cardiac index (CI), systemic vascular resistance (SVR), left forearm blood flow (LFBF), left leg blood flow (LLBF), RPF, glomerular filtration rate (GFR), UNaV, plasma renin activity (PRA), plasma concentration of antidiuretic hormone (ADH), and the serum levels of nitrite and nitrate (NOx) were evaluated in 25 cirrhotic patients with ascites (17 without HRS and 8 with type 2 HRS) before and during the 6 hours following the oral administration of 15 mg of midodrine. During the first 3 hours after the drug administration, a significant increase in MAP (89.6 +/- 1.7 vs. 81.80 +/- 1.3 mm Hg; P < .0001) and SVR (1, 313.9 +/- 44.4 vs. 1,121.2 +/- 60.1 dyn . sec . cm-5; P < .0001) accompanied by a decrease in HR (69 +/- 2 vs. 77 +/- 3 bpm; P < .005) and CI (2,932.7 +/- 131.4 vs. 3,152.5 +/- 131.4 mL . min-1 . m2 BSA; P < .0025) was observed in patients without HRS. No change was observed in LFBF and LLBF. The improvement in systemic hemodynamics, which was also maintained during the the 3- to 6-hour period after midodrine administration, was accompanied by a significant increase in RPF (541.5 +/- 43.1 vs. 385.7 +/- 39.9 mL . min-1; P < .005), GFR (93.1 +/- 6.5 vs. 77.0 +/- 6.7 mL . min-1; P < .025), and UNaV (92.7 +/- 16.4 vs. 72.2 +/- 10.7 microEq . min-1; P < .025). In addition, a decrease in PRA (5.33 +/- 1.47 vs. 7.74 +/- 2.17 ng . mL-1 . h; P < .05), ADH (1.4 +/- 0.2 vs. 1.7 +/- 0.2 pg . mL-1; P < .05), and NOx (33.4 +/- 5.0 vs. 49.3 +/- 7.3 micromol-1; P < .05) was found. In patients with HRS, the effects of the drug on the systemic hemodynamics was smaller and shorter. Accordingly, regardless of a significant decrease in PRA (15.87 +/- 3.70 vs. 20.70 +/- 4.82 ng . mL-1 . h; P < .0025) in patients with HRS, no significant improvement was observed in RPF, GFR, or UNaV. In conclusion, the acute oral administration of midodrine is associated with a significant improvement in systemic hemodynamics in nonazotemic cirrhotic patients with ascites. As a result, renal perfusion and UNaV also improve in these patients. By contrast, midodrine only slightly improves systemic hemodynamics in patients with type 2 HRS, with no effect on renal hemodynamics and renal function.

Nitric oxide synthase (NOS) inhibition for one week improves renal sodium and water excretion in cirrhotic rats with ascites

Normalization of the increased vascular nitric oxide (NO) generation with low doses of NG-nitro-L-arginine methyl ester (L-NAME) corrects the hemodynamic abnormalities of cirrhotic rats with ascites. We have undertaken this study to investigate the effect of the normalization of vascular NO production, as estimated by aortic cyclic guanosine monophosphate (cGMP) concentration and endothelial nitric oxide synthase (eNOS) protein expression in the aorta and mesenteric artery, on sodium and water excretion. Rats with carbon tetrachloride-induced cirrhosis and ascites were investigated using balance studies. The cirrhotic rats were separated into two groups, one receiving 0.5 mg/kg per day of L-NAME (CIR-NAME) during 7 d, whereas the other group (CIR) was administrated the same volume of vehicle. Two other groups of rats were used as controls, one group treated with L-NAME and another group receiving the same volume of vehicle. Sodium and water excretion was measured on days 0 and 7. On day 8, blood samples were collected for electrolyte and hormone measurements, and aorta and mesenteric arteries were harvested for cGMP determination and nitric oxide synthase (NOS) immunoblotting. Aortic cGMP and eNOS protein expression in the aorta and mesenteric artery were increased in CIR as compared with CIR-NAME. Both cirrhotic groups had a similar decrease in sodium excretion on day 0 (0.7 versus 0.6 mmol per day, NS) and a positive sodium balance (+0.9 versus +1.2 mmol per day, NS). On day 7, CIR-NAME rats had an increase in sodium excretion as compared with the CIR rats (sodium excretion: 2.4 versus 0.7 mmol per day, P < 0.001) and a negative sodium balance (-0.5 versus +0.8 mmol per day, P < 0.001). The excretion of a water load was also increased after L-NAME administration (from 28+/-5% to 65+/-7, P < 0.05). Plasma renin activity, aldosterone and arginine vasopressin were also significantly decreased in the CIR-NAME, as compared with the CIR rats. The results thus indicate that normalization of aortic cGMP and eNOS protein expression in vascular tissue is associated with increased sodium and water excretion in cirrhotic rats with ascites.

Reversibility of hepatorenal syndrome by prolonged administration of ornipressin and plasma volume expansion

Hepatorenal syndrome is caused by a marked vasoconstriction of the renal circulation. It is suggested that the renal vasoconstriction is related to an overactivity of vasoconstrictor systems secondary to a vasodilation of the arterial circulation that causes a reduction in effective arterial blood volume. To test this hypothesis, 16 cirrhotic patients with hepatorenal syndrome were treated with a combination of ornipressin, a potent vasoconstrictor agent, and plasma volume expansion with albumin to improve effective arterial blood volume. The combined treatment was administered either for 3 or 15 days (8 patients each), and the effects on renal function, vasoactive systems, and systemic hemodynamics were assessed. The 3-day treatment with ornipressin and albumin was associated with a normalization of the overactivity of renin-angiotensin and sympathetic nervous systems, a marked increase in atrial-natriuretic peptide levels, and only a slight improvement in renal function. However, when ornipressin and albumin were administered for 15 days, a remarkable improvement in renal function was observed, with normalization of serum-creatinine concentration, a marked increase in renal plasma flow and glomerular filtration rate, and a persistent suppression in the activity of vasoconstrictor systems. However, 3 of 8 patients on 15-day therapy treatment had to be discontinued because of ischemic complications. In conclusion, the decrease in effective arterial blood volume and the activation of vasoconstrictor systems play a crucial role in the pathogenesis of hepatorenal syndrome. Although the prolonged administration of ornipressin combined with plasma volume expansion reverses hepatorenal syndrome, this treatment should be used with great caution in clinical practice because of the risk of ischemic complications.

Effect of therapeutic paracentesis on plasma volume and transvascular escape rate of albumin in patients with cirrhosis

BACKGROUND/AIMS

Circulatory abnormalities with activation of vasoconstrictor systems after large-volume paracentesis are generally considered secondary to an increased extravasation of fluid from the intravascular compartment to the extravascular space with subsequent reduction in plasma volume. To test this hypothesis, plasma volume, the transvascular escape rate of albumin, the absolute escape rate of albumin and the activity of vasoconstrictor systems were measured in 25 cirrhotic patients with ascites in baseline conditions and 2 days after total paracentesis with plasma volume expansion.

METHODS

Plasma volume and the transvascular escape rate of albumin, the fraction of albumin passing from the intravascular to the extravascular space per unit of time, were assessed through the plasma disappearance curve of radioiodinated human albumin. The absolute escape rate of albumin, the total flux of albumin from intravascular to extravascular space per unit of time, was also calculated.

RESULTS

Eight of the 25 patients (32%) developed marked activation of vasoconstrictor systems after paracentesis. In these patients, plasma renin activity and plasma norepinephrine concentration increased from 6.6+/-2 to 23.4+/-11 ng x ml(-1) x h(-1) and 776+/-229 to 989+/-258 pg/ml, respectively (p<0.05). No significant changes in these parameters were found in the remaining 17 patients. The activation of vasoconstrictor systems occurred in the absence of changes in plasma volume (3456+/-276 vs 3476+/-264 ml, NS), transvascular escape rate of albumin (10.4+/-1 vs 10.9+/-2%/h, NS) and absolute escape rate of albumin (9.9+/-1.9 vs 10.5+/-0.7 g/h, NS).

CONCLUSIONS

These results do not support a contraction of plasma volume as the mechanism responsible for activation of vasoconstrictor systems after paracentesis. Rather, the activation of vasoconstrictor systems in the absence of changes in plasma volume suggests that paracentesis accentuates the impairment of "effective" blood volume present in cirrhotic patients with ascites.

Renal and neurohormonal changes following simultaneous administration of systemic vasoconstrictors and dopamine or prostacyclin in cirrhotic patients with hepatorenal syndrome

BACKGROUND/AIMS

Intravenous ornipressin in cirrhotic patients with hepatorenal syndrome causes marked improvement of systemic hemodynamics and suppression of plasma renin and norepinephrine but only moderate improvement of renal function. This study was designed to investigate whether these beneficial effects could be enhanced by the simultaneous administration of dopamine. The renal effects of the i.v. infusion of norepinephrine plus prostacyclin in patients with hepatorenal syndrome were also assessed.

METHODS

Renal plasma flow, glomerular filtration rate, free water clearance, sodium excretion and the plasma levels of renin and norepinephrine were measured in baseline conditions and during the administration of ornipressin (6 i.u./h) and ornipressin (6 i.u./h) plus dopamine (2 micrograms/kg.min) in nine patients with hepatorenal syndrome. Five additional patients with hepatorenal syndrome were studied prior to and following the administration of norepinephrine (0.45 +/- 0.1 microgram/kg.min) and norepinephrine (0.85 +/- 0.2 microgram/kg.min) plus prostacyclin (5 ng/kg.min).

RESULTS

Despite a significant increase in arterial pressure and marked suppression of plasma renin activity during ornipressin and ornipressin plus dopamine administration, no significant improvement in renal function was observed. Norepinephrine and norepinephrine plus prostacyclin also failed to increase renal perfusion and glomerular filtration rate.

CONCLUSIONS

The combined administration of systemic vasoconstrictors (ornipressin or norepinephrine) and vasodilators (dopamine or prostacyclin), at the doses used in the current study and for a short period of time, does not improve renal function in cirrhotic patients with hepatorenal syndrome. The current study does not confirm a potential role for ornipressin in the treatment of hepatorenal syndrome.

Hemodynamic effects of peritoneovenous shunts in hemodialysis patients with ascites

Ascites in hemodialysis patients has been reported in association with systemic diseases, such as cirrhosis or congestive heart failure, and as an idiopathic form. Regardless of the etiology, these patients often are refractory to treatment with intradialytic ultrafiltration because of recurrent hypotensive episodes. In this report we describe the hemodynamic effects of peritoneovenous shunts (PVSs) in three hemodialysis patients with ascites refractory to conventional treatment. One patient had idiopathic ascites and the other two had associated liver disease. Patients were monitored for lowest blood pressure, number of intradialytic hypotensive episodes, number of grams of albumin infused to treat hypotensive episodes, interdialytic weight gain, and hemodynamic stability (defined as the difference between the predialysis mean arterial pressure and the lowest intradialytic mean arterial pressure). In all three patients the hemodynamic parameters stabilized after PVS placement despite equal or greater ultrafiltration during dialysis (due to a significant increase in the lowest measured intradialytic blood pressure). The total number of hypotensive episodes decreased from 219 prior to PVS placement to zero after shunt placement. The need for albumin infusion during hemodialysis (for blood pressure support) decreased (significantly in two patients), as did the volume of ascites in all three patients. One patient required PVS replacement secondary to infection, which was the only complication. We believe that refractory ascites in end-stage renal disease patients can be successfully treated by placement of a PVS, which often results in relief of the ascites and significant improvement in intradialytic hemodynamic stability.

Aquaretic agents: a new potential treatment of dilutional hyponatremia in cirrhosis

An impairment in the renal capacity to excrete water is a common finding in patients with cirrhosis and ascites. In some patients this abnormality is minor since it is only detectable by measuring urine volume or free water clearance after a water load and is not associated with changes in plasma osmolality and serum sodium concentration. In other patients the intensity of the disorder is such that they are not able to eliminate their regular water intake, and develop dilutional hyponatremia and hypoosmolality. The renal capacity to excrete water is one of the most useful prognostic indicators in patients with cirrhosis and ascites. The main pathogenic factors of the impaired water excretion in human cirrhosis are an increased plasma concentration of AVP, a reduced renal synthesis of prostaglandins and a reduced delivery of filtrate to the ascending limb of the loop of Henle. At present, no effective therapy exists for the management of this complication. Two types of drugs have recently been reported that selectively increase renal water excretion, antagonists of the AVP V2 receptors and kappa-opioid agonists. Experimental studies have shown that both substances improve water excretion in rats with cirrhosis and ascites. Therefore, these drugs may represent a novel therapeutic tool in the management of spontaneous hyponatremia in cirrhosis and in the treatment or prevention of diuretic-induced hyponatremia in these patients.

Normalization of nitric oxide production corrects arterial vasodilation and hyperdynamic circulation in cirrhotic rats

BACKGROUND & AIMS

Recent studies suggest that production of nitric oxide is increased in cirrhosis. This study determines to what extent this increased production contributes to arterial vasodilation and hyperdynamic circulation in cirrhosis.

METHODS

Mean arterial pressure (MAP), cardiac index, and systemic vascular resistance (SVR) were determined in cirrhotic rats with ascites undergoing long-term treatment with different doses of the NO synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME) (3 mg or 0.5 mg.kg-1.day-1). Untreated cirrhotic rats with ascites and controls were also studied. The vascular production of NO was estimated by the aortic concentration of guanosine 3',5'-cyclic monophosphate (cGMP).

RESULTS

Untreated cirrhotic rats had significantly lower MAP and SVR and higher cardiac index and aortic cGMP concentration than controls. When administrated to cirrhotic rats, an L-NAME dose of 3 mg.kg-1.day-1 induced a reduction of cGMP concentration less than normal levels. In these rats, MAP and SVR increased to greater than and cardiac index decreased to less than values in controls. By contrast, cirrhotic rats treated with 0.5 mg.kg-1.day-1 L-NAME had similar aortic cGMP concentrations as controls, suggesting a normalization of NO production. This was associated with a normalization of MAP, cardiac index, and SVR and a reduction in the elevated plasma renin activity and vasopressin concentration.

CONCLUSIONS

Normalization of vascular NO production corrects systemic hemodynamic abnormalities in cirrhotic rats with ascites.

Renal sodium handling in cirrhosis with ascites: mechanisms of impaired natriuretic response to reclining

We recently showed that patients with compensated cirrhosis can dispose of their fluid overload while reclining. In contrast, patients with ascites fail to develop supine-induced natriuresis. To assess the effect of reclining on renal sodium handling in patients with advanced cirrhosis and the mechanisms blunting natriuresis in this situation, renal function and plasma concentrations of atrial natriuretic factor, aldosterone and norepinephrine were evaluated in 10 nonazotemic patients with cirrhosis and ascites and 10 healthy controls standing for 2 h and reclining for 2 h. While standing, all patients showed marked sodium retention and significantly elevated plasma atrial natriuretic factor levels, aldosterone and norepinephrine. Glomerular filtration rate did not differ from healthy controls. The reclining increased renal sodium excretion in both groups, but this change was far less marked in patients; natriuresis only rose to the control range in two of them. An increase in atrial natriuretic factor and a depression of plasma aldosterone and norepinephrine was seen in both controls and patients. In the latter, despite the greater change in atrial natriuretic factor and aldosterone, the aldosterone to atrial natriuretic factor ratio, which was inversely correlated with natriuresis during both standing and reclining remained significantly elevated. In the two patients who achieved normal natriuresis during reclining, reclining was associated with both the normalization of the aldosterone/atrial natriuretic factor ratio, and with an increase in glomerular filtration rate. The supine-induced increase in atrial natriuretic factor was not only preserved but was even enhanced in cirrhosis with ascites.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial natriuretic factor in cirrhosis: relationship to renal function and hemodynamic changes

Plasma atrial natriuretic factor concentrations and different hemodynamic parameters, including the evaluation of femoral arteriovenous shunting by measuring the arteriovenous difference of oxygen content (Ca-vO2), were determined in eight healthy subjects and 24 patients with cirrhosis without renal failure (group I: seven patients without ascites, group II: nine patients with ascites and UNaV > 10 mEq/24 h and group III: eight patients with ascites and UNaV < or = 10 mEq/24 h). Atrial natriuretic factor was 34 +/- 4.7 pg/ml in the control group and 44.28 +/- 5.4, 67.89 +/- 8.8 and 84 +/- 10.8 pg/ml in groups I, II and III respectively (p < 0.001. group III vs. I and control and II vs. control). Atrial natriuretic factor directly correlated with cardiac index (p < 0.01), blood volume (p: 0.01), femoral blood flow (p < 0.01) and inversely with systemic and femoral vascular resistances (p < 0.02), Ca-vO2 (p < 0.01), serum albumin (r: -0.61; p < 0.01) and prothrombin index (r: -0.63; p < 0.02). These results indicate that plasma atrial natriuretic factor is increased in patients with cirrhosis, especially in those with advanced disease and marked renal sodium retention. This suggests that in cirrhosis, arteriolar vasodilation and peripheral arteriovenous shunting influence renal function while inducing a state of overflow at the central venous compartment leading to increased atrial natriuretic factor secretion. Increased production of this vasodilatory hormone may thus contribute to the hyperkinetic circulation of cirrhosis.

Therapeutic efficacy of the non-peptide AVP antagonist OPC-31260 in cirrhotic rats

The present study was undertaken to determine whether a non-peptide arginine vasopressin (AVP) antagonist [5-dimethylamino-1-(4-(2-methylbenzoylamino)benzoyl]-2,3,4,5-tetra hydro-1H- benzazepine] (OPC-31260) improves the impaired water excretion in rats with experimental liver cirrhosis. Male Wistar rats weighing 200 to 250 g were injected in an equal volume (4 ml/kg) of carbon tetrachloride and olive oil at an interval of seven days for three months, causing liver cirrhosis with ascites. Control rats were injected with only olive oil. Body weight (body wt) and hematocrit (Hct) were lower in the cirrhotic rats than the control rats (body wt 360.7 vs. 238.5 g, P < 0.01; Hct 46.3 vs. 39.2%, P < 0.01). A water loading test (30 ml/kg) was carried out and 20-minute urine collections were made for three hours. The percent of water load excreted was 62.5% in the cirrhotic rats, a value significantly less than that of 102.1% in the control rats. However, its percent increased to 215.1% after the oral administration of 5 mg/kg OPC-31260 (P < 0.01). Minimal urinary osmolality (UOsm) was 185.5 mOsm/kg H2O in the cirrhotic rats receiving the vehicle, a value greater than the control rats of 125.5 mOsm/kg H2O (P < 0.01). The oral administration of 5 mg/kg OPC-31260 reduced minimal UOsm to 85.2 mOsm/kg H2O in the cirrhotic rats (P < 0.01). Urinary excretion of sodium was lower in the cirrhotic rats than the control rats (87.1 vs. 312.4 microEq/3 hr, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of somatostatin on renal function in cirrhosis

To investigate the renal effects of somatostatin in cirrhosis, renal function and plasma and urinary levels of endogenous neurohumoral vasoactive substances were measured in conditions of intravenous water overload (20 mL/kg body wt with 5% glucose) before and during the intravenous infusion of somatostatin (250-500 micrograms/h) in 6 cirrhotic patients without ascites and 17 nonazotemic cirrhotic patients with ascites. Somatostatin induced a significant reduction of renal plasma flow, glomerular filtration rate, and free water clearance in both groups of patients. In patients with ascites, somatostatin also reduced urinary sodium excretion. Changes in renal function were significantly more marked in patients with ascites than in those without ascites and occurred in the absence of changes in mean arterial pressure and plasma levels of renin, aldosterone, norepinephrine, antidiuretic hormone, and atrial natriuretic peptide. Somatostatin induced a significant reduction in the plasma concentration of glucagon and urinary excretion of prostaglandin E2 that was not related to changes in renal function. These findings indicate that somatostatin administration induces renal vasoconstriction and impairs glomerular filtration rate, free water clearance, and sodium excretion in cirrhosis by a mechanism unrelated to systemic hemodynamics and endogenous neurohumoral vasoactive systems.

The hemodynamic status of preascitic cirrhosis: an evaluation under steady-state conditions and after postural change

To assess the hemodynamic status of patients with compensated cirrhosis, mean arterial pressure, cardiac index and peripheral vascular resistance and markers of central (plasma concentrations of atrial natriuretic factor) and arterial volemia (plasma norepinephrine concentration, plasma renin activity) were studied in 10 patients and 10 healthy control subjects under steady-state conditions (after 2 hr of standing) and after assumption of the supine position (30, 60, and 120 min). After standing, neither hemodynamics nor markers of effective volemia differed significantly between controls and patients. By evaluating the areas under the curve during the 2 hr of supine posture, the increase in cardiac output and plasma natriuretic factor and the decrease in peripheral vascular resistance were greater in patients (2.59 +/- 0.43 [S.E.M.] L/min/hr; 32.8 +/- 7.2 pg/ml/hr -1,103 +/- 248.4 dyn.sec/cm5/hr, respectively) than in controls (0.53 +/- 0.24 L/min/hr, p = 0.005; 17.4 +/- 4.7 pg/ml/hr, p = 0.005; -265.5 +/- 206.2 dyn.sec/cm5/hr, p = 0.02). The declines in heart rate, plasma norepinephrine concentration and plasma renin activity did not differ significantly. Mean arterial pressure did not significantly change. Our results suggest that during periods of upright posture, cirrhotic patients in the preascitic stage, who are known to have expanded blood volume, compensate for dilatation of the splanchnic vascular bed through total hypervolemia. The latter becomes excessive during recumbency, leading to supernormal increases in venous return, central volemia and cardiac index. The decline in peripheral vascular resistance appears to be a compensatory mechanism to maintain steady arterial blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased total vascular capacity in conscious cirrhotic rats

The purpose of the present study was to determine the role of the systemic venous circulation in the hemodynamic alterations of the cirrhotic disease. Cardiac output (thermodilution; n = 8), mean circulatory filling pressure (balloon technique; n = 6), and blood volume (Evans blue dye; n = 7) were investigated in a rat model of liver cirrhosis without ascites induced by a 12-week individualized CCl4/phenobarbital treatment. Compared with control rats, conscious cirrhotic rats showed a hyperdynamic circulation characterized by normotension, high cardiac output (51 +/- 4.8 vs. 28.6 +/- 1.3 mL.min-1.100 g-1; P less than 0.01), and expanded blood volume (6.5 +/- 0.15 vs. 5.4 +/- 0.22 mL.100 g-1; P less than 0.05). There were no significant differences between control and cirrhotic rats in mean circulatory filling pressure (6.40 +/- 0.27 vs. 5.99 +/- 0.22 mm Hg, respectively) or in the pressure gradient for venous return (6.17 +/- 0.19 vs. 5.8 +/- 0.21 mm Hg, respectively). To further examine the venous tone, effective vascular compliance was estimated with the vascular filling-blood volume relationship by measuring the vascular filling before and after rapid changes in volume (+/- 8 mL.kg-1). Compliance was similar in both control and cirrhotic rats (3.15 +/- 0.26 and 3.41 +/- 0.21 mL.mm Hg-1), but the vascular filling-total blood volume relationship of the cirrhotic rats was displaced toward the volume axis. In conclusion, the increase in blood volume without changes in mean circulatory filling pressure (or venous tone) of the cirrhotic rats indicates a situation with venodilation and elevated total venous capacity; this is likely to be an important mechanism that could explain the hyperdynamic circulation of the cirrhotic disease.

Renal insensitivity to atrial natriuretic peptide in patients with cirrhosis and ascites. Effect of increasing systemic arterial pressure

The IV infusion of pharmacological doses (0.05 microgram.kg-1.min-1) of atrial natriuretic peptide to 16 patients with cirrhosis and ascites induced a significant increase in sodium excretion (65 +/- 23 to 517 +/- 231 mu Eq/min), urine volume (10.7 +/- 2.3 to 15.7 +/- 3.7 mL/min), and glomerular filtration rate (89 +/- 4 to 110 +/- 4 mL/min) in only 5 patients (responders). No significant changes in these parameters (15 +/- 6 to 11 +/- 4 mu Eq/min, 5.5 +/- 1.0 to 4.2 +/- 1.1 mL/min, and 81 +/- 5 to 79 +/- 6 mL/min, respectively) were observed in the remaining patients (nonresponders). Compared with responders, nonresponders had significantly lower baseline sodium excretion (P less than 0.02), urine flow (P less than 0.05), free water clearance (2.5 +/- 0.9 vs. 6.9 +/- 2.1 mL/min; P less than 0.05), and mean arterial pressure (82 +/- 3 vs. 96 +/- 2 mm Hg; P less than 0.01) and significantly higher plasma renin activity (16.3 +/- 4.9 vs. 1.8 +/- 0.2 ng.mL-1.h-1; P less than 0.05) and aldosterone level (99 +/- 24 vs. 13 +/- 2 ng/dL; P less than 0.05). Atrial natriuretic peptide produced a similar reduction of arterial pressure in both groups. To investigate whether the blunted natriuretic response to atrial natriuretic peptide in nonresponders was caused by their lower arterial pressure, atrial natriuretic peptide was infused in 7 of these patients after increasing their arterial pressure to the levels of responders with nonrepinephrine. The increase in arterial pressure (from 81 +/- 5 to 95 +/- 5 mm Hg), which was not associated with significant changes in plasma renin activity and aldosterone concentration, did not reverse the blunted renal response to atrial natriuretic peptide in any of these patients. These results indicate that cirrhotic patients with blunted renal response to atrial natriuretic peptide are characterized by low arterial pressure, marked overactivity of the renin-aldosterone system, and severe sodium and water retention. Correction of hypotension without increasing effective blood volume does not restore renal insensitivity to atrial natriuretic peptide.

Ornipressin in the treatment of functional renal failure in decompensated liver cirrhosis. Effects on renal hemodynamics and atrial natriuretic factor

In 11 patients with decompensated cirrhosis and deteriorating renal function, the effect of the vasoconstrictor substance 8-ornithin vasopressin (ornipressin; POR 8; Sandoz, Basel, Switzerland) on renal function, hemodynamic parameters, and humoral mediators was studied. Ornipressin was infused at a dose of 6 IU/h over a period of 4 hours. During ornipressin infusion an improvement of renal function was achieved as indicated by significant increases in inulin clearance (+65%), paraaminohippuric acid clearance (+49%), urine volume (+45%), sodium excretion (+259%), and fractional elimination of sodium (+130%). The hyperdynamic circulation was reversed to a nearly normal circulatory state. The increase in systemic vascular resistance (+60%) coincided with a decrease of a previously elevated renal vascular resistance (-27%) and increase in renal blood flow (+44%). The renal fraction of the cardiac output increased from 2.3% to 4.7% (P less than 0.05). A decline of the elevated plasma levels of noradrenaline (2.08-1.13 ng/mL; P less than 0.01) and renin activity (27.6-14.2 ng.mL-1.h-1; P less than 0.01) was achieved. The plasma concentration of the atrial natriuretic factor increased in most of the patients, but slightly decreased in 3 patients. The decrease of renal vascular resistance and the increase of renal blood flow and of the renal fraction of cardiac output play a key role in the beneficial effect of ornipressin on renal failure. These changes develop by an increase in mean arterial pressure, the reduction of the sympathetic activity, and probably of an extenuation of the splanchnic vasodilation. A significant contribution of atrial natriuretic factor is less likely. The present findings implicate that treatment with ornipressin represents an alternative approach to the management of functional renal failure in advanced liver cirrhosis.

Reduced central blood volume in cirrhosis

The pathogenesis of ascites formation in cirrhosis is uncertain. It is still under debate whether the effective blood volume is reduced (underfilling theory) or whether the intravascular compartment is expanded (overflow theory). This problem has not yet been solved because of insufficient tools for measuring the central blood volume. We have developed a method that enables us to determine directly the central blood volume, i.e., the blood volume in the heart cavities, lungs, and central arterial tree. In 60 patients with cirrhosis and 16 control subjects the central blood volume was assessed according to the kinetic theory as the product of cardiac output and mean transit time of the central vascular bed. Central blood volume was significantly smaller in patients with cirrhosis than in controls (mean 21 vs. 27 ml/kg estimated ideal body weight, p less than 0.001; 25% vs. 33% of the total blood volume, p less than 0.0001). The lowest values (18 ml/kg) were found in patients with gross ascites and a reduced systemic vascular resistance. In patients with cirrhosis central blood volume was inversely correlated to the hepatic venous pressure gradient (r = -0.41, p less than 0.01), and the total blood volume was inversely correlated to the systemic vascular resistance (r = -0.49, p less than 0.001), the latter being significantly reduced in the patient group. Patients with cirrhosis apparently are unable to maintain a normal central blood volume. This may be due to arteriolar vasodilation, portosystemic collateral flow, or sequestration of fluid in the peritoneal cavity, or any combination thereof. The present results indicate that central circulatory underfilling is an integral part of the hemodynamic and homeostatic derangement observed in cirrhosis.

Mechanisms of hypertension during and after orthotopic liver transplantation in children

The aim of this study was to assess the hormonal alterations that may mediate the systemic hypertension that develops in patients during the perioperative period of orthotopic liver transplantation. We studied nine pediatric patients without previous hypertension or renal disease during six time points, starting before transplantation and ending at 48 hours after surgery. Hypertension developed in all patients in association with central venous pressures less than 10 mm Hg. Free water clearance was negative in all nine patients. Vasopressin levels increased intraoperatively but fell as hypertension developed. Atrial natriuretic factor levels increased as systemic blood pressure rose. A high level of plasma renin activity was observed in four patients with renal insufficiency. In six patients, postoperative 24-hour urinary norepinephrine excretion was within the normal age-adjusted range. These findings suggest that the combination of cyclosporine, corticosteroids, and, in some patients, an elevated plasma renin activity prevents the kidney from responding to the acute volume and salt overload with an appropriate diuresis and natriuresis, thus leading to systemic hypertension. The treatment of hypertension after liver transplantation may include salt restriction, diuretics, and, in those patients with a low creatinine excretion index, angiotensin coverting enzyme inhibitors.

Role of altered systemic hemodynamics in the blunted renal response to atrial natriuretic peptide in rats with cirrhosis and ascites

The natriuretic effect of pharmacological doses of atrial natriuretic peptide (ANP) is markedly reduced in cirrhosis with ascites. The current study, which includes two protocols, was carried out to investigate whether this phenomenon is related to the altered systemic hemodynamics present in cirrhosis. In protocol A, the administration of ANP (2.5 micrograms.kg-1 as a bolus followed by a constant infusion of 0.1 microgram.kg-1.min-1) to 10 rats with carbon tetrachloride-induced cirrhosis and ascites produced a significantly lower increase in diuresis (13.4 +/- 1.3 microliters/min) and natriuresis (2.3 +/- 0.3 mu Equiv/min) than in 10 control rats (56.3 +/- 1.4 microliters/min and 8.7 +/- 0.5 mu Equiv/min, respectively), indicating a renal resistance to the effect of ANP in this experimental model of cirrhosis. The reduction of arterial pressure induced by ANP was similar in both groups. However, since baseline mean arterial pressure was significantly lower in cirrhotic rats, the degree of hypotension during ANP infusion was also greater in this group of animals (82 +/- 3 vs. 109 +/- 2 mmHg). The aim of protocol B was to assess whether normalization of arterial pressure in cirrhotic rats increases the renal response to ANP. This protocol includes two groups of 10 rats with cirrhosis and ascites infused with a glucose solution containing norepinephrine (CT-NE rats) or angiotensin II (CT-AII rats) at doses to normalize arterial pressure and an additional control group of 10 cirrhotic rats with ascites receiving only glucose solution (CT rats). Angiotensin II, but not norepinephrine or glucose solution administration, was associated with a significant increase in urine volume and sodium excretion. During ANP infusion, CT rats showed a blunted diuretic and natriuretic response. In contrast, the ANP-induced increase in urine volume and sodium excretion observed in CT-NE (53.6 +/- 10.4 microliters/min and 9.3 +/- 2.2 mu Equiv/min) and CT-AII rats (98.3 +/- 11.6 microliters/min and 15.5 +/- 2.9 mu Equiv/m), was similar or even greater than that showed by the healthy rats of protocol A. The degree of hypotension during ANP administration was also similar (CT-NE, 104 +/- 2; CT-AII, 108 +/- 5 mmHg). These results suggest that the blunted response to pharmacological doses of ANP in cirrhosis with ascites is related to altered systemic hemodynamics of cirrhosis, which further deteriorates during the infusion of the peptide.