Introduction
Initial reports by Frerichs (1861) and Flint (1863) [1], who had noted an association between advanced liver disease with ascites and acute oliguric renal failure in the absence of significant histological changes in the kidneys, led Heyd [2], and later Helwig and Schutz [3], to introduce the concept of the hepatorenal syndrome (HRS) to explain the increased frequency of acute renal failure after biliary surgery. However, because HRS could not be reproduced in animal models, pathophysiological concepts remained speculative and its clinical entity was not generally accepted. During the 1950s, HRS was more specifically characterised as a functional renal failure in patients with advanced liver disease, electrolyte disturbances and low urinary sodium concentrations [4]. Hecker and Sherlock [5] showed its temporal reversibility by norepinephrine administration. Over the next few decades, haemodynamic and perfusion studies by Epstein and other investigators [6] identified splanchnic and systemic vasodilatation and active renal vasoconstriction as the pathophysiological hallmarks of HRS. Improved models of ascites and circulatory dysfunction contributed to therapeutic advances, including the introduction of large-volume paracentesis, vasopressin analogues, and transjugular intrahepatic stent-shunt (TIPS), which in turn have led to an improved pathophysiological understanding of HRS [7]. Definition HRS is defined as the development of renal failure in patients with severe liver disease (acute or chronic) in the absence of any other identifiable cause of renal pathology. It is diagnosed following the exclusion of other causes of renal failure in patients with liver disease, such as hypovolaemia, drug nephrotoxicity, sepsis or glomerulonephritis. A similar syndrome can also occur in the setting of acute liver failure [8]. In the kidney there is marked renal vasoconstriction, resulting in a low glomerular filtration rate (GFR). In the extrarenal circulation arterial vasodilatation predominates, resulting in reduction of the total systemic vascular resistance and arterial hypotension [9].
Initial reports by Frerichs (1861) and Flint (1863) [1], who had noted an association between advanced liver disease with ascites and acute oliguric renal failure in the absence of significant histological changes in the kidneys, led Heyd [2], and later Helwig and Schutz [3], to introduce the concept of the hepatorenal syndrome (HRS) to explain the increased frequency of acute renal failure after biliary surgery. However, because HRS could not be reproduced in animal models, pathophysiological concepts remained speculative and its clinical entity was not generally accepted. During the 1950s, HRS was more specifically characterised as a functional renal failure in patients with advanced liver disease, electrolyte disturbances and low urinary sodium concentrations [4]. Hecker and Sherlock [5] showed its temporal reversibility by norepinephrine administration. Over the next few decades, haemodynamic and perfusion studies by Epstein and other investigators [6] identified splanchnic and systemic vasodilatation and active renal vasoconstriction as the pathophysiological hallmarks of HRS. Improved models of ascites and circulatory dysfunction contributed to therapeutic advances, including the introduction of large-volume paracentesis, vasopressin analogues, and transjugular intrahepatic stent-shunt (TIPS), which in turn have led to an improved pathophysiological understanding of HRS [7]. Definition HRS is defined as the development of renal failure in patients with severe liver disease (acute or chronic) in the absence of any other identifiable cause of renal pathology. It is diagnosed following the exclusion of other causes of renal failure in patients with liver disease, such as hypovolaemia, drug nephrotoxicity, sepsis or glomerulonephritis. A similar syndrome can also occur in the setting of acute liver failure [8]. In the kidney there is marked renal vasoconstriction, resulting in a low glomerular filtration rate (GFR). In the extrarenal circulation arterial vasodilatation predominates, resulting in reduction of the total systemic vascular resistance and arterial hypotension [9].
Diagnostic Criteria
The International Ascites Club (1996) group has defined the diagnostic criteria for HRS, and these are listed in Table 1 [8].
The International Ascites Club (1996) group has defined the diagnostic criteria for HRS, and these are listed in Table 1 [8].
Major criteria
Chronic or acute liver disease with advanced hepatic failure and portal hypertension
Low GFR, as indicated by serum creatinine > 1.5 mg/dl or 24-h creatinine clearance <> 500 g/d for several days in patients with ascites without peripheral oedema or > 1000 ml in patients with peripheral oedema)
No sustained improvement in renal function (decrease of serum creatinine to 1.5 mg/dl or less or increase in 24 h creatinine clearance to 40 ml/min or more) after withdrawal of diuretics and expansion of plasma volume with 1.5 l of isotonic saline
Proteinuria < style="font-weight: bold;">Additional criteria
Urine sodium <> plasma osmolality
Urine red blood cells <>
Chronic or acute liver disease with advanced hepatic failure and portal hypertension
Low GFR, as indicated by serum creatinine > 1.5 mg/dl or 24-h creatinine clearance <> 500 g/d for several days in patients with ascites without peripheral oedema or > 1000 ml in patients with peripheral oedema)
No sustained improvement in renal function (decrease of serum creatinine to 1.5 mg/dl or less or increase in 24 h creatinine clearance to 40 ml/min or more) after withdrawal of diuretics and expansion of plasma volume with 1.5 l of isotonic saline
Proteinuria < style="font-weight: bold;">Additional criteria
Urine sodium <> plasma osmolality
Urine red blood cells <>
Epidemiology
HRS occurs in about 4% of patients admitted to hospital with decompensated cirrhosis, the cumulative probability being 18% at 1 year, increasing to 39% at 5 years. Retrospective studies [12] indicate that HRS is present in approximately 17% of patients admitted to hospital with ascites and in more than 50% of cirrhotic patients dying of liver failure. The most frequent cause of renal failure in cirrhosis is spontaneous bacterial peritonitis (SBP). Approximately 30% of patients with SBP develop renal failure. Type 1 HRS is characterised by rapid and progressive renal impairment and is precipitated most commonly by SBP. Type 1 HRS occurs in approximately 25% of patients with SBP, even when rapid resolution of the infection is obtained with antibiotics. Without treatment, the median survival of patients with HRS type 1 is less than 2 weeks, and virtually all patients die within 10 weeks after the onset of renal failure. Type 2 HRS is characterised by a moderate and stable reduction in GFR and commonly occurs in patients with relatively well-preserved hepatic function. The median survival is 3–6 months. Although this is markedly longer than that in type 1 HRS, it is still shorter than that of patients with cirrhosis and ascites who do not have renal failure. People of all races who have chronic liver disease are at risk of HRS, and its frequency is equal in both sexes; most patients with chronic liver disease are in the 4th–8th decade of life.
HRS occurs in about 4% of patients admitted to hospital with decompensated cirrhosis, the cumulative probability being 18% at 1 year, increasing to 39% at 5 years. Retrospective studies [12] indicate that HRS is present in approximately 17% of patients admitted to hospital with ascites and in more than 50% of cirrhotic patients dying of liver failure. The most frequent cause of renal failure in cirrhosis is spontaneous bacterial peritonitis (SBP). Approximately 30% of patients with SBP develop renal failure. Type 1 HRS is characterised by rapid and progressive renal impairment and is precipitated most commonly by SBP. Type 1 HRS occurs in approximately 25% of patients with SBP, even when rapid resolution of the infection is obtained with antibiotics. Without treatment, the median survival of patients with HRS type 1 is less than 2 weeks, and virtually all patients die within 10 weeks after the onset of renal failure. Type 2 HRS is characterised by a moderate and stable reduction in GFR and commonly occurs in patients with relatively well-preserved hepatic function. The median survival is 3–6 months. Although this is markedly longer than that in type 1 HRS, it is still shorter than that of patients with cirrhosis and ascites who do not have renal failure. People of all races who have chronic liver disease are at risk of HRS, and its frequency is equal in both sexes; most patients with chronic liver disease are in the 4th–8th decade of life.
In a prospective study published by Gines et al., once HRS had developed the median survival was only 1.7 weeks, and it was poorer particularly in patients with apparent precipitating factors. Overall survival at 4 and 10 weeks was 20% and 10%, respectively. Patients with low urinary sodium excretion (<>
Table 2. Risk factors for development of hepatorenal syndrome
Previous episodes of ascites
Absence of hepatomegaly
Poor nutritional status
Presence of oesophageal varices
Serum sodium <> 553 mosmol/l
Norepinephrine levels > 544pg/ml
Plasma renin activity > 3.5 ng /ml
Mean arterial pressure < class="MsoNormal">
Pathophysiology
The hallmark of HRS is renal vasoconstriction, although the pathogenesis is not fully understood.Multiple mechanisms are probably involved and include interplay between disturbances in systemic haemodynamics, activation of vasoconstrictor systems and a reduction in activity of the vasodilator systems [16–19]. The haemodynamic pattern of patients with HRS is characterised by increased cardiac output, low arterial pressure and reduced systemic vascular resistance. Renal vasoconstriction occurs in the absence of reduced cardiac output and blood volume, which is a point of contrast to most clinical conditions associated with renal hypoperfusion. Although the pattern of increased renal vascular resistance and decreased peripheral resistance is characteristic of HRS, it also occurs in other conditions, such as anaphylaxis and sepsis. Doppler studies of the brachial, middle cerebral and femoral arteries suggest that extrarenal resistance is increased in patients with HRS, while the splanchnic circulation is responsible for arterial vasodilatation and reduced total systemic vascular resistance. The renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system (SNS) are the predominant systems responsible for renal vasoconstriction [20]. The activity of both systems is increased in patients with cirrhosis and ascites, and this effect is magnified in HRS. In contrast, an inverse relationship exists between the activity of these two systems and renal plasma flow (RPF) and the glomerular filtration rate (GFR). Endothelin is another renal vasoconstrictor that is present in increased concentration in HRS, although its role in the pathogenesis of this syndrome has yet to be identified. Adenosine is well known for its vasodilator properties, although it acts as a vasoconstrictor in the lungs and kidneys. Elevated levels of adenosine are more common in patients with heightened activity of the RAAS and may work synergistically with angiotensin II to produce renal vasoconstriction in HRS. This effect has also been described with the powerful renal vasoconstrictor, leukotriene E4. The vasoconstricting effect of these various systems is antagonised by local renal vasodilatory factors, the most important of which are the prostaglandins. Perhaps the strongest evidence supporting their role in renal perfusion is the marked decrease in RPF and the GFR when nonsteroidal medications known to bring about a sharp reduction in PG levels are administered. Nitrous oxide (NO) is another vasodilator that is believed to play an important part in renal perfusion. Preliminary studies, predominantly based on animal experiments, have demonstrated that NO production is increased in the presence of cirrhosis, although NO inhibition does not result in renal vasoconstriction owing to a compensatory increase in PG synthesis.However, when both NO and PG production are inhibited, marked renal vasoconstriction develops. These findings demonstrate that renal vasodilators have a critical role in maintaining renal perfusion, particularly in the presence of overactivity of renal vasoconstrictors. However, we do not yet know for certain whether vasoconstrictor activity becomes the predominant system in HRS and whether a reduction in the activity of the vasodilator system contributes to this [21–29].Various theories have been proposed to explain the development of HRS in cirrhosis. The two main ones are the arterial vasodilatation theory and the hepatorenal reflex theory. The first not only describes sodium and water retention in cirrhosis, but may also be the most rational hypothesis for the development of HRS. Splanchnic arteriolar vasodilatation in patients with compensated cirrhosis and portal hypertension may be mediated by several factors, the most important of which is probably NO. In the early phases of portal hypertension and compensated cirrhosis, this underfilling of the arterial bed causes a decrease in the effective arterial blood volume and results in homeostatic reflex activation of the endogenous vasoconstrictor systems. Activation of the RAAS and SNS occurs early with antidiuretic hormone secretion, a later event when a more marked derangement in circulatory function is present. This results in vasoconstriction not only of the renal vessels, but also in the vascular beds of the brain,muscle, spleen and extremities. The splanchnic circulation is resistant to these effects because of the continuous production of local vasodilators, such as NO. In the early phases of portal hypertension, renal perfusion is maintained within normal or near-normal limits as the vasodilatory systems antagonise the renal effects of the vasoconstrictor systems. However, as liver disease progress in severity, a critical level of vascular underfilling is achieved; renal vasodilatory systems are unable to counteract the maximal activation of the endogenous vasoconstrictors and/or intrarenal vasoconstrictors, which leads to uncontrolled renal vasoconstriction. Support for this hypothesis is provided by studies in which the administration of splanchnic vasoconstrictors in combination with volume expanders results in improvement in arterial pressure, RPF and GFR [30–34]. The alternative theory proposes that renal vasoconstriction in HRS is not related to systemic haemodynamics but is due either to a deficiency in the synthesis of a vasodilator factor or to a hepatorenal reflex that leads to renal vasoconstriction. Evidence points to the vasodilatation theory as a more tangible explanation for the development of HRS.
The hallmark of HRS is renal vasoconstriction, although the pathogenesis is not fully understood.Multiple mechanisms are probably involved and include interplay between disturbances in systemic haemodynamics, activation of vasoconstrictor systems and a reduction in activity of the vasodilator systems [16–19]. The haemodynamic pattern of patients with HRS is characterised by increased cardiac output, low arterial pressure and reduced systemic vascular resistance. Renal vasoconstriction occurs in the absence of reduced cardiac output and blood volume, which is a point of contrast to most clinical conditions associated with renal hypoperfusion. Although the pattern of increased renal vascular resistance and decreased peripheral resistance is characteristic of HRS, it also occurs in other conditions, such as anaphylaxis and sepsis. Doppler studies of the brachial, middle cerebral and femoral arteries suggest that extrarenal resistance is increased in patients with HRS, while the splanchnic circulation is responsible for arterial vasodilatation and reduced total systemic vascular resistance. The renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system (SNS) are the predominant systems responsible for renal vasoconstriction [20]. The activity of both systems is increased in patients with cirrhosis and ascites, and this effect is magnified in HRS. In contrast, an inverse relationship exists between the activity of these two systems and renal plasma flow (RPF) and the glomerular filtration rate (GFR). Endothelin is another renal vasoconstrictor that is present in increased concentration in HRS, although its role in the pathogenesis of this syndrome has yet to be identified. Adenosine is well known for its vasodilator properties, although it acts as a vasoconstrictor in the lungs and kidneys. Elevated levels of adenosine are more common in patients with heightened activity of the RAAS and may work synergistically with angiotensin II to produce renal vasoconstriction in HRS. This effect has also been described with the powerful renal vasoconstrictor, leukotriene E4. The vasoconstricting effect of these various systems is antagonised by local renal vasodilatory factors, the most important of which are the prostaglandins. Perhaps the strongest evidence supporting their role in renal perfusion is the marked decrease in RPF and the GFR when nonsteroidal medications known to bring about a sharp reduction in PG levels are administered. Nitrous oxide (NO) is another vasodilator that is believed to play an important part in renal perfusion. Preliminary studies, predominantly based on animal experiments, have demonstrated that NO production is increased in the presence of cirrhosis, although NO inhibition does not result in renal vasoconstriction owing to a compensatory increase in PG synthesis.However, when both NO and PG production are inhibited, marked renal vasoconstriction develops. These findings demonstrate that renal vasodilators have a critical role in maintaining renal perfusion, particularly in the presence of overactivity of renal vasoconstrictors. However, we do not yet know for certain whether vasoconstrictor activity becomes the predominant system in HRS and whether a reduction in the activity of the vasodilator system contributes to this [21–29].Various theories have been proposed to explain the development of HRS in cirrhosis. The two main ones are the arterial vasodilatation theory and the hepatorenal reflex theory. The first not only describes sodium and water retention in cirrhosis, but may also be the most rational hypothesis for the development of HRS. Splanchnic arteriolar vasodilatation in patients with compensated cirrhosis and portal hypertension may be mediated by several factors, the most important of which is probably NO. In the early phases of portal hypertension and compensated cirrhosis, this underfilling of the arterial bed causes a decrease in the effective arterial blood volume and results in homeostatic reflex activation of the endogenous vasoconstrictor systems. Activation of the RAAS and SNS occurs early with antidiuretic hormone secretion, a later event when a more marked derangement in circulatory function is present. This results in vasoconstriction not only of the renal vessels, but also in the vascular beds of the brain,muscle, spleen and extremities. The splanchnic circulation is resistant to these effects because of the continuous production of local vasodilators, such as NO. In the early phases of portal hypertension, renal perfusion is maintained within normal or near-normal limits as the vasodilatory systems antagonise the renal effects of the vasoconstrictor systems. However, as liver disease progress in severity, a critical level of vascular underfilling is achieved; renal vasodilatory systems are unable to counteract the maximal activation of the endogenous vasoconstrictors and/or intrarenal vasoconstrictors, which leads to uncontrolled renal vasoconstriction. Support for this hypothesis is provided by studies in which the administration of splanchnic vasoconstrictors in combination with volume expanders results in improvement in arterial pressure, RPF and GFR [30–34]. The alternative theory proposes that renal vasoconstriction in HRS is not related to systemic haemodynamics but is due either to a deficiency in the synthesis of a vasodilator factor or to a hepatorenal reflex that leads to renal vasoconstriction. Evidence points to the vasodilatation theory as a more tangible explanation for the development of HRS.
Histopathology of HRS
In previous definitions of HRS, changes in renal histology were reported to be absent or minimal, which reflected a rapid progression to death after development of HRS. Considering that many patients with HRS currently receive aggressive supportive treatment including renal replacement therapy to prolong survival until liver transplantation, it seems obvious that prolonged renal hypoperfusion, renal medullary hypoxia and the high frequency of infectious complications ultimately contribute to histologically detectable renal damage. However, it is increasingly recognised that structural renal damage may already be found even before renal dysfunction becomes manifest. In a series of cirrhotic patients [35] undergoing liver transplantation, 100% of renal biopsies showed glomerular abnormalities. Tubular function is usually well preserved at the time when HRS develops, but tubular abnormalities, including increased B2 microglobulin excretion, have been reported in deeply jaundiced patients with HRS [36–38]. With progressive circulatory dysfunction, prolonged renal hypoperfusion may eventually result in acute tubular necrosis by increasing the susceptibility to additional insults by radiographic contrast agents, aminoglycosides, haemorrhage, endotoxinaemia or any other cause of medullary hypoxia. The presence of acute tubular necrosis could partially explain the slow or absent renal recovery in HRS type 1 even after the initiation of vasopressor support. For instance, a recent case study reports full recovery of renal function in dialysis-dependent HRS after 7 weeks of treatment with ornipressin, dopamine and intravenous albumin [39].
In previous definitions of HRS, changes in renal histology were reported to be absent or minimal, which reflected a rapid progression to death after development of HRS. Considering that many patients with HRS currently receive aggressive supportive treatment including renal replacement therapy to prolong survival until liver transplantation, it seems obvious that prolonged renal hypoperfusion, renal medullary hypoxia and the high frequency of infectious complications ultimately contribute to histologically detectable renal damage. However, it is increasingly recognised that structural renal damage may already be found even before renal dysfunction becomes manifest. In a series of cirrhotic patients [35] undergoing liver transplantation, 100% of renal biopsies showed glomerular abnormalities. Tubular function is usually well preserved at the time when HRS develops, but tubular abnormalities, including increased B2 microglobulin excretion, have been reported in deeply jaundiced patients with HRS [36–38]. With progressive circulatory dysfunction, prolonged renal hypoperfusion may eventually result in acute tubular necrosis by increasing the susceptibility to additional insults by radiographic contrast agents, aminoglycosides, haemorrhage, endotoxinaemia or any other cause of medullary hypoxia. The presence of acute tubular necrosis could partially explain the slow or absent renal recovery in HRS type 1 even after the initiation of vasopressor support. For instance, a recent case study reports full recovery of renal function in dialysis-dependent HRS after 7 weeks of treatment with ornipressin, dopamine and intravenous albumin [39].
The following measures may decrease the incidence of renal failure or HRS in patients with liver disease.
Bacterial Infections Bacterial infections occur in approximately 50% of patients with variceal haemorrhage, and antibiotic prophylaxis improves survival by approximately 10%. Patients who have had a previous episode of SBP have a 68% chance of recurrent infection at 1 year, and this carries a 33% chance of developing renal failure. As bacterial infections are an important cause of renal dysfunction in cirrhotic patients, prophylaxis with antibiotics is recommended in two clinical settings, namely variceal bleeding and a history of previous SBP [40, 41].
To prevent the development of renal failure in patients who develop SBP, it is now recommended that plasma volume expansion should be implemented in these patients by giving 20% albumin (1–1.5 g/kg over 1–3 days) at diagnosis to prevent circulatory dysfunction, renal impairment and mortality. Use of low-salt albumin as fluid replacement in patients undergoing large-volume paracentesis (8 g for each litre of ascitic fluid removed) is known to prevent paracentesis-induced circulatory dysfunction [42–45].
It is important to identify the lowest effective dose of a diuretic for any individual patient, as diuretic-induced renal impairment is seen in approximately 20% of patients with ascites. It develops when the rate of diuresis exceeds the rate of ascites reabsorption, leading to intravascular volume depletion. Diuretic-induced renal impairment is usually moderate and rapidly reversible following diuretic withdrawal.
Patients with cirrhosis and ascites are predisposed to the development of acute tubular necrosis during the use of aminoglycosides, with renal failure occurring in 33% of such patients as against 3–5% in the general population. Another important cause of renal failure is the use of nonsteroidal antiinflammatory drugs (NSAIDs) [46].
The ideal treatment for HRS is liver transplantation; however, because of the long waiting lists in the majority of transplant centres, most patient die before being offered a transplant. There is an urgent need for effective alternative therapies to increase survival chances for patients with HRS until transplantation can be performed. Treatment can be divided into initial management, pharmacological treatment and surgical manoeuvres.
Initial Management Optimise fluid management.
Renal function rarely recovers in the absence of liver recovery. The key goal in the management of these patients is to exclude reversible or treatable lesions (mainly hypovolaemia) and to support the patient until liver recovery or liver transplantation. The treatment of HRS is directed at reversing the haemodynamic changes induced by reduced renal perfusion pressure, stimulated sympathetic nervous system and increased synthesis of humoral and renal vasoconstrictor factors. In cirrhotic patients renal failure is frequently secondary to hypovolaemia (diuretics or gastrointestinal bleeding), NSAIDs or sepsis. Precipitating factors should be recognised and treated and nephrotoxic drugs, discontinued. All patients should be challenged with up 1.5 l of fluid, such as albumin solution or normal saline, to assess the renal response, as many patients with subclinical hypovolaemia will respond to this simple measure. This should be done with careful monitoring to avoid fluid overload. In practice, fluid overload is not usually a problem, as patients with severe liver disease function as ‘fluid sumps’ and their vasculature adapts to accommodate the extra fluid. This has been described by Hadengue et al., who reported increased venous compliance following fluid challenge in advanced cirrhosis [47, 48]. Monitor for sepsis. Evidence of sepsis should be sought in blood, ascitic, cannulae and urine cultures, and nonnephrotoxic broad-spectrum antibiotics should be started regardless of whether such evidence is found, as any delay in effective treatment of undiagnosed infection can increase mortality. In advanced cirrhosis, endotoxins and cytokines play important parts in fostering the hyperdynamic circulation and worsening renal function. Optimise blood pressure. If mean arterial pressure is low (<>
Renal function rarely recovers in the absence of liver recovery. The key goal in the management of these patients is to exclude reversible or treatable lesions (mainly hypovolaemia) and to support the patient until liver recovery or liver transplantation. The treatment of HRS is directed at reversing the haemodynamic changes induced by reduced renal perfusion pressure, stimulated sympathetic nervous system and increased synthesis of humoral and renal vasoconstrictor factors. In cirrhotic patients renal failure is frequently secondary to hypovolaemia (diuretics or gastrointestinal bleeding), NSAIDs or sepsis. Precipitating factors should be recognised and treated and nephrotoxic drugs, discontinued. All patients should be challenged with up 1.5 l of fluid, such as albumin solution or normal saline, to assess the renal response, as many patients with subclinical hypovolaemia will respond to this simple measure. This should be done with careful monitoring to avoid fluid overload. In practice, fluid overload is not usually a problem, as patients with severe liver disease function as ‘fluid sumps’ and their vasculature adapts to accommodate the extra fluid. This has been described by Hadengue et al., who reported increased venous compliance following fluid challenge in advanced cirrhosis [47, 48]. Monitor for sepsis. Evidence of sepsis should be sought in blood, ascitic, cannulae and urine cultures, and nonnephrotoxic broad-spectrum antibiotics should be started regardless of whether such evidence is found, as any delay in effective treatment of undiagnosed infection can increase mortality. In advanced cirrhosis, endotoxins and cytokines play important parts in fostering the hyperdynamic circulation and worsening renal function. Optimise blood pressure. If mean arterial pressure is low (<>
Pharmacological Treatment
All the drugs that have been investigated in HRS have one overriding aim: to increase renal blood flow. This has been achieved either indirectly, by splanchnic vasoconstriction, or directly, using renal vasodilators. One of the principal difficulties has been the lack of agents that act purely on the splanchnic circulation. Drugs that ‘spill over’ into the systemic circulation may actually exacerbate the intense renal vasoconstriction already present. Currently, there is significant enthusiasm for the use of vasoconstrictor agents in HRS. However, the numbers of patients studied have been small, mortality remains high and there have been no randomised placebo-controlled trials. This deficit clearly needs to be addressed but the possibilities are limited by the relative rarity of patients with ‘pure’ HRS without such confounding variables as sepsis and gastrointestinal bleeding. Important aspect of the situation mentioned in these reports are the need for a pressor response to the agents used and the recurrence of abnormal renal function after the cessation of vasoconstrictor therapy. HRS is effectively a marker of poor hepatic function, and these agents are probably best utilised as a bridge to further improvement in liver function following either cessation of alcohol abuse or liver transplantation. Thus, the decision to use vasoconstrictor agents for HRS should be based on whether the patient is a realistic transplant candidate and, if not, whether liver function might improve. Patients who do not satisfy these criteria will be tested unnecessarily, merely prolonging the process of dying when palliative care would be more appropriate. Dopamine. Nonpressor renal doses of dopamine [2–5 μg kg–1 min–1) are frequently prescribed to patients with acute deterioration of renal function. As shown by a recent, large scale, randomised trial, early renal dose dopamine has no role in the prevention of acute renal failure in critically ill patients and does not significantly improve renal function in patients with HRS.At higher doses, dopamine worsens the hyperdynamic circulation by exaggerating splanchnic hyperaemia and increasing portal pressure and may cause tachyarrhythmia. Thus, the use of dopamine monotherapy seems to offer no benefit in HRS. Combination therapy with dopamine and vasopressors has produced inconsistent results in HRS. Because beneficial renal effects have been reported only with vasopressor, and not with dopamine, monotherapy, it seems unlikely that dopamine contributed to renal improvement in these studies [51–54]. Misoprostol. Misoprostol, a synthetic prostaglandin E-1 analogue, has been used to reverse renal vasoconstriction in HRS. Low doses of misoprostol are vasodilatory, natriuretic and diuretic, whereas high-dose misoprostol increases renal vascular tone and inhibits sodium and water excretion. None of the five studies investigating misoprostol in HRS seems to indicate substantial benefit. Improvement of renal function occurred in 1 of these studies, but could also be explained by volume expansion [55]. N-Acetylcysteine. In 1999, the group at the Royal Free Hospital reported their experience with N-acetylcysteine (NAC) for the treatment of HRS [56]. This was based on experimental models of acute cholestasis, in which the administration of NAC resulted in an improvement in renal function. Twelve patients with HRS were treated with intravenous NAC, without any adverse effects, and the survival rates were 67% and 58% at 1 month and 3 months, respectively (this included 2 patients who received liver transplantation after improvement in renal function). The mechanism of action remains unknown, but this interesting study encourages further optimism for medical treatment of a condition that once carried a hopeless diagnosis without liver transplantation. Controlled studies with longer follow-up may help answer these pressing questions. Renal vasoconstrictor antagonists. Saralasin, an antagonist of angiotensin II receptors, was first used in 1979 in an attempt to reverse renal vasoconstriction. Because this drug inhibited the homeostatic response to hypotension commonly observed in patients with cirrhosis, it led to worsening hypotension and deterioration in renal function. Poor results were also observed with phentolamine, an alpha-adrenergic antagonist, highlighting the importance of the sympathetic nervous system in maintaining renal haemodynamics in patients with HRS. Antagonists of endothelin A receptor. A recent case series by Soper et al. reported an improvement in GFR in patients with cirrhosis, ascites and HRS who received an endothelin A receptor antagonist. All patients showed a dosedependent response in the form of improved inulin and para-aminohippurate excretion, RPF and GFR without changes in systemic haemodynamics. These patients were not candidates for liver transplantation and subsequently died. More work is needed to explore this therapeutic approach as a possible bridge to transplantation for patients with HRS [57-59]. Systemic vasoconstrictors. These medications have shown the most promise for treatment of HRS in recent years. Hecker and Sherlock used norepinephrine in 1956 to treat patients with cirrhosis who had HRS, and they were the first to describe an improvement in arterial pressure and urine output. However, no improvement was observed in the biochemical parameters of renal function, and all patients subsequently died. Octapressin, a synthetic vasopressin analogue, was first used in 1970 to treat HRS type 1. RPF and the GFR improved in all patients, all of whom subsequently died of sepsis, gastrointestinal bleeding or liver failure.Because of these discouraging results, the use of alternative vasopressin analogues, particularly ornipressin, attracted attention. Two important studies by Lenz et al. [60, 61] demonstrated that short term use of ornipressin resulted in an improvement in circulatory function and a significant increase in RPF and the GFR. The combination of ornipressin and albumin was subsequently tried by Guevera in patients with HRS [49]. This idea was based on data suggesting that the combination of plasma volume expansion and vasoconstrictors normalised renal sodium and water handling in patients who had cirrhosis with ascites. In this study, 8 patients were originally treated for 15 days with ornipressin and albumin. Treatment had to be discontinued in 4 patients after fewer than 9 days because of complications of ornipressin use that included ischaemic colitis, tongue ischaemia and glossitis. Although a marked improvement in the serum creatinine was observed during treatment, renal function deteriorated on treatment withdrawal. In the remaining 4 patients the improvement in RPF and the GFR was significant and was associated with a lowering of serum creatinine levels. These patients subsequently died, but no recurrence of HRS was observed. Owing to the high incidence of severe adverse effects with ornipressin, the same investigators used another vasopressin analogue with fewer adverse effects, namely terlipressin. In this study, nine patients were treated with terlipressin + albumin for 5–15 days. This treatment was associated with a marked fall in serum creatinine levels and an improvement in mean arterial pressure. Reversal of HRS was noted in seven of the nine patients, and HRS did not recur when treatment was discontinued. No adverse ischemic effects were reported: according to this study, terlipressin with albumin is a safe and effective treatment for HRS [59-62]. Alpha adrenergic agonists.Angeli et al. showed that long-term administration of midodrine (an alpha-adrenergic agonist) and octreotide improved renal function in patients with HRS type 1 [65]. All patients also received albumin, and the results obtained with this approach were compared against those observed with dopamine at nonpressor doses. None of the patients treated with dopamine showed any improvement in renal function, but in all the patients treated with midodrine, octreotide and volume expansion renal function did improve. No adverse effects were reported in these patients. Gulberg et al. treated seven patients who had cirrhosis and HRS type 1 with a combination of ornipressin and dopamine for infusion periods as long as 27 days, but only three of the seven patients survived [62]. This treatment can be used as a bridge to liver transplantation [61, 65]. Aquaretic agents. K-Opioid antagonists inhibit antidiuretic hormone secretion by the neurohypophysis and induce water excretion.Administration of niravoline at doses ranging from 0.5 to 2 mg induced a strong aquaretic response and was well tolerated in 18 cirrhotic patients with preserved renal function, but no data are available on the use of niravoline in patients with HRS.
All the drugs that have been investigated in HRS have one overriding aim: to increase renal blood flow. This has been achieved either indirectly, by splanchnic vasoconstriction, or directly, using renal vasodilators. One of the principal difficulties has been the lack of agents that act purely on the splanchnic circulation. Drugs that ‘spill over’ into the systemic circulation may actually exacerbate the intense renal vasoconstriction already present. Currently, there is significant enthusiasm for the use of vasoconstrictor agents in HRS. However, the numbers of patients studied have been small, mortality remains high and there have been no randomised placebo-controlled trials. This deficit clearly needs to be addressed but the possibilities are limited by the relative rarity of patients with ‘pure’ HRS without such confounding variables as sepsis and gastrointestinal bleeding. Important aspect of the situation mentioned in these reports are the need for a pressor response to the agents used and the recurrence of abnormal renal function after the cessation of vasoconstrictor therapy. HRS is effectively a marker of poor hepatic function, and these agents are probably best utilised as a bridge to further improvement in liver function following either cessation of alcohol abuse or liver transplantation. Thus, the decision to use vasoconstrictor agents for HRS should be based on whether the patient is a realistic transplant candidate and, if not, whether liver function might improve. Patients who do not satisfy these criteria will be tested unnecessarily, merely prolonging the process of dying when palliative care would be more appropriate. Dopamine. Nonpressor renal doses of dopamine [2–5 μg kg–1 min–1) are frequently prescribed to patients with acute deterioration of renal function. As shown by a recent, large scale, randomised trial, early renal dose dopamine has no role in the prevention of acute renal failure in critically ill patients and does not significantly improve renal function in patients with HRS.At higher doses, dopamine worsens the hyperdynamic circulation by exaggerating splanchnic hyperaemia and increasing portal pressure and may cause tachyarrhythmia. Thus, the use of dopamine monotherapy seems to offer no benefit in HRS. Combination therapy with dopamine and vasopressors has produced inconsistent results in HRS. Because beneficial renal effects have been reported only with vasopressor, and not with dopamine, monotherapy, it seems unlikely that dopamine contributed to renal improvement in these studies [51–54]. Misoprostol. Misoprostol, a synthetic prostaglandin E-1 analogue, has been used to reverse renal vasoconstriction in HRS. Low doses of misoprostol are vasodilatory, natriuretic and diuretic, whereas high-dose misoprostol increases renal vascular tone and inhibits sodium and water excretion. None of the five studies investigating misoprostol in HRS seems to indicate substantial benefit. Improvement of renal function occurred in 1 of these studies, but could also be explained by volume expansion [55]. N-Acetylcysteine. In 1999, the group at the Royal Free Hospital reported their experience with N-acetylcysteine (NAC) for the treatment of HRS [56]. This was based on experimental models of acute cholestasis, in which the administration of NAC resulted in an improvement in renal function. Twelve patients with HRS were treated with intravenous NAC, without any adverse effects, and the survival rates were 67% and 58% at 1 month and 3 months, respectively (this included 2 patients who received liver transplantation after improvement in renal function). The mechanism of action remains unknown, but this interesting study encourages further optimism for medical treatment of a condition that once carried a hopeless diagnosis without liver transplantation. Controlled studies with longer follow-up may help answer these pressing questions. Renal vasoconstrictor antagonists. Saralasin, an antagonist of angiotensin II receptors, was first used in 1979 in an attempt to reverse renal vasoconstriction. Because this drug inhibited the homeostatic response to hypotension commonly observed in patients with cirrhosis, it led to worsening hypotension and deterioration in renal function. Poor results were also observed with phentolamine, an alpha-adrenergic antagonist, highlighting the importance of the sympathetic nervous system in maintaining renal haemodynamics in patients with HRS. Antagonists of endothelin A receptor. A recent case series by Soper et al. reported an improvement in GFR in patients with cirrhosis, ascites and HRS who received an endothelin A receptor antagonist. All patients showed a dosedependent response in the form of improved inulin and para-aminohippurate excretion, RPF and GFR without changes in systemic haemodynamics. These patients were not candidates for liver transplantation and subsequently died. More work is needed to explore this therapeutic approach as a possible bridge to transplantation for patients with HRS [57-59]. Systemic vasoconstrictors. These medications have shown the most promise for treatment of HRS in recent years. Hecker and Sherlock used norepinephrine in 1956 to treat patients with cirrhosis who had HRS, and they were the first to describe an improvement in arterial pressure and urine output. However, no improvement was observed in the biochemical parameters of renal function, and all patients subsequently died. Octapressin, a synthetic vasopressin analogue, was first used in 1970 to treat HRS type 1. RPF and the GFR improved in all patients, all of whom subsequently died of sepsis, gastrointestinal bleeding or liver failure.Because of these discouraging results, the use of alternative vasopressin analogues, particularly ornipressin, attracted attention. Two important studies by Lenz et al. [60, 61] demonstrated that short term use of ornipressin resulted in an improvement in circulatory function and a significant increase in RPF and the GFR. The combination of ornipressin and albumin was subsequently tried by Guevera in patients with HRS [49]. This idea was based on data suggesting that the combination of plasma volume expansion and vasoconstrictors normalised renal sodium and water handling in patients who had cirrhosis with ascites. In this study, 8 patients were originally treated for 15 days with ornipressin and albumin. Treatment had to be discontinued in 4 patients after fewer than 9 days because of complications of ornipressin use that included ischaemic colitis, tongue ischaemia and glossitis. Although a marked improvement in the serum creatinine was observed during treatment, renal function deteriorated on treatment withdrawal. In the remaining 4 patients the improvement in RPF and the GFR was significant and was associated with a lowering of serum creatinine levels. These patients subsequently died, but no recurrence of HRS was observed. Owing to the high incidence of severe adverse effects with ornipressin, the same investigators used another vasopressin analogue with fewer adverse effects, namely terlipressin. In this study, nine patients were treated with terlipressin + albumin for 5–15 days. This treatment was associated with a marked fall in serum creatinine levels and an improvement in mean arterial pressure. Reversal of HRS was noted in seven of the nine patients, and HRS did not recur when treatment was discontinued. No adverse ischemic effects were reported: according to this study, terlipressin with albumin is a safe and effective treatment for HRS [59-62]. Alpha adrenergic agonists.Angeli et al. showed that long-term administration of midodrine (an alpha-adrenergic agonist) and octreotide improved renal function in patients with HRS type 1 [65]. All patients also received albumin, and the results obtained with this approach were compared against those observed with dopamine at nonpressor doses. None of the patients treated with dopamine showed any improvement in renal function, but in all the patients treated with midodrine, octreotide and volume expansion renal function did improve. No adverse effects were reported in these patients. Gulberg et al. treated seven patients who had cirrhosis and HRS type 1 with a combination of ornipressin and dopamine for infusion periods as long as 27 days, but only three of the seven patients survived [62]. This treatment can be used as a bridge to liver transplantation [61, 65]. Aquaretic agents. K-Opioid antagonists inhibit antidiuretic hormone secretion by the neurohypophysis and induce water excretion.Administration of niravoline at doses ranging from 0.5 to 2 mg induced a strong aquaretic response and was well tolerated in 18 cirrhotic patients with preserved renal function, but no data are available on the use of niravoline in patients with HRS.
Surgical Manoeuvres
Transjugular intrahepatic portosystemic shunting. It is well documented that portal hypertension plays a central role in the development of refractory ascites and HRS. Earlier studies showed improved renal function after sideto- side portocaval shunting, but at the cost of a high surgical mortality in advanced cirrhosis. The transjugular intrahepatic portosystemic shunt (TIPS) was introduced as a less invasive method of reducing increased portal pressure. Guevarra et al. have investigated hepatic and renal haemodynamic changes after placement of TIPS in patients with HRS. One month after placement of TIPS a marked improvement in renal function was observed, as indicated by a significant reduction in serum creatinine and blood urea nitrogen and increased urine volume, RPF and GFR. These improvements were associated with a reduction in plasma rennin, aldosterone and norepinephrine activity. These changes were statistically significant, albeit less pronounced than observed in a similar group of patients receiving ornipressin and albumin infusions. Renal improvements were more pronounced at 30 days than at 7 days, possibly because of the deleterious effects of contrast media or the resolution of concomitant problems. After TIPS, GFR improved significantly but did not reach normal values, suggesting that TIPS does not correct all mechanisms contributing to HRS. Brensing et al. [65] found a sustained improvement of renal function after TIPS in 31 patients with type 1 or 2 HRS, allowing the discontinuation of haemodialysis in four of seven patients.After TIPS 3-, 6-, 12- and 18-month survival rates were 81%, 71%, 48% and 35%, respectively, in the total patient cohort, with survival in HRS type 1 patients being significantly worse than in the others. The use of TIPS to prolong survival until liver transplantation seems promising [65-68]. Other surgical shunts. Despite the theoretical benefit of improving portal hypertension and thus HRS by means of a portosystemic shunt, only a few scattered case reports have shown any benefit. Currently, particularly with the recent introduction of TIPS, portocaval shunts are not indicated in this setting. Renal replacement therapy. Many clinicians are reluctant to institute renal replacement therapy in advanced cirrhosis, because the outcome is poor unless liver transplantation is a realistic option. Intermittent haemodialysis can be a problem because patients with HRS are prone to develop circulatory and coagulation problems, and biocompatibility is also a problematic issue [69]. In an early study in the United Kingdom 100% mortality was observed in cirrhotic patients with HRS despite early institution of renal support [70]. However, modern renal replacement therapies such as continuous endogenous haemofiltration (CVVH) are certainly capable of prolonging life in patients with type 1 HRS who have not responded to medical therapies or TIPS. Because the underlying hepatic problem persists, the long-term prognosis is grim and treatment should be confined to patients who are candidates for liver transplantation or have a realistic chance of hepatic recovery. The molecular adsorbent recirculating system (MARS) is a modified dialysis method that uses albumin-containing dialysate in a closed-loop secondary circuit for adsorptive removal of albumin-bound toxins. In a randomised study, short-term survival of eight HRS patients treated with MARS was superior to that of five other HRS patients treated with CVVH [71]. In contrast to previous reports on haemodialysis, treatment was well tolerated. Unfortunately, the study was terminated after enrolment of only 13 patients, which makes evaluation of any influence on mortality difficult.Moreover, the control group seems to have received a smaller dialytic dose: creatinine levels were decreased in the MARS group only.Nonetheless, the favourable effects of this system deserve evaluation in a prospective study of adequate power. Liver transplantation. Liver transplantation is the ideal treatment for HRS, but is completely dependent on the availability of Donors. Patients with HRS have a higher risk of postoperative morbidity, early mortality and longer hospitalisation than other transplant recipients.Gonwa et al. [72] reported that at least one third of such patients require haemodialysis postoperatively, with a smaller proportion (5%) requiring long-term dialysis. Because renal dysfunction is common in the first few days after transplantation, avoidance nephrotoxic immunosuppressants is generally recommended until renal function is recovered. However, the GFR gradually improves to an average of 40–50 ml/min by the 6th postoperative week. The systemic and neurohumoral abnormalities associated with HRS also resolve in the 1st postoperative month. Long-term survival rates are excellent, with the survival rate at 3 years approaching approximately 60%. This is only slightly lower than the 70–80% survival rate of transplant recipients without HRS and is markedly better than the survival rate of patients with HRS who do not receive transplants, which is virtually nil at 3 years [73, 74].
Transjugular intrahepatic portosystemic shunting. It is well documented that portal hypertension plays a central role in the development of refractory ascites and HRS. Earlier studies showed improved renal function after sideto- side portocaval shunting, but at the cost of a high surgical mortality in advanced cirrhosis. The transjugular intrahepatic portosystemic shunt (TIPS) was introduced as a less invasive method of reducing increased portal pressure. Guevarra et al. have investigated hepatic and renal haemodynamic changes after placement of TIPS in patients with HRS. One month after placement of TIPS a marked improvement in renal function was observed, as indicated by a significant reduction in serum creatinine and blood urea nitrogen and increased urine volume, RPF and GFR. These improvements were associated with a reduction in plasma rennin, aldosterone and norepinephrine activity. These changes were statistically significant, albeit less pronounced than observed in a similar group of patients receiving ornipressin and albumin infusions. Renal improvements were more pronounced at 30 days than at 7 days, possibly because of the deleterious effects of contrast media or the resolution of concomitant problems. After TIPS, GFR improved significantly but did not reach normal values, suggesting that TIPS does not correct all mechanisms contributing to HRS. Brensing et al. [65] found a sustained improvement of renal function after TIPS in 31 patients with type 1 or 2 HRS, allowing the discontinuation of haemodialysis in four of seven patients.After TIPS 3-, 6-, 12- and 18-month survival rates were 81%, 71%, 48% and 35%, respectively, in the total patient cohort, with survival in HRS type 1 patients being significantly worse than in the others. The use of TIPS to prolong survival until liver transplantation seems promising [65-68]. Other surgical shunts. Despite the theoretical benefit of improving portal hypertension and thus HRS by means of a portosystemic shunt, only a few scattered case reports have shown any benefit. Currently, particularly with the recent introduction of TIPS, portocaval shunts are not indicated in this setting. Renal replacement therapy. Many clinicians are reluctant to institute renal replacement therapy in advanced cirrhosis, because the outcome is poor unless liver transplantation is a realistic option. Intermittent haemodialysis can be a problem because patients with HRS are prone to develop circulatory and coagulation problems, and biocompatibility is also a problematic issue [69]. In an early study in the United Kingdom 100% mortality was observed in cirrhotic patients with HRS despite early institution of renal support [70]. However, modern renal replacement therapies such as continuous endogenous haemofiltration (CVVH) are certainly capable of prolonging life in patients with type 1 HRS who have not responded to medical therapies or TIPS. Because the underlying hepatic problem persists, the long-term prognosis is grim and treatment should be confined to patients who are candidates for liver transplantation or have a realistic chance of hepatic recovery. The molecular adsorbent recirculating system (MARS) is a modified dialysis method that uses albumin-containing dialysate in a closed-loop secondary circuit for adsorptive removal of albumin-bound toxins. In a randomised study, short-term survival of eight HRS patients treated with MARS was superior to that of five other HRS patients treated with CVVH [71]. In contrast to previous reports on haemodialysis, treatment was well tolerated. Unfortunately, the study was terminated after enrolment of only 13 patients, which makes evaluation of any influence on mortality difficult.Moreover, the control group seems to have received a smaller dialytic dose: creatinine levels were decreased in the MARS group only.Nonetheless, the favourable effects of this system deserve evaluation in a prospective study of adequate power. Liver transplantation. Liver transplantation is the ideal treatment for HRS, but is completely dependent on the availability of Donors. Patients with HRS have a higher risk of postoperative morbidity, early mortality and longer hospitalisation than other transplant recipients.Gonwa et al. [72] reported that at least one third of such patients require haemodialysis postoperatively, with a smaller proportion (5%) requiring long-term dialysis. Because renal dysfunction is common in the first few days after transplantation, avoidance nephrotoxic immunosuppressants is generally recommended until renal function is recovered. However, the GFR gradually improves to an average of 40–50 ml/min by the 6th postoperative week. The systemic and neurohumoral abnormalities associated with HRS also resolve in the 1st postoperative month. Long-term survival rates are excellent, with the survival rate at 3 years approaching approximately 60%. This is only slightly lower than the 70–80% survival rate of transplant recipients without HRS and is markedly better than the survival rate of patients with HRS who do not receive transplants, which is virtually nil at 3 years [73, 74].
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