Renal duplex Doppler ultrasonography: a noninvasive predictor of kidney dysfunction and hepatorenal failure in liver disease

Seeing and Sensing the Hepatorenal Syndrome (HRS): The Growing Role of Ultrasound-Based Techniques as Non-Invasive Tools for the Diagnosis of HRS

More than half of patients hospitalized with liver cirrhosis are dealing with an episode of acute kidney injury; the most severe pattern is hepatorenal syndrome due to its negative prognosis. The main physiopathology mechanisms involve renal vasoconstriction and systemic inflammation. During the last decade, the definition of hepatorenal syndrome changed, but the validated criteria of diagnosis are still based on the serum creatinine level, which is a biomarker with multiple limitations. This is the reason why novel serum and urinary biomarkers have been intensively studied in recent years. Meanwhile, the imaging studies that use shear wave elastography are using renal stiffness as a surrogate for an early diagnosis. In this article, we focus on the physiopathology definition and highlight the novel tools used in the diagnosis of hepatorenal syndrome.

Peritransplant Renal Dysfunction in Liver Transplant Candidates

Renal function is intricately tied to Model for End-Stage Liver Disease score and overall prognosis among patients with cirrhosis. The estimation of glomerular filtration rate (GFR) and etiology of renal impairment are even more magnified among cirrhotic patients in the period surrounding liver transplantation. Novel biomarkers including cystatin C and urinary neutrophil gelatinase-associated lipocalin have been demonstrated to more accurately assess renal dysfunction and aid in the diagnosis of competing etiologies. Accurately identifying the severity and chronicity of renal dysfunction among transplant candidates is an imperative component with respect to stratifying patients toward simultaneous liver-kidney transplantation versus liver transplantation alone.

Can we predict early renal impairment in pediatric cirrhosis?

AIMS

Published literature on renal dysfunction (RD) in pediatric cirrhosis are limited. We aimed to detect early RD in cirrhotic children by renal resistive index (RI) and plasma aldosterone (PA). We evaluated the effects of large-volume paracentesis (LVP) and albumin infusion on the same.

METHODS

Non-azotemic cirrhotic children with tense ascites (undergoing LVP with albumin infusion) were prospectively enrolled. Blood biochemistry and doppler ultrasonography for RI and PA were measured at regular intervals. RI >0.7 was considered as RD. Outcomes were noted at D90 and 1 year. Chronic liver disease children without ascites were included as controls.

RESULTS

Of the 99 cirrhotic children, tense ascites (n=51) had higher baseline RI than controls (n=48) (p<0.001). Overall, baseline RD was observed in 32% and was significantly higher in tense ascites compared to controls (59% vs. 4%, p<0.001). Tense ascites with RD at admission had higher chances of acute kidney injury (AKI) (p=0.009), ascites recurrence (p=0.043), hospital readmission (p=0.048), and mortality (p=0.009) compared to patients without RD by D90. Significant reduction in RI was noted at 48 h, D7, D30, and D90 compared to baseline after LVP with albumin. Pediatric End-stage Liver Disease (PELD) score and PA had a strong positive correlation with baseline RI (R²=0.51, R²=0.47). Using multivariate analysis, PELD score and PA were predictors of AKI (odds ratio [OR]: 1.14; 95% confidence interval [CI]: 1.04-1.24; p=0.003) and mortality (OR: 1.82; 95% CI: 1.22-2.72; p=0.004), respectively.

CONCLUSIONS

Abnormal baseline RI can be used as an early predictor of RD and predict long-term renal ouctomes in pediatric cirrhosis. Baseline RI correlated well with the severity of liver disease and PA. Paracentesis and albumin infusion effectively reduced RI.

Ultrasonography in the diagnosis of complications in patients with portal hypertension

This review focuses on ultrasonography (US) to diagnose patients with complications in portal hypertension. Clinicians first use US to evaluate patients with suspected portal hypertension, because US is quick, simple, and radiation free. US is necessary for grading and performing paracentesis for ascites. Doppler US-based detection of reverse splanchnic vein flow or the presence of a spontaneous portosystemic shunt is highly specific in patients with cirrhosis. Since it is important to estimate spleen size in patients with portal hypertension, spleen size is usually measured by US. Spleen volume can be more accurately measured with 3D-US. Estimation of viable residual splenic volume after partial splenic embolization should be limited to cases with total splenic volume less than 1000 ml. Portal vein thrombosis is often detected during the US examination performed when symptoms first appear or during the follow-up. Two-dimensional transthoracic echocardiography is an excellent noninvasive screening test in patients with pulmonary portal hypertension who can undergo it. By measuring the maximum and minimum diastolic blood flow velocities in the renal arteries using renal color Doppler US, the pulsatility index (PI) and resistive index (RI) can be calculated. The PI and RI in cirrhotic patients were significantly higher than those in healthy subjects and patients with chronic hepatitis, and showed a significant positive correlation with the Child-Pugh Score. In conclusion, US is an essential tool for the diagnosis and treatment of patients with portal hypertension.

Renal arterial resistance index among subjects with liver cirrhosis in a Nigerian population

PURPOSE

To describe the relationship between renal artery resistance index (RARI) and liver function based on Child-Pugh system among patients with liver cirrhosis (LC) in Southwest Nigeria.

METHODS

About 50 patients with LC and 50 controls were consecutively recruited into this prospective comparative case control study. Each LC patient was classed based on Child-Turcotte-Pugh (CTP) system after relevant tests. Subjects underwent abdominal ultrasonography with triplex Doppler examination of the right kidney to obtain RARI.

RESULTS

About 50 cirrhotic and 50 controls completed the study. Age range of cirrhotic subjects was 19-69 years (mean ± SD = 47.5 ± 13.3) while that of controls was 18-69 years (46.9 ± 15.0). RARI was higher (P = <.001) in patients with LC (0.68) than in controls (0.57). RARI was also significantly higher (P = <.001) in cirrhotic subjects in CTP class C (0.72) than in those in classes B (0.66) and A (0.58). Additionally, RARI showed significant correlation with CTP total score (r = .662; P = <.001), serum bilirubin (r = .297; P = .036), serum albumin (r = -.494; P = <.001), serum sodium (r = -.369; P = .008), Model for End Stage Liver Disease (MELD) score (r = .316; P = .026) and MELD-Na score (r = .470; P = .001). RARI showed no significant relationship with serum creatinine (r = .110; P = .445) and blood urea nitrogen (r = .112; P = .437).

CONCLUSION

Liver cirrhosis is associated with renovascular changes which manifest as increased resistance in the renal arteries. RARI is a useful noninvasive tool for the assessment of these changes and should be done routinely in the evaluation of patients with LC.

Role of renal Duplex ultrasonography in evaluation of hepatorenal syndrome

Background

Hepatorenal syndrome is a potentially fatal complication of advanced liver disease. Markers for early diagnosis and identification of high-risk patients are lacking. Our aim was to evaluate the role of renal Duplex ultrasonography in the diagnosis and early prediction of hepatorenal syndrome. This study included 50 patients. Clinical assessment, liver function tests, hepatitis C virus antibody, kidney function tests, and abdominal and renal color Duplex ultrasound were done to all subjects.

Results

Univariate regression analysis for hepatorenal syndrome showed a statistically significant positive correlation with the Model For End-Stage Liver Disease score (p-value <0.0001) and renal artery hilum resistivity index (p-value = 0.0017). Logistic multivariable regression analysis proved that the renal artery hilum resistivity index was an independent predictor of hepatorenal syndrome. Renal artery hilum resistivity index can be used as a predictor of hepatorenal syndrome with 100% sensitivity and 66.7% specificity with a cut-off value > 0.77.

Conclusion

The renal resistive index could be a good predictor of hepatorenal syndrome.

Renal intraparenchymal resistive index: the ultrasonographic answer to many clinical questions

The use of renal resistive indices (RRIs) for the study of renal microcirculation has in the past been proposed for the identification of renal organ damage or even to specifically identify injury to some areas of the renal parenchyma. Nevertheless, according to the most recent evidences from literature this organ-based conception of RRIs has been proven to be partial and unable to explain the RRIs variations in clinical settings of sepsis or combined organ failure of primitively extrarenal origin or, more generally, the deep connection between RRIs and hemodynamic factors such as compliance and pulsatility of the large vessels. The aim of this review is to explain the physiopathological basis of RRIs determination and the most common interpretative errors in their analysis. Moreover, through a comprehensive vision of these Doppler indices, the traditional and emerging clinical application fields for RRIs are discussed.

Artificial Liver and Renal Support System for Cynomolgus Monkeys with Surgery-Induced Acute Renal Failure: A Preclinical Study

Renal dysfunction is one of the most common complications of liver cirrhosis and is associated with increased morbidity and mortality. However, no available technology can simultaneously support liver and renal function in these patients. The aim of this study was to evaluate the safety and efficacy of an artificial liver and renal support system in cynomolgus monkeys with surgery-induced ARF. The ARF model was established by ligature of bilateral renal arteries in eight cynomolgus monkeys, which were randomly divided into a treatment group (n = 4) and control group (n = 4). Biochemical indexes were determined before and after surgery. Blood endotoxin levels, biochemical indexes, and bacterial cultures were assessed at 0, 3, and 6 h during treatment. System pressures and vital signs were recorded at 1 h intervals. Pathological examination was performed after death. ARF was successfully established, based on significant elevation of biochemical indexes and pathological examination. The treatment group had significantly reduced biochemical indexes relative to the control group. Measurement of blood endotoxins and aerobic and anaerobic bacteria cultures indicated no bacterial growth. The system pressures and vital signs were stable during treatment. The results indicate that our support system for the treatment of cynomolgus monkeys with surgery-induced acute renal failure is safe and effective.

[Prevention of acute kidney injury in critically ill patients : Recommendations from the renal section of the DGIIN, ÖGIAIN and DIVI]

BACKGROUND

Acute kidney injury (AKI) has both high mortality and morbidity.

OBJECTIVES

To prevent the occurrence of AKI, current recommendations from the renal section of the DGIIN (Deutschen Gesellschaft für Internistische Intensivmedizin und Notfallmedizin), ÖGIAIN (Österreichischen Gesellschaft für Internistische und Allgemeine Intensivmedizin und Notfallmedizin) and DIVI (Deutschen Interdisziplinären Vereinigung für Intensiv- und Notfallmedizin) are stated.

MATERIALS AND METHODS

The recommendations stated in this paper are based on the current Kidney Disease Improving Global Outcomes (KDIGO) guidelines, the published statements of the "Working Group on Prevention, AKI section of the European Society of Intensive Care Medicine" and the expert knowledge and clinical experience of the authors.

RESULTS

Currently there are no approved clinically effective drugs for the prevention of AKI. Therefore the mainstay of prevention is the optimization of renal perfusion by improving the mean arterial pressure (>65 mm Hg, higher target may be considered in hypertensive patients). This can be done by vasopressors, preferably norepinephrine and achieving or maintaining euvolemia. Hyperhydration that can lead to AKI itself should be avoided. In patients with maintained diuresis this can be done by diuretics that are per se no preventive drug for AKI. Radiocontrast enhanced imaging should not be withheld from patients at risk for AKI; if indicated, however, the contrast media should be limited to the smallest possible volume.

Dual Organ Duel: The Hepatorenal Axis

Recent developments in our understanding of the pathogenesis of kidney disease in the setting of liver failure have highlighted that kidney injury, rather than occurring in isolation, is a marker of systemic disease and poor prognosis. The differential diagnosis of kidney disease associated with liver failure is broader than formerly described and new biopsy data, along with better acute kidney injury classification tools, have increased appreciation for distinct pathophysiological mechanisms. Evidence suggests that acute kidney injury contributes to worsening hepatic failure by directly injuring hepatic cells and by imposing restrictions on therapeutic strategies for portal hypertension. Furthermore, kidney injury limits the use of various therapeutic agents and increases their toxicity due to altered pharmacodynamics. A greater appreciation of CKD in this population is also overdue because management decisions are affected and increased vigilance may avoid further kidney injury. A multidisciplinary approach to kidney injury in the setting of liver failure will enable targeted therapeutic strategies that are safe and effective and serve to guide further research, while limiting clinical potential for harm. Finally, new hepatitis C antiviral therapies promise to change the landscape of liver failure, and a discussion of kidney risk factors and antiviral therapy of patients with kidney disease and hepatitis C is worthwhile.

Systematic review with meta-analysis: vasoactive drugs for the treatment of hepatorenal syndrome type 1

BACKGROUND

Hepatorenal syndrome type 1 (HRS1) is a functional, rapidly progressive, potentially reversible form of acute kidney injury occurring in patients with cirrhosis. Characterised by intense renal arterial vasoconstriction, it carries a very poor prognosis. There is a significant unmet need for a widely approved, safe and effective pharmacological treatment.

AIM

To re-evaluate efficacy and safety of pharmacological treatments for HRS1, in the light of recently published randomised controlled trials (RCTs).

METHODS

MEDLINE (OvidSP), EMBASE, PubMed and Cochrane registers were searched for RCTs reporting efficacy and adverse events related to pharmacological treatment of HRS1. Search terms included: 'hepatorenal syndrome', 'terlipressin', 'noradrenaline', 'octreotide', 'midodrine', 'vasopressin', 'dopamine', 'albumin' and synonyms. Comparison of vasoactive drugs vs. placebo/no treatment, and two active drugs were included. Meta-analysis was performed for HRS1 reversal, creatinine improvement, mortality and adverse events.

RESULTS

Twelve RCTs enrolling 700 HRS1 patients were included. Treatment with terlipressin and albumin led to HRS1 reversal more frequently than albumin alone or placebo (RR: 2.54, 95% CI: 1.51-4.26). Noradrenaline was effective in reversing HRS1, but trials were small and nonblinded. Overall, there was mortality benefit with terlipressin (RR: 0.79, 95% CI: 0.63-1.01), but sensitivity analysis including only trials with low risk of selection bias weakened this relationship (RR: 0.87, 95% CI: 0.71-1.06). Notably, there was a significant risk of adverse events with terlipressin therapy (RR: 4.32, 95% CI: 0.75-24.86).

CONCLUSIONS

Terlipressin treatment is superior to placebo for achieving HRS1 reversal, but mortality benefit is less clear. Terlipressin is associated with significant adverse events, but infusion regimens may be better tolerated. There is continued need for safe and effective treatment options for hepatorenal syndrome.

Resistive index for kidney evaluation in normal and diseased cats

OBJECTIVES

The objectives were to determine the resistive index (RI) in normal cats and in cats with various renal diseases, and to evaluate the effect of age on RI.

METHODS

The subjects were cats that had ultrasonography (US) of the urinary tract and RI measurement at our centre between January 2003 and April 2014. Based on clinical evaluation, biochemical and haematological tests, urinalysis and US, the cats were classified as healthy or diseased. RI measurements were made from the interlobar or arcuate arteries. Data were analysed for differences between the right and the left kidney, the two sexes, different age groups in healthy cats, and between healthy and diseased cats.

RESULTS

A total of 116 cats (68 males, 48 females) were included: 24 healthy and 92 diseased. In the healthy cats, RI (mean ± SD) differed significantly (P = 0.02) between the right kidney (0.54 ± 0.07) and the left kidney (0.59 ± 0.08). For the left kidney, RI was significantly higher in cats with chronic kidney disease (0.73 ± 0.12) and acute kidney injury (0.72 ± 0.08) (P = 0.0008). For the right kidney, RI was significantly higher in cats with chronic kidney disease (0.72 ± 0.11), acute kidney injury (0.74 ± 0.08), polycystic kidney disease (0.77 ± 0.11) and renal tumour (0.74 ± 0.001) (P <0.0001). There was no significant effect on RI value in either kidney in terms of age or sex.

CONCLUSIONS AND RELEVANCE

RI could be considered a valuable diagnostic tool in cats, useful in the differential diagnosis of diffuse renal diseases. While it does not change with the age of the cat, ultrasonographers should be aware that RI may differ between the two kidneys.

Kidney Failure and Liver Allocation: Current Practices and Potential Improvements

In February 2002, the United Network for Organ Sharing implemented a system for prioritizing candidates for liver transplantation that was based on the risk of 90-day mortality as determined by the Model for End-Stage Liver Disease (MELD) score. As the MELD score is driven in part by serum creatinine as a marker of kidney function, the prevalence of kidney dysfunction and failure in patients with end-stage liver disease at the time of listing and at transplantation has steadily risen. In this review, we discuss current practices in liver transplantation in patients with kidney dysfunction focusing briefly on the decision to perform simultaneous liver-kidney transplantation. We then discuss pitfalls to the current practices of liver transplantation in patients with kidney dysfunction. We conclude by discussing potential improvements to current practices including the use of the MELD-Na score, alternatives to creatinine and creatinine-based equation for estimating kidney function, and the use of intraoperative kidney replacement therapy during liver transplantation.

Resistive index and MELD-Na: nephrologic monitoring in cirrhotic patients awaiting liver transplantation

Renal dysfunction in cirrhotic patients is primarily related to disturbances in circulatory function. In decompensated cirrhosis, ascites and water retention are associated with development of dilutional hyponatremia. The arterial resistive index (RI) is a measure of resistance to arterial flow within the renal vascular bed. Hyponatremia is an independent predictor of mortality in patients with ascites. The aim of this study was to evaluate intrarenal RI in end-stage liver disease (ESLD) patients awaiting liver transplantation (LT) and its association with renal and hepatic function as assessed by Model for End-Stage Liver Disease (MELD) and MELD-Na scores. We evaluated 40 cirrhotic patients (23 males, 17 females) awaiting LT from January 2009 to January 2012. Twenty-six of the 40 patients (65%) showed a renal RI ≥ 0.70, the normal value according to standard reported evaluations. Patients with RI ≥ 0.70 showed significantly higher MELD and MELD-Na scores as well as greater higher serum creatinine and lower serum sodium concentrations compared with subject displaying RI <0.70. The most relevant result of our study was the strong association between elevated renal RI in ESLD patients and advanced liver dysfunction, as demonstrated by MELD and MELD-Na scores, hyponatremia, ascites, and acute renal failure episodes. In conclusion, this study suggested that intrarenal RI assessment should be considered in the clinical and nephrologic monitoring of cirrhotic patients awaiting LT.

Doppler assessment of splanchnic arterial flow in patients with liver cirrhosis: correlation with ammonia plasma levels and MELD score

PURPOSE

To assess the clinical significance of blood flow velocity and resistance index (RI) in the visceral arteries of patients with liver cirrhosis with respect to plasma ammonia (NH3) level and liver function.

METHODS

We included 80 patients with liver cirrhosis (58 men) and 20 healthy controls (11 men). Duplex Doppler ultrasonography was used to assess flow velocity and RI in the hepatic (HA), right (RRA), and left renal (LRA), and splenic (SA) (LA) artery. Plasma NH3 was measured by biochemistry. Liver function was assessed by MELD score (model of end-stage liver disease).

RESULTS

HA, LRA, and SA systolic flow velocities were greater, whereas RRA diastolic velocity was lower in patients with liver cirrhosis than in controls RI was higher in LRA, RRA, SA, and HA in patients with liver cirrhosis than in controls. NH3 levels were significantly elevated in all patients with liver cirrhosis (p < 0.05) and significantly correlated with RI of RRA, LRA, and SA.

CONCLUSION

We found greater renal, hepatic, and LA RI in patients with liver cirrhosis than in healthy controls. The correlation we found between elevated renal artery RI (≥0.70) and MELD score emphasizes the risk of renal dysfunction during progression of liver cirrhosis.

Hepatorenal syndrome: are we missing some prognostic factors?

BACKGROUND

Hepatorenal syndrome (HRS) is the functional renal failure associated with advanced cirrhosis and has also been described in fulminant hepatic failure. Without liver transplantation its prognosis is dismal. Our study included patients with type 1 HRS associated with cirrhosis, who were not liver transplant candidates.

AIM

To identify variables associated with improved survival.

METHODS

Sixty-eight patients fulfilled the revised Ascites Club Criteria for type 1 HRS. None of them was suitable for liver transplantation. All the patients were treated with combinations of: albumin, midodrine and octreotide, pressors, and hemodialysis.

RESULTS

Median survival was 13 days for the whole group. Survival varied with the end-stage liver disease (ESLD) etiology: autoimmune, 49 days, cardiac cirrhosis, 22 days, idiopathic, 15.5 days, viral, 15 days, hepatitis C and alcohol, 14.5 days, alcohol 8 days, and neoplasia 4 days (p = 0.048). Survival of HRS associated with alcoholic liver disease versus other etiologies was not statistically significant (p = 0.1). Increased serum creatinine (p = 0.02) and urinary sodium 6-10 mEq/l (p = 0.027) at the initiation of therapy were prognostic factors for mortality. HRS treatment modalities (p = 0.73), use of dialysis (p = 0.56), dialysis modality (p = 0.35), use of vasopressors (p = 0.26), pre-existing renal disease (p = 0.49), gender (p = 0.90), and age (p = 0.57) were not associated with survival.

CONCLUSIONS

We report for the first time ESLD etiology as a prognostic factor for survival. The renal function (expressed as serum creatinine) and urinary Na (<5 mEq/l) at the time of diagnosis were found to be associated with survival, suggesting that early treatment might increase survival.

The impact of visit-to-visit variability in blood pressure on renal function

Hypertension is an important risk factor for cardiovascular diseases such as chronic kidney disease. It is still not fully understood how blood pressure impacts the kidneys. In this study, we aimed to establish the significance of visit-to-visit variability in blood pressure for renal function. We analyzed 143 consecutive patients undergoing renal Doppler ultrasonography in our hospital ward and measured blood pressure at outpatient visits six or more times. We analyzed the correlation between visit-to-visit variability in blood pressure and multiple clinical parameters, including albuminuria and resistive index evaluated by renal Doppler ultrasonography, which is thought to be a good indicator of renal vascular resistance. Subjects with higher variability in systolic blood pressure showed a significantly higher prevalence rate of clinical albuminuria and microalbuminuria, and showed significantly higher resistive index. Stepwise multiple regression analysis showed that variability in systolic blood pressure was a significant risk factor for higher resistive index, independent of other renal risk factors. Visit-to-visit variability in blood pressure correlates significantly with renal function and renal arteriosclerotic change. This parameter could provide additional information about renal arteriosclerotic change independent of estimated glomerular filtration rate and albuminuria, and should be considered a therapeutic target for renal protection.

Severe hepatotoxicity and probable hepatorenal syndrome associated with sulfadiazine

PURPOSE. The case of a patient who developed hepatorenal syndrome during treatment with sulfadiazine for toxoplasmosis retinitis is reported.

SUMMARY

A 20-year-old Caucasian woman weighing 59 kg was admitted to the infectious diseases ward of a hospital in May 2009 with nausea, vomiting, and jaundice. In March 2009, she was diagnosed with toxoplasmosis retinitis and received sulfadiazine 3 g daily, pyrimethamine 50 mg daily, leucovorin 15 mg daily, and prednisolone 75 mg daily; she continued these medications for three weeks. After the development of gastrointestinal symptoms, she stopped taking the prescribed medications (five days before hospital admission). One day before hospital admission, her skin appeared jaundiced. At the time of admission, the patient had high transaminase levels, hyperbilirubinemia, abnormal prothrombin time and International Normalized Ratio values, and clinical evidence of acute fulminant hepatitis complicated by hepatorenal syndrome. Autoimmune hepatitis was excluded as a cause of her hepatotoxicity, as was Wilson's disease, herpes simplex virus, cytomegalovirus, hepatitis A virus, hepatitis E virus, and Epstein-Barr virus. She was diagnosed with probable drug-related fulminant hepatitis, presumably caused by sulfadiazine treatment. Lactulose 20 g was started for the prevention of encephalopathy. She received phytonadione 10 mg daily for three consecutive days, ranitidine 50 mg thrice daily, ciprofloxacin 250 mg twice daily, and acetylcysteine 600 mg thrice daily. The patient underwent hemodialysis five times during her hospital stay. Her symptoms gradually improved, and she was discharged on hospital day 20.

CONCLUSION

Probable hepatorenal syndrome requiring hemodialysis occurred in a patient receiving sulfadiazine for the treatment of toxoplasmosis retinitis.

Balancing volume resuscitation and ascites management in cirrhosis

PURPOSE OF REVIEW

Patients with cirrhosis have total extracellular fluid overload but central effective circulating hypovolaemia. The resulting neurohumoral compensatory response favours the accumulation of fluids into the peritoneal cavity (ascites) and may hinder renal perfusion (hepatorenal syndrome). Their deranged systemic haemodynamics (hyperdynamic circulatory syndrome) is characterized by elevated cardiac output with decreased systemic vascular resistance and low blood pressure.

RECENT FINDINGS

Molecular and biological mechanisms determining cirrhosis-induced haemodynamic alterations are progressively being elucidated. The need for a goal-directed assessment of volume resuscitation (especially with volumetric techniques) in patients with cirrhosis is becoming more and more evident. The role of fluid expansion with albumin and the use of splanchnic vasopressors in a variety of cirrhosis-related conditions has recently been investigated.

SUMMARY

The response to fluid loading in patients with advanced cirrhosis is abnormal, primarily resulting in expansion of their noncentral blood volume compartment. Colloid solutions, in particular albumin, are best used in these patients. Albumin may be effective in preventing the haemodynamic derangements associated with large-volume paracentesis (paracentesis-induced circulatory dysfunction), in preventing renal failure during spontaneous bacterial peritonitis and, in association with splanchnic vasopressors, in caring for patients with the hepatorenal syndrome.

Determination of intrarenal resistance index (RI) in patients with multiple myeloma

Background

Renal impairment is a common complication of multiple myeloma occuring in up to 50% of patients at some stage in their disease. Due to occurrence of cast nephropathies we hypothesized circulatory dysregulation (vasoconstriction) in the kidneys with measurable elevation of the resistance index among these patients which would have a diagnostic impact.

Subjects and methods

36 patients with treated multiple myeloma (21 females, 15 males, mean age 61.6 ± 8.5 years) were prospectively examined by conventional abdominal ultrasound with focussed investigation of the kidneys. First, length of the organs, parenchymal width and characterization of parenchymal echogenicity were determined. Then, intrarenal RI values were measured in segmental and arcuate arteries, respectively, in both kidneys. Additionally, serum creatinine, BUN and GFR of each patient were evaluated. RI values were compared to values of 78 healthy control subjects.

Results

Mean renal RI was 0.68 ± 0.07 which was slightly higher than in controls with 0.62 ± 0.05, but without statistical significance. Due to the laboratory analyses patients were subdivided in those with normal (group 1, n = 21) and those with impaired (group 2, n = 15) renal function. In both groups kidney size and parenchymal width were normal. Significant more group 2 patients (60%) revealed hyperechogenic par enchyma than group 1 patients (24%) (p < 0.01). Mean renal RI indices were 0.67 ± 0.06 (right) and 0.69 ± 0.06 (left) in group 1 patients and 0.71 ± 0.08 (right) and 0.71 ± 0.07 (left) in group 2 patients and showed no significant difference (p = 0.06 and 0.15).

Conclusion

Renal RI values are not significantly elevated in patients with multiple myeloma even in those with renal impairment so that no hints to a relevant vasoconstriction could be evaluated. RI seems not to be a relevant parameter for the diagnosis of cast nephro pathy of multiple myeloma patients. Routinely performed ultrasound examination should be more focussed on the qualification of parenchymal echogenicity.

The evaluation of renal function and disease in patients with cirrhosis

The MELD score has shown that, besides markers of liver function, serum creatinine has a strong prognostic value in cirrhosis. However, even though creatinine has a good prognostic value, it is an inaccurate marker of renal function in cirrhosis. Creatinine and creatinine-based equations tend to overestimate glomerular filtration rate (GFR), and creatinine clearance from timed urine collection also overestimates GFR. Hence, clearance of exogenous markers such as iohexol remains the only reliable method for assessing precisely GFR in cirrhosis. Whereas these investigations are limited by their costs and complexity, and they can hardly be repeated at short intervals, serum cystatin C could be an alternative, although it needs further validation. Accurate markers and/or specific equations are therefore still needed to assess GFR in cirrhotic patients. Pre-renal failure and hepatorenal syndrome (HRS) are the main causes of acute renal failure in cirrhosis. Both result from decreased renal blood flow and both can result in acute tubular necrosis. HRS is not always fully reversible with liver transplantation possibly due to underlying chronic kidney damage. A number of cirrhotic patients with acute renal failure may also have chronic kidney damage ("acute-on-chronic renal failure"); furthermore, cirrhotic patients frequently have co-morbidities such as diabetes that may result in chronic impairment in renal function. Since conventional urinary markers are biased in cirrhosis, a biopsy is the only way to document and quantify renal lesions; moreover, transvenous route should be preferred to percutaneous route. In candidates for transplantation, attention should therefore be focused on vascular lesions which may represent a risk factor for nephrotoxicities induced by calcineurin-inhibitors.

Non-invasive evaluation of liver cirrhosis using ultrasound

Ultrasound (US) is essential in both assessment of the potentially cirrhotic liver and surveillance of selected patients with chronic hepatitis as liver biopsy can be misleading or inaccurate in up to 25% of cases. Various techniques are already in routine use, such as grey-scale imaging, Doppler US, and contrast-enhanced US (CEUS), while newer techniques such as elastography and hepatic vein transit time (HVTT) have the potential to exclude patients without significant fibrosis or cirrhosis; however, they are operator dependent and require specific software. Grey-scale imaging may demonstrate changes, such as volume redistribution, capsule nodularity, parenchymal nodularity, and echotexture changes. The Doppler findings in the hepatic and portal veins, hepatic artery, and varices allow assessment of liver cirrhosis. However, the operator needs to be aware of limitations of these techniques. Low mechanical index CEUS plays an important role in the assessment of complications of cirrhosis, such as hepatocellular carcinoma and portal vein thrombus. Optimized US technique is crucial for accurate diagnosis of the cirrhotic liver and its complications.

Renal resistive index and long-term outcome in chronic nephropathies

PURPOSE

To assess the clinical validity of renal resistive index (RI) to determine prognosis and guide therapy over a long-term follow-up in patients with chronic nephropathies and to verify the commonly used threshold value of 0.70.

MATERIALS AND METHODS

Of patients referred to the nephrology center since 1995, 177 were initially enrolled and 86 were followed up for RI and renal function annually for 2-11 years (mean, 5.93 years +/- 2.92 [standard deviation]). All patients gave informed consent for the institutional review board-approved study. Correlations were determined between initial RI and age, estimated glomerular filtration rate (eGFR), proteinuria, hematuria, blood pressure, and biopsy scores. The sample was categorized in four groups on the basis of whether initial values of RI and eGFR were normal, and progression to renal failure was compared. With grouping of the sample by using initial RI (< or =0.61, 0.62-0.69, and > or =0.70), Kaplan-Meier analysis was used to obtain survival curves.

RESULTS

Initial RI correlated with final eGFR (R = -0.4, P < .001), systolic blood pressure (R = 0.39, P < .001), proteinuria (R = 0.28, P = .009), and age (R = 0.28, P = .007). In stepwise multiple regression analysis, RI emerged as the only independent risk factor for the progression to renal failure (P < .001). Among the four groups of patients with different initial RIs and eGFRs, the group with an initial RI of 0.70 or higher showed a worse outcome, independent of initial eGFR. In the Kaplan-Meier analysis by using initial RI, only the group with a value of 0.70 or higher showed a rapid decline of renal function (>50% decrease in eGFR in 6 years).

CONCLUSION

An RI of 0.70 or higher is predictive of an unfavorable outcome in patients with chronic nephropathies.

The role of ultrasonography in the study of medical nephropathy

Diagnostic techniques in nephrology include clinical history, physical examination, laboratory tests, scintigraphy, diagnostic imaging techniques as well as renal biopsy. In kidney diseases, ultrasonography is used as a first-line imaging technique, and its role in medical nephropathy is to exclude urological pathologies, to differentiate between acute and chronic renal failure, to follow-up on the course of a disease, to guide needle biopsy, etc. Ultrasound images are useful at characterizing the pelvis, assessing renal dimensions and parenchymal echogenicity, sampling color-power Doppler signals and evaluating their characteristics and distribution as well as measuring parenchymal resistive index. Taken together, these data can provide useful clues to the diagnosis and help to reduce the number of possible differential diagnoses.

Analysis of glomerular filtration rate, serum cystatin C levels, and renal resistive index values in cirrhosis patients

BACKGROUND

The aim of this study was to evaluate the relation of glomerular filtration rate (GFR) to serum cystatin C levels, renal resistive index (RRI), serum creatinine and creatinine clearance in patients with different stages of cirrhosis.

METHODS

The study sample was 25 cirrhotic patients (10 females and 15 males; mean age 57.3+/-2.04 years), 10 in the compensated stage without ascites and 15 in the decompensated stage with new-onset ascites. None had azotemia nor were on diuretic treatment. The control group comprised 25 healthy adults (11 female and 14 men; mean age 56.56+/-1.91 years). Serum cystatin C, RRI, serum creatinine and creatinine clearance were measured. GFR was determined by technetium(99m)-diethylene triamine pentaacetic acid renal scintigraphy.

RESULTS

Cirrhosis cases had lower mean scintigraphic GFR than controls (64.5+/-4.03 vs. 87.96+/-4.16 mL/min, p<0.05). Serum cystatin C and RRI were significantly higher in the cirrhotic group compared to controls (1.16+/-0.09 mg/L and 0.68+/-0.01 vs. 0.86+/-0.03 mg/L and 0.64+/-0.01, respectively; p<0.05). Subgroup comparative analysis showed that only two parameters, scintigraphic GFR and serum cystatin C, were significantly different between compensated and decompensated cirrhotics (75.62+/-4.9 mL/min and 0.89+/-0.07 mg/L vs. 57.23+/-5.14 mL/min and 1.34+/-0.13 mg/L, respectively; p<0.05). Scintigraphic GFR showed significant correlation with cystatin C, but not with serum creatinine or creatinine clearance (r=-0.877, p<0.05) in decompensated patients. No correlation was observed between scintigraphic GFR and RRI or between serum cystatin C and RRI in all subjects. A receiver operator characteristics curve showed that cystatin C at a cutoff value of 1.01 mg/L can significantly differentiate patients with GFR <70 mL/min with 80% sensitivity and 80% specificity.

CONCLUSIONS

Serum cystatin C, but not serum creatinine or RRI measurement, correlates with GFR in each stage of liver failure and has a significant diagnostic advantage in detecting lower GFR in such cases.

Outcomes for hepatorenal syndrome and acute kidney injury in patients undergoing liver transplantation: a single-center experience

Acute kidney injury occurs commonly among patients with advanced liver disease. These patients may undergo liver transplantation with subsequent improvement in hepatic function. However, the renal outcomes of these patients after liver transplantation has only occasionally been reported. Knowledge of these outcomes would be useful to identify patients who may benefit from combined liver-renal transplantation. We retrospectively analyzed 29 patients who subsequently went on to have a liver transplantation. Seventeen of cases could be ascribed to hepatorenal syndrome (HRS) and 12 cases to ATN. Four patients with non-HRS and 12 patients with HRS required hemodialysis prior to transplantation. The duration of kidney injury prior to transplantation was 7.75 +/- 7.53 weeks in the HRS group and 5.09 +/- 4.47 weeks in the ATN group (P = NS). Demographic variables between patients with HRS and ATN were similar with the exception of a higher prevalence of diabetes among the ATN group (P < .05). At 3 months post-liver transplantation, 66% of patients with non-HRS and 77% of those surviving patients with HRS showed serum creatinine values less than 1.5 mg/dL. No patients remained on chronic hemodialysis at 3 months post-liver transplantation. The outcome of kidney dysfunction and more specifically, HRS, among those patients surviving to liver transplantation was excellent with subsequent resolution in the majority of patients. Determination of prognostic factors for renal outcome will require multicenter prospective trials, which would be useful to determine which patients benefit from combined liver-renal transplantation.

Increased renal vascular resistance in dogs with hepatic disease

Doppler ultrasound is a non-invasive technique that can be used to estimate vascular resistance by calculation of resistive index (RI) and pulsatility index (PI). Liver disease may increase renal RI and PI, and in humans with liver disease the indices are monitored to attain prognostic information. Systemic hypertension has been found in dogs with hepatic disease and is also related to increased renal vascular resistance in humans. The aim of this study was to examine renal vascular resistance increases in dogs with hepatic disease and to ascertain whether these may be related to blood pressure increases and biochemical parameters. Twenty dogs with hepatic disease were evaluated. The mean renal RI, PI, and systolic blood pressure were significantly higher than in normal animals. A positive correlation was found between the indices and alkaline phosphatase but not with systolic blood pressure. It is concluded that renal vascular resistance may increase in dogs with hepatic disease and in this study was above the limit value in 50% of the animals.

Hepatorenal syndrome

Hepatorenal syndrome (HRS) is a “functional” and reversible form of renal failure that occurs in patients with advanced chronic liver disease. The distinctive hallmark feature of HRS is the intense renal vasoconstriction caused by interactions between systemic and portal hemodynamics. This results in activation of vasoconstrictors and suppression of vasodilators in the renal circulation. Epidemiology, pathophysiology, as well as current and emerging therapies of HRS are discussed in this review.

Effect of potassium canrenoate, an anti-aldosterone agent, on incidence of ascites and variceal progression in cirrhosis

BACKGROUND & AIMS

Because aldosterone-dependent sodium and water retention contribute to portal hypertension, the safety and effect of an antialdosteronic drug (Kcanrenoate) have been evaluated on the occurrence of de novo appearance of ascites and the development of esophageal varices or the progression of small varices.

METHODS

Inclusion criteria were as follows: Child-Pugh A viral pre-ascitic cirrhosis, with either F1 esophageal varices or no varices, but endoscopic and/or ultrasound evidence of portal hypertension. Thirteen Italian Liver Units prospectively enrolled 120 patients randomized to receive double-blind either Kcanrenoate (100 mg/day; 66 patients) or placebo (54 patients). Endoscopy and sonography were performed at entry and at 52 weeks unless the patient developed ascites earlier, whereas laboratory examinations were performed at entry and every 3 months thereafter. An intention-to-treat analysis was performed, with each end point assessed by the Fisher exact test; the cumulative risk for the appearance of any end point was analyzed by the adjusted log-rank test (Tarone-Ware), with censoring for drop-outs.

RESULTS

The progression of variceal status or appearance of ascites, analyzed independently, was not significantly more frequent on placebo (24.1% and 9.2%, respectively) than on Kcanrenoate (12.1% and 1.5%, respectively), whereas the cumulative occurrence of end points was decreased on Kcanrenoate (17.6% vs 38.3% with placebo; P < .05, Tarone-Ware test). The incidence of adverse events was negligible and did not differ between groups.

CONCLUSIONS

This preliminary study shows that 100 mg/day of Kcanrenoate is well tolerated and does not reduce the individual incidence of ascites and/or the appearance or progression of esophageal varices in preascitc cirrhosis, but may decrease their 1-year cumulative occurrence.

Renovascular Impedance Correlates with Portal Pressure in Patients with Liver Cirrhosis

PURPOSE

To prospectively evaluate, in patients with liver cirrhosis, the correlation between the renovascular impedance measured by using color flow and pulsed wave Doppler ultrasonography (US) and the portal pressure measured by using the hepatic venous pressure gradient (HVPG).

MATERIALS AND METHODS

The study was approved by the senior staff committee (comparable to institutional review board) of the university hospital, and written informed consent was obtained from all patients. Thirty-one patients with cirrhosis (22 men, nine women; mean age, 57.6 years +/- 8.8 [standard deviation]) and esophageal varices were consecutively enrolled in the study. Having fasted, the patients underwent color flow and pulsed wave Doppler US of the right interlobar renal artery (RRA) and the left interlobar renal artery (LRA). The resistance index (RI) and pulsatility index (PI) were determined. On the same day, with fluoroscopic guidance, a 5-F balloon-tipped catheter was advanced, via the right basilic vein, into the right hepatic vein; HVPG was calculated as the difference between the wedged and free hepatic pressures. All measurements were performed in triplicate, and permanent tracings were recorded. Correlations were made by using the Pearson test. The positive predictive value of renovascular impedance for detection of severe portal hypertension was determined.

RESULTS

Mean RI and PI values were 0.67 +/- 0.07 and 1.21 +/- 0.25, respectively, for the RRA, and 0.68 +/- 0.07 and 1.24 +/- 0.26, respectively, for the LRA. All patients had portal hypertension (mean HVPG, 19.3 mm Hg +/- 4.7; range, 11.5-33.5 mm Hg). Neither portal pressure nor renal impedance correlated with Child-Pugh score for cirrhosis. Renal artery impedance indexes correlated with the HVPG (for RRA RI: R = 0.424, P = .03; for RRA PI: R = 0.402, P = .04; for LRA RI: R = 0.352, P = .05; for LRA PI: R = 0.393, P = .02). A higher-than-normal renal impedance had a high positive predictive value (RRA RI and PI, 100%; LRA RI, 92%; LRA PI, 84%) for the detection of severe portal hypertension.

CONCLUSION

Renovascular impedance had a direct correlation with HVPG.

The role of ultrasound in renal insufficiency: the essentials

Sonography is the best screening modality to evaluate patients presenting with renal insufficiency. Ultrasound findings can be normal in patients with renal disease, especially in prerenal azotemia and acute parenchymal renal disease. Echogenic kidneys indicate the presence of parenchymal renal disease; the kidneys may be of a normal size or enlarged. Small kidneys suggest advanced stage chronic kidney disease. Uncommonly, cystic disease of the kidney, especially adult type polycystic kidney disease may be the cause of the patient's renal insufficiency with bilaterally enlarged kidneys containing multiple cysts of various sizes. If hydronephrosis is present, the level and cause of the obstruction should be sought. When ultrasound cannot diagnose the level and cause of obstruction, other imaging modalities, including CT and MRI may be useful. When renovascular disease (arterial stenosis or venous thrombosis) is suspected, spectral and color Doppler can be useful in detecting abnormalities.

Hepatorenal syndrome

This article summarizes the literature on current definition, suggested pathogenetic mechanisms and the role of laboratory assessment in the differential diagnosis of hepatorenal syndrome (HRS) from other causes of renal disease that may arise during hepatic cirrhosis and some diseases affecting both liver and kidney. It should be remembered that the main theory suggested for the pathogenesis of HRS is the arterial vasodilation hypothesis of portal hypertension, ending in type 1 and type 2 HRS, but there is no consensus supporting either mechanism as a solid theory for initiation of HRS pathogenesis to date. No laboratory test can firmly establish a diagnosis of HRS, which is mainly based on the absence of any specific cause of renal failure. Laboratory and ultrasonographic tests based on non-invasive techniques are being investigated as possible diagnostic approaches.

Renal failure in patients with cirrhosis and sepsis unrelated to spontaneous bacterial peritonitis: value of MELD score

BACKGROUND & AIMS

Although renal failure is a common complication of sepsis and patients with cirrhosis frequently develop sepsis, there have been no studies specifically assessing renal function in patients with cirrhosis and sepsis unrelated to spontaneous bacterial peritonitis. The aim of this study was to investigate prospectively the frequency, characteristics, and outcome of renal failure in patients with cirrhosis and sepsis unrelated to spontaneous bacterial peritonitis.

METHODS

One hundred six consecutive patients with cirrhosis and sepsis were studied prospectively. Patients with spontaneous bacterial peritonitis were excluded.

RESULTS

Twenty-nine out of 106 patients (27%) with cirrhosis and sepsis developed acute renal failure as compared with only 8 of 100 patients (8%) from a control group of cirrhotic patients without infection (P < .0001). Renal failure in the sepsis group was reversible in 22 (76%; 21% of all patients) patients and nonreversible in 7 (24%; 6% of all patients) patients. Renal failure was associated with impairment of effective arterial blood volume, without evidence of tubular damage. The occurrence and type of renal failure correlated strongly with mortality (mortality at 3 months: nonreversible renal failure, 100%; reversible renal failure, 55%; no renal failure, 13%). Among variables obtained at diagnosis of sepsis, the Model for End-Stage Liver Disease (MELD) score was the only independent predictive factor of mortality.

CONCLUSIONS

Renal failure is common in patients with cirrhosis and sepsis unrelated to spontaneous bacterial peritonitis and is associated with arterial underfilling and renal vasoconstriction. Outcome is poor, even in the setting of reversible renal failure. The MELD score is the best prognostic marker of patients with cirrhosis and sepsis.

Impact of pretransplant renal failure: when is listing for kidney-liver indicated?

Renal and hepatic function are often intertwined both through the existence of associated primary organ diseases and hemodynamic interrelationships. This connection occasionally results in the chronic failure of both organs, necessitating the need for combined kidney-liver transplantation. Since 1990, over 1,790 patients in the United States have received such transplants with a patient survival somewhat less than that for patients receiving either organ alone. Patients with renal failure due to acute injury or to the hepatorenal syndrome have classically not been included as candidates for combined transplantation due to the reversibility of the renal dysfunction following liver transplantation. However, the rate and duration of renal failure prior to liver transplantation continues to be prolonged even with the new allocation scheme prioritizing liver transplants to those with renal failure. Thus the issue of when kidney transplantation should be offered and what evaluation is necessary prior to the decision continues to confront the transplant community.

Impact of liver transplantation on renal function of patients with congenital hepatic fibrosis associated with autosomal recessive polycystic kidney disease

Congenital hepatic fibrosis (CHF) is an uncommon autosomal recessive malformation. It may be associated with extrahepatic manifestations such as polycystic kidney disease. The main consequence is portal hypertension and bleeding from varices. Despite liver transplantation as a therapeutic option for this patient, long-term impact of liver transplantation on renal functions of patients with autosomal recessive polycystic kidney disease with associated liver disease is not well known. In this study, we aimed to analyze the patient's renal function after liver transplantation by creatinine clearance, glomerular filtration rate, and renal resistive indexes. Between March 1997 and September 2002, three of 50 orthotopic liver transplantation (OLT) were performed because of CHF associated with ARPKD at Ege University Organ Transplantation and Research Center. Baseline immunosuppression consisted of prednisone and cyclosporine A (CSA). The mean follow-up of the patients was 2.1 yr. Blood urea and creatinine levels were decreased after operation in all patients and remained within the normal range at the sixth and 12th month, whereas the level of the third patient were increased at the 18th month. RRI values of patients were not found different at the sixth month whereas, RRI values of patients were decreased at the 12th month and remained unchanged at the 18th month of follow-up. During the study period hypertension developed in one patient at the 16th month and resolved with antihypertensive treatment and decreasing dosage of CSA. Kidney function has remained satisfactory in all of the patients despite the use of cyclosporine. OLT can provide good survival in patients with CHF associated with ARPKD.

Abnormally high resistive index of central retinal artery by ultrasound color Doppler in patients with viral chronic liver disease: correlation with worsening liver staging

Retrobulbar-ocular circulation provides an opportunity to assess the terminal circulation of the arterial cerebral tree. To evaluate whether retrobulbar circulation in patients with chronic liver disease is affected by adaptive mechanisms, we assessed by echo color Doppler, 1. The resistive-index of the central retinal artery, a terminal branch of the ophthalmic artery, and 2. the potential interrelationships with both liver staging and the most important splanchnic Doppler-parameters used to assess portal hypertension. The resistance index (RI) of the central retinal artery was obtained and compared with other classical Doppler parameters known to be affected by portal hypertension. The RI of the central retinal artery (CRA) was higher in cirrhotic patients than in controls or subjects with chronic hepatitis; it correlated with all the Doppler parameters of portal hypertension considered, with plasma renin-activity, and norepinephrine concentrations. Similarly to renal and splanchnic hemodynamics, retinal arterial circulation assessed by duplex Doppler seems to be affected by the histology of liver disease and by the overactivity of vasoconstrictor systems.