The effects of fenoldopam, a selective dopamine receptor agonist, on systemic and renal hemodynamics in normotensive subjects

Cardiopulmonary bypass associated acute kidney injury: better understanding and better prevention

Cardiopulmonary bypass (CPB) is a common technique in cardiac surgery but is associated with acute kidney injury (AKI), which carries considerable morbidity and mortality. In this review, we explore the range and definition of CPB-associated AKI and discuss the possible impact of different disease recognition methods on research outcomes. Furthermore, we introduce the specialized equipment and procedural intricacies associated with CPB surgeries. Based on recent research, we discuss the potential pathogenesis of AKI that may result from CPB, including compromised perfusion and oxygenation, inflammatory activation, oxidative stress, coagulopathy, hemolysis, and endothelial damage. Finally, we explore current interventions aimed at preventing and attenuating renal impairment related to CPB, and presenting these measures from three perspectives: (1) avoiding CPB to eliminate the fundamental impact on renal function; (2) optimizing CPB by adjusting equipment parameters, optimizing surgical procedures, or using improved materials to mitigate kidney damage; (3) employing pharmacological or interventional measures targeting pathogenic factors.

Dopamine Receptors in Breast Cancer: Prevalence, Signaling, and Therapeutic Applications

Breast cancer (BC) is the most common malignancy among women, with over one million cases occurring annually worldwide. Although therapies against estrogen receptors and HER2 have improved response rate and survival, patients with advanced disease, who are resistant to anti-hormonal therapy and/or to chemotherapy, have limited treatment options for reducing morbidity and mortality. These limitations provide major incentives for developing new, effective, and personalized therapeutic interventions. This review presents evidence on the involvement of dopamine (DA) and its type 1 receptors (D1R) in BC. DA is produced in multiple peripheral organs and is present in the systemic circulation in significant amounts. D1R is overexpressed in ~ 30% of BC cases and is associated with advanced disease and shortened patient survival. Activation of D1R, which signals via the cGMP/PKG pathway, results in apoptosis, inhibition of cell invasion, and increased chemosensitivity in multiple BC cell lines. Fenoldopam, a peripheral D1R agonist that does not penetrate the brain, dramatically suppressed tumor growth in mouse models with D1R-expressing BC xenografts. It is proposed that D1R should serve as a novel diagnostic/prognostic factor through the use of currently available D1R detection methods. Fenoldopam, which is FDA-approved to treat renal hypertension, could be repurposed as an effective therapeutic agent for patients with D1R-expressing tumors. Several drugs that interfere with the cGMP/PKG pathway and are approved for treating other diseases should also be considered as potential treatments for BC.

Use of Fenoldopam in Children with Congenital Heart Disease to Decrease Fluid Balance: A Retrospective, Descriptive Study and Insights into Predictors of Decreased Fluid Balance

This retrospective study aimed to determine if fenoldopam is associated with a decrease in fluid balance and to define the factors that may promote this in children with a history of congenital heart disease at the cardiac intensive care unit (CICU). Patients cared from January 2014 to December 2018 in the CICU were reviewed, and those on fenoldopam infusion were identified. Patient cohort data included demographics, clinical information, laboratory results, hemodynamic and urine output measurements, and information regarding fenoldopam infusion were compared between those with and without decrease in fluid balance. Forty-six patients were identified. Patients received a starting dose of fenoldopam of 0.2 mcg/kg/h, a maximum dose of 0.3 mcg/kg/h, and duration of 64 hours. Over the 4-hour study period, statistically significant change was noted in systolic pressure (decrease of 5.4%; p < 0.001), diastolic pressure (decrease of 3.5%; p = 0.01), fluid balance, and urine output (decrease of 1.3%; p = 0.027). In the cohort, 34 patients (74%) had a decrease in fluid balance, 18 (39%) had an increase in urine output, and 25 (54%) had a decrease in fluid input after the initiation of fenoldopam. Patients that had a decrease in fluid balance tended to have a higher blood urea nitrogen level at the time of fenoldopam initiation. Fenoldopam was associated with decrease in fluid balance and fluid input, but not associated with an increase in urine output. The identification of factors that can decrease fluid balance may help identify those patients who can be benefited with this treatment.

Effects of Fenoldopam in the Pediatric Population: Fluid Status, Serum Biomarkers, and Hemodynamics: A Systematic Review and Meta-Analysis

Fluid overload is a frequent complication in children during critical illness. Fluid restriction and diuretic agents have been the mainstay therapies so far. Fenoldopam, a selective dopamine-1 receptor agonist, is a diuretic agent with promising effects in the pediatric population. The purpose of this meta-analysis is to evaluate the outcomes of pediatric patients who received fenoldopam. We hypothesized that the administration of fenoldopam will cause an increase in urine output and decrease in serum creatinine in this patient population. A comprehensive database search of PubMed, EMBASE, and Cochrane libraries from the databases' inception through December 2018 was undertaken. Independent reviewers selected appropriate studies and the reviewed data. A meta-analysis was then conducted to determine the effects of fenoldopam on hemodynamics, the amount of vasoactive support, and renal function in children under the critical care setting. The selected end points were measured prior to the administration of fenoldopam and 24 hours after the initiation of the infusion: urine output, serum creatinine, serum sodium, inotrope score, heart rate, central venous pressure, systolic blood pressure, and mean blood pressure. Forest plots were generated to demonstrate individual study data as well as pooled data for each end point. A total of five studies (three retrospective cohort studies, two randomized trials) with 121 patients were included for analysis. No significant difference was observed in urine output, inotrope score, systolic blood pressure, or mean blood pressure. There was a statistically significant increase in serum creatinine and central venous pressure. There was statistically significant decrease in serum sodium and heart rate, and central venous pressure. This meta-analysis did not identify significant renoprotective or vasodilator effects from fenoldopam in this patient population. Although mild electrolyte and hemodynamic changes were identified, larger studies are warranted to determine the clinical significance of fenoldopam in this patient population.

Does Fenoldopam Protect Kidney in Cardiac Surgery? A Systemic Review and Meta-Analysis With Trial Sequential Analysis

PURPOSE

To assess the benefits and harms of fenoldopam for nephroprotective effects in adult patients undergoing cardiac surgery.

METHODS

We conducted a systematic review with meta-analysis of randomized controlled trials (RCTs) comparing fenoldopam with placebo in cardiac surgery. Trials were systematically searched from PubMed, EMBASE, CENTRAL, and CNKI databases, up to July 30, 2018. A trial sequential analysis (TSA) was used to determine whether the present evidence was valid and conclusive for the primary outcomes.

RESULTS

A total of seven randomized controlled trials involving 1,107 adult patients undergoing cardiac surgery fulfilled the inclusion criteria. The pooled analysis suggested that the use of fenoldopam was associated with a reduction in the incidence of AKI (18 of 216 [8.3%] in the fenoldopam group versus 45 of 222 [20.3%] in the placebo group, RR = 0.42 [0.26, 0.69], P = 0.0006) and with a higher rate of hypotension (92/357 [25.8%] versus 51/348 [14.7%], RR = 1.76 [1.29, 2.39], P = 0.0003). There was no significant effect on renal replacement therapy requirement (77 of 540 [14.3%] versus 75 of 536 [14.0%], P = 0.96) or hospital mortality (87/392 [22.2%] versus 83/383 [21.7%], P = 0.86). TSA supported the results of the conventional analysis on AKI.

CONCLUSIONS

Low-dose dopamine offers transient improvements in renal physiology, but no good evidence shows that it offers important clinical benefits to patients with or at risk for acute renal failure.Among patients treated with fenoldopam, there was a decrease in AKI and an increased incidence of hypotension, had no significant effect on RRT or mortality. Given that most studies were small and the definition of AKI was variable between studies, there is not enough evidence to support the systematic use of fenoldopam in cardiac surgery.

Acute Kidney Injury: From Diagnosis to Prevention and Treatment Strategies

Acute kidney injury (AKI) is characterized by an acute decrease in renal function that can be multifactorial in its origin and is associated with complex pathophysiological mechanisms. In the short term, AKI is associated with an increased length of hospital stay, health care costs, and in-hospital mortality, and its impact extends into the long term, with AKI being associated with increased risks of cardiovascular events, progression to chronic kidney disease (CKD), and long-term mortality. Given the impact of the prognosis of AKI, it is important to recognize at-risk patients and improve preventive, diagnostic, and therapy strategies. The authors provide a comprehensive review on available diagnostic, preventive, and treatment strategies for AKI.

A cardiovascular model for renal perfusion during cardiopulmonary bypass surgery

Acute kidney injury (AKI) is a major complication following cardiac surgery requiring cardiopulmonary bypass (CPB). It is likely that poor renal perfusion contributes to the occurrence of AKI, via renal hypoxia, so it is imperative to maintain optimal renal perfusion during CPB. We have developed a straightforward cardiovascular perfusion model with parameter values calibrated against experimental and/or clinical data from several independent studies of CPB in humans and animals. Following model development and calibration, we performed a one-at-a-time parametric study to investigate the response of renal perfusion to several variables during CPB, namely pump flow (denoted CO for 'cardiac output'), renal vascular resistance, and non-renal vascular resistance. From the parametric study, we have found that all three parameters had a similarly strong influence on renal perfusion. We simulated three potential strategies for maintaining optimum renal perfusion during CPB and tested their effectiveness. The strategies were: (1) increasing the pump flow; (2) administrating noradrenaline (vasopressor); and (3) administrating fenoldopam (renal vasodilator). Simulations have revealed that administration of fenoldopam is likely to be the most effective of the three strategies. Other findings from our simulations are that increasing pump flow is less effective when central venous pressure is elevated. Further, renal autoregulation is likely inoperative during CPB, as evidenced by an unchanging renal vascular resistance with increasing CO and blood pressure. The cardiac-renal perfusion model developed in this study can be linked with other kidney models to simulate the changes in renal oxygenation during CPB.

Fenoldopam Mesylate: A Narrative Review of Its Use in Acute Kidney Injury

Background:

Fenoldopam mesylate is a selective agonist of DA-1 receptors. It is currently used for the in-hospital treatment of severe hypertension. DA-1 receptors have high density in renal pa-renchyma and for this reason, a possible reno-protective role of Fenoldopam mesylate was investigated.

Methods:

We examined all studies regarding the role of Fenoldopam mesylate in Acute Kidney Injury (AKI); particularly, those involving post-surgical patients, intensive care unit patients and contrast-induced nephropathy.

Results:

Fenoldopam mesylate was found to be effective in reducing the onset of postoperative AKI, when used before the development of the kidney damage. Positive results were also obtained in the management of intensive care unit patients with AKI, although the clinical studies investigated were few and conducted on small samples.

Conclusion:

Conflicting results were achieved in contrast-induced nephropathy.

Effects of fenoldopam on renal blood flow in hypertensive chronic kidney disease

BACKGROUND AND AIM

The synthetic drug fenoldopam mesylate (FM) may have a renoprotective role, and a "renal dose" of 0.1 µg/kg/min intravenous (IV) infusion of FM has been reported as able to increase renal blood flow without affecting systemic blood pressure. But conclusive data are still lacking. We aimed to investigate by color-Doppler ultrasonography the effects of IV administration of FM at this dosage in hypertensive chronic kidney disease (CKD) patients, and verify whether it may induce any systemic hemodynamic alteration.

METHODS

In 60 hypertensive CKD patients, we measured by duplex Doppler ultrasonography, at baseline and during infusion of 0.1 µg/kg/min of FM, the systolic and diastolic flow velocity (sampled at the renal hilum, intermediate section and origin of both renal arteries) and the intra-parenchymal renal resistive index (RRI) sampled on interlobular arteries of both kidneys. Patients were divided into four subgroups (I-IV) according to classification of National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-DOQI).

RESULTS

Infusion of 0.1 µg/kg/min FM significantly decreased the RRI (0.73 ± 0.05 vs. 0.65 ± 0.06; p < 0.0001) and increased the systolic and diastolic flow velocities in all renal artery tracts examined. No single episode of systemic hypotension was observed.

CONCLUSIONS

Very low-dose FM may significantly increase renal blood flow and exert a renal protective effect in hypertensive CKD patients. Infusion of FM at such low dosage appears also to be quite safe, even in CKD and hypertensive patients.

Effects of fenoldopam on kidney function parameters and its therapeutic efficacy in the management of acute kidney injury in dogs with heatstroke

Background

Acute kidney injury (AKI) is common in dogs, but evidence of efficacy of its treatment is lacking.

Objective

To evaluate the efficacy of fenoldopam in the management of AKI.

Animals

Forty dogs with naturally occurring heatstroke.

Methods

Dogs were prospectively enrolled and divided into treatment and the placebo groups (fenoldopam, constant rate infusion [CRI] of 0.1 µg/kg/min or saline, respectively). Urine production (UP) was measured using a closed system. Urinary clearances were performed at 4, 12, and 24 hours after presentation to estimate the effect of fenoldopam on UP, glomerular filtration rate (GFR) and sodium fractional excretion (NaFE).

Results

At presentation, severity of heatstroke, based on a previously developed scoring system, was similar between the study groups, but was significantly worse in nonsurvivors compared with survivors. Fenoldopam administration was not associated with hypotension. Overt AKI was diagnosed, based on the International Renal Interest Society guidelines in 22/40 (55%) of the dogs. Overall, 14/40 dogs (35%) died, with no significant (P = .507) mortality rate difference between the fenoldopam (6/20 dogs; 30%) and placebo (8/20; 40%) groups. The proportion of dogs with AKI did not differ between the fenoldopam and the placebo groups (9/20; 45% versus 13/20; 65%, respectively; P = .204). There were no differences in UP, GFR, and NaFE between the fenoldopam and the placebo groups.

Conclusion and Clinical Importance

Fenoldopam CRI at 0.1 µg/kg/min did not have a clinically relevant effect on kidney function parameters in dogs with severe heatstroke‐associated AKI.

Effect of Fenoldopam Continuous Infusion on Glomerular Filtration Rate and Fractional Excretion of Sodium in Healthy Dogs

BACKGROUND

Acute kidney injury (AKI) is a common problem in small-animal patients and carries a guarded prognosis with substantial morbidity and mortality, particularly in oligoanuric dogs. Fenoldopam, a selective dopamine agonist, has been shown to increase urine output in healthy dogs and cats; however, the mechanism of action is unknown.

HYPOTHESIS/OBJECTIVES

To evaluate the effect of fenoldopam infusion on glomerular filtration rate (GFR) and fractional excretion of sodium (FeNa) in healthy dogs.

ANIMALS

Ten healthy, privately owned dogs.

METHODS

Randomized, crossover design with negative control. Ten healthy dogs were given fenoldopam diluted in 5% dextrose (D5W) as a continuous IV infusion of 0.8 μg/kg/min for 5 hours and a control infusion of D5W alone, 7 days apart. Glomerular filtration rate was measured by exogenous iohexol clearance, beginning 1 hour after the start of the fenoldopam infusion. Fractional excretion of sodium (FeNa) was measured before and after the infusion. Glomerular filtration rate and change in FeNa were compared between treatment days.

RESULTS

Fenoldopam infusion resulted in a significantly increased (P = .0166) GFR (median GFR, 3.33 mL/min/kg) in healthy dogs compared with D5W infusion (median GFR, 2.71 mL/kg/min). Fenoldopam also resulted in a significantly increased (P = .0148) FeNa (mean change, 0.106), whereas infusion of D5W alone did not (mean change, 0.016).

CONCLUSIONS AND CLINICAL IMPORTANCE

In healthy dogs, fenoldopam significantly increased GFR and FeNa compared with infusion of D5W alone. No adverse effects were seen.

Fenoldopam for the prevention of contrast-induced nephropathy (CIN)-do we need more trials? A meta-analysis

We conducted a pooled analysis of clinical trials comparing intravenous Fenoldopam (FP) with Saline/Placebo/N-acetyl cysteine (NAC) for the prevention of contrast-induced nephropathy (CIN). Five studies were eligible. Quantitative analyses were done with Review Manager (RevMan version 5.2.). A total of 85 out of 353 patients in Fenoldopam group while 73 among 366 in the control group were affected due to CIN. The risk ratio for the development of CIN in the Fenoldopam group was 1.19 compared to the control group. This was not statistically significant. Fenoldopam is no better than Placebo/Saline or NAC in preventing CIN, but more studies are required.

Intravenous fenoldopam for early acute kidney injury after liver transplantation

PURPOSE

Acute kidney injury remains a serious complication after orthotopic liver transplantation. To date, several 'renal-protective' agents have been explored in this setting but with conflicting and disappointing results. Therefore, our aim is to evaluate the effects of fenoldopam in liver transplant patients with an established renal injury.

METHODS

In this prospective study, intravenous fenoldopam 0.1 µg/kg/min was administered to consecutive liver transplant patients with postoperative (within 7 days from surgery) stage 2 acute kidney injury (AKI) according to the Acute Kidney Injury Network classification. Actual glomerular filtration rate (GFR; calculated by the iohexol plasma clearance), serum creatinine (SCr) and cystatin C (SCyC) were used to assess the effect of the medication on the patients.

RESULTS

During the study, 295 patients underwent liver transplant. Fifty-one patients (17.6%) met the inclusion criteria and the data from 48 patients were analysed. SCr and SCyC levels decreased (p < 0.001 after 48 h; p < 0.0001 after 72 h) and GFR increased (p < 0.001 after 24 h; p < 0.0001 after 72 h). When compared to a cohort of comparable patients with AKI from our historical series, the patients in the present study showed better SCr and SCyC levels. It was not necessary to discontinue the infusion of fenoldopam in any patient because of the occurrence of adverse events potentially attributable to it.

CONCLUSION

We showed that fenoldopam was capable of improving some renal function parameters in postoperative liver transplantation patients with on-going AKI. This preliminary study now sets the stage for a multicenter, randomized, placebo-controlled trial in order to provide definite evidence.

Dopamine-1 Receptor Agonist: Renal Effects and Its Potential Role in the Management of Radiocontrast-Induced Nephropathy

Radiocontrast-induced nephropathy remains the third leading cause of hospital-acquired acute renal failure. Once established, this syndrome is associated with increased morbidity and mortality as well as increased health care costs. Recently, studies have been initiated to evaluate the potential of a selective dopamine-1 receptor agonist (fenoldopam) in ameliorating radiocontrast-induced renal failure. Selective dopamine-1 receptor agonists exhibit many desirable renal effects that support their use for the prophylaxis of radiocontrast-induced nephropathy, including decreases in renal vascular resistance and increases in renal blood flow, glomerular filtration, and sodium and water excretion. Several reports have documented a beneficial effect of fenoldopam administration in attenuating radiocontrast-induced nephropathy. In contrast, a recent multicenter, randomized study did not demonstrate a renoprotective effect of fenoldopam against radiocontrast-induced nephropathy. The presence of multiple confounders, however, precludes a definitive conclusion regarding the ability of fenoldopam to protect against radiocontrast-induced nephropathy. Additional studies are needed to properly evaluate the role of fenoldopam in radiocontrast-induced nephropathy prophylaxis.

Contrast induced nephropathy in urology

Intravenous contrast agents have a distinct role in urological imaging: to study precise anatomical delineation, vascularity, and to assess the function of the renal unit. Contrast induced nephropathy (CIN) is a known adverse effect of intravenous contrast administration. The literature on incidence, pathophysiology, clinical features, and current preventive strategies available for CIN relevant to urologists was reviewed. A search of the PubMed database was done using the keywords nephropathy and media, prevention and control or prevention Contrast media (explode), all adverse effects, and kidney diseases (explode). An online search of the EMBASE database for the time ranging from 1977 to February 2009 was performed using the keywords ionic contrast medium, adverse drug reaction, major or controlled clinical study, human, nephrotoxicity, and kidney disease. Current publications and data most relevant to urologists were examined. CIN was the third most common cause of hospital-acquired renal failure. The incidence is less common with intravenous contrast administration as compared with intra-arterial administration. The pathogenesis of contrast mediated nephropathy is due to a combination of toxic injury to renal tubules and medullary ischemic injury mediated by reactive oxygen species. CIN most commonly manifests as a nonoliguric and asymptomatic transient decline in renal function. Patients who developed CIN were found to have increased mortality, longer hospital stay, and complicated clinical course. An overview of risk factors and risk prediction score for prognostication of CIN are elaborated. Preventive strategies including choice of contrast agents, maximum tolerated dose, role of hydration, hydration regime, etc. are discussed. The role of N- acetyl cysteine, Theophylline, Fenoldapam, Endothelin receptor antagonists, iloprost, atrial natriuretic peptide, and newer therapies such as targeted renal therapy (TRT) are discussed. A working algorithm based on current evidence is proposed. No current treatment can reverse or ameliorate CIN once it occurs, but prophylaxis is possible.

Preliminary pharmacokinetics and cardiovascular effects of fenoldopam continuous rate infusion in six healthy dogs

Fenoldopam is a selective dopamine-1 receptor agonist that causes peripheral arterial vasodilation, increased renal blood flow, and diuresis. Enthusiasm exists for the use of fenoldopam in nonpolyuric kidney injury in dogs, although pharmacokinetic data are lacking. The purpose of this study was to collect basic pharmacokinetic and hemodynamic effect data for fenoldopam when administered to healthy awake dogs. Six healthy, awake beagles were given a 180-min fenoldopam constant rate infusion at 0.8 μg/kg per minute followed by a 120-min washout period. Citrated blood was collected during and after infusion for the measurement of plasma fenoldopam concentration by HPLC with mass spectrometry. Heart rate and indirect systolic blood pressure were concurrently measured. Mean ± SD, steady-state plasma fenoldopam concentrations of 20 ± 17 ng/mL were achieved within 10 min of starting the infusion. Area under the plasma concentration-time curve was 3678 ± 3030 ng/mL · min, and plasma clearance was 66 ± 43 mL/min per kg. Elimination was rapidly achieved in all dogs. Heart rate and systolic blood pressure were unaffected by the fenoldopam infusion. Based on the results of this study, further evaluation of the effects of fenoldopam in dogs at differing doses and in dogs with clinical conditions such as acute nonpolyuric kidney injury is warranted.

Dopamine and renal function and blood pressure regulation

Dopamine is an important regulator of systemic blood pressure via multiple mechanisms. It affects fluid and electrolyte balance by its actions on renal hemodynamics and epithelial ion and water transport and by regulation of hormones and humoral agents. The kidney synthesizes dopamine from circulating or filtered L-DOPA independently from innervation. The major determinants of the renal tubular synthesis/release of dopamine are probably sodium intake and intracellular sodium. Dopamine exerts its actions via two families of cell surface receptors, D1-like receptors comprising D1R and D5R, and D2-like receptors comprising D2R, D3R, and D4R, and by interactions with other G protein-coupled receptors. D1-like receptors are linked to vasodilation, while the effect of D2-like receptors on the vasculature is variable and probably dependent upon the state of nerve activity. Dopamine secreted into the tubular lumen acts mainly via D1-like receptors in an autocrine/paracrine manner to regulate ion transport in the proximal and distal nephron. These effects are mediated mainly by tubular mechanisms and augmented by hemodynamic mechanisms. The natriuretic effect of D1-like receptors is caused by inhibition of ion transport in the apical and basolateral membranes. D2-like receptors participate in the inhibition of ion transport during conditions of euvolemia and moderate volume expansion. Dopamine also controls ion transport and blood pressure by regulating the production of reactive oxygen species and the inflammatory response. Essential hypertension is associated with abnormalities in dopamine production, receptor number, and/or posttranslational modification.

The effect of fenoldopam and dopexamine on cytokine and endotoxin release following on-pump coronary artery bypass grafting: a prospective randomized double-blind trial

BACKGROUND

Surgical trauma, exposure to an external circuit, and reduced organ perfusion contribute to the systemic inflammatory response following cardiopulmonary bypass (CPB). Reduced splanchnic perfusion causes disruption of the gastrointestinal mucosal barrier and the release of endotoxins. Fenoldopam (a new dopamine 1 receptor agonist) has been shown to be a specific renosplanchnic vasodilator in animal and human studies. We studied the effects of fenoldopam on the systemic inflammatory response and the release of endotoxins after CPB and compared the results with those for dopexamine.

METHODS

Our prospective randomized study included 42 consecutive patients with good to moderate left ventricular function who were to undergo elective or inpatient coronary artery bypass grafting. We used closed envelope method to randomize patients to receive 0.2 μg/kg per minute of fenoldopam (n = 14), 2 μg/kg per minute of dopexamine (n = 14), or normal saline (n = 14). Patients received their respective treatments continuously from anesthesia induction until the end of the first 24 postoperative hours. Interleukin 1β (IL-1β), IL-6, IL-8, IL-10, IL-12, tumor necrosis factor α, complement 3a (C3a), C4a, C5a, and endotoxins were measured during the perioperative period. Repeated-measures analysis of variance was used to evaluate the results for the timed samples.

RESULTS

There were no statistical differences between the groups with respect to pre- and intraoperative variables. Release of C3a was attenuated in the fenoldopam group (P = .002), and release of IL-6 and IL-8 was attenuated in the postoperative period in the fenoldopam group (P = .012 and .015, respectively). The other interleukins showed no uniform release in any of the 3 groups. There were no statistically significant differences in serum endotoxin elevation between the 3 groups.

CONCLUSION

A partial attenuation in the inflammatory response is possible with fenoldopam infusion. The elevation in serum endotoxin levels was not affected by dopexamine or fenoldopam infusion.

Fenoldopam use in a burn intensive care unit: a retrospective study

BACKGROUND

Fenoldopam mesylate is a highly selective dopamine-1 receptor agonist approved for the treatment of hypertensive emergencies that may have a role at low doses in preserving renal function in those at high risk for or with acute kidney injury (AKI). There is no data on low-dose fenoldopam in the burn population. The purpose of our study was to describe our use of low-dose fenoldopam (0.03-0.09 mug/kg/min) infusion in critically ill burn patients with AKI.

METHODS

We performed a retrospective analysis of consecutive patients admitted to our burn intensive care unit (BICU) with severe burns from November 2005 through September 2008 who received low-dose fenoldopam. Data obtained included systolic blood pressure, serum creatinine, vasoactive medication use, urine output, and intravenous fluid. Patients on concomitant continuous renal replacement therapy were excluded. Modified inotrope score and vasopressor dependency index were calculated. One-way analysis of variance with repeated measures, Wilcoxson signed rank, and chi-square tests were used. Differences were deemed significant at p < 0.05.

RESULTS

Seventy-seven patients were treated with low-dose fenoldopam out of 758 BICU admissions (10%). Twenty (26%) were AKI network (AKIN) stage 1, 14 (18%) were AKIN stage 2, 42 (55%) were AKIN stage 3, and 1 (1%) was AKIN stage 0. Serum creatinine improved over the first 24 hours and continued to improve through 48 hours (p < 0.05). There was an increase in systolic blood pressure in the first 24 hours that was sustained through 48 hours after initiation of fenoldopam (p < 0.05). Urine output increased after initiation of fenoldopam without an increase in intravenous fluid requirement (p < 0.05; p = NS). Modified inotrope score and vasopressor dependency index both decreased over 48 hours (p < 0.0001; p = 0.0012).

CONCLUSIONS

These findings suggest that renal function was preserved and that urine output improved without a decrease in systolic blood pressure, increase in vasoactive medication use, or an increase in resuscitation requirement in patients treated with low-dose fenoldopam. A randomized controlled trial is required to establish the efficacy of low-dose fenoldopam in critically ill burn patients with AKI.

Impaired blood flow in acute kidney injury: pathophysiology and potential efficacy of intrarenal vasodilator therapy

PURPOSE OF REVIEW

Acute kidney injury (AKI) is a common complication of hospitalized patients and associated with significant morbidity and mortality. Numerous studies have documented that acute reductions in glomerular filtration rates are associated with significant in-hospital mortality. Moreover, patients progressing to dialysis-dependent AKI can have mortality rates that exceed 60%. The pathophysiology of AKI is unknown, but marked reductions in corticomedullary blood flow leads to significant reductions in glomerular filtration rate during early phases of the disease. The recognition that hypoperfusion of the outer medulla is common to many forms of AKI and contributes to tubular ischemia has led many investigators to re-examine the use of vasodilators to restore blood flow and stabilize renal function.

RECENT FINDINGS

Numerous prospective trials have studied the efficacy of various vasoactive compounds with primarily negative results. However, trial designs that failed to fully examine the dose response of many investigational agents contributed to the development of systemic hypotension, thus offsetting potential benefits of the treatment. Emerging devices that allow for intrarenal administration of drugs have led to the concept of 'targeted renal' prophylaxis and treatment. The rationale is that local renal administration can improve the safety profile of many vasoactive agents. Recent studies confirm that higher doses of fenoldopam or other vasodilators can be administered intrarenally without the development of systemic hypotension.

SUMMARY

Previous trials utilizing vasodilator therapy to stabilize renal function in AKI have given conflicting results. This study will critically review trial design and dose selection used in previous studies of vasodilator therapy in AKI. Lastly, the potential for high-dose therapy using intrarenal drug delivery systems will be discussed.

The effect of fenoldopam and dopexamine on hepatic blood flow and hepatic function following coronary artery bypass grafting with hypothermic cardiopulmonary bypass

BACKGROUND

Hypothermic cardiopulmonary bypass is associated with low perfusion state causing a mismatch between demand and supply to various organs such as gut, kidneys and brain. The consequences are thought to be responsible for postoperative complications like systemic inflammatory response, renal failure, neurological injury, etc. Pharmacological agents like dopamine, dopexamine and dobutamine have been used in an attempt to reduce hypoperfusion and hence complications. Fenoldopam, a dopamine analog (DA-1 receptor agonist), has recently been shown to be specific reno-splanchnic vasodilator in animal studies. We studied the haemodynamic effects of fenoldopam and its effect on hepatic blood flow (HBF) during and after cardiopulmonary bypass and compared these with dopexamine.

METHODS

Ethics committee approval was obtained. Forty-two consecutive patients with good/moderate left ventricular function undergoing either elective/urgent coronary artery bypass grafting were included in the study. Patients were randomised to receive either fenoldopam (0.2 microg/kgmin) (F; n=14) or dopexamine (2.0 microg/kgmin) (Dx; n=14) normal saline (NS; n=14) continuously after induction of anaesthesia for 24h following completion of surgery. HBF was measured using the Indocyanine green dye disappearance rate method, before, during and after cardiopulmonary bypass. Data were collected pre-, intra- and postoperatively. Serum liver enzymes were measured during the perioperative period. Repeated measures ANOVA test was used to compare timed samples in both groups.

RESULTS

The study groups were comparable in pre- and intraoperative variables. In the fenoldopam and dopexamine groups there was a significant increase in heart rate 15 min following the commencement of the infusion (NS:F:DX::-2.0+/-7.8 beats/min:13.6+/-8.1 beats/min (p=0.007):18.36+/-20.2 beats/min (p=0.004)). However the change in mean arterial blood pressure was similar (NS:F:DX::-12.7+/-14.9:-4.0+/-23.1 (p=0.699):-2.6+/-22.3) (p=0.235). Cardiac index increased and systemic vascular resistance decreased (requiring noradrenaline infusion) in the fenoldopam group, however this did not reach statistical significance. Hepatic blood flow reduced during CPB and returned to near preoperative levels in all three groups with no statistical difference between groups.

CONCLUSIONS

Fenoldopam infusion induced transient tachycardia, with no augmentation of hepatic blood flow whereas dopexamine induced tachycardia and did not augment hepatic blood flow. Fenoldopam and dopexamine may have hepato-protective effect.

Safety and performance of targeted renal therapy: the Be-RITe! Registry

PURPOSE

To evaluate the safety and patterns of use of targeted renal therapy (TRT) with the Benephit system. TRT, the delivery of therapeutic agents directly to the kidneys by renal arterial infusion, has the advantage of providing a higher local effective dose with potentially greater renal effects, while limiting systemic adverse effects due to renal first-pass elimination.

METHODS

The Benephit System Renal Infusion Therapy (Be-RITe!) Multicenter Registry was a post-market registry following patients treated using the Benephit systems for TRT. The registry enrolled 501 patients (332 men; mean age 72.2+/-9.5 years) at high risk for contrast-induced nephropathy (CIN) during coronary or peripheral angiography/intervention or cardiovascular surgery. The Mehran score was used to compare the actual to predicted incidence of CIN within 48 hours post procedure.

RESULTS

Bilateral renal artery cannulation was successful in 94.2%, with a mean cannulation time of 2.0 minutes. Either fenoldopam mesylate, sodium bicarbonate, alprostadil, or B-type natriuretic peptide (BNP) was infused for 184+/-212 minutes. Mean creatinine levels did not change significantly (baseline, 24, and 48 hours post procedure: 1.95, 1.99, and 1.98 mg/dL, respectively; p = NS). In 285 patients who received TRT with fenoldopam and were followed for at least 48 hours, the incidence of CIN was 71% lower than predicted (8.1% actual CIN versus 28.0% predicted; p<0.0001). Only 4 (1.4%) patients required dialysis (versus the 2.6% predicted rate, p = NS).

CONCLUSION

The Benephit system and TRT during coronary and endovascular procedures in patients at high risk for renal failure is simple to use and safe. With the infusion of intrarenal fenoldopam, the incidence of CIN was significantly lower than predicted by risk score calculations.

Management of acute kidney injury in children: a guide for pediatricians

Acute kidney injury (AKI; previously called acute renal failure) is characterized by a usually reversible increase in the blood concentration of creatinine and nitrogenous waste products and by the inability of the kidney to appropriately regulate fluid and electrolyte homeostasis. The incidence of AKI in children appears to be increasing and the etiology of AKI over the past decades has shifted from primary renal disease to multifactorial causes, particularly in hospitalized children. Renal failure can be divided into prerenal failure, intrinsic renal disease including vascular insults, and obstructive uropathies. The history, physical examination, and laboratory studies including a urinalysis and radiographic studies can establish the likely cause(s) of AKI. Once intrinsic renal failure has become established, management of the metabolic complications of AKI requires meticulous attention to fluid balance, electrolyte status, acid-base balance, and nutrition. Many children with AKI will need renal replacement therapy to remove endogenous and exogenous toxins and to maintain fluid, electrolyte, and acid-base balance until renal function improves. Renal replacement therapy may be provided by peritoneal dialysis (PD), intermittent hemodialysis (HD), or hemofiltration with or without a dialysis circuit. Many factors--including the age and size of the child, the cause of renal failure, the degree of metabolic derangements, blood pressure, and nutritional needs--are considered in deciding when to initiate renal replacement therapy and which modality of therapy to use. The prognosis of AKI is highly dependent on the underlying etiology of the AKI. Children who have AKI as a component of multisystem failure have a much higher mortality rate than children with intrinsic renal disease. Recovery from intrinsic renal disease is also highly dependent on the underlying etiology of the AKI. Children who have experienced AKI from any cause are at risk for late development of renal failure long after the initial insult. Such children need life-long monitoring of their renal function, blood pressure, and urinalysis.

The prevention of acute kidney injury an in-depth narrative review: Part 2: Drugs in the prevention of acute kidney injury

The second part of this in-depth clinical review focuses on drugs used in the prevention of AKI in the patient at risk and/or in the management of the patient with incipient AKI. Among the drugs used to maintain a normal renal perfusion pressure, norepinephrine and vasopressin are most commonly used in hypotensive critically ill patients. The most recent RCT did not find a difference between low-dose vasopressin plus norepinephrine and norepinephrine alone in patients with septic shock, suggesting that either approach is reasonable. However, vasopressin may be beneficial in the less severe septic shock subgroup. Loop diuretics may convert an oliguric into a non-oliguric form of AKI that may allow easier fluid and/or nutritional support of the patient. Volume overload in AKI patients is common and diuretics may provide symptomatic benefit in that situation. However, loop diuretics are neither associated with improved survival, nor with better recovery of renal function in AKI. Among the renal vasodilating drugs, the routine administration of dopamine to patients for the prevention of AKI or incipient AKI is no longer justified. On the other hand, although additional studies may be warranted, fenoldopam may appear to be a likely candidate for the prevention of AKI, particularly in critically ill patients, if the positive results obtained in some recent studies are confirmed. Trials with natriuretic peptides were in general inconclusive but despite the fact that nesiritide is currently approved by the FDA only for the treatment of heart failure, this vasodilator may in the future play a role in the prevention of AKI, particularly in association with heart failure and cardiac surgery. The most recent trials seem to confirm a potential positive preventive effect of N-acetylcysteine (NAC), particularly in contrast-induced nephropathy (CIN), NAC alone should never take the place of IV hydration in patients at risk for CIN; fluids likely have a more substantiated benefit. At present, initiation of statin therapy for the prevention of CIN cannot be recommended, but these drugs should not be stopped before a radiological intervention in patients on chronic statin therapy. Rasburicase is very effective in the prevention of acute tumour lysis syndrome. Erythropoietin (EPO) has tissue-protective effects and prevents tissue damage during ischaemia and inflammation, and currently trials are performed with EPO in the prevention of AKI post-cardiac surgery, CIN and post-kidney transplantation. From this review it becomes clear that single-drug therapy will probably never be effective in the prevention of AKI and that multiple agents may be needed to improve outcomes. In addition, drugs should be administered early during the course of the disease.

Acute kidney injury in children

Acute kidney injury (AKI) (previously called acute renal failure) is characterized by a reversible increase in the blood concentration of creatinine and nitrogenous waste products and by the inability of the kidney to regulate fluid and electrolyte homeostasis appropriately. The incidence of AKI in children appears to be increasing, and the etiology of AKI over the past decades has shifted from primary renal disease to multifactorial causes, particularly in hospitalized children. Genetic factors may predispose some children to AKI. Renal injury can be divided into pre-renal failure, intrinsic renal disease including vascular insults, and obstructive uropathies. The pathophysiology of hypoxia/ischemia-induced AKI is not well understood, but significant progress in elucidating the cellular, biochemical and molecular events has been made over the past several years. The history, physical examination, and laboratory studies, including urinalysis and radiographic studies, can establish the likely cause(s) of AKI. Many interventions such as 'renal-dose dopamine' and diuretic therapy have been shown not to alter the course of AKI. The prognosis of AKI is highly dependent on the underlying etiology of the AKI. Children who have suffered AKI from any cause are at risk for late development of kidney disease several years after the initial insult. Therapeutic interventions in AKI have been largely disappointing, likely due to the complex nature of the pathophysiology of AKI, the fact that the serum creatinine concentration is an insensitive measure of kidney function, and because of co-morbid factors in treated patients. Improved understanding of the pathophysiology of AKI, early biomarkers of AKI, and better classification of AKI are needed for the development of successful therapeutic strategies for the treatment of AKI.

Hepatic and renal protection during cardiac surgery

Hepatic injury in cardiac surgery is a rare complication but is associated with significant morbidity and mortality. A high index of suspicion postoperatively will lead to earlier treatment directed at eliminating or minimizing ongoing hepatic injury while preventing additional metabolic stress from ischemia, hemorrhage, or sepsis. The evidence-basis for perioperative renal risk factors remains hampered by the inconsistent definitions for renal injury. Although acute kidney injury (as defined by the Risk, Injury, Failure, Loss, End-stage criteria) has become accepted, it does not address pathogenesis and bears little relevance to cardiac surgery. Although acute renal failure requiring renal replacement therapy after cardiac surgery is rare, it has a devastating impact on morbidity and mortality, and further studies on protective strategies are essential.

Management of acute renal failure in the elderly patient: a clinician's guide

Numerous anatomical and functional changes occurring in the aging kidney lead to reduced glomerular filtration rate, lower renal blood flow and impaired renal autoregulation. The elderly are especially vulnerable to the development of renal dysfunction and in this population acute renal failure (ARF) is a common problem. ARF is often iatrogenic and multifactorial; common iatrogenic combinations include pre-existing renal dysfunction and exposure to nephrotoxins such as radiocontrast agents or aminoglycosides, use of NSAIDs in patients with congestive cardiac failure and use of ACE inhibitors and diuretics in patients with underlying atherosclerotic renal artery stenosis. The aetiology of ARF is classically grouped into three categories: prerenal, intrinsic and postrenal. Prerenal ARF is the second most common cause of ARF in the elderly, accounting for nearly one-third of all hospitalized cases. Common causes can be grouped into true volume depletion (e.g. decreased fluid intake), decreased effective blood volume (e.g. systemic vasodilation) and haemodynamic (e.g. renal artery stenosis, NSAID use). Acute tubular necrosis (ATN) is the most common cause of intrinsic ARF and is responsible for over 50% of ARF in hospitalized patients, and up to 76% of cases in patients in intensive care units. ATN usually occurs after an acute ischaemic or toxic event. The pathogenesis of ATN involves an interplay of processes that include endothelial injury, microvascular flow disruption, tubular hypoxia, dysfunction and apoptosis, tubular obstruction and trans-tubular back-leak. Vasculitis causing ARF should not be missed as this condition is potentially life threatening. The likelihood of a postrenal cause for ARF increases with age. Benign prostatic hypertrophy, prostatic carcinoma and pelvic malignancies are all important causes. Early identification of ARF secondary to obstruction with renal imaging is essential, and complete or partial renal recovery usually ensues following relief of the obstruction.A comprehensive medical and drug history and physical examination are all invaluable. Particular attention should be paid to the fluid status of the patient (skin turgor, jugular venous pressure, lying and standing blood pressure, urine output). Urinalysis should be performed to detect evidence of proteinuria and haematuria, which will aid diagnosis. Fractional excretion of sodium and urine osmolality may be measured but the widespread use of diuretics in the elderly gives rise to unreliable results. Renal imaging, usually ultrasound scanning, is routinely performed for assessment of renal size and to exclude urinary obstruction. In some cases, renal biopsy is necessary to provide specific diagnostic information. The general principles of managing ARF include treatment of life-threatening features such as shock, respiratory failure, hyperkalaemia, pulmonary oedema, metabolic acidosis and sepsis; stopping and avoiding administration of nephrotoxins; optimization of haemodynamic and fluid status; adjustment of drug dosage appropriate to glomerular filtration rate; early nutritional support; and early referral to nephrologists for diagnosis of ARF cause, timely initiation of dialysis and initiation of specific treatment. The treatment of prerenal and ATN ARF is largely supportive with little evidence of benefit from current pharmacological therapies. Despite advances in critical care medicine and renal replacement therapy, the mortality of ARF has not changed significantly over the last 40 years, with current mortality rates being up to 75%.

Renal effects of fenoldopam in critically ill pediatric patients: A retrospective review

OBJECTIVE

Published data describe the use of fenoldopam in adults for treatment of oliguria/anuria and for renal perfusion and protection, but pediatric data are scant. We assessed the effects of fenoldopam on urine output and potential deleterious changes in hemodynamics or serum creatinine in children.

DESIGN

Retrospective analysis.

SETTING

Academic institution.

PATIENTS

: All patients <or=18 yrs old at our institution who received >or=24 hrs of fenoldopam therapy. Exclusion criteria included mechanical circulatory support, initiation of fenoldopam in the operating room, and age >18 yrs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Demographics, renal function, fenoldopam dosing, concomitant inotropes, and inotrope score data were collected and analyzed. Thirteen patients (age 0.3-18.7 yrs, median 5.5 yrs) received a mean infusion dose of 0.07 +/- 0.08 microg/kg/min (range 0.01-0.26 microg/kg/min) over the first 24 hrs of therapy. Eight patients received fenoldopam to augment urine output, and five patients received fenoldopam to increase renal perfusion. Nine (69%) patients received dopamine concurrently. Mean inotrope score at the beginning of therapy was 11.3 +/- 7.6 and did not change during therapy. Mean urine output increased from 1.82 +/- 1.5 mL/kg/hr to 2.74 +/- 1.4 mL/kg/hr (p = .009) in the first 24 hrs of fenoldopam therapy. No change in serum creatinine occurred (p not significant). Blood urea nitrogen was significantly different from baseline (41.7 +/- 18.7 vs. 49.0 +/- 19.8 mg/dL, p = .02). Patients with lower baseline urine output had a greater increase in urine output with fenoldopam. One patient experienced clinically significant hypotension while receiving fenoldopam, which was thought to be due to a concurrent nitroprusside infusion.

CONCLUSIONS

Fenoldopam increases urine output in select critically ill pediatric patients without requiring escalation of inotropic support. There were no adverse hemodynamic effects or alterations in serum creatinine. Further prospective pediatric studies to define the role of fenoldopam in children are warranted.

N-acetylcysteine and fenoldopam protect the renal function of patients with chronic renal insufficiency undergoing cardiac surgery

OBJECTIVE

To determine whether fenoldopam and N-acetylcysteine prevent renal deterioration and improve hospital outcome for patients with chronic renal insufficiency undergoing cardiac surgery.

DESIGN

Prospective, randomized, double-blinded, placebo-controlled trial.

SETTING

A community hospital that is a cardiac referral center.

PATIENTS

Seventy-nine adult patients with chronic renal insufficiency (creatinine clearance < or = 40 mL/min) who underwent cardiac surgery.

INTERVENTIONS

Group 1 received intravenous fenoldopam 0.1 microg/kg/min started at surgical induction and continued for 48 hrs. Group 2 received N-acetylcysteine 600 mg orally twice a day, from preoperative day 1 to postoperative day 1. Group 3 received both fenoldopam and N-acetylcysteine, and group 4 patients served as controls.

MEASUREMENTS AND MAIN RESULTS

Using multiple comparisons (analysis of variance) with change scores, and statistically adjusting for group differences in aortic cross-clamp time, use of intraoperative aprotinin, and preoperative use of statin, we found that the change in creatinine clearance from preoperative to postoperative day 3 was statistically less for group 1 (-1.47 mL/min +/- 2.06 SE, p = .0286) and for group 2 (-0.67 mL/min +/- 2.11 SE, p = .0198) and less but not quite significant for group 3 (-3.08 mL/min +/- 1.95 SE, p = .0891) compared with controls (-8.15 mL/min +/- 2.18 SE). Furthermore, the adjusted weight gain on postoperative day 3 was 5.55 kg +/- 1.00 SE (p = .0988) for group 1, 5.06 kg +/- 1.06 SE (p = .0631) for group 2, and 5.14 kg +/- .91 SE (p = .0445) for group 3 compared with 8.03 kg +/- 1.07 SE for group 4. However, there was no decrease in length of critical care or hospital stay or hospital costs. Finally, fenoldopam contributed to perioperative hypotension.

CONCLUSIONS

Perioperative fenoldopam and N-acetylcysteine abrogate the early postoperative decline in renal function of patients who have chronic renal insufficiency, although these agents do not affect other parameters of cardiac surgical outcome.

Fenoldopam for acute kidney injury in children

We report two cases of children with severe cardiomyopathy requiring treatment with ventricular assist devices who developed acute kidney injury and were treated with fenoldopam. Therapy with fenoldopam appeared successful in one case in that renal replacement therapy was avoided with improvement in urine output and renal function. These are the first reported cases of fenoldopam use in children with acute kidney injury receiving mechanical circulatory support.

Fenoldopam and Gastric Tonometry During Orthotopic Liver Transplantation

The aim of this study was to evaluate the effects of continuous infusion of fenoldopam on splanchnic perfusion in orthotopic liver transplant (OLT) recipients.

PATIENTS AND METHODS

We enrolled 40 patients of mean age 57+/-16 years who underwent (OLT). They were randomly divided into two double blinded groups; continuous fenoldopam (0.06 mcg/kg per minute) or placebo infusion. Hemodynamics, gastric tonometry, urine output, renal function parameters, and diuretics use were collected during selected phases of the surgery and postoperatively every 12 hours for 72 hours in the intensive care unit.

RESULTS

No significant differences were observed between the two groups concerning hemodynamics, though in the fenoldopam group we observed increased splanchnic perfusion during the whole study period but particularly after arterial unclamping (pHi 7,31+/-0.04 vs 7.28+/-0.05; P < .05) and at 48 hours after surgery (pHi 7.49+/-0.15 vs 7.39+/-0.15; P < .05). Creatinine and blood urea nitrogen values were slightly higher in the placebo group, but this data did not reach statistical significance, while higher doses of furosemide were administered to the placebo group to maintain a urinary output over 200 mL/hour during the whole study.

DISCUSSION

In this study we observed that continuous fenoldopam infusion (0.06 mg/kg per minute) improved splanchnic perfusion without affecting systemic pressure.

CONCLUSION

Patients undergoing OLT have altered splanchnic perfusion related to cirrhosis, surgical manipulation, and fluid shifts during and after surgery. The use of a splanchnic vasodilator drug improved outcomes in these patients.