Augmentation of renal blood flow and sodium excretion in hypertensive patients during blood pressure reduction by intravenous administration of the dopamine1 agonist fenoldopam

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.

Pharmacological Review of Postoperative Hypertension

Postoperative hypertension is an acute, transient increase in blood pressure that develops within 30 to 90 minutes following a surgical procedure and typically lasts for 4 to 8 hours after surgery. It is defined as a systolic blood pressure greater than 160 mm Hg or a diastolic blood pressure greater than 90 mm Hg. The increase in blood pressure is primarily due to increased systemic vascular resistance brought about by reflex changes in humoral factors, including increased levels of catecholamines, renin, and serotonin as well as alterations in baroreceptor function and carotid reflexes. Potential complications of untreated postoperative hypertension include depressed left ventricular performance, increased myocardial oxygen demand resulting in ischemic episodes, cerebrovascular accidents, arrhythmias, and suture line disruption and bleeding. Despite longstanding recognition that high blood pressure is a frequent complication after surgery, formal guidelines for the treatment of postoperative hypertension have not been developed. Postoperative hypertension is a pathophysiological state that requires rapid assessment and appropriate treatment. Several pharmacologic agents are available to achieve and maintain normotension after surgery, including nitrovasodilators (nitroglycerin and sodium nitroprusside), adrenergic blocking agents, and dihydroperidine calcium channel antagonists. Angiotensin-converting enzyme inhibitors and fenoldopam also have been used. Each has its own distinct mechanism of action and adverse effect profile. In cardiac surgery, nicardipine is as effective as nitrovasodilators and offers coronary selectivity. In patients who are hypertensive after neurosurgical procedures, avoid direct-acting vasodilators, which may exacerbate increased intracranial pressure; β-adrenergic receptor antagonists and ACEIs are the preferred agents in these patients. More data are needed to define roles and benefits of fenoldopam in managing postoperative hypertension.

Radiocontrast-Induced Acute Renal Failure

The intravascular administration of iodinated radiocontrast media can lead to acute renal dysfunction. Even small changes in renal function have been associated with increased morbidity and mortality, making the prevention of radiocontrast nephropathy of paramount importance. This review summarizes the principal risk factors for radiocontrast nephropathy and evidence-based preventive strategies that should be used to limit its occurrence. Risk factors for radiocontrast nephropathy include preexistent kidney disease, diabetes mellitus, dose of radiocontrast used, advanced congestive heart failure, and intravascular volume depletion. Proven preventive measures include volume expansion with intravenous saline or sodium bicarbonate and the use of low-osmolar or iso-osmolar radiocontrast media. Studies evaluating N-acetylcysteine have been conflicting, with meta-analyses suggesting a small beneficial effect. Studies of other pharmacologic agents have not demonstrated clinical benefit.

The Renin-Angiotensin and Renal Dopaminergic Systems Interact in Normotensive Humans

The renin-angiotensin-aldosterone (RAAS) and renal dopaminergic systems interact to maintain sodium balance. High NaCl intake increases renal synthesis of dopamine and dopaminergic receptor activity, decreasing epithelial sodium transport, whereas sodium deficit activates the RAAS, increasing epithelial sodium transport. We tested the hypothesis that attenuation of the natriuretic effect of dopamine D1-like receptors during salt restriction results in part from increased RAAS activity in seven salt-resistant normotensive adults using a double-blind placebo-controlled balanced crossover design. All subjects attained sodium balance on low (50 mmol Na(+)/day) and high (300 mmol Na(+)/day) NaCl diets, administered 4 weeks apart. Sodium, potassium, lithium, para-aminohippurate, and creatinine clearances were measured before, during, and after a 3-hour infusion of fenoldopam, a D1-like receptor agonist, with and without pretreatment with enalapril, an angiotensin converting enzyme inhibitor. On the high NaCl diet, fenoldopam-induced natriuresis was associated with the inhibition of renal proximal and distal tubule sodium transport. On the low NaCl diet, fenoldopam decreased renal distal tubule sodium transport but did not cause natriuresis. The addition of enalapril to fenoldopam restored the natriuretic effect of fenoldopam and its inhibitory effect on proximal tubule sodium transport. Thus, on a high NaCl diet fenoldopam causes natriuresis by inhibiting renal proximal and distal tubule transport, but on a low NaCl diet the increased RAAS activity prevents the D1-like receptor from inhibiting renal proximal tubule sodium transport, neutralizing the natriuretic effect of fenoldopam. These results demonstrate an interaction between the renin-angiotensin and renal dopaminergic systems in humans and highlight the influence of dietary NaCl on these interactions.

Administration of fenoldopam in critically ill small animal patients with acute kidney injury: 28 dogs and 34 cats (2008-2012)

OBJECTIVE

To describe the clinical features and outcomes of critically ill dogs and cats with acute kidney injury (AKI) receiving fenoldopam infusions compared to patients with AKI that did not receive fenoldopam.

DESIGN

Retrospective clinical study from May 1, 2008 until June 1, 2012.

SETTING

Private emergency and specialty referral hospital.

ANIMALS

Client-owned dogs (28) and cats (34) with AKI that received fenoldopam compared with similar patients with AKI (30 dogs and 30 cats) that did not.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The medical records of 62 critically ill dogs and cats with AKI that received fenoldopam were reviewed. Presenting clinical signs, physical examination findings, and primary and secondary disease processes were identified in all patients. The mean number of days on fenoldopam was 1.5 days (range 0.3-4.0 days) for dogs and 1.9 days (range 1.0-4.0 days) for cats. Eleven of 28 (39%) dogs survived to discharge and 13 of 34 (38%) of the cats survived to discharge. Of the animals in the group receiving fenoldopam that died, the majority (84%) were euthanized. Potential adverse reactions were evaluated, with hypotension being the most commonly encountered adverse effect (7% of fenoldopam group [FG] dogs and 23% of FG cats). When compared with patients with AKI that did not receive fenoldopam, no significant differences were found between the groups with regards to survival, length of hospital stay, adverse effects, or changes in creatinine, BUN, or sodium concentrations except that patients receiving fenoldopam were significantly more likely to have received other renally active medications.

CONCLUSIONS

In this study of patients with AKI, fenoldopam administration at 0.8 μg/kg/min in dogs and 0.5 μg/kg/min in cats appeared relatively safe but was not associated with improvement in survival to discharge, length of hospital stay, or improvement in renal biochemical parameters when compared to patients with AKI not receiving fenoldopam.

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.

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.

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.

Beneficial Impact of Fenoldopam in Critically Ill Patients With or at Risk for Acute Renal Failure: A Meta-Analysis of Randomized Clinical Trials

BACKGROUND

Acute kidney injury is common in critically ill patients. Fenoldopam mesylate is a potent dopamine A-1 receptor agonist that increases blood flow to the renal cortex and outer medulla. Because there is uncertainty about the benefits of fenoldopam in such a setting, we performed a systematic review of randomized controlled trials of intensive care unit patients or those undergoing major surgery.

METHODS

BioMedCentral, CENTRAL, PubMed, and conference proceedings were searched (updated October 2005). Investigators and external experts were contacted. Two unblinded reviewers selected randomized controlled trials that used fenoldopam in the prevention or treatment of acute kidney injury in postoperative or intensive care patients. Studies involving the prevention of contrast nephropathy or containing duplicate data were excluded from analysis. Two reviewers independently abstracted patient data, treatment characteristics, and outcomes.

RESULTS

A total of 1,290 patients from 16 randomized studies were included in the analysis. Pooled estimates showed that fenoldopam consistently and significantly reduced the risk for acute kidney injury (odds ratio [OR], 0.43; 95% confidence interval [CI], 0.32 to 0.59; P < 0.001), need for renal replacement therapy (OR, 0.54; 95% CI, 0.34 to 0.84; P = 0.007), and in-hospital death (OR, 0.64; 95% CI, 0.45 to 0.91; P = 0.01). These benefits were associated with shorter intensive care unit stay (weighted mean difference, -0.61 days; 95% CI, -0.99 to -0.23; P = 0.002). Sensitivity analyses, tests for small-study bias, and heterogeneity assessment further confirmed the main analysis.

CONCLUSION

This analysis suggests that fenoldopam reduces the need for renal replacement and mortality in patients with acute kidney injury. A large, multicenter, appropriately powered trial will need to be performed to confirm these results.

Fenoldopam improves corticomedullary oxygen delivery and attenuates angiogenesis gene expression in acute ischemic renal injury

BACKGROUND/AIMS

Vasoactive compounds are known to affect intrarenal hemodynamics and gene transcription, but specific effects of fenoldopam in the setting of acute renal ischemia are not known. We utilized a rat model of acute ischemic nephropathy to test the hypothesis that fenoldopam improves corticomedullary tissue oxygen tension (PtO2) and attenuates angiogenesis gene expression in acute renal ischemia.

METHODS

Rats anesthetized with 50 mg/kg urethane were divided into 4 groups (n = 6 each): (1) sham with infusion of 0.9% saline; (2) sham with infusion of 0.1 microg x kg(-1) x min(-1) fenoldopam; (3) unilateral renal ischemia followed by 6 h of reperfusion with saline, and (4) ischemia/reperfusion with fenoldopam. Renal artery blood flow (RBF), renal cortical perfusion (RCP), and PtO2 were recorded throughout. Total RNA from left kidneys was used to probe microarrays. Gene expression was measured as percent positive control (GAPDH) and confirmed using RT-PCR.

RESULTS

Fenoldopam significantly increased RBF (p < 0.05), RCP (p < 0.01) and PtO2 (p <0.01) in both non-ischemic and post-ischemic kidneys. Fenoldopam attenuated 11 of the 13 ischemia-induced genes and 44 of 78 ischemia-suppressed genes. This attenuation was statistically significant (p < 0.05) for five genes.

CONCLUSION

Data from this rat model of ischemic nephropathy suggest that fenoldopam improves intrarenal hemodynamics and attenuates ischemia-related changes in angiogenesis gene expression.

Comparison of N-acetylcysteine and fenoldopam for preventing contrast-induced nephropathy (CAFCIN)

BACKGROUND

N-acetylcysteine and fenoldopam are commonly prescribed for prevention of contrast mediated nephropathy, however, comparative superiority of either agent is unknown.

METHODS

In a prospective, randomized, parallel-group trial, adult cardiac catheterization patients at the university and veterans' hospitals with pre-existing stable renal insufficiency were randomized to N-acetylcysteine 600 mg orally twice daily for 4 doses or fenoldopam 0.1 mcg/kg/min intravenously for a minimum of 8 h. All patients received intravenous hydration with normal saline (5% dextrose in normal saline for diabetics on insulin). Randomization was stratified for diabetes. The primary endpoint was mean change in Scr at 72 h. Secondary endpoint was the incidence of contrast-induced nephropathy (25% increase above baseline Scr or absolute increase of 0.5 mg/dL).

RESULTS

Study termination occurred after ninety-five patients (mean age 68+/-10 years, female 25%, diabetic 42%, mean baseline Scr 1.5+/-0.4 mg/dL) were randomized, with 84 completing follow-up (44 N-acetylcysteine, 40 fenoldopam). Overall, there were no significant differences in mean change in Scr at 72 h (N-acetylcysteine 0.20+/-0.72 vs. fenoldopam 0.08+/-0.48 mg/dL, p=0.4) or incidence of contrast-induced nephropathy (N-acetylcysteine 5 vs fenoldopam 8, p=0.4). No differences were detected in subgroup analyses for diabetes, baseline Scr >1.7 or 2.0 mg/dL, gender, age >70 years, or contrast volume >150 mL. Results were similar after multivariate adjustment for diabetes, contrast volume, heart failure and gender.

CONCLUSIONS

Our randomized comparison failed to demonstrate a significant difference in the abilities of N-acetylcysteine and fenoldopam to prevent the decline in renal function or the incidence of contrast-induced nephropathy during cardiac catheterization.

A comparison between fenoldopam and low-dose dopamine in early renal dysfunction of critically ill patients*

OBJECTIVE

Fenoldopam mesylate is a selective dopamine-1 agonist, with no effect on dopamine-2 and alpha1 receptors, producing a selective renal vasodilation. This may favor the kidney oxygen supply/demand ratio and prevent acute renal failure. The aim of the study was to investigate if fenoldopam can provide greater benefit than low-dose dopamine in early renal dysfunction of critically ill patients.

DESIGN

Prospective, multiple-center, randomized, controlled trial.

SETTING

University and city hospital intensive care units.

PATIENTS

One hundred adult critically ill patients with early renal dysfunction (intensive care unit stay<1 wk, hemodynamic stability, and urine output<or=0.5 mL/kg over a 6-hr period and/or serum creatinine concentration>or=1.5 mg/dL and<or= 3.5 mg/dL).

INTERVENTIONS

Patients were randomized to receive 2 microg/kg/min dopamine (group D) or 0.1 microg/kg/min fenoldopam mesylate (group F). Drugs were administered as continuous infusion over a 4-day period.

MEASUREMENTS AND MAIN RESULTS

Systemic hemodynamic and renal function variables were recorded daily. The two groups were well matched at enrollment for illness severity and hemodynamic and renal dysfunction. No differences in heart rate or systolic, diastolic, or mean arterial pressure were observed between groups. Fenoldopam produced a more significant reduction in creatinine values compared with dopamine after 2, 3, and 4 days of infusion (change from baseline at time 2, -0.32 vs. -0.03 mg/dL, p=.047; at time 3, -0.45 vs. -0.09 mg/dL, p=.047; and at time 4, -.041 vs. -0.09 mg/dL, p=.02, in groups F and D, respectively). The maximum decrease in creatinine compared with baseline was significantly greater in group F than group D (-0.53+/-0.47 vs. -0.34+/-0.38 mg/dL, p=.027). Moreover, 66% of patients in group F had a creatinine decrease>10% of the baseline value at the end of infusion, compared with only 46% in dopamine group (chi-square=4.06, p=.04). Total urinary output during drug infusion was not significantly different between groups. After 1 day, urinary output was lower in group F compared with group D (p<.05).

CONCLUSIONS

In critically ill patients, a continuous infusion of fenoldopam at 0.1 microg/kg/min does not cause any clinically significant hemodynamic impairment and improves renal function compared with renal dose dopamine. In the setting of acute early renal dysfunction, before severe renal failure has occurred, the attempt to reverse renal hypoperfusion with fenoldopam is more effective than with low-dose dopamine.

Prophylactic fenoldopam for renal protection in sepsis: a randomized, double-blind, placebo-controlled pilot trial

OBJECTIVE

Acute renal failure is common in septic patients. Fenoldopam, a dopamine-1 receptor agonist, increases renal blood flow and may, therefore, reduce the risk of acute renal failure in such patients. Accordingly, we sought to determine the safety and efficacy of fenoldopam for the prevention of acute renal failure in septic patients.

DESIGN

Prospective, double-blind, placebo-controlled trial.

SETTING

Three multidisciplinary intensive care units at a university hospital.

PATIENTS

Three hundred septic patients with baseline serum creatinine concentrations <150 micromol/L.

INTERVENTIONS

We randomized patients to a continuous infusion of either fenoldopam (n = 150) at 0.09 microg x kg x min or placebo (n = 150) while in the intensive care unit. The primary outcome measure was the incidence of acute renal failure, defined as a serum creatinine concentration increase to >150 micromol/L, during study drug infusion.

MEASUREMENTS AND MAIN RESULTS

The incidence of acute renal failure was significantly lower in the fenoldopam group compared with the control group (29 vs. 51 patients; p = .006). The odds ratio of developing acute renal failure for patients treated with fenoldopam was estimated to be 0.47 (p = .005). The difference in the incidence of severe acute renal failure (creatinine >300 mumol/L), however, failed to achieve statistical significance (10 vs. 21; p = .056). The length of intensive care unit stay in surviving patients was significantly lower in the fenoldopam group compared with the control group (10.64 +/- 9.3 vs. 13.4 +/- 14.0; p < .001). There were no complications of fenoldopam infusion. A direct effect of treatment on the probability of death, beyond its effect on acute renal failure, was not significant (odds ratio = 0.68, p = .1).

CONCLUSIONS

Compared with placebo, low-dose fenoldopam resulted in a smaller increase in serum creatinine in septic patients. The clinical significance of this finding is uncertain. A large multiple-center trial is now needed to confirm these findings.

Complications of major aortic and lower extremity vascular surgery

Atheromatous disease and invasive intervention of the aortoiliac and distal arteries are common. Morbidity and mortality have been reduced through understanding and management of patient risk factors. Complications of this form of treatment affect all organ systems; mortality is most frequently caused by a cardiovascular complication (eg, myocardial infarction). Infection, leading to aortoenteric fistula is a dreaded complication, and paraplegia, though rare, is a devastating outcome. Multiorgan failure and death may result from a systemic inflammatory response syndrome. Vascular surgery for infrainguinal disease also has a significant cardiovascular complication rate. Resulting complications may affect all organs; loss of an extremity may occur. The first part of this article reviews perioperative and postoperative complications of open aortic repair and lower-extremity revascularization and addresses the issue of regional anesthesia for major vascular surgery. The second part reviews endovascular aortic repair (EVAR). EVAR is a new intervention that combines surgery and radiology. Complications of EVAR are similar to open repair, but early results suggest they may be less frequent. New technology leads to new complications; endoleaks, migration of the endoprosthesis, and surgical conversion are unique to EVAR. The benefits of EVAR may be less blood loss, shorter hospitalization, and less cardiovascular stress; the risks may be aneurysm recurrence, prolonged surveillance and repeated secondary procedures. The development of EVAR, the complications, and the anesthesia-related concerns of EVAR, including its use in management of acute abdominal aortic aneurysm are reviewed.

Renal protection strategies in the perioperative period

The development of acute renal failure (ARF) in the perioperative period continues to be a vexing condition associated with high morbidity and mortality rates which have been unchanged for several decades. In this article I briefly review recent research categorizing pathogenesis of ARF and mechanisms of recovery. Once ARF is established, its maintenance phase is dependent on several mechanisms that interact with cellular integrity. The main focus of the article is on assessing clinical and experimental interventions to prevent ARF. Unfortunately, existing pharmacological and other interventions show a rather limited efficacy in preventing ARF.

The Abnormal Renal Vasodilator Response to D1-Like Receptor Stimulation in Conscious SHR Can Be Normalized by AT1 Blockade

BACKGROUND

We previously showed that the renal vasodilator response to a D1-like receptor agonist is blunted in conscious SHR compared with WKY rats. The mechanism of this impaired dopaminergic responsiveness in SHR is unclear. An altered balance between the renin-angiotensin-aldosterone system (RAAS) and the dopaminergic system may be involved. To determine the interaction between the RAAS and the dopaminergic system in the blunted D1-like responsiveness in SHR, we studied the renal vasodilator response to the D1-like receptor agonist fenoldopam before and after 7 days of pretreatment with the AT1-receptor antagonist (AT1-A) L158,809 in conscious SHR and WKY rats.

METHODS

Effective renal plasma flow (ERPF) was measured by the clearance of I-hippuran. Mean arterial pressure (MAP) was measured via an intraarterial catheter.

RESULTS

Without pretreatment, MAP was reduced to comparable degrees by fenoldopam in WKY (-7 +/- 4%, ns) and SHR (-6 +/- 1%, P < 0.05). However, ERPF was significantly more increased (P < 0.006) by fenoldopam in WKY (+26 +/- 2%, P < 0.0001) than in SHR (+2 +/- 2%, ns). AT1-A treatment reduced MAP and increased ERPF and glomerular filtration rate significantly in both strains. Pretreatment with AT1-A significantly potentiated the fenoldopam-induced rise in ERPF in SHR, but not in WKY, without affecting the blood pressure responses in either strain. As a result, during pretreatment with an AT1-A, the rise in ERPF by fenoldopam was similar in both strains (SHR +25 +/- 2%, P < 0.0001; WKY +33 +/- 2%, P < 0.0001).

CONCLUSIONS

These results suggest that the RAAS accounts for the blunted renal vasodilator response to a D1-like receptor agonist in SHR. A dysbalance between the dopaminergic system and the RAAS may be involved in the abnormal renal hemodynamic regulation in SHR.

Monitoring Renal Oxygen Supply in Critically-Ill Patients Using Urinary Oxygen Tension

Critically-ill patients are at risk of developing renal disorders as a consequence of systemic hypoperfusion. Ischemic acute tubular necrosis and resulting acute renal failure are caused by hypotension or therapeutic management. In this study, we tested the change of O(2) availability induced by fenoldopam mesylate using the continuous measurement of urinary oxygen tension (PuO(2)), a relatively noninvasive technique that could provide potentially important real-time data regarding renal oxygenation in intensive care unit patients. Fenoldopam was administered at different doses (0.03, 0.06, and 0.09 microg x kg(-1) x min(-1)) to 50 stable critically-ill patients. Urine output was collected every hour to assess volume and urinary electrolytes. Heart rate, mean arterial blood pressure, cardiac output, pulmonary artery occlusion pressure, arterial oxygen delivery index, and oxygen consumption index were analyzed after fenoldopam dose modifications and at infusion end. PaO(2) and PuO(2) continuous measurements were obtained through two sensors inserted in the radial artery and in the bladder. After a fenoldopam dose increase, PuO(2) significantly increased (P < 0.05), whereas PaO(2) remained unchanged. During the study, heart rate, mean arterial blood pressure, cardiac output, central venous pressure, pulmonary artery occlusion pressure, arterial oxygen delivery index, and oxygen consumption remained unchanged. Dose-dependent PuO(2) increases, unrelated to indexes of systemic perfusion and cardiac function, demonstrate that fenoldopam affects the balance between renal oxygen supply and demand in stable critically-ill patients.

IMPLICATIONS

Acute renal failure in critically-ill patients is associated with frequent mortality. Prolonged renal hypoperfusion cannot be detected by current systemic hemodynamic indexes. Using continuous measurement of urinary oxygen tension, which could indirectly provide real-time data regarding renal oxygenation, our study showed that fenoldopam increases the ratio between oxygen supply and demand.

Fenoldopam mesylate for the prevention of contrast-induced nephropathy: a randomized controlled trial

CONTEXT

The development of contrast-induced nephropathy in patients undergoing invasive cardiac procedures is associated with a marked increase in cardiovascular morbidity and mortality. Fenoldopam mesylate, a specific agonist of the dopamine-1 receptor, preserves renal blood flow after iodinated contrast administration and has shown promise in ameliorating contrast nephropathy in previous observational and small randomized trials.

OBJECTIVE

To examine the efficacy of fenoldopam mesylate in preventing contrast nephropathy after invasive cardiovascular procedures.

DESIGN

Prospective, placebo-controlled, double-blind, multicenter randomized trial with serial serum creatinine levels measured at a central biochemistry laboratory (at baseline and 1, 24, 48, and 72 to 96 hours after study drug administration) and 30-day clinical follow-up.

PATIENTS AND SETTING

Between March 2001 and July 2002, 315 patients with creatinine clearance less than 60 mL/min (1.00 mL/s) at 28 centers in the United States were randomized to receive fenoldopam mesylate (n = 157) or placebo (n = 158).

INTERVENTIONS

Patients were hydrated and randomized to receive intravenous fenoldopam (0.05 microg/kg/min titrated to 0.10 microg/kg/min) vs matching placebo, starting 1 hour prior to angiography and continuing for 12 hours.

MAIN OUTCOME MEASURE

Contrast-induced nephropathy, defined as an increase of 25% or more in serum creatinine level within 96 hours postprocedure.

RESULTS

Mean (SD) patient age was 70 (11) years, and 49% had diabetes mellitus. Mean (SD) baseline creatinine clearance was 29.0 (10.0) mL/min (0.48 [0.16] mL/s) (range, 7.5-56.8 mL/min [0.12-0.94 mL/s]), and 157 (108) mL of contrast was administered during the procedures. The primary end point of contrast-induced nephropathy occurred in 33.6% of patients assigned to receive fenoldopam vs 30.1% assigned to receive placebo (relative risk, 1.11; 95% confidence interval, 0.79-1.57; P =.61). There were no significant differences in the 30-day rates of death (2.0% vs 3.8%, P =.50), dialysis (2.6% vs 1.9%, P =.72), or rehospitalization (17.6% vs 19.9%, P =.66) in fenoldopam vs placebo randomized patients, respectively.

CONCLUSION

The selective dopamine-1 agonist fenoldopam mesylate does not prevent further renal function deterioration after contrast administration in patients with chronic renal insufficiency.

Effect of fenoldopam on renal function after nephrotomy in normal dogs

OBJECTIVE

To evaluate effects of fenoldopam on renal function in normal dogs subjected to bisection nephrotomy. In addition, effects of bisection nephrotomy on renal function in normal dogs were evaluated.

STUDY DESIGN

Controlled, randomized, blinded experiment.

SAMPLE POPULATION

Sixteen mixed-breed adult dogs.

METHODS

Dogs were paired for sex, body weight, and approximate age and assigned to 1 of 2 groups: fenoldopam (F) or placebo (P). Baseline glomerular filtration rate (GFR) based on quantitative renal scintigraphy using (99m)Tc-DTPA, blood urea nitrogen (BUN), serum creatinine (SCr), urinalysis, and urine culture were performed before surgery. Left nephrotomy was performed via median celiotomy. Group F dogs were administered intravenous (IV) fenoldopam (0.1 microg/kg/min) for 90 minutes, whereas group P dogs were administered an equivalent volume of saline (0.9 % NaCl) solution for 90 minutes. Temperature, heart rate, respiration, direct arterial blood pressure, and urine volume were recorded during anesthesia. Renal function was assessed by measuring SCr, BUN, and GFR at 1, 21, and 42 days after surgery.

RESULTS

There was no significant difference between groups in measured physiologic variables. No significant difference in GFR, BUN, or SCr between groups or between operated or control kidneys was detected.

CONCLUSIONS

Bisection nephrotomy in normal dogs with renal arterial occlusion of 15 minutes and using a simple continuous capsular closure does not adversely affect renal function.

CLINICAL RELEVANCE

Bisection nephrotomy, as described in this study, does not decrease renal function; perioperative administration of renoprotective agents is not necessary in normal dogs.

Fenoldopam for renal protection in patients undergoing cardiopulmonary bypass

OBJECTIVE

To evaluate the possible protective effects of fenoldopam on renal function in patients undergoing cardiopulmonary bypass.

DESIGN

Prospective, randomized trial.

SETTING

University teaching hospital.

PARTICIPANTS

One hundred sixty consecutive patients with serum creatinine >1.5 mg/dL who underwent uncomplicated moderate hypothermic cardiopulmonary bypass for cardiac surgery.

INTERVENTIONS

A random group of 80 patients was managed conventionally (group A), whereas another random group of 80 patients received continuous intravenous administration of low-dose fenoldopam (0.1-0.3 microg/kg/min) during cardiopulmonary bypass and in the early postoperative period (group B).

MEASUREMENTS AND MAIN RESULTS

An improvement of postoperative renal parameters were observed only in group B: preoperative serum creatinine 1.82 +/- 0.2 versus 1.43 +/- 0.73 postoperatively (p < 0.001), preoperative creatinine clearance 51.34 +/- 22.26 versus 67.14 +/- 18.55 postoperatively (p < 0.001).

CONCLUSIONS

In this study, fenoldopam was an effective agent in the prevention of renal dysfunction after cardiopulmonary bypass.

Fenoldopam mesylate blocks reductions in renal plasma flow after radiocontrast dye infusion: a pilot trial in the prevention of contrast nephropathy

BACKGROUND

Radiocontrast nephropathy (RCN) is a common source of acute renal failure in hospitalized patients and is associated with increased morbidity and mortality rates. Fenoldopam mesylate is a dopamine A1 receptor agonist that augments renal plasma flow (RPF) in patients with normotensive and hypertensive conditions. To determine whether fenoldopam mesylate attenuates reductions in RPF after contrast infusion, we conducted a double-blind, randomized, placebo-controlled pilot trial of fenoldopam mesylate in patients who underwent contrast angiography.

METHODS

Fifty-one patients with chronic renal insufficiency (creatinine level, 2.0-5.0 mg/dL) who were undergoing contrast angiography were screened, and 45 patients were randomized to receive normal saline solution (1/2 NS) or 1/2 NS plus fenoldopam mesylate at 0.1 microg/kg/min at lease 1 hour before infusion with contrast dye. Serum creatinine level was measured at baseline and at 24, 48, and 72 hours after angiography. The primary endpoint was change in RPF 1 hour after contrast infusion. The secondary endpoint was incidence of RCN, defined as a 0.5 mg/dL or a 25% rise in serum creatinine level at 48 hours.

RESULTS

RPF at 1 hour after angiography was 15.8% above baseline in the fenoldopam mesylate group compared with 33.2% below baseline in the 1/2 NS group (P <.05). The incidence rate of RCN at 48 hours was 41.0% in the 1/2 NS group versus 21% in the fenoldopam mesylate group (P =.148). Among patients with diabetes, the incidence rate of RCN tended to be higher in the 1/2 NS group compared with the fenoldopam mesylate group (64% vs 33%; P =.14). The peak serum creatinine level at 72 hours after contrast infusion was significantly higher at in the 1/2 NS group (creatinine level, 3.6 +/- 1.0 mg/dL) compared with the fenoldopam mesylate group (creatinine level, 2.8 +/- 0.35 mg/dL; P <.05). RPF was significantly (P <.0001) reduced in patients with RCN compared with patients in whom RCN did not develop.

CONCLUSION

The results of this pilot trial suggest that fenoldopam mesylate is a promising prophylactic agent for RCN and that larger multicenter trials should be conducted to prove its efficacy.

Fenoldopam: renal and splanchnic effects in patients undergoing coronary artery bypass grafting

Impairment of renal and splanchnic perfusion during and after cardiopulmonary bypass may be responsible for acute renal failure and endotoxin-mediated systemic inflammation, respectively. We hypothesised that fenoldopam, a selective dopamine receptor agonist, would preserve renal function after cardiopulmonary bypass through its selective renal vasodilatory and natriuretic effects, and increase gastrointestinal mucosal perfusion by selective splanchnic vasodilation. We examined the effects of fenoldopam on haemodynamic parameters, creatinine clearance, fractional excretion of sodium, urine output, free water clearance and gastric mucosal pH in 31 patients undergoing elective coronary revascularisation. Patients were randomly assigned to receive continuous infusions of fenoldopam 0.1 microg x kg(-1) x min(-1) (n = 16) or placebo (n = 15). Renal parameters were measured: during a 24-h period before hospital admission, during cardiopulmonary bypass, from completion of cardiopulmonary bypass until 4 h later, from 4 to 8 h after cardiopulmonary bypass, and from 8 to 14 h after cardiopulmonary bypass. Gastric intramucosal pH was measured using a gastric tonometer before, during and after cardiopulmonary bypass. In the placebo group, but not the fenoldopam group, mean (SD) creatinine clearance decreased after separation from cardiopulmonary bypass, from 107 (36) to 71 (22) ml x min(-1) (p < 0.01) and from 107 (36) to 79 (26) ml x min(-1) (p < 0.01) for the 0-4 h and 4-8 h intervals after cardiopulmonary bypass, respectively. Changes in intramucosal pH were similar in both groups. The findings are consistent with the hypothesis that fenoldopam possesses a renoprotective effect in patients undergoing cardiopulmonary bypass.

Effects of prophylactic fenoldopam infusion on renal blood flow and renal tubular function during acute hypovolemia in anesthetized dogs

OBJECTIVE

It was hypothesized that fenoldopam mesylate, a selective dopamine agonist, may preserve renal perfusion and decrease tubular oxygen consumption during states of hypoperfusion, such as hypovolemic shock. The objective of this study was to quantify the effects of fenoldopam (0.1 microg x kg(-1) x min(-1)) on renal blood flow, urine output, creatinine clearance, and sodium clearance in pentobarbital anesthetized dogs that had undergone partial exsanguination to acutely decrease cardiac output.

DESIGN

Prospective, randomized, controlled experiment.

SETTING

University-based animal laboratory and research unit.

SUBJECTS

Eight female beagle dogs.

INTERVENTIONS

Arterial blood pressure, heart rate, cardiac output, renal blood flow, urine output, creatinine clearance, and fractional excretion of sodium were measured and calculated at four times: a) before infusion of fenoldopam or normal saline; b) during infusion of fenoldopam or normal saline (1 hr); c) during a 90-min period of hypovolemia (induced by acute partial exsanguination), with concurrent infusion of fenoldopam or normal saline; and d) during a 1-hr period after retransfusing the dogs.

MEASUREMENTS AND MAIN RESULTS

Administration of fenoldopam (0.1 microg x kg(-1) x min(-1)) was not associated with hemodynamic instability. Renal blood flow and urine output decreased significantly from baseline (p <.01) during the hypovolemic period in the placebo group (72 +/- 20 to 47 +/- 6 mL/min and 0.26 +/- 0.15 to 0.08 +/- 0.05 mL/min, respectively) but not in the fenoldopam group (75 +/- 14 to 73 +/- 17 mL/min and 0.3 +/- 0.19 to 0.14 +/- 0.05 mL/min, respectively). Creatinine clearance and fractional excretion of sodium decreased significantly from baseline (p <.01) in the placebo group during the hypovolemic period (3.0 +/- 0.4 to 1.8 +/- 0.8 mL x kg(-1) x min(-1) and 1.7% +/- 0.9% to 0.4% +/- 0.2%, respectively) but not in the dogs that received fenoldopam (3.0 +/- 1.0 to 2.9 +/- 0.5 mL x kg(-1) x min(-1) and 1.9% +/- 1.1% to 1.7% +/- 2.7%, respectively).

CONCLUSIONS

Fenoldopam ablated the tubular prerenal response to profound hypovolemia and maintained renal blood flow, glomerular filtration rate, and natriuresis without causing hypotension. This suggests that fenoldopam may have a renoprotective effect in acute ischemic injury.

Renal blood flow changes induced with endothelin-1 and fenoldopam mesylate at quantitative Doppler US: initial results in a canine study

PURPOSE

To evaluate quantitative Doppler ultrasonography (US) for assessing renal blood flow changes induced with endothelin-1 (ET-1) and fenoldopam mesylate in conscious dogs.

MATERIALS AND METHODS

A blood flow probe was surgically implanted around the renal artery in eight adult dogs. Color and power Doppler US images were acquired in conscious restrained dogs during intravenous infusion of ET-1 and fenoldopam mesylate. Simultaneous with imaging, blood flow through the renal artery was measured with the implanted probe. The color level of the images within the region representing the kidney was analyzed to derive flow indices. These indices were compared with direct-flow measurements.

RESULTS

The flow indices, color-weighted flow area (CWFA), and percentage of area of color, derived from color and power Doppler US images, correlated linearly with direct flow. The mean color level of color and power Doppler US images correlated weakly with direct flow. Pre- versus postinfusion CWFA decreased with all ET-1 infusions (P < or =.032). Infusion of fenoldopam mesylate increased CWFA in all cases (P < or =.032).

CONCLUSION

Quantitative Doppler US enabled successful measurement of the flow changes induced with ET-1 and fenoldopam mesylate. Quantitative Doppler US is potentially useful as a noninvasive surrogate endpoint in evaluating the action of various therapeutic agents.

Use of fenoldopam for prevention of radiocontrast nephropathy in the cardiac catheterization laboratory: a case series

Many of the longstanding challenges in interventional cardiology, such as restenosis and thrombosis, have been met. However, radiocontrast-induced nephropathy (RCN) continues to be problematic, particularly as the population of patients who are diagnosed and treated for vascular occlusions in the cardiac catheterization laboratory have become increasingly older and more complex. Introduction of nonionic contrast media has not eliminated this problem. We present the cases of four high risk patients whom we treated with a newly available renal vasodilator, fenoldopam, as a strategy to prevent RCN and its associated morbidity and mortality.

The effects of fenoldopam on coronary conduit blood flow after coronary artery bypass graft surgery

OBJECTIVE

To quantify the effects of fenoldopam, 0.1 microg/kg/min, on left internal mammary artery (LIMA) and saphenous vein blood flow after coronary anastomosis.

DESIGN

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

SETTING

University teaching hospital, single institution.

PARTICIPANTS

Thirty-one American Society of Anesthesiologists III patients undergoing elective coronary revascularization.

INTERVENTIONS

A perivascular ultrasonic flow probe (Linton Instrumentation, Norfolk, UK) was placed around the LIMA and saphenous vein graft after coronary anastomosis.

MEASUREMENTS AND MAIN RESULTS

Immediately before and at 5-minute intervals for 15 minutes after starting the infusion, blood flow was measured in the LIMA and one saphenous vein graft using a transit time ultrasonic flow probe. Heart rate, blood pressure, and central venous pressure were documented at these time points. Administration of fenoldopam, 0.1 microg/kg/min, did not alter heart rate or blood pressure. A small, nonsignificant increase in LIMA blood flow occurred during the 15-minute study period (30 +/- 12 to 35 +/- 10 mL/min) in patients who received fenoldopam. No significant changes occurred in the placebo group.

CONCLUSIONS

The findings indicate that fenoldopam, 0.1 microg/kg/min, did not influence coronary conduit blood flow to a clinically significant extent. The small increase in LIMA blood flow may be of greater importance in high-risk patients or in the prevention of coronary arterial spasm.

Fenoldopam infusion associated with preserving renal function after aortic cross-clamping for aneurysm repair

BACKGROUND

Cross-clamping of the descending aorta during operative repairs causes sudden, significant reductions in renal function that may persist well beyond arterial clamp release. Commonly used agents, such as dopamine and mannitol, have not consistently affected renal outcome in these high-risk patients. Fenoldopam mesylate is a novel, highly selective dopamine type-1 agonist that preferentially dilates the renal and splanchnic vasculature, but has not been investigated in patients undergoing prolonged aortic clamping for whom adverse renal outcomes should be more likely.

METHODS AND RESULTS

Twenty-two adult patients without significant pre-existing renal dysfunction and presenting for elective repairs of abdominal aortic aneurysms were studied. Fenoldopain mesylate was infused after obtaining baseline values ranging from 0.1 to 1.0 microg/kg/min for the first 24 hours postoperatively to maintain mean arterial pressure +/-25% baseline. Serial renal function indices, including creatinine clearance and electrolyte fractional excretions, were measured at baseline, at aortic clamping and unclamping, and post-clamp release, and were estimated through hospital discharge. Creatinine clearance fell during abdominal exploration and clamping, reaching a nadir with clamp removal. Partial recovery occurred by 2 hours after clamp removal, and returned to baseline values by postoperative day 1 and thereafter. Fractional excretions rose rapidly throughout the operative phase. Total fenoldopam dose was directly related to the baseline creatinine clearance; after clamp removal, creatinine clearance was directly related to the mean arterial pressure at the lowest dose of fenoldopam, and inversely related to the mean arterial pressure at clamp release.

CONCLUSIONS

In elderly patients with severe vascular disease undergoing aneurysmal repairs, the use of a fenoldopam infusion in this open-label, uncontrolled trial was associated with a relatively rapid return of renal function to baseline values, despite profound decreases during aortic cross-clamping. Further studies will be necessary to investigate how fenoldopam infusions compare with traditional therapies.

Oliguria in the ICU. Systematic approach to diagnosis and treatment

Perioperative oliguria is common but rarely implies acute renal failure. We should interpret oliguria as a sign of intravascular hypovolemia and treat it as prerenal until proven otherwise. On the other hand, the absence of oliguria does not exclude acute renal failure. The most reliable clinical indicator of progressive renal dysfunction is a serial decline in creatinine clearance estimation, a measure of glomerular filtration rate.

New pharmacologic options for renal preservation

The understanding of the cause and pathophysiology of renal failure has guided the rational development of pharmacologic renoprotective strategies. Although traditionally anesthesiologists have focused on renal hemodynamic derangements, newer information suggests that cellular interactions amplify and perpetuate the insult. Consequently, the potential renoprotective armamentarium not only encompasses the more traditional vasoactive agents but also therapeutic approaches that may modify the cellular response to injury. Although few of these agents have reached the clinical arena, preliminary work suggests that this new approach to renal injury and protection may be promising.

Fenoldopam, a dopamine agonist, for hypertensive emergency: a multicenter randomized trial. Fenoldopam Study Group

Despite successful therapies for chronic hypertension, hospital admissions for hypertensive emergency more than tripled between 1983 and 1992.

OBJECTIVE

To examine the safety and efficacy of fenoldopam, the first antihypertensive with selective and specific action on vascular dopamine (DA1) receptors, in a clinical trial involving emergency department patients with true hypertensive emergencies.

METHODS

Patients with a sustained diastolic blood pressure (DBP) of > or =120 mm Hg and evidence of target organ compromise were randomized in a double-blinded manner to one of four fixed doses of intravenous fenoldopam (0.01, 0.03, 0.1, or 0.3 microg/kg/min) for 24 hours. The primary endpoint was the magnitude of DBP reduction in each of the three higher-dose groups after four hours of fenoldopam treatment compared with the lowest-dose group.

RESULTS

One hundred seven participants from 21 centers were enrolled, and 94 patients received fenoldopam. Evidence of acute target-organ damage included new renal dysfunction or hematuria (50%), acute congestive heart failure or myocardial ischemia (48%), and papilledema or grade III-IV hypertensive retinopathy (34%). The DBP decreased in a dose-dependent fashion, with significant differences between the 0.1- and 0.3-microg/kg/min groups compared with the lowest-dose group. Treatment was well tolerated, and there were no deaths or serious adverse events during follow-up, up to 48 hours. All patients were successfully transitioned to oral or transdermal antihypertensives with maintenance of blood pressure control.

CONCLUSIONS

Fenoldopam safely and effectively lowers blood pressure in a dose-dependent manner in patients with hypertensive emergencies. Observations supporting potential risk factors for hypertensive emergency are discussed.

Renal dopaminergic mechanisms and hypertension: a chronology of advances

Dopamine (DA) has been shown to influence kidney function through endogenous synthesis and subsequent interaction with locally expressed dopamine receptor subtypes (D1, D5 as D1-like and D2, D3, and D4 as D2-like). DA, and DA-receptor specific agonists and antagonists can alter renal water and electrolyte excretion along with renin release when infused systemically or intrarenally. Such effects are brought about by a combination of renal hemodynamic and direct tubular effects evoked along the full length of the nephron. The cellular mechanisms that direct these dopamine-mediated renal electrolyte fluxes have recently been clarified and include alterations in adenylyl cyclase, phospholipase C, and phospholipase A1 activity. The dopaminergic system also interacts directly with the renal kallikrein-kinin, prostaglandin and other neurohumoral systems. Aberrant renal dopamine production and/or dopamine receptor function have been reported in salt-dependent and low-renin forms of human primary hypertension as well as in genetic models of animal hypertension, including the SHR and Dahl SS rat. DA D1 or D3 receptor knockout mice have been shown to develop hypertension.

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

OBJECTIVE

Acute renal failure, frequently a consequence of renal vasoconstriction and subsequent renal ischemia, is a common problem for which no proven preventive or therapeutic agents exist. Fenoldopam is a new, selective, dopamine-1 receptor agonist that causes both systemic and renal arteriolar vasodilation. In hypertensive patients, fenoldopam rapidly decreases blood pressure, increases renal blood flow, and maintains or improves the glomerular filtration rate. We sought to determine a dose of fenoldopam that increases renal blood flow without inducing hypotension in normotensive patients and to explore the role of volume status (sodium replete vs. deplete) in these effects.

DESIGN

Randomized, double-blind, placebo-controlled, cross-over study.

SETTING

Clinical research unit.

PATIENTS

Fourteen normal male volunteers.

INTERVENTIONS

Renal plasma flow (para-aminohippurate clearance) and glomerular filtration rate (inulin clearance) were measured during three fixed, escalating doses of fenoldopam (0.03, 0.1, and 0.3 Lg/kg/min) on both a high-sodium and a low-sodium diet.

MEASUREMENTS AND MAIN RESULTS

Fenoldopam significantly increased renal plasma flow in a dose-dependent manner compared with placebo: 670 + 148 vs. 576 + 85 mUmin at 0.03 iLg/kg/min; 777 + 172 vs. 579 + 80 mUmin at 0.1 tig/kg/min; and 784 + 170 vs. 592 + 165 mUmin at 0.3 ilg/kg/min (p < .05 fenoldopam vs. placebo at all three doses). Glomerular filtration rate was maintained. At the lowest dose (i.e., 0.03 ILg/kg/min), significant renal blood flow increases occurred without changes in systemic blood pressure or heart rate. At 0.1 and 0.3 Lgl/kg/ min, systolic blood pressure did not change, but diastolic blood pressure was slightly lower in the fenoldopam group than in the placebo group: 62.5 + 6.4 vs. 63.6 + 2.6 mm Hg, respectively, at 0.3 tg/kg/min (p < .05). None of the effects of fenoldopam were altered by volume status.

CONCLUSIONS

Fenoldopam increased renal blood flow in a dose-dependent manner compared with placebo, and, at the lowest dose, significantly increased renal blood flow occurred without changes in systemic blood pressure or heart rate. These findings will be useful in designing future studies exploring the role of fenoldopam in preventing or treating renal failure in patients who are not hypertensive.

Impaired renal vascular response to a D1-like receptor agonist but not to an ACE inhibitor in conscious spontaneously hypertensive rats

The natriuretic response to a dopamine 1-like receptor agonist is blunted in spontaneously hypertensive rats (SHRs). Whether the renal vasodilator response to D1-like receptor stimulation in SHRs is defective also is unclear. To determine whether the renal hemodynamic response to a D1-like receptor is impaired in SHR, we examined the effect of a continuous infusion of the D1-like receptor agonist fenoldopam (2 microg/kg/min) on systemic and renal hemodynamics in conscious SHRs and Wistar-Kyoto (WKY) rats. As an active control, we used an equivalent antihypertensive dosage of captopril (10 mg/kg). Fenoldopam significantly increased effective renal plasma flow (ERPF) in WKY rats (+22 +/- 5%; p < 0.01), whereas this response was absent in SHRs (+7 +/- 3%; NS). Mean arterial pressure (MAP) was significantly reduced in SHRs (-11 +/- 2%; p < 0.001), demonstrating a systemic vasodilator response to fenoldopam in SHRs. The reduction in renal vascular resistance (RVR) was more pronounced in WKY rats (-24 +/- 2%) than in SHRs (-13 +/- 4%; p < 0.05). Captopril significantly increased ERPF in SHRs (+16 +/- 3%; p < 0.001), demonstrating a preserved renal vasodilatory capacity in SHRs. The blunting of the renal vasodilatory response to fenoldopam in SHRs is present during a high as well as a low sodium intake. In conscious SHRs, the renal vasodilatory response to a D1-like receptor agonist is impaired, whereas the blood pressure response is more pronounced. The preserved renal vasodilatory response to captopril indicates that the defective vasodilatory response in SHRs is functional rather than due to altered structural properties of the renal vascular bed.

Cardiac management in the ICU

Coronary artery disease (CAD) is common in the surgical population, with up to 50% of postoperative deaths due to cardiac events. Most of these events are ischemic, with some being exacerbations of underlying congestive heart failure (CHF). Recent data indicate that acute perioperative beta-adrenergic blockade can reduce ischemia and ischemic events. Postoperative monitoring should focus on myocardial ischemia, with preparation for rapid treatment using IV therapy. A few studies suggest that elderly patients with known CAD undergoing major procedures might benefit from perioperative treatment guided by information from a pulmonary artery catheter. Postoperative CHF, which is likely to present early after surgery, may need aggressive management with diuretics, vasodilators, and inotropic drugs. Mechanical ventilation should be considered. When the patient develops severe or refractory dysrhythmias, serum magnesium levels should be supplemented and consideration given to IV use of amiodarone. Postoperative hypertension is common and can precipitate ischemia, CHF, and arrhythmias as well as cause bleeding. Newer IV drugs are arterial specific and can lower BP in a smooth and predictable manner. All acute cardiac disorders can be precipitated or exacerbated by inadequate pain control, hypoxemia, and fluid or electrolyte disorders.

The effect of fenoldopam on the blood pressure of the rat

1. Fenoldopam mesylate, a benzazepine derivative, is a D1 receptor agonist that lowers blood pressure through vasodilation of renal, mesenteric, coronary and cerebral vascular beds. 2. Experiments were performed in rats, and mean carotid blood pressure and heart rate were registered. Two series of experiments were performed: (1) fenoldopam as control group and (2) fenoldopam after pretreatment with one of the following drugs: the D1 antagonist SCH 23390, the D2 antagonist sulpiride, the selective beta1-adrenergic antagonist atenolol, the selective beta2-adrenergic antagonist ICI 118.551, the nonselective beta-adrenergic antagonist propranolol and the neurotoxin that destroys catecholaminergic nerve terminals 6-hydroxydopamine (6-OH-DA). 3. Fenoldopam produced a dose-dependent hypotensive effect that was not modified by pretreatment of the rat with atenolol or propranolol; however, ICI 118.551 produced a significant reduction of the hypotensive response induced by fenoldopam. 4. Pretreatment of the animals with SCH 23390 produced a significant dose-related reversal of the rat blood pressure reduction induced by low doses of fenoldopam. Sulpiride produced a result similar to that induced by pretreatment with SCH 23390. 5. The pretreatment of the animals with 6-OH-DA surprisingly attenuated the response induced by fenoldopam and produced only a significant reversal of the reduction of mean blood pressure induced with the lower dose of fenoldopam. 6. The findings obtained in the present work do not provide further evidence of direct participation of beta2-adrenergic receptors on the mechanism of action of fenoldopam. Its action seems to be mainly due to activation of D1 cardiovascular receptors.

DA1-receptor stimulation by fenoldopam in the treatment of postcardiac surgical hypertension

BACKGROUND

Besides adequate analgesia, sedation and ventilation, postcardiac surgical hypertension has to be treated frequently with vasoactive drugs to avoid possible complications. In this study the hemodynamic effects of the DA1-receptor agonist fenoldopam (F) are compared to those of the Ca-channel antagonist nifedipine (N).

METHODS

Postoperatively, 64 CABG-patients with a mean arterial pressure (MAP) of more than 105 mmHg over 10 min were investigated. Patients with compromised ventricular function, insufficient surgical repair, arrhythmia or an ECG unable to detect myocardial ischemia were excluded. The study drugs (initial dosage: F: 0.8; N: 0.3 micrograms.kg-1.min-1) were given continuously via a central venous catheter to reduce and to maintain the MAP between 80 and 95 mmHg. Hemodynamic parameters were determined using thermodilution technique.

RESULTS

A significant reduction of the MAP (F: from 121 +/- 11 to 83 +/- 4, N: from 119 +/- 8 to 82 +/- 9 mmHg) and of the calculated systemic vascular resistance (SVR) (F: 2110 +/- 500 to 970 +/- 200, N:1980 +/- 660 to 1020 +/- 300 dyn.s.cm-5) were noted in both groups, whereby in the F group the therapeutic goal could be achieved more quickly with the dosage regimen chosen. As a result, a marked increase of heart rate, cardiac index and stroke volume index could be observed, which was more pronounced due to the initially stronger decrease of SVR with F. There was also a stronger decrease of pulmonary vascular resistance in the F group, but the indices of right ventricular function did not differ between the groups.

CONCLUSION

Fenoldopam seems to be an efficient alternative to nifedipine, especially because of its more rapid onset of action.

Fenoldopam: a new dopamine agonist for the treatment of hypertensive urgencies and emergencies

Fenoldopam is a selective dopamine agonist that is being considered for the parenteral treatment of systemic hypertension. In both an oral and parenteral form, the drug causes peripheral vasodilation by stimulating dopamine-1 adrenergic receptors. Its pharmaco-dynamics are reviewed in this article, along with the clinical experiences in patients with hypertensive urgencies and emergencies. Intravenous fenoldopam may provide advantages over sodium nitroprusside because it can induce both a diuresis and natriuresis, is not light sensitive, and is not associated with cyanide toxicity. There is no evidence for rebound hypertension after discontinuation of fenoldopam influsion.

Fenoldopam: a review of its pharmacodynamic and pharmacokinetic properties and intravenous clinical potential in the management of hypertensive urgencies and emergencies

Fenoldopam is a dopamine agonist that causes peripheral vasodilation via stimulation of dopamine 1 (D1) receptors. The efficacy of an intravenous infusion of fenoldopam in decreasing blood pressure in patients with a hypertensive urgency, including patients who developed hypertension after coronary artery bypass graft surgery, and in a small number of patients with hypertensive emergency, is similar to that of sodium nitroprusside. However, unlike sodium nitroprusside, fenoldopam also increases renal blood flow and causes diuresis and natriuresis. There is no evidence of rebound hypertension after stopping the infusion. As the tolerability profile of fenoldopam is generally similar to that of sodium nitroprusside, fenoldopam appears to be an effective alternative to sodium nitroprusside in the immediate treatment of patients who develop severe hypertension and in whom oral treatment is not practical. Fenoldopam may be particularly useful in patients who develop hypertension after coronary artery bypass graft surgery, but further studies are required to confirm its role in hypertensive emergency.

Selective and nonselective dopamine receptor agonists: an innovative approach to cardiovascular disease treatment

Dopamine and a new group of selective and nonselective peripheral dopaminergic receptor effectors are being evaluated for the treatment of various cardiovascular disorders, including shock, CHF, and systemic hypertension. Dopamine, in relatively low intravenous doses, will stimulate both peripheral DA1 receptors, which mediate arterial vasodilation of different vascular beds, and the DA2 receptors, which mediate the inhibition of norepinephrine release. Ibopamine is a new oral, nonspecific peripheral dopaminergic agonist with an active metabolite (epinine) that is being evaluated in patients with CHF. Fenoldopam is a selective peripheral DA1 agonist now being developed as a parenteral treatment for hypertensive emergencies. Dopexamine is a parenteral agent that selectively activates both DA1 and beta 2 adrenergic receptors and is being evaluated in patients with CHF and in individuals with postoperative left ventricular dysfunction. A group of selective DA2 receptor agonists is being evaluated as long-term treatment for systemic hypertension.