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

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.

Prevention of Acute Renal Failure: Role of Vaso-Active Drugs, Mannitol and Diuretics

Evidence exists that acute renal failure (ARF) independently increases mortality risk in critically-ill patients. Therefore prevention of ARF seems of paramount importance. Preservation of renal blood flow and (sufficient) perfusion pressure favourably influences the prevention of renal function deterioration in the critically-ill septic patient. The first step to achieve this is infusion of fluids, either crystalloids or colloids, with the aim of optimal fluid resuscitation. Although “optimal fluid resuscitation” is poorly defined, in clinical practice it can be considered as the point where a certain preload is obtained, after which no further increase of cardiac output is observed with further fluid infusion. Vasoactive drugs can be added to this regimen in case of insufficient restoration of flow and especially perfusion pressure. The addition of norepinephrine can be of value if high doses of dopamine fail to restore perfusion pressure. No evidence exists that low-dose dopamine prevents renal failure and, therefore, dopamine should not be given for this indication. The use of diuretic agents can be harmful, as indicated by observational and cohort studies. Although mannitol flushes out intratubular casts and increases tubular flow, which is favorable in myoglobinuria or hemoglobinuria, so far no well designed clinical studies have demonstrated its efficacy in ARF. In conclusion, there is currently no convincing evidence for any benefit from diuretic agents and/or (low dose) dopamine in the prevention of ARF. High quality intenisve care and avoidance of harm is, therefore, the current standard of the prevention of ARF.

Prevention of Cardiac Surgery-Associated Acute Kidney Injury

Numerous strategies have been evaluated to prevent early CSA-AKI. Although correction of hemodynamic problems is paramount, there are no clinical studies that compare different hemodynamic management or monitoring strategies with regard to their effect on kidney function. Pharmacologic strategies including diuretics, different classes of vasodilators and drugs with anti-inflammatory effects such as N-acetyl-cysteine, do not appear to be effective. Most of the studies are underpowered and use physiological rather than clinical endpoints. Further trials are warranted with fenoldopam and nesiritide (rhBNP). Observational and underpowered randomized studies show beneficial renal effects of off-pump technique and avoidance of aortic manipulation. There is very limited evidence for preoperative fluid loading and preemptive RRT. Potentially nephrotoxic agents should be used with caution in patients at risk of CSA-AKI. Tranexamic acid or aminocaproic acid should be preferred over aprotinin. No pharmacologic intervention has been adequately tested in the prevention of late CSA-AKI. A single-center study, including a predominance of patients after cardiac surgery, showed a decrease of kidney injury with tight glycemic control.

Treatment of Patients with Cardiac Surgery Associated-Acute Kidney Injury

Members of the Acute Dialysis Quality Initiative (ADQI) participated in a 3-day conference in Vicenza in May 2007 to evaluate the available literature on this topic and draft consensus recommendations for research studies in this area. This report summarizes the available evidence and describes the key questions that will need to be addressed with the goal of standardizing the care of patients with cardiac surgery-associated acute kidney injury (CSA-AKI) and improving outcomes.

Renal Insufficiency After Cardiac Surgery

The new millennium ushered in a number of changes in cardiac surgery. Off-pump coronary artery bypass surgery became technically easier so that multivessel surgery became less of a challenge and cardiologists were supplied with new catheters that accessed lesions that were previously thought of as being unapproachable. New drugs were introduced that made the management of heart failure patients feasible on an outpatient basis, and new devices extend the bridging period to transplantation. However, these advances have not necessarily been attended by significant improvements in outcome, possibly because the less challengng a procedure becomes, the sicker the patients that can be managed. This observation is particularly true with the incidence and outcome of renal failure after cardiac surgery. Bypass factors have been manipulated without much effect, and the traditional drugs that were found to increase renal blood flow in animal experiments did not translate into clinical improvement in renal outcome. Recent research has given us insight into the pathophysiology of ischemic acute renal failure, and it has been found that the paradigm was not as simple as previously thought, possibly accounting for the failure of the more traditional renal drugs (dopamine, mannitol and diuretics). However, these new insights open up the possibility of novel targets for renal protection and repair.

Comparison of Intraoperative Aminophylline Versus Furosemide in Treatment of Oliguria During Pediatric Cardiac Surgery

OBJECTIVES

To determine if intraoperative aminophylline was superior to furosemide to prevent or attenuate postoperative cardiac surgery-associated acute kidney injury.

DESIGN

Single-center, historical control, retrospective cohort study.

SETTING

PICU, university-affiliated children's hospital.

PATIENTS

Children with congenital heart disease in PICU who received furosemide or aminophylline to treat intraoperative oliguria.

INTERVENTIONS

Intraoperative oliguria was treated either with furosemide (September 2007 to February 2012) or with aminophylline (February 2012 to June 2013). The postoperative 48 hours renal outcomes of the aminophylline group were compared with the furosemide group. The primary outcomes were acute kidney injury and renal replacement therapy use at 48 hours postoperatively. Surgical complexity was accounted for by the use of Risk Adjustment for Congenital Heart Surgery-1 score.

MEASUREMENTS AND MAIN RESULTS

The study involves 69 months of observation. There were 200 cases younger than 21 years old reviewed for this study. Eighty-five cases (42.5%) developed acute kidney injury. The aminophylline group patients produced significantly more urine (mL/kg/hr) during the first 8 hours postoperatively than furosemide patients (5.1 vs 3.4 mL/kg/hr; p = 0.01). The urine output at 48 hours postoperatively was similar between the two groups. There was no difference in acute kidney injury incidence at 48 hours between the aminophylline and furosemide groups (38% vs 47%, respectively; p = 0.29). Fewer aminophylline group subjects required renal replacement therapy compared to the furosemide group subjects (n = 1 vs 7, respectively; p = 0.03). In the multi-variant predictive model, intraoperative aminophylline infusion was noted as a negative predictive factor for renal replacement therapy, but not for cardiac surgery-associated acute kidney injury.

CONCLUSION

The intraoperative use of aminophylline was more effective than furosemide in reversal of oliguria in the early postoperative period. There were less renal replacement therapy-requiring acute kidney injury in children in the aminophylline group. Future prospective studies of intraoperative aminophylline to prevent cardiac surgery-associated acute kidney injury may be warranted.

Acute bowel ischemia after heart operations

Acute bowel ischemia is a perioperative complication that is frequently unrecognized as a cause of death after cardiac surgical procedures, with an in-hospital mortality of 50% to 100%. In recent years, controversy regarding the most appropriate approach to resolve clinical or laboratory suspicion and the limited therapeutic options have led to very little improvement in patient prognosis. This article reviews the related literature examining the actual prevalence, pathophysiologic mechanisms, predisposing factors, diagnostic tests, and therapeutic approaches providing a glance at new promising tools in diagnostic workup.

Interventions for protecting renal function in the perioperative period

BACKGROUND

Various methods have been used to try to protect kidney function in patients undergoing surgery. These most often include pharmacological interventions such as dopamine and its analogues, diuretics, calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, N-acetyl cysteine (NAC), atrial natriuretic peptide (ANP), sodium bicarbonate, antioxidants and erythropoietin (EPO).

OBJECTIVES

This review is aimed at determining the effectiveness of various measures advocated to protect patients' kidneys during the perioperative period.We considered the following questions: (1) Are any specific measures known to protect kidney function during the perioperative period? (2) Of measures used to protect the kidneys during the perioperative period, does any one method appear to be more effective than the others? (3) Of measures used to protect the kidneys during the perioperative period,does any one method appear to be safer than the others?

SEARCH METHODS

In this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2012), MEDLINE (Ovid SP) (1966 to August 2012) and EMBASE (Ovid SP) (1988 to August 2012). We originally handsearched six journals (Anesthesia and Analgesia, Anesthesiology, Annals of Surgery, British Journal of Anaesthesia, Journal of Thoracic and Cardiovascular Surgery, and Journal of Vascular Surgery) (1985 to 2004). However, because these journals are properly indexed in MEDLINE, we decided to rely on electronic searches only without handsearching the journals from 2004 onwards.

SELECTION CRITERIA

We selected all randomized controlled trials in adults undergoing surgery for which a treatment measure was used for the purpose of providing renal protection during the perioperative period.

DATA COLLECTION AND ANALYSIS

We selected 72 studies for inclusion in this review. Two review authors extracted data from all selected studies and entered them into RevMan 5.1; then the data were appropriately analysed. We performed subgroup analyses for type of intervention, type of surgical procedure and pre-existing renal dysfunction. We undertook sensitivity analyses for studies with high and moderately good methodological quality.

MAIN RESULTS

The updated review included data from 72 studies, comprising a total of 4378 participants. Of these, 2291 received some form of treatment and 2087 acted as controls. The interventions consisted most often of different pharmaceutical agents, such as dopamine and its analogues, diuretics, calcium channel blockers, ACE inhibitors, NAC, ANP, sodium bicarbonate, antioxidants and EPO or selected hydration fluids. Some clinical heterogeneity and varying risk of bias were noted amongst the studies, although we were able to meaningfully interpret the data. Results showed significant heterogeneity and indicated that most interventions provided no benefit.Data on perioperative mortality were reported in 41 studies and data on acute renal injury in 44 studies (all interventions combined). Because of considerable clinical heterogeneity (different clinical scenarios, as well as considerable methodological variability amongst the studies), we did not perform a meta-analysis on the combined data.Subgroup analysis of major interventions and surgical procedures showed no significant influence of interventions on reported mortality and acute renal injury. For the subgroup of participants who had pre-existing renal damage, the risk of mortality from 10 trials (959 participants) was estimated as odds ratio (OR) 0.76, 95% confidence interval (CI) 0.38 to 1.52; the risk of acute renal injury (as reported in the trials) was estimated from 11 trials (979 participants) as OR 0.43, 95% CI 0.23 to 0.80. Subgroup analysis of studies that were rated as having low risk of bias revealed that 19 studies reported mortality numbers (1604 participants); OR was 1.01, 95% CI 0.54 to 1.90. Fifteen studies reported data on acute renal injury (criteria chosen by the individual studies; 1600 participants); OR was 1.03, 95% CI 0.54 to 1.97.

AUTHORS' CONCLUSIONS

No reliable evidence from the available literature suggests that interventions during surgery can protect the kidneys from damage. However, the criteria used to diagnose acute renal damage varied in many of the older studies selected for inclusion in this review, many of which suffered from poor methodological quality such as insufficient participant numbers and poor definitions of end points such as acute renal failure and acute renal injury. Recent methods of detecting renal damage such as the use of specific biomarkers and better defined criteria for identifying renal damage (RIFLE (risk, injury, failure, loss of kidney function and end-stage renal failure) or AKI (acute kidney injury)) may have to be explored further to determine any possible benefit derived from interventions used to protect the kidneys during the perioperative period.

Acute kidney injury and critical cardiac disease

The field of cardiac intensive care continues to advance in tandem with congenital heart surgery. The survival of patients with critical congenital heart disease is seldom in question. Consequently, the focus has now shifted to that of morbidity reduction and eventual elimination. Acute kidney injury (AKI) after cardiac surgery is associated with adverse outcomes, including prolonged intensive care and hospital stays, diminished quality of life, and increased long-term mortality. Acute kidney injury occurs frequently, complicating 30% to 40% of adult and pediatric cardiac surgeries. Patients who require dialysis are at high risk of mortality, but even minor degrees of postoperative AKI portend a significant increase in mortality and morbidity.

Acute kidney injury clinical trial design: old problems, new strategies

Apart from supportive dialysis there are no universally accepted interventions in acute kidney injury (AKI). We have summarized the outcomes of all published randomized, placebo-controlled studies of non-dialysis treatment of AKI. Forty-nine trials were identified, only one of which was in a paediatric population. Sixteen trials had positive outcomes; these trials are not comparable in terms of methodology used or outcomes assessed, and they share many of the problems of the negative trials. We discuss the flaws in clinical trial design that have contributed to poor or uncertain outcomes and propose minimum requirements for future trials. In particular, future trials should incorporate biomarkers specific to the etiology of the AKI, and treatment should match the phase of injury.

Peri-operative renal protection: The strategies revisited

Postoperative acute renal failure (ARF) is a serious complication which can result in a prolonged hospital stay and a high mortality and morbidity. Underlying renal disease, cardiac diseases, nephrotoxin exposure and renal hypoperfusion are the possible predisposing risk factors which can create a high probability for the development of ARF. The incidence of ARF is highest after major vascular, cardiac and high-risk thoraco-abdominal surgery. Among the various renal protection strategies, adequate peri-operative volume expansion and avoidance of hypovolemia is the most accepted and practiced strategy. Numerous bio-markers of renal injury are used to estimate the presence and extent of renal insult and various new are currently under trial. Traditional pharmacological interventions like dopamine, diuretics and calcium antagonists are not currently the first line of reno-protective agents. The new non-pharmacological and pharmacological methods may improve outcome in renal transplantation, contrast-induced nephropathy and in various other settings of ARF. The current review is an attempt to refresh the knowledge and put forth the various renal protection strategies during the peri-operative period.

Fenoldopam and acute renal failure in cardiac surgery: a meta-analysis of randomized placebo-controlled trials

OBJECTIVE

Because at present no pharmacologic prevention or treatment of acute kidney injury seems to be available, the authors updated a meta-analysis to investigate the effects of fenoldopam in reducing acute kidney injury in patients undergoing cardiac surgery, focusing on randomized placebo-controlled studies only.

DESIGN

A meta-analysis of randomized, placebo-controlled trials.

SETTING

Hospitals.

PARTICIPANTS

A total of 440 patients from 6 studies were included in the analysis.

INTERVENTIONS

None. The ability of fenoldopam to reduce acute kidney injury in the perioperative period when compared with placebo was investigated.

MEASUREMENTS AND MAIN RESULTS

Google Scholar and PubMed were searched (updated January 1, 2012). Authors and external experts were contacted. Pooled estimates showed that fenoldopam consistently and significantly reduced the risk of acute kidney injury (odds ratio [OR] = 0.41; 95% confidence interval [CI], 0.23-0.74; p = 0.003), with a higher rate of hypotensive episodes and/or use of vasopressors (30/109 [27.5%] v 21/112 [18.8%]; OR = 2.09; 95% CI, 0.98-4.47; p = 0.06) and no effect on renal replacement therapy, survival, and length of intensive care unit or hospital stay.

CONCLUSIONS

This analysis suggests that fenoldopam reduces acute kidney injury in patients undergoing cardiac surgery. Because the number of the enrolled patients was small and there was no effect on renal replacement therapy or survival, a large, multicenter, and appropriately powered trial is needed to confirm these promising results.

Pharmacological therapies for the prevention of acute kidney injury following cardiac surgery: a systematic review

Post-cardiac surgery acute kidney injury (AKI) is common and is associated with a significant increase in morbidity and mortality. We aimed to systematically review randomised trials that assessed the renoprotective utility of pharmacological agents in patients undergoing cardiac surgery. We searched PubMed, Embase and the Cochrane Central Register of Controlled Trials for randomised controlled trials comparing renoprotective pharmacological interventions with control in adult patients undergoing cardiac surgery with cardiopulmonary bypass. We extracted data for mortality, need for renal replacement therapy (RRT), incidence of AKI, and creatinine clearance at 24-48 h. About 49 randomised controlled trials involving 4605 patients were included. Pharmacological interventions included dopamine, fenoldopam, calcium channel antagonists, natriuretic peptides, diuretics, and N-acetylcysteine. Most trials were of poor quality, with small sample sizes, under-reporting of randomisation procedure, allocation concealment and method of blinding. No pharmacological intervention significantly reduced mortality. Fenoldopam and Atrial Natriuretic Peptide (ANP) reduced the need for renal replacement therapy by 5% (NNT 20, 95% CI 11.3, 83.0) and 3.5% (NNT 29, 95% CI 17.1, 84.4), respectively. Brain Natriuretic Peptide resulted in a 10% reduction in the incidence of AKI (NNT 11, 95% CI 6.2, 32.0). Dopamine caused a significant reduction in creatinine clearance (-4.26 ml/min, 95% CI -7.14, -1.39). The quality of studies that have assessed pharmacological renoprotective agents in cardiac surgery is generally poor. Fenoldopam, ANP and BNP show evidence of renoprotection. Randomised studies evaluating the effect of novel renoprotective agents that are powered to detect clinically relevant differences in outcomes are required.

Acute kidney injury during aortic arch surgery under deep hypothermic circulatory arrest

PURPOSE

The aim of this investigation was to describe the renal outcome and to identify risk factors for acute kidney injury (AKI), as defined by the Acute Kidney Injury Network (AKIN), during aortic arch surgery (AAS) under deep hypothermic circulatory arrest (DHCA).

METHODS

A retrospective and observational study has been performed. One hundred thirty-five patients requiring AAS under DHCA were studied.

RESULTS

Seventy-one patients (52.6%) developed AKI during the postoperative period. A logistic regression analysis identified three independent risk factors for AKI: preoperative hypertension (HT), emergency surgery, and duration of DHCA. Renal replacement therapy (RRT) was required in four patients (3.0%). The postoperative mortality rate among the patients with AKI was 2.8%, which was not statistically different from the rate of 1.6% observed in the non-AKI group (P = 0.62).

CONCLUSIONS

A high incidence of AKI during AAS under DHCA was confirmed. Because AKI is highly associated with aortic surgery, novel approaches for protecting the kidneys other than deep hypothermia are needed. The logistic regression model identified HT, emergency surgery, and duration of DHCA as independent risk factors for AKI.

Renal failure: emergency evaluation and management

Patients with altered renal function are frequently encountered in the emergency department (ED) and emergency physicians often play an important role in the evaluation and management of renal disease. Early recognition, diagnosis, prevention of further iatrogenic injury, and management of renal disease have important implications for long-term morbidity and mortality. This article reviews basic renal physiology, discusses the differential diagnosis and approach to therapy, as well as strategies to prevent further renal injury, for adult patients who present to the ED with renal injury or failure.

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.

Novel aspects of pharmacological therapies for acute renal failure

Acute renal failure (ARF) comprises several syndromes that are associated with a sudden decrease in renal function. ARF is common among critically ill patients, is typically multifactorial and is of great prognostic significance. Indeed, even moderate changes in renal function significantly add to the morbidity and worsen mortality associated with ARF. Recent definitions, namely the renal Risk, Injury, Failure, Loss of renal function and End-stage kidney disease (RIFLE) classification or Acute Kidney Injury Network (AKIN) criteria, which incorporate the levels of oliguria in addition to fractional serum creatinine elevation, are important because the magnitude of kidney injury according to those definitions correlates very well with both short- and long-term patient survival. However, preventive strategies are most effective when started before oliguria or elevated serum creatinine is detectable, as those criteria already reflect established renal tubular cell injury. New biomarkers, including neutrophil gelatinase-associated lipocalin (NGAL), liver-type fatty acid binding protein (L-FABP) or kidney injury molecule-1 (KIM-1) that increase prior to the serum creatinine elevation are promising and have been proven to be useful in this regard in a few clinical trials. In addition, genetic profiling may define patients at risk earlier and help to individualize preventive strategies. Well established strategies include limiting dehydration and hypotension by the use of intravenous isotonic fluids at an optimal and individualized rate, as well as avoiding exposure to nephrotoxins, which include aminoglycosides, amphotericin or non-ionic contrast. Generally accepted and evidence-based pharmacological preventive or therapeutic options have not yet been established, although many drugs (e.g. renal vasodilators, diuretics and HMG-CoA reductase inhibitors [statins]) have been tested. New promising agents interfere with the apoptotic signalling that can occur in the setting of toxin exposure or ischaemia-reperfusion injury, limit inflammatory responses or modulate endothelial cell activation. In the future, these new approaches will enable us to extend our therapeutic repertoire.

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.

Prevention and treatment of acute kidney injury in patients undergoing cardiac surgery: a systematic review

BACKGROUND

Acute kidney injury (AKI) is common in patients undergoing cardiac surgery and is associated with a high rate of death, long-term sequelae and healthcare costs. We conducted a systematic review of randomized controlled trials for strategies to prevent or treat AKI in cardiac surgery.

METHODS

We screened Medline, Scopus, Cochrane Renal Library, and Google Scholar for randomized controlled trails in cardiac surgery for prevention or treatment of AKI in adults.

RESULTS

We identified 70 studies that contained a total of 5,554 participants published until November 2008. Most studies were small in sample size, were single-center, focused on preventive strategies, and displayed wide variation in AKI definitions. Only 26% were assessed to be of high quality according to the Jadad criteria. The types of strategies with possible protective efficacy were dopaminergic agents, vasodilators, anti-inflammatory agents, and pump/perfusion strategies. When analyzed separately, dopamine and N-acetylcysteine did not reduce the risk for AKI.

CONCLUSIONS

This summary of all the literature on prevention and treatment strategies for AKI in cardiac surgery highlights the need for better information. The results advocate large, good-quality, multicenter studies to determine whether promising interventions reliably reduce rates of acute renal replacement therapy and mortality in the cardiac surgery setting.

Effects of allopurinol and vitamin E on renal function in patients with cardiac coronary artery bypass grafts

Background:

Acute renal failure is a common complication of cardiac surgery, with oxidants found to play an important role in renal injury. We therefore assessed whether the supplemental antioxidant vitamin E and the inhibitor of xanthine oxidase allopurinol could prevent renal dysfunction after coronary artery bypass graft (CABG) surgery.

Methods:

Of 60 patients with glomerular filtration rate (GFR) < 60 mL/min scheduled to undergo CABG surgery, 30 were randomized to treatment with vitamin E and allopurinol for 3–5 days before surgery and 30 to no treatment. Serum creatinine levels and potassium and creatinine clearances were measured preoperatively and daily until day 5 after surgery.

Results:

The patients consisted of 31 males and 29 females, with a mean age of 63 ± 9 years. After surgery, there were no significant differences in mean serum creatinine (1.2 ± 0.33 vs 1.2 ± 0.4 mg/dL; p = 0.43) concentrations, or creatinine clearance (52 ± 12.8 vs 52 ± 12.8 mL/min; p = 0.9). The frequency of acute renal failure did not differ in treatment group compared with control (16% vs 13%; p = 0.5). Length of stay in the intensive care unit (ICU) was significantly longer in the control than in the treated group (3.9 ± 1.5 vs 2.6 ± 0.7 days; p < 0.001).

Conclusion:

Prophylactic treatment with vitamin E and allopurinol had no renoprotective effects in patients with pre-existing renal failure undergoing CABG surgery. Treatment with these agents, however, reduces the duration of ICU stay.

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.

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.

Interventions for protecting renal function in the perioperative period

BACKGROUND

A number of methods have been used to try to protect kidney function in patients undergoing surgery. These include the administration of dopamine and its analogues, diuretics, calcium channel blockers, angiotensin converting enzyme inhibitors and hydration fluids.

OBJECTIVES

For this review, we selected randomized controlled trials which employed different methods to protect renal function during the perioperative period. In examining these trials, we looked at outcomes that included renal failure and mortality as well as changes in renal function tests, such as urine output, creatinine clearance, free water clearance, fractional excretion of sodium and renal plasma flow.

SEARCH STRATEGY

We searched the Cochrane Central register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 2), MEDLINE (1966 to June, 2007), and EMBASE (1988 to June, 2007); and handsearched six journals (Anesthesia and Analgesia, Anesthesiology, Annals of Surgery, British Journal of Anaesthesia, Journal of Thoracic and Cardiovascular Surgery, and Journal of Vascular Surgery).

SELECTION CRITERIA

We selected all randomized controlled trials in adults undergoing surgery where a treatment measure was used for the purpose of renal protection in the perioperative period.

DATA COLLECTION AND ANALYSIS

We selected 53 studies for inclusion in this review. As well as data analysis from all the studies, we performed subgroup analysis for type of intervention, type of surgical procedure, and pre-existing renal dysfunction. We undertook sensitivity analysis on studies with high and moderately good methodological quality.

MAIN RESULTS

The review included data from 53 studies, comprising a total of 2327 participants. Of these, 1293 received some form of treatment and 1034 acted as controls. The interventions mostly consisted of different pharmaceutical agents, such as dopamine and its analogues, diuretics, calcium channel blockers, ACE inhibitors, or selected hydration fluids. The results indicated that certain interventions showed minimal benefits. All the results suffered from significant heterogeneity. Hence we cannot draw conclusions about the effectiveness of these interventions in protecting patients' kidneys during surgery.

AUTHORS' CONCLUSIONS

There is no reliable evidence from the available literature to suggest that interventions during surgery can protect the kidneys from damage. There is a need for more studies with high methodological quality. One particular area for further study may be patients with pre-existing renal dysfunction undergoing surgery.

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.

Prevention of Acute Renal Failure

Acute renal failure (ARF) comprises a family of syndromes that is characterized by an abrupt and sustained decrease in the glomerular filtration rate. In the ICU, ARF is most often due to sepsis and other systemic inflammatory states. ARF is common among the critically ill and injured and significantly adds to morbidity and mortality of these patients. Despite many advances in medical technology, the mortality and morbidity of ARF in the ICU continue to remain high and have not improved significantly over the past 2 decades. Primary strategies to prevent ARF still include adequate hydration, maintenance of mean arterial pressure, and minimizing nephrotoxin exposure. Diuretics and dopamine have been shown to be ineffective in the prevention of ARF or improving outcomes once ARF occurs. Increasing insight into mechanisms leading to ARF and the importance of facilitating renal recovery has prompted investigators to evaluate the role of newer therapeutic agents in the prevention of ARF.

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.

Preoperative intravenous hydration confers renoprotection in patients with chronic kidney disease undergoing cardiac surgery

Patients with chronic kidney disease (CKD) are at risk to develop acute renal failure (ARF) after open heart surgery. This complication is associated with high morbidity, mortality, and cost. Because the ability to concentrate urine is lost early in the progression of CKD, renal patients kept on fluid restriction prior to surgery may develop severe dehydration, a situation consistently found to be one of the most critical risk factors for postoperative ARF. Our goal was to investigate whether intravenous hydration for 12 h prior to cardiac surgery could prevent acute renal injury in patients with CKD. This is a prospective study in a tertiary cardiac surgery center. Forty-five patients admitted for elective open heart surgery with moderate-to-severe CKD, as evidenced by a quantified glomerular filtration rate less than 45 mL/min, were assigned using a 2/1 randomization process, to either receive an intravenous infusion of half-isotonic saline (1 mL/kg/h) for 12 h before the operation (hydration group, n = 30, 29 men, 64 + 1.7 years old), or to be simply kept on fluid restriction (control group, n = 15, 14 men, 64.2 + 2.8 years old). Groups were not different in clinical and intraoperative variables associated with postoperative renal injury. ARF developed in 8 of 15 (53%) patients in the control group, but in only 9 of the 30 (30%) patients in the hydration group. Four patients in the control group (27%), but no one in the hydration group, required dialysis after the operation (P < 0.01). Peak creatinine and blood urea nitrogen values were two to three times higher in the control group than in the hydration group. Preoperative intravenous hydration may ameliorate renal damage in patients with moderate-to-severe renal insufficiency undergoing cardiac surgery.

Use of fenoldopam to increase urine output in a patient with renal insufficiency secondary to septic shock: A case report

OBJECTIVE

We describe the use of fenoldopam to increase urine output in a pediatric patient with sepsis, heart failure, oliguria, and volume overload.

DESIGN

Case report.

SETTING

A tertiary pediatric intensive care unit.

PATIENT

A 17-year-old male who was being treated for acute lymphoblastic leukemia and was admitted from outside the hospital to the pediatric intensive care unit, in septic shock, after a course of chemotherapy.

INTERVENTIONS

A continuous fenoldopam infusion of 0.03 microg/kg/min was added to a regimen of multiple inotropic and vasopressor agents and a furosemide continuous infusion.

MEASUREMENTS AND MAIN RESULTS

Urine output increased 586% 12 hrs after starting the fenoldopam infusion and 775% from baseline 24 hrs after starting the infusion. Diuretics were decreased while maintaining adequate urine output. No hypotension was noted.

CONCLUSIONS

Fenoldopam increased urine output in a pediatric patient who was in septic shock and oliguria. The mechanism for this effect is unclear, and further trials are necessary to determine the role of fenoldopam in this patient population.

Acute renal failure in the critically ill

PURPOSE OF REVIEW

Acute renal failure occurs frequently in hospitalized patients and is associated with significant morbidity and mortality. An effort to better understand the epidemiology and pathophysiology of this disease will hopefully lead to improvement in patient outcomes. Considerable effort has been expended to develop techniques to prevent acute renal failure or to facilitate its resolution. In this review we attempt to summarize some of these recent advances.

RECENT FINDINGS

Attempts have been made to clearly define acute renal failure. Among the available pharmacologic agents, current evidence suggests that with the possible exception of radio-contrast-induced acute renal failure, no drugs are capable of preventing the condition or hastening its recovery. Advances in techniques and understanding of how to best provide renal replacement therapy appear to have improved patient outcomes and several newer treatments are under preclinical evaluation and may hold promise for the future.

SUMMARY

Preventing acute renal failure, improving clinical outcomes of the condition and attempts to hasten renal recovery have all been very attractive but difficult propositions. Recent efforts to explore the underlying pathophysiology and insight into mechanisms leading to acute renal failure have triggered investigators to evaluate novel therapeutic agents and enhance existing dialytic techniques. These hold great promise for improving patient outcomes in the near future.

Fenoldopam Inhibits Nuclear Translocation of Nuclear Factor Kappa B in a Rat Model of Surgical Ischemic Acute Renal Failure

OBJECTIVE

Vasoactive compounds are known to modulate gene transcription, including nuclear factor kappa B (NF-kappaB), in renal tissues, but the molecular effects of fenoldopam in this setting are not known. The authors used a rat model of surgical acute ischemic nephropathy to test the hypothesis that fenoldopam attenuates ischemia/reperfusion (I/R)-induced NF-kappaB-mediated inflammation.

DESIGN

Prospective, single-blind, randomized, controlled animal study.

SETTING

Academic Department of Anesthesiology laboratory.

SUBJECTS

Twenty-four male Sprague-Dawley rats.

INTERVENTIONS

Rats were anesthetized by intraperitoneal administration of 50 mg/kg of urethane and randomly allocated into 4 groups (n = 6 each): sham operation, sham operation with infusion of 0.1 microg/kg/min of fenoldopam, unilateral renal ischemia (1 hour, left renal artery cross-clamping) followed by 4 hours of reperfusion, and unilateral renal I/R with fenoldopam infusion.

MEASUREMENTS AND MAIN RESULTS

Kidney samples were used to measure NF-kappaB DNA-binding activity with an electrophoretic mobility shift assay. NF-kappaB signaling-dependent gene transcription was assessed with microarray analysis, and validated with reverse transcriptase polymerase chain reaction (RT-PCR). Expression of insulin-like growth factor-1 and nitric oxide synthetase-3 messenger RNA (not included in the array) was studied with RT-PCR. NF-kappaB DNA binding activity was significantly higher (p < 0.001) after I/R injury. Of the 96 genes analyzed, 75 were induced and another 8 were suppressed completely (2-fold or greater change v control) after I/R. Treatment with fenoldopam prevented activation of NF-kappaB DNA binding activity (p < 0.001) and attenuated 72 of 75 I/R-induced genes and 3 of 8 I/R-suppressed genes.

CONCLUSION

Data from this rat model of renal I/R suggest that the mechanism by which fenoldopam attenuates I/R-induced inflammation appears to involve inhibition of NF-kappaB translocation and signal transduction.

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.

Initial experience with fenoldopam after cardiac surgery in neonates with an insufficient response to conventional diuretics

OBJECTIVE

Fenoldopam, a selective dopamine-1 receptor agonist, causes systemic vasodilation and increased renal blood flow and tubular sodium excretion. We hypothesized that urine output would improve when fenoldopam was added to conventional diuretic therapy after neonatal cardiopulmonary bypass.

DESIGN

Retrospective cohort study using a time-series design.

SETTING

Pediatric cardiac intensive care unit.

PATIENTS

All neonates who received fenoldopam to promote diuresis after cardiac surgery requiring cardiopulmonary bypass from February 2002 through December 2004.

INTERVENTIONS

Fenoldopam infusion for inadequate urine output despite conventional diuretics.

MEASUREMENTS

Demographics, diagnostic information, and surgical procedures were recorded. Urine output, fluid balance, inotrope scores, diuretic doses, and other clinical variables that may influence diuresis were recorded for the 24-hr period immediately preceding fenoldopam initiation and during the initial 24 hrs of drug administration.

MAIN RESULTS

A total of 25 neonates received fenoldopam to promote diuresis after the modified Norwood (n = 14), arterial switch (n = 4), or other operations (n = 7). Heart rate, conventional diuretic dosing, and fluid intake were similar during the 24-hr periods of conventional therapy and fenoldopam use (p = not significant for all), whereas inotrope scores decreased during the study (p = .021). There was a small but statistically significant increase in blood pressure during the 48-hr study period. Median urine output was 3.6 mL x kg(-1) x hr(-1) (range, 0.2-7.2 mL x kg(-1) x hr(-1)) during the 24-hr period of conventional therapy and 5.8 mL x kg(-1) x hr(-1) (range, 1.6-11.7 mL x kg(-1) x hr(-1)) during the initial 24 hrs of fenoldopam administration (Wilcoxon's signed-rank test, p = .001).

CONCLUSIONS

Fenoldopam may improve urine output in neonates who are failing to achieve an adequate negative fluid balance despite conventional diuretic therapy after cardiac surgery and cardiopulmonary bypass. This study is limited by its retrospective design and the possibility that urine output improved spontaneously during the treatment period. A randomized, placebo-controlled clinical trial will be required to confirm these findings.

Renal failure secondary to acute tubular necrosis: epidemiology, diagnosis, and management

Acute tubular necrosis (ATN) is a form of acute renal failure (ARF) that is common in hospitalized patients. In critical care units, it accounts for about 76% of cases of ARF. Despite the introduction of hemodialysis > 30 years ago, the mortality rates from ATN in hospitalized and ICU patients are about 37.1% and 78.6%, respectively. The purpose of this review is to discuss briefly the cause, diagnosis, and epidemiology of ARF, and to review in depth the clinical trials performed to date that have examined the influence of growth factors, hormones, antioxidants, diuretics, and dialysis. In particular, the role of the dialysis modality, dialyzer characteristics, and dosing strategies are discussed.

Interventions for protecting renal function in the perioperative period

BACKGROUND

A number of methods have been used to try to protect kidney function in patients undergoing surgery. These include the administration of dopamine, diuretics, calcium channel blockers, angiotensin converting enzyme inhibitors and hydration fluids.

OBJECTIVES

For this review, we selected randomized controlled trials, which employed different methods to protect renal function during the perioperative period. In examining these trials, we looked at outcomes such as renal failure and mortality, as well as changes in the renal function tests, including urine output, creatinine clearance, free water clearance, fractional excretion of sodium and renal plasma flow.

SEARCH STRATEGY

We searched the Cochrane Central register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 4, 2004), MEDLINE (1966 to 2004) and EMBASE (1988 to 2004) and hand searched six journals (British Journal of Anaesthesia; Anesthesia and Analgesia; Anesthesiology; Annals of Surgery; Journal of Thoracic and Cardiovascular Surgery and Journal of Vascular Surgery).

SELECTION CRITERIA

We selected all randomized controlled trials in adult population undergoing surgery where a treatment measure was used for the purpose of renal protection in the perioperative period.

DATA COLLECTION AND ANALYSIS

We selected 37 studies for inclusion in this review. As well as analysis of the data from all the studies, we also performed subgroup analysis for type of interventions, types of surgical procedures and those with pre-existing renal dysfunction. We undertook sensitivity analysis on studies with high methodological quality.

MAIN RESULTS

The review included data from 37 studies, comprising a total of 1227 patients. Of these, 658 received some form of treatment and 569 acted as controls. The interventions were mostly employing different pharmaceutical agents such as dopamine, diuretics, calcium channel blockers. ACE inhibitors or selected hydration fluids. The results indicated that certain interventions showed some benefits, but all the results suffered from significant heterogeneity. Hence we can draw no conclusions about the effectiveness of these interventions in protecting the kidneys during surgery.

AUTHORS' CONCLUSIONS

There is no reliable evidence from available literature to suggest that interventions during surgery can protect the kidneys from damage. However, there is a need for more studies of high methodological quality. One particular area for further studies may be on patients with pre-existing renal dysfunction undergoing surgery.

Renoprotective Action of Fenoldopam in High-Risk Patients Undergoing Cardiac Surgery

Background— Acute renal failure is a serious complication of cardiac surgery causing high morbidity and mortality. The aim of this study was to evaluate the usefulness of fenoldopam, a specific agonist of the dopamine-1 receptor, in patients at high risk of perioperative renal dysfunction.

Methods and Results— A prospective single-center, randomized, double-blind trial was performed after local ethical committee approval and after written consent was obtained from 80 patients undergoing cardiac surgery. Patients received either fenoldopam at 0.05 μg/kg per minute or dopamine at 2.5 μg/kg per minute after the induction of anesthesia for a 24-hour period. All these patients were at high risk of perioperative renal dysfunction as indicated by Continuous Improvement in Cardiac Surgery Program score >10. Primary end point was defined as 25% creatinine increase from baseline levels after cardiac surgery. The 2 groups (fenoldopam versus dopamine) were homogeneous cohorts, and no difference in outcome was observed. Acute renal failure was similar: 17 of 40 (42.5%) in the fenoldopam group and 16 of 40 (40%) in the dopamine group ( P =0.9). Peak postoperative serum creatinine level, intensive care unit and hospital stay, and mortality were also similar in the 2 groups.

Conclusions— Despite an increasing number of reports of renal protective properties from fenoldopam, we observed no difference in the clinical outcome compared with dopamine in a high-risk population undergoing cardiac surgery.

Prevention of Acute Renal Failure

Acute renal failure (ARF) complicates the clinical course of many critically ill patients and significantly adds to their morbidity and mortality. Efforts to develop techniques to prevent ARF or to facilitate its resolution largely have been unsuccessful. Aggressive hydration, minimizing nephrotoxins, and maintenance of "adequate" mean arterial pressure remain the main nonpharmacologic strategies to prevent ARF in the ICU. Increasing insight into mechanisms that lead to ARF prompted investigators to evaluate the role of novel therapeutic agents in the prevention of ARF. Recent data suggest that N-acetylcysteine may reduce the incidence of ARF secondary to radio-contrast agents.

Abdominal organ injury after cardiac surgery

Gastrointestinal complications occur in about 2.5% of patients undergoing cardiac surgery, are associated with a high mortality (about 33%), and account for nearly 15% (and perhaps increasing) of all postoperative deaths. The various complications and risk factors are reviewed. Splanchnic ischemia prior to, during, and especially postoperatively appears to be an important cause of these complications. In addition, splanchnic ischemia is hypothesized to be one cause of the systemic inflammatory response syndrome and multiorgan failure that may follow cardiac surgery. The physiology of splanchic perfusion and the effects of cardiac surgery, including cardiopulmonary bypass, on it are reviewed. Finally, possible methods to minimize splanchnic ischemia and reduce the incidence of abdominal complications are discussed.

Fenoldopam mesylate and renal function in patients undergoing liver transplantation: a randomized, controlled pilot trial

To test the relative effects on serum creatinine (CRE), blood urea nitrogen (BUN), and urine output of small-dose dopamine and fenoldopam in patients undergoing liver transplantation, we randomized 43 patients to 1 of 2 continuous infusions over 48 h, starting with anesthesia induction: fenoldopam, 0.1 microg . kg(-1) . min(-1) or dopamine, 2 microg . kg(-1) . min(-1). We used predetermined hemodynamic and intravascular volume goals (intrathoracic blood volume index 800-1000 mL/m(2), extravascular lung water index <7 mL/kg) to manage patients with an algorithm for use of mannitol and furosemide to maintain urine output >1 mL . kg(-1) . h(-1). At postoperative day 3, the median CRE increase was 0.2 mg/dL (interquartile range [IQR] -0.2-0.5) with fenoldopam and 0.5 mg/dL (IQR 0.3-0.9, P = 0.004) in the dopamine group. The BUN increase was median 2 mg/dL (IQR -2-8) versus 8.5 mg/dL (IQR 5-12, P = 0.01), respectively, with fenoldopam versus dopamine. Urine output was similar; however, significantly fewer fenoldopam patients required furosemide compared with dopamine patients (median 1 [IQR 0-3] versus 3 [IQR 2-4], respectively, P = 0.003). The hemodynamic effects of dopamine and fenoldopam were similar. Compared with dopamine, in the setting of liver transplantation, fenoldopam is associated with better CRE and BUN values.

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.

Prevention of perioperative acute renal failure: what works?

Perioperative acute renal failure (ARF) is associated with increased morbidity and mortality. Patients undergoing cardiac, vascular and major abdominal surgery and those with pre-operative renal insufficiency are at increased risk for developing post-operative ARF. The aetiologies of perioperative ARF are multi-factorial. However, pre-renal azotaemia and ischaemic acute tubular necrosis (ATN) are the predominant causes. Preventive strategies involve identifying patients at risk, optimizing intravascular volume as well as renal function with perioperative haemodynamic monitoring, and avoiding nephrotoxins. Various pharmacological agents have been used to optimize renal perfusion and tubular function. Unfortunately, none has been shown to be effective in randomized placebo-controlled trials. In this chapter, we discuss the prophylactic use of fluids, vasoactive drugs, diuretics and other agents, as well as modification of surgical techniques to reduce the incidence of perioperative ARF.

Vasoactive drugs and the kidney

Protection of renal function and prevention of acute renal failure (ARF) are important goals of resuscitation in critically ill patients. Beyond fluid resuscitation and avoidance of nephrotoxins, little is known about how such prevention can be achieved. Vasoactive drugs are often administered to improve either cardiac output or mean arterial pressure in the hope that renal blood flow will also be improved and, thereby, renal protection achieved. Some of these drugs (especially low-dose dopamine) have even been proposed to have a specific beneficial effect on renal blood flow. However, when all studies dealing with vasoactive drugs and their effects on the kidney are reviewed, it is clear that none have been demonstrated to achieve clinically important benefits in terms of renal protection. It is also clear that, with the exception of low-dose dopamine, there have been no randomized controlled trials of sufficient statistical power to detect differences in clinically meaningful outcomes. In the absence of such data, all that is available is based on limited physiological gains (changes in renal blood flow or urine output) with one or another drug in one or another subpopulation of patients. Furthermore, given our lack of understanding of the pathogenesis of ARF, it is unclear whether haemodynamic manipulation is an appropriate avenue to achieve renal protection. There is a great need for large randomized controlled trials to test the clinical, instead of physiological, effects of vasoactive drugs in critical illness.