A protocol for prevention of radiographic contrast nephropathy during percutaneous coronary intervention: effect of selective dopamine receptor agonist fenoldopam

Impact of Geriatric Nutritional Index in Contrast-Induced Nephropathy Developed in Patients with Non-ST Segment Elevation Myocardial Infarction who Underwent Percutaneous Coronary Intervention

Objective:

Geriatric nutritional risk index (GNRI) is a useful tool to determine the nutritional status of patients. Any study has not evaluated the impact of GNRI in development of contrast- induced nephropathy (CIN) after percutaneous coronary intervention (PCI). We aimed to evaluate whether GNRI could predict CIN after PCI.

Method:

A total of 1116 patients with non-ST elevation myocardial infarction (non-STEMI) that underwent PCI were enrolled to the present study. The GNRI was calculated using a previously reported formula: GNRI=14.89 × albumin (g/dL) + 41.7 × body weight (kg)/ideal body weight (kg). CIN was defined as an increase in serum creatinine level of ≥0.5 mg/dL or ≥25% above baseline within 72 hours after the PCI procedure. The patients were categorized into two groups as CIN (+) and CIN (-).

Results:

The mean age of the CIN (+) group was significantly higher than the CIN (–) group (64.8±10.67 vs. 60.5±10.61 years; p<0.001). The mean values of height, weight, and body mass index were significanlty lower in CIN (+) group than CIN (-) group (p<0.001, for all). The mean of GNRI was significantly lower in the CIN (+) group than the CIN (-) group (101.4±8.7 vs. 112.1±12.9; p<0.001). Serum albumin level was significantly lower in the CIN (+) group (3.71±0.52 g/dL vs. 3.94±0.53 g/dL; p<0.001). Left ventricular ejection fraction (LVEF) was significantly lower in the CIN (+) group (50.7%±9.07 vs. 54.3%±7.20; p<0.001).

Conclusion:

In this study, GNRI, serum albumin level, BMI, and LVEF were independent predictors of CIN. Moreover, GNRI was better than both serum albumin level and BMI in predicting development of CIN.

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.

Contrast Volume and Decline in Kidney Function in Optical Coherence Tomography-Guided Percutaneous Coronary Intervention

Optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) may increase contrast volume. However, the impact of OCT-guided PCI on the decline in kidney function (DKF) in actual clinical practice remains unclear.Among 1,003 consecutive patients who underwent either OCT-guided or intravascular ultrasound (IVUS)-guided PCI in our institute, we identified 202 propensity score-matched pairs adjusted by baseline factors. The incidence of DKF was compared between the OCT-guided PCI group and the IVUS-guided PCI group. DKF was defined as an increase in serum creatinine level of ≥ 0.5 mg/dL or a relative increase of ≥ 25% over baseline within 48 hours (acute DKF) or 1 month (sustained DKF) after PCI.Baseline characteristics, including the prevalence of chronic kidney disease (54% versus 46%, P = 0.09), were comparable between the OCT- and IVUS-guided PCI groups except for the age. The contrast volume was comparable between the two groups (153 ± 56 versus 144 ± 60 mL, P = 0.09), although it was significantly greater in the OCT-guided PCI group in patients with acute coronary syndrome (ACS; 175 ± 55 versus 159 ± 43 mL, P = 0.04). The incidence of acute DKF (0.5% versus 2.5%, P = 0.22) and sustained DKF (5.0% versus 10.4%, P = 0.31) was comparable between the two groups. Multivariate analysis demonstrated that ACS (odds ratio 4.74, 95% confidence interval 2.72-8.25, P < 0.001) was a predictor of sustained DKF.Compared with IVUS-guided PCI, OCT-guided PCI did not increase the incidence of DKF in actual clinical practice, although the increased contrast volume was observed in ACS cases.

Contrast-induced acute kidney injury in interventional cardiology: Emerging evidence and unifying mechanisms of protection by remote ischemic conditioning

Contrast-induced acute kidney injury (CI-AKI) is a common complication of many diagnostic and therapeutic cardiovascular procedures. It is associated with longer in-hospital stay, more complicated hospitalization course, and higher in-hospital morbidity and mortality. With increasing use of contrast media in various diagnostic and interventional procedures, the prevalence of CI-AKI is expected to rise. Although pre-hydration with intravenous normal saline is recommended in patients with elevated risk of CI-AKI, this approach is often not feasible in many clinical settings. Remote ischemic conditioning (RIC), elicited by application of one or more, brief, non-injurious episodes of ischemia and reperfusion of a limb, is a promising therapy for preventing or attenuating the deleterious effects of contrast media on the kidney. Although the mechanisms of protection by RIC have not been completely defined, complex humoral, neural, and inflammatory pathways have been hypothesized to be in play. Given that RIC is non-invasive and cheap, it is attractive from clinical and economic perspective as a therapy to protect the kidney from CI-AKI. In this succinct review, we highlight the unifying mechanisms of CI-AKI and provide an overview of proposed biological mechanisms of renal protection by RIC. Emerging pre-clinical and clinical evidence in interventional cardiology is also discussed.

Impact of low hemoglobin on the development of contrast-induced nephropathy: A retrospective cohort study

An increase in the use of iodinated contrast media, such as iohexol, iodixanol, iopamidol and iopromide, occasionally causes contrast-induced nephropathy (CIN) in patients undergoing coronary angiography (CAG) and/or percutaneous coronary intervention (PCI). The present study aimed to assess the effects of low levels of hemoglobin on the development of CIN in patients with normal renal function following CAG/PCI. A total of 841 consecutive patients undergoing CAG/PCI were divided into two groups: Patients with low levels of hemoglobin (male, <120 g/l; female, <110 g/l; n=156) and normal levels of hemoglobin (male, 120-160 g/l; female, 110-150 g/l; n=685). Multiple logistic regression analysis was performed to identify risk factors for CIN, which developed in 14.7% of patients with low levels of hemoglobin (relative risk, 3.07) and 5% of patients with normal levels of hemoglobin (P<0.01). Independent risk factors for developing CIN in patients with low levels of hemoglobin were a contrast media volume ≥200 ml, diuretic usage, low levels of hemoglobin and diabetes mellitus. For the patients with normal hemoglobin levels, the independent risk factors for developing CIN were a contrast media volume ≥200 ml and diuretic usage. The change in serum creatinine in patients with low levels of hemoglobin was significantly greater compared with patients with normal levels of hemoglobin (7.35±22.60 vs. 1.40±12.00; P<0.01). A similar incidence of developing CIN was observed when patients were administered each type of contrast media: Iohexol, iodixanol, iopamidol and iopromide. The optimal cut-off point at which the serum hemoglobin concentration resulted in a high probability of developing CIN was determined as 111.5 g/l in females and 115.5 g/l in males. In conclusion, low levels of hemoglobin were observed to be an independent risk factor for developing CIN. Patients with reduced hemoglobin levels should, therefore, be closely monitored prior to, and during, the administration of iodinated contrast media.

Contrast Induced Nephropathy with Intravenous Iodinated Contrast Media in Routine Diagnostic Imaging: An Initial Experience in a Tertiary Care Hospital

Background. Contrast induced nephropathy (CIN) is common cause of hospital acquired renal failure, defined as iatrogenic deterioration of renal function following intravascular contrast administration in the absence of another nephrotoxic event. Objectives. Objectives were to calculate incidence of CIN with routine IV contrast usage and to identify its risk factors. Materials and Methods. Study was conducted on 250 patients (having eGFR ≥ 45 mL/min/1.73 m²) receiving intravenous contrast. Various clinical risk factors and details of contrast media were recorded. Patients showing 25% increase in postprocedural serum creatinine value or an absolute increase of 0.5 mg/dL (44.2 mmol/L) were diagnosed as having CIN. Results and Conclusions. Postprocedural serum creatinine showed significant increase from baseline levels. 25 patients (10%) developed CIN. CIN was transient in 21 (84%) patients developing CIN. One patient (4%) developed renal failure and another died due to unknown cause. Dehydration, preexisting renal disease, cardiac failure, previous contrast administration, and volume of contrast had significant correlation with development of CIN (p < 0.05); whereas demographic variables, baseline serum creatinine/eGFR, previous renal surgery, diabetes mellitus, hypertension, nephrotoxic drug intake, abnormal routine hematology, and contrast characteristics had no correlation with CIN. CIN is a matter of concern even in routine imaging requiring intravenous contrast media, in our set-up.

Contrast-induced nephropathy following chronic total occlusion percutaneous coronary intervention in patients with chronic kidney disease

OBJECTIVES

Contrast-induced nephropathy (CIN) has not been systematically studied in high-risk patients with chronic kidney disease (CKD) undergoing percutaneous coronary intervention (PCI) for chronic total occlusion (CTO).

METHODS

We prospectively observed 515 consecutive patients with CKD undergoing PCI. Patients were divided into three groups: patients who underwent attempted PCI for CTO (group A, n = 85), patients who did not receive PCI for CTO (group B, n = 45) and patients without CTO (group C, n = 385).

RESULTS

CIN developed in 55 patients (10.68 %). Group A patients received a larger CM dose than group B or group C (p = 0.024). The intravenous hydration volume, age and CIN Mehran score were not significantly different between the three groups. The incidence of CIN was 9.4 % for group A, 6.7 % for group B and 11.4 % for group C (p = 0.344). In-hospital mortality and required renal replacement therapy (p = 0.325) were not significantly different between the groups. Multivariate analysis showed that after adjusting for potential confounding factors, the odds ratio for CIN was 1.03 (p = 0.944) for group A and 0.64 for group B (p = 0.489) compared to group C.

CONCLUSIONS

Attempts to achieve recanalization of CTO in patients with CKD might not increase the risk of CIN if appropriate preventative measures are taken.

KEY POINTS

• Contrast-induced nephropathy can increase morbidity and mortality • Chronic kidney disease patients are at the greatest risk of CIN • Patients with CKD undergoing CTO-PCI are common • Incidence of CIN has not been reported in CKD patients • CTO-PCI in CKD patients might not increase the risk of CIN.

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

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

Renal protection: preconditioning for the prevention of contrast-induced nephropathy

As the numbers of interventional procedures are rising exponentially, identification of those patients at risk for renal complications has become even more important. Renal complications have been associated with increased morbidity and mortality after interventions. Risk factors have been studied to help identify those patients at increased risk for developing contrast-induced nephropathy. Hydration and medications have been studied as protective measures to decrease risk of renal complications. Preconditioning patients with intravenous hydration has been found to be the most helpful in circumventing postprocedural contrast-induced nephropathy.

A human serum albumin-thioredoxin fusion protein prevents experimental contrast-induced nephropathy

Contrast-induced nephropathy (CIN), caused by a combination of the direct tubular toxicity of contrast media, a reduction in medullary blood flow, and the generation of reactive oxygen species, is a serious clinical problem. A need exists for effective strategies for its prevention. Thioredoxin-1 (Trx) is a low-molecular-weight endogenous redox-active protein with a short half-life in the blood due to renal excretion. We produced a long-acting form of Trx as a recombinant human albumin-Trx fusion protein (HSA-Trx) and examined its effectiveness in preventing renal injury in a rat model of ioversol-induced CIN. Compared with saline, a mixture of HSA and Trx, or Trx alone, intravenous HSA-Trx pretreatment significantly attenuated elevations in serum creatinine, blood urea nitrogen, and urinary N-acetyl-β-D-glucosaminidase along with the decrease in creatinine clearance. HSA-Trx also caused a substantial reduction in the histological features of renal tubular injuries and in the number of apoptosis-positive tubular cells. Changes in the markers 8-hydroxy deoxyguanosine and malondialdehyde indicated that HSA-Trx significantly suppressed renal oxidative stress. In HK-2 cells, HSA-Trx decreased the level of reactive oxygen species induced by hydrogen peroxide, and subsequently improved cell viability. Thus, our results suggest that due to its long-acting properties, HSA-Trx has the potential to effectively prevent CIN.

Chronic total occlusions: successful recanalization of very old lesions

PURPOSE

The treatment of chronic total occlusion is thought to be the final frontier in treating coronary artery disease nonsurgically. In the past, an old occlusion was not likely to be treated successfully percutaneous. We have had success in revascularizing some very old 20 plus year old occlusions percutaneously.

METHODS

Six patients were treated who had >20-year-old occlusions. Five patients were male; mean age of patients was 72.2 years (range 63-86). Mean age of the occlusion was 24.8 years. All patients had ischemia in the corresponding territory. Four of the patients had right coronary artery occlusions; one had a left circumflex occlusion and one had left anterior descending artery occlusion.

RESULTS

Using a combination of radial and/or femoral approach, we successfully recanalized all of these old occlusions. No patients had major adverse cardiac events. Two patients developed restenosis at follow-up that was subsequently treated uneventfully. All the patients had a complete relief of angina.

CONCLUSION

In a small single center experience, even very old occlusions >20-year old can be effectively treated with dedicated systems, excellent guiding catheter support and experienced physicians.

Clinical pharmacology, uses, and adverse reactions of iodinated contrast agents: a primer for the non-radiologist

Iodinated contrast agents have been in use since the 1950s to facilitate radiographic imaging modalities. Physicians in almost all specialties will either administer these agents or care for patients who have received these drugs. Different iodinated contrast agents vary greatly in their properties, uses, and toxic effects. Therefore, clinicians should be at least superficially familiar with the clinical pharmacology, administration, risks, and adverse effects associated with iodinated contrast agents. This primer offers the non-radiologist physician the opportunity to gain insight into the use of this class of drugs.

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.

Preventing acute decrease in renal function induced by coronary angiography (PRECORD): a prospective randomized trial

BACKGROUND

Infusion of saline attenuates the decrease in renal function induced by radiographic contrast agents among patients with chronic renal insufficiency.

AIM

The Preventing Renal alteration in Coronary Disease (PRECORD) trial was a randomized trial to assess the effect on renal function of saline infusion during and after coronary angiography in 201 patients without severe chronic renal insufficiency (serum creatinine<140micromol/L).

METHODS

All patients received standard oral hydration: 2000mL of tap water within the 24 hours after coronary angiography. Patients were randomized before the procedure to intravenous hydration (1000mL of 0.9% saline infusion) or no additional hydration. The infusion was started in the catheterization laboratory and continued for 24 hours. The primary endpoint was the change in calculated creatinine clearance between baseline and 24 hours after coronary angiography. The same ionic low osmolar radiographic contrast agent (ioxaglate) was used in all patients.

RESULTS

Both groups had similar baseline characteristics, including age, serum creatinine, volume of contrast and proportion of patients undergoing ad hoc coronary angioplasty. The overall decrease in serum creatinine clearance 24 hours after the procedure was -3.44 (0.68)mL/min. The change in serum creatinine clearance 24 hours after the procedure was -2.81 (1.07)mL/min in the infusion group vs -4.09 (0.91)mL/min in the control group (p=0.38).

CONCLUSION

Renal function is altered only slightly 24 hours after coronary angiography with standard oral hydration alone and is not affected by saline infusion started at the beginning of coronary angiography, even in patients with mild-to-moderate renal dysfunction.

Contrast-induced nephropathy

Contrast induced nephropathy (CIN) is an iatrogenic disorder, resulting from exposure to contrast media. Contrast-induced hemodynamic and direct cytotoxic effects on renal structures are highly evident in its pathogenesis, whereas other mechanisms are still poorly understood. CIN is typically defined as an increase in serum creatinine by either > or =0.5 mg/dl or by > or =25% from baseline within the first 2-3 days after contrast administration. Although rare in the general population, CIN has a high incidence in patients with an underlying renal disorder, in diabetics, and the elderly. The risk factors are synergistic in their ability to produce CIN. The best way to prevent CIN is to identify the patients at risk and to provide adequate peri-procedural hydration. The role of various drugs in prevention of CIN is still controversial and warrants future studies. Despite remaining uncertainty regarding the degree of nephrotoxicity produced by various contrast agents, in current practice non-ionic low-osmolar contrast media are preferred over the high-osmolar contrast media in patients with renal impairment.

Contrast Medium Administration in the Elderly Patient: Is Advancing Age an Independent Risk Factor for Contrast Nephropathy after Angiographic Procedures?

Contrast medium-induced nephropathy (CMIN) is the third leading cause of hospital-acquired acute renal dysfunction. Even if the number of patients over 75 years of age undergoing diagnostic and/or interventional procedures and requiring administration of contrast medium (CM) is growing constantly, at present there is no definitive consensus regarding the role of advancing age and related morphologic or functional renal changes as an independent risk factor for CMIN. The authors review the evidence from recent medical literature on the definition, pathophysiology, and clinical presentation of CMIN as well as therapeutic approaches to its prophylaxis. Attention is focused on advancing age as a preexisting physiologic condition that is, per se, able to predispose the patient to CM-induced renal impairment, assuming that every elderly patient is potentially at risk for CMIN.

Strategies to reduce the risk of contrast-induced nephropathy

In view of the clinical importance of contrast-induced nephropathy (CIN), numerous potential risk-reduction strategies have been evaluated. Adequate intravenous volume expansion with isotonic crystalloid (1.0-1.5 mL/kg per hr) for 3-12 hours before the procedure and continued for 6-24 hours afterward can lessen the probability of CIN in patients at risk. There are insufficient data on oral fluids (as opposed to intravenous volume expansion) as a CIN-prevention strategy. No adjunctive medical or mechanical treatment has been proved to be efficacious in reducing risk for CIN. Prophylactic hemodialysis and hemofiltration have not been validated as effective strategies. The CIN Consensus Working Panel considered that, of the pharmacologic agents that have been evaluated, theophylline, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), ascorbic acid, and prostaglandin E(1) deserve further evaluation. N-acetylcysteine is not consistently effective in reducing the risk for CIN. Fenoldopam, dopamine, calcium channel blockers, atrial natriuretic peptide, and l-arginine have not been shown to be effective. Use of furosemide, mannitol, or an endothelin receptor antagonist is potentially detrimental. Nephrotoxic drugs should be withdrawn before contrast administration in patients at risk for CIN.

Epidemiology and prognostic implications of contrast-induced nephropathy

Contrast-induced nephropathy (CIN), usually defined as an increase in serum creatinine of 0.5 mg/dL (44.2 mumol/L), or a 25% increase from the baseline value 48 hours after the procedure, is a common and potentially serious complication of the use of iodinated contrast media in patients at risk of acute renal injury. It is an important cause of hospital-acquired renal failure, responsible for approximately 11% of cases. CIN may be difficult to distinguish from cholesterol embolization, another cause of postprocedure renal impairment. The reported incidence of CIN varies depending on the patient population studied. The impact of postprocedural renal impairment on clinical outcomes has been evaluated most extensively in patients undergoing percutaneous coronary intervention. CIN is associated with increased mortality both in hospital and at 1 year. A higher incidence of in-hospital and late cardiovascular events, as well as longer hospital stays, has been reported in patients developing CIN. In a small proportion of patients, CIN is severe enough to require dialysis, and these patients have a particularly poor prognosis. Many of the risk markers for CIN are also predictive of a worse prognosis.

Contrast-induced nephropathy: definition, epidemiology, and patients at risk

Radiological procedures utilizing intravascular iodinated contrast media injections are being widely applied for both diagnostic and therapeutic purposes. This has resulted in an increasing incidence of procedure-related contrast-induced nephropathy (CIN). The definition of CIN includes absolute (> or = 0.5 mg/dl) or relative increase (> or = 25%) in serum creatinine at 48-72 h after exposure to a contrast agent compared to baseline serum creatinine values, when alternative explanations for renal impairment have been excluded. Although the risk of renal function impairment associated with radiological procedures is low (0.6-2.3%) in the general population, it may be very high in selected patient subsets (up to 20%), especially in patients with underlying cardiovascular disease. This review provides information on the known risk factors for the development of CIN, and completes with describing user-friendly CIN risk score based on the readily available information.

Selective renal arterial infusion of fenoldopam for the prevention of contrast-induced nephropathy

Contrast-induced nephropathy (CIN) remains an important complication of angiographic procedures, particularly among patients with significant renal impairment. To date, vasodilator therapies such as fenoldopam have failed to prevent CIN, possibly because significant hypotension as a result of systemic infusion has limited the ability to deliver adequate drug levels to the renal vasculature. We present a case of averted CIN after multivessel coronary intervention in a diabetic patient with severe renal insufficiency, potentially due to bilateral renal arterial infusion of fenoldopam. Our subsequent experience with intrarenal fenoldopam in nine additional procedures in eight other high risk patients resulted in one case of asymptomatic transient CIN. Further studies are warranted to evaluate the efficacy of intrarenal administration of vasodilator therapies such as fenoldopam for the prevention of CIN.

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.

Uroangiographic Contrast Media-Induced Nephropathy: Correlations between Their Physicochemical Properties and Renal Damage

Contrast media-induced nephropathy (CN) is an important cause of hospital-acquired acute renal failure. Patients with both diabetes mellitus and renal impairment are at high risk. CN pathophysiology involves activation of the tubulo-glomerular feedback and vasoactive mediators such as renin-angiotensin 2, endothelin, adenosine, ADH, etc. The risk of CN can be minimized by the use of non-ionic, low or isoosmolar, contrast material, adequate hydration and prophylactic pharmacological measures. In patients with chronic renal failure who are undergoing arteriography (e.g. coronary angiography and angioplasty), periprocedural hemofiltration appears effective in preventing further renal damage due to contrast agents.

Prevention of Contrast Media–induced Nephrotoxicity after Angiographic Procedures

Contrast medium-induced nephrotoxicity (ie, contrast nephrotoxicity [CN]) remains an important complication of angiographic procedures. If administration of iodinated contrast medium is deemed necessary in patients at high risk of CN, volume expansion should be offered and the lowest possible dose of nonionic isosmolar dimeric or nonionic low-osmolar monomeric contrast medium should be used. Prophylactic administration of fenoldopam or acetylcysteine has not offered consistent protection against CN. Intravenous acetylcysteine could be considered in emergency situations. Recently, sodium bicarbonate infusion has been shown to reduce the risk of CN. Hemofiltration for several hours before and after contrast medium injection may offer good protection against CN in patients with advanced renal disease. Prophylactic hemodialysis does not offer any protection against CN.

Clinical and Experimental Evidence for Prevention of Acute Renal Failure Induced by Radiographic Contrast Media

Acute renal failure still occurs as a complication after radiographic examination using iodinated radiocontrast medium. The incidence rate of radiocontrast medium-induced nephropathy (radiocontrast nephropathy) is low (2 - 3%) in general. However, the rate is remarkably elevated in patients with pre-existing renal insufficiency. Radiocontrast nephropathy is associated with increased morbidity and mortality, particularly in patients with percutaneous coronary interventions. Although the reduction in renal blood flow and direct toxic action on renal tubular cells are considered to be involved, little is known about the etiology of radiocontrast nephropathy. A number of agents that improve renal circulation have been clinically tested for prevention of radiocontrast nephropathy, but none of them has succeeded. Protection of renal tubular cells against oxidative stress is another approach to avoid radiocontrast nephropathy. Prophylactic effects of antioxidants such as N-acetylcysteine and ascorbic acid have been reported by several investigators, although the effectiveness of these compounds is still a matter of debate. At present, hydration is regarded as the only effective, though incomplete, prophylactic regimen for radiocontrast nephropathy. Recently, we have shown that caspase-dependent apoptosis is an important factor in the pathogenesis of radiocontrast nephropathy and clarified cellular mechanisms underlying the radiocontrast media-induced apoptosis. This review summarizes clinical and experimental evidence for the etiology and prevention of radiocontrast nephropathy.

Contrast-induced nephropathy after percutaneous coronary interventions in relation to chronic kidney disease and hemodynamic variables

We previously found that contrast-induced nephropathy (CIN) complicating percutaneous coronary intervention adversely affects patients with chronic kidney disease (CKD). Therefore, we further investigated whether the predictors and outcome of CIN after percutaneous coronary intervention differ among patients with versus without CKD. Among 7,230 consecutive patients, CIN (>or=25% or >or=0.5 mg/dl increase in preprocedure serum creatinine 48 hours after the procedure) developed in 381 of 1,980 patients (19.2%) with baseline CKD (estimated glomerular filtration rate [eGFR] <60 ml/min/1.73 m(2)) and in 688 of 5,250 patients (13.1%) without CKD. Decreased eGFRs, periprocedural hypotension, higher contrast media volumes, lower baseline hematocrit, diabetes, pulmonary edema at presentation, intra-aortic balloon pump use, and ejection fraction <40% were the most significant predictors of CIN in patients with CKD. Apart from intra-aortic balloon pump use, predictors of CIN in patients without CKD were the same as mentioned, plus older age and type of contrast media. Regardless of baseline renal function, CIN correlated with longer in-hospital stay and higher rates of in-hospital complications and 1-year mortality compared with patients without CIN. By multivariate analysis, CIN was 1 of the most powerful predictors of 1-year mortality in patients with preexisting CKD (odds ratio 2.37, 95% confidence interval 1.63 to 3.44) or preserved eGFR (odds ratio 1.78; 95% confidence interval 1.22 to 2.60). Thus, regardless of the presence of CKD, baseline characteristics and periprocedural hemodynamic parameters predict CIN, and this complication is associated with worse in-hospital and 1-year outcomes.

Anaphylactoid and adverse reactions to radiocontrast agents

Over the past 75 years, radiocontrast agents have provided numerous diagnostic and therapeutic advances. The benefits of these agents must be weighed against the potential risks for each individual undergoing radiologic tests. This summary is intended to be a guide for the allergy and immunology specialist to direct him or her to the current literature regarding adverse reactions to traditional and less commonly used radiologic contrast agents.

Impact of chronic kidney disease on prognosis of patients with diabetes mellitus treated with percutaneous coronary intervention

Chronic kidney disease (CKD) is a frequent complication of diabetes mellitus. However, the role of CKD in outcomes of patients with diabetes who have undergone percutaneous coronary intervention (PCI) has not been studied specifically. Therefore, we investigated the impact of CKD on prognosis of patients with diabetes who underwent PCI. Of 1,575 diabetic patients who underwent PCI, 1,046 (66%) had preserved renal function, 492 (31%) had CKD (baseline serum creatinine >1.5 mg/dl or estimated glomerular filtration rate <60 ml/min/1.73 m(2)) without dialysis, and 37 (2.3%) were dependent on dialysis. Patients with CKD versus those without CKD had more in-hospital complications, including mortality (2.6% vs 0.5%, respectively; p <0.0001), neurologic events (3.1% vs 0.6%, p = 0.0001), and gastrointestinal bleeding (2.9% vs 0.9%, p = 0.01). Contrast-induced nephropathy after PCI (increase > or =25% and/or > or =0.5 mg/dl of serum creatinine before PCI vs 48 hours after PCI) was found in 15% of patients without CKD versus 27% of those with CKD, and de novo dialysis was instituted in 0.1% versus 3.1%, respectively. Contrast-induced nephropathy was independently predicted (all p <0.0001) by peri-PCI hypotension (odds ratio [OR] 2.62), insulin treatment (OR 1.84), and volume of contrast medium (OR 1.30). The 1-year mortality rate was strikingly higher (all p <0.0001) in patients with CKD who did not receive dialysis (16%) and those on dialysis (44%) compared with the group with preserved renal function (5%). Contrast-induced nephropathy was among the independent predictors of a 1-year mortality rate (OR 2.75, p <0.001).

N-acetylcysteine versus fenoldopam mesylate to prevent contrast agent-associated nephrotoxicity

OBJECTIVES

We performed a study to assess the efficacy of fenoldopam mesylate (a specific agonist of the dopamine-1 receptor) as compared with N-acetylcysteine (NAC) in preventing contrast agent-associated nephrotoxicity (CAN).

BACKGROUND

Prophylactic administration of NAC, along with hydration, prevents CAN in patients with chronic renal insufficiency who are undergoing contrast media administration. Preliminary data support the hypothesis that fenoldopam might be as effective as NAC.

METHODS

One hundred ninety-two consecutive patients with chronic renal insufficiency, referred to our institution for coronary and/or peripheral procedures, were assigned randomly to receive 0.45% saline intravenously and NAC (1,200 mg orally twice daily; NAC group; n = 97) or fenoldopam (0.10 microg/kg/min; fenoldopam group; n = 95) before and after a nonionic, iso-osmolality contrast dye administration.

RESULTS

Baseline creatinine levels were similar in the two groups: NAC group = 1.72 mg/dl (interquartile range, 1.55 to 1.90 mg/dl) and fenoldopam group = 1.75 mg/dl (interquartile range, 1.62 to 2.01 mg/dl) (p = 0.17). An increase of at least 0.5 mg/dl of the creatinine concentration 48 h after the procedure occurred in 4 of 97 patients (4.1%) in the NAC group and in 13 of 95 patients (13.7%) in the fenoldopam group (p = 0.019; odds ratio 0.27; 95% confidence interval 0.08 to 0.85). The amount of contrast media administration was similar in the two groups (NAC group = 160 +/- 82 ml; fenoldopam group = 168 +/- 104 ml; p = 0.54).

CONCLUSIONS

N-acetylcysteine seems to be more effective than fenoldopam in preventing CAN.

Morbidity and mortality associated with renal insufficiency and endovascular repair of abdominal aortic aneurysms: a 5-year experience

To evaluate the outcome of patients with renal insufficiency undergoing endovascular repair of abdominal aortic aneurysm (AAA), data were prospectively collected between 1998 and 2003 on patients undergoing elective repair of their AAA with a stent graft. The patients were divided into 2 groups: those with serum creatinine (Crs) concentrations <1.2 (Group A) and those with Crs > or =1.2 mg/dL not requiring hemodialysis (Group B). The outcomes of the procedure for these 2 groups were compared. Different variables that existed between the 2 groups and contributed to mortality included estimated blood loss (EBL), volume of contrast used in the operating room, incidence of diabetes (DM), tobacco use, and history of myocardial infarction (MI). In total, 213 patients underwent elective repair of their AAA with use of a stent graft: 61% who had a Crs <1.2 mg/dL (Group A) and 39% who had a Crs > or =1.2 mg/dL not requiring dialysis (Group B). Among 129 patients with normal renal function there was an 18.6% complication rate and 1.6% mortality rate. Of 83 patients with renal insufficiency not on hemodialysis 30.1% (Fisher's Exact Test = 0.076) had 1 or more complications and there was a 6% (Fisher's Exact Test = 0.166) mortality rate. One patient in Group A (0.8%) progressed to hemodialysis and 5 (6%) patients in Group B progressed to end-stage renal disease requiring hemodialysis (p=0.068). A statistically significant higher proportion of the patients in Group B had a history of MI (p<0.001). There was no difference in the amount of EBL between the 2 groups, but a significantly lower amount of contrast (p<0.05) was used in patients with renal insufficiency.

Preventing contrast nephropathy: what is the best strategy? A review of the literature

Patients receiving radiocontrast for diagnostic and interventional procedures are at risk for developing contrast nephropathy (CN). In fact, radiocontrast nephropathy is currently the third leading cause of hospital-acquired renal failure. Understanding that CN has been associated with increased length of hospitalization and mortality, determining the best prevention strategy is of utmost importance. Patients at the greatest risk for developing acute renal failure are patients with diabetes and underlying renal insufficiency. Several therapies have been investigated for the prevention of CN; unfortunately, very few have shown a consistent benefit. Therapies that have been studied include saline hydration, N-acetylcysteine (NAC), theophylline, calcium channel blockers, diuretics, dopamine, endothelin receptor antagonists, atrial natriuretic peptide, angiotensin-converting enzyme inhibitors, and prostaglandin E-1. Using adequate hydration, using low-osmolar dyes, and minimizing the dose of contrast have all been shown to be effective in reducing CN and are considered the standard of care. While trials with many pharmacologic agents have produced conflicting results, intervention with NAC has also been promising. This article reviews the pathophysiology, risk factors, and therapies that are currently available for the prevention of CN.

Prevention of contrast media nephrotoxicity--the story so far

Contrast media nephrotoxicity (CMN) in patients with pre-existing renal impairment remains a clinically significant problem. The first step to reduce the chance of CMN is to identify patients at risk through the use of screening questionnaires and renal function measurement. Patients at risk requiring injection of contrast medium (CM) because of important clinical indications should receive a small dose of either non-ionic iso-osmolar dimeric or non-ionic low osmolar monomeric CM and hydration. Intravenous infusion (1 ml/kg body weight/h) of 0.9% saline starting 4 h before CM injection and continuing for at least 12 h afterwards is effective in reducing the incidence of CMN. Prophylactic haemodialysis does not lower the risk of this complication. The value of pharmacological manipulation with renal vasodilators (calcium channel blockers, dopamine, atrial natriuretic peptide, fenoldopam (selective dopamine-1 receptor agonist), prostaglandin E(1), non-selective adenosine receptors antagonist (theophylline), non-selective endothelin receptor antagonist or the antioxidant acetylcysteine has not been fully proven. However, haemofiltration for several hours before and after contrast medium injection offers good protection against CMN in patients with advanced renal disease.

Prophylaxis of Iodinated Contrast Media-Induced Nephropathy

Iodinated contrast media are a frequent cause of acute renal failure, especially in patients whose renal function is already impaired. In addition to hydration, which remains the most commonly acknowledged means of protection, numerous pharmacological approaches for the prophylaxis of contrast nephropathy have been tested so far. They include diuretics, calcium channel blockers, adenosine receptor antagonists, N-acetylcysteine, low-dose dopamine and the dopamine D1 receptor agonist fenoldopam, endothelin receptor antagonists, and even captopril. The present review of the literature critically discusses the drugs used to prevent contrast nephropathy from a pharmacological point of view.

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.

Contrast nephropathy after coronary angiography

Contrast nephropathy after coronary angiography is associated with considerable morbidity and mortality. We discuss the incidence, definition, and pathologic mechanisms of contrast nephropathy; provide an overview of risk factors; highlight proven preventive interventions; clarify which interventions have shown no benefit; and discuss future possibilities. The prevention of contrast nephropathy is crucial for the care of patients undergoing coronary angiography and should be possible with an understanding of risk factors and proven management strategies.

Fenoldopam andN-acetylcysteine for the Prevention of Radiographic Contrast Material-Induced Nephropathy: A Review

Radiographic contrast material-induced nephropathy (RCIN) is the third most common cause of hospital-acquired renal insufficiency and has been associated with an increase in patient mortality. Many strategies to prevent RCIN have been explored unsuccessfully. The standard of care remains hydration with 0.45% sodium chloride before and after administration of contrast material. Recently, N-acetylcysteine and fenoldopam have been studied to determine their efficacy in preventing RCIN. Of seven prospective studies using various dosing regimens of N-acetylcysteine, four revealed beneficial results. Although some discrepancies exist, the data strongly suggest that N-acetylcysteine has a role in patients at risk for the development of RCIN. The data for fenoldopam are more limited, with only one retrospective study showing benefit. Additional prospective data are required to determine if fenoldopam has a role in the prevention of RCIN.

Critical issues in nephrology

Renal and electrolyte problems are common in patients in the ICU. Several advances that occurred in the recent past have been incorporated in the diagnosis and management of these disorders and were reviewed in this article. Unfortunately, many important questions remain unanswered, especially in the area of ARF, where new therapies are anxiously awaited to make the transition from bench to bedside. Better studies are sorely needed to define the best approach to dialysis in patients who have ARF.

The prevention of radiocontrast-agent-induced nephropathy by hemofiltration

BACKGROUND

Nephropathy induced by exposure to radiocontrast agents, a possible complication of percutaneous coronary interventions, is associated with significant in-hospital and long-term morbidity and mortality. Patients with preexisting renal failure are at particularly high risk. We investigated the role of hemofiltration, as compared with isotonic-saline hydration, in preventing contrast-agent-induced nephropathy in patients with renal failure.

METHODS

We studied 114 consecutive patients with chronic renal failure (serum creatinine concentration, >2 mg per deciliter [176.8 micromol per liter]) who were undergoing coronary interventions. We randomly assigned them to either hemofiltration in an intensive care unit (ICU) (58 patients, with a mean [+/-SD] serum creatinine concentration of 3.0+/-1.0 mg per deciliter [265.2+/-88.4 micromol per liter]) or isotonic-saline hydration at a rate of 1 ml per kilogram of body weight per hour given in a step-down unit (56 patients, with a mean serum creatinine concentration of 3.1+/-1.0 mg per deciliter [274.0+/-88.4 micromol per liter]). Hemofiltration (fluid replacement rate, 1000 ml per hour without weight loss) and saline hydration were initiated 4 to 8 hours before the coronary intervention and were continued for 18 to 24 hours after the procedure was completed.

RESULTS

An increase in the serum creatinine concentration of more than 25 percent from the base-line value after the coronary intervention occurred less frequently among the patients in the hemofiltration group than among the control patients (5 percent vs. 50 percent, P<0.001). Temporary renal-replacement therapy (hemodialysis or hemofiltration) was required in 25 percent of the control patients and in 3 percent of the patients in the hemofiltration group. The rate of in-hospital events was 9 percent in the hemofiltration group and 52 percent in the control group (P<0.001). In-hospital mortality was 2 percent in the hemofiltration group and 14 percent in the control group (P=0.02), and the cumulative one-year mortality was 10 percent and 30 percent, respectively (P=0.01).

CONCLUSIONS

In patients with chronic renal failure who are undergoing percutaneous coronary interventions, periprocedural hemofiltration given in an ICU setting appears to be effective in preventing the deterioration of renal function due to contrast-agent-induced nephropathy and is associated with improved in-hospital and long-term outcomes.

Cardiovascular mortality in end-stage renal disease

Cardiovascular disease accounts for more than 50% of end-stage renal disease (ESRD) deaths. The reported cardiovascular death rates in patients receiving dialysis are substantially higher than in the general population. Cardiovascular mortality in ESRD is particularly high after acute myocardial infarction, but it is also elevated in ESRD patients with other forms of atherosclerotic vascular disease (eg, chronic coronary artery disease, strokes, transient ischemic attacks, and peripheral arterial disease). Left ventricular hypertrophy and dilation are associated with increased cardiovascular mortality, as is congestive heart failure. One of the major reasons for such high cardiovascular mortality in ESRD is the large burden of cardiovascular disease present in patients with chronic artery disease before renal replacement therapy. These observations mandate not only aggressive diagnosis and treatment of cardiovascular disease in patients with ESRD, but also active screening, diagnosis, and treatment in those with chronic kidney disease before renal replacement therapy.

Radiocontrast-induced nephropathy

Radiocontrast administration remains the third leading cause of hospital-acquired acute renal failure. Clinically, radiocontrast-induced nephropathy (RIN) is defined as a sudden decline in renal function after radiocontrast administration. Typically, the serum creatinine level begins to increase at 24 to 72 hours after the administration of contrast, peaks at 3 to 5 days, and requires another 3 to 5 days to return to baseline. RIN increases the incidence of life-threatening complications such as sepsis, bleeding, and respiratory failure and increases the cost of medical care by extending the hospital stay. The increased mortality associated with acute renal failure encountered in this scenario calls for a heightened awareness of the diagnosis and prevention of RIN. Whereas individuals with healthy renal function are not generally considered to be at particular risk for RIN, patients with preexisting renal insufficiency and diabetes mellitus are much more likely to experience acute renal failure after contrast administration. In the past, a variety of therapeutic interventions have been used to prevent or attenuate RIN, including saline hydration, diuretics, mannitol, calcium channel antagonists, theophylline, endothelin receptor antagonists, hemodialysis, and dopamine. More recently, studies demonstrate a positive impact of fenoldopam (dopamine-1 receptor, dopamine-1 agonist) and the antioxidant N-acetylcysteine in ameliorating RIN. This article discusses the pathophysiology, risk factors, and prevention of RIN.

Gadolinium-based percutaneous coronary intervention in a patient with renal insufficiency

We report the first case of using gadolinium as a contrast agent to perform percutaneous coronary intervention in a patient with an acute coronary syndrome and a history of renal insufficiency. The procedure was well tolerated without any complications or nephrotoxicity. The images obtained with gadolinium were of good quality.

Strategies for Treatment and Prevention of Acute Renal Failure

Acute renal failure (ARF) is a potentially life-threatening medical condition that often complicates the hospitalization of critically ill patients. A variety of therapeutic strategies has been studied for both preventing ischemic and nephrotoxic injury to the kidney and improving renal function in established ARF. This article summarizes the role of pharmacologic therapy in the treatment of ARF. Strategies to reduce extracellular fluid volume and preserve renal function with loop diuretics, low-dose dopamine, and renal replacement therapy will be discussed. The value of preventative therapy has increased, and identifying patients at high risk for development of ARF is critical. Modification of drug regimens, administration of less nephrotoxic medications, and volume expansion prior to nephrotoxin administration can minimize toxicity to the kidney. The search for new agents that can improve survival, decrease the need for renal replacement therapy, and hasten the recovery of renal function in ARF is ongoing.