Acetylcysteine and nephrotoxic effects of radiographic contrast agents--a new use for an old drug

Perioperative Management of Complex Hepatectomy for Colorectal Liver Metastases: The Alliance between the Surgeon and the Anesthetist

Simple Summary

Major high-risk surgery (HRS) exposes patients to potential perioperative adverse events. Hepatic resection of colorectal metastases can surely be included into the HRS class of operations. Limiting such risks is the main target of the perioperative medicine. In this context the collaboration between the anesthetist and the surgeon and the sharing of management protocols is of utmost importance and represents the key issue for a successful outcome. In our institution, we have been adopting consolidated protocols for patients undergoing this type of surgery for decades; this made our mixed team (surgeons and anesthetists) capable of achieving a safe outcome for the majority of our surgical population. In this narrative review, we report the most recent state of the art of perioperative management of hepatic resection of colorectal metastases along with our experience in this field, trying to point out the main issues.

Abstract

Hepatic resection has been widely accepted as the first choice for the treatment of colorectal metastases. Liver surgery has been recognized as a major abdominal procedure; it exposes patients to a high risk of perioperative adverse events. Decision sharing and the multimodal approach to the patients’ management are the two key items for a safe outcome, even in such a high-risk surgery. This review aims at addressing the main perioperative issues (preoperative evaluation; general anesthesia and intraoperative fluid management and hemodynamic monitoring; intraoperative metabolism; administration policy for blood-derivative products; postoperative pain control; postoperative complications), in particular, from the anesthetist’s point of view; however, only an alliance with the surgery team may be successful in case of adverse events to accomplish a good final outcome.

Investigation Of Reducing Omniscan Toxicity Using Intracellular And Targeted N-Acetylcysteine Lysine Complex

Background:

The main issue is finding the most efficient method in the treatment of cancer in terms of early and accurate diagnostic. One of the most modern diagnostic techniques is imaging methods. The accuracy and detection speed of MRI and CT SCAN are high.

Methods:

The most important complication of iodinated contrast agents in medical imaging is severe renal toxicity Nephrogenic Systemic Fibrosis (NSF). In order to reduce the cytotoxicity of kidney cells caused by the usage of iodized contrast agents a complex agent should be designed. The two drugs which have been used for the synthesis of this compound are L -lysine amino acid and NAcetyl- Cysteine (NAC).

Results:

The synthesis of this complex due to two dimer molecules with each other and NAC greatly a helper for an antioxidant activity and L-lysine amino acid helps in drug entry into the cells. However, helping for an antioxidant activity heavily reinforce and eventually will successfully reduce the cytotoxicity. When its exposure to HEK 293 cell line (P<0.05). The reduction in toxicity at the dosage of 100 µM has been showed as the greatest reduction. The amount of renal toxicity was reported 40% in Omniscan.

Conclusion:

Omniscan was tested when iodinated contrast medium was combined with the synthesized 2NAC-LYS-OMNISCAN complex and the human embryonic kidney 293 (HEK293) cell line. Then, the cytotoxicity was reduced to 10 %. On the other hand, the viability increased from 60 % to 90 %, or in other words, the cytotoxicity was reduced from 40 % to 10 %.

Contrast media-induced nephropathy: how has Italy contributed in the past 30 years? A systematic review

Background and objective

The use of contrast media in Italy has exponentially increased in the past 3 decades. However, it is unknown whether there has been an increase in clinical research evaluating the risks associated with contrast media usage, especially regarding contrast-induced nephropathy. To fill this gap in knowledge, we performed a systematic review.

Study eligibility criteria

Meta-analyses, observational studies, and clinical trials assessing contrast media-induced nephropathy as the safety outcome, in which at least one author was affiliated with an Italian university/health care structure, were eligble.

Data sources

Ovid MEDLINE, Ovid Embase, Cochrane Methodology Register, and Web of Science were screened.

Participants

Men and women exposed to contrast media.

Results

In total, 60 original articles were retrieved with an incremental trend between 1990 and 2017. Cohort studies were the most common study design represented. In total, 45 of 60 (75.0%) studies were monocenter studies and 41 of 60 (68.3%) received no funding. In all, 91.7% of studies disclosed no conflicts of interest and 81.7% had no external collaboration. Most of the studies provided a level of evidence of III-2 (32/60; 53.3%) and II (23/60; 38.3%). In total, 50 of 60 studies (83.3%) were published in a scientific journal ranked in the first quartile of their subject area.

Conclusion

There was an increased number of studies evaluating contrast-induced nephropathy in Italy during the last three decades. These studies covered procedures to prevent contrast-induced nephropathy or aimed to identify risk factors, biomarkers, and scores, and their related prognosis.

Update on the renal toxicity of iodinated contrast drugs used in clinical medicine

An important side effect of diagnostic contrast drugs is contrast-induced acute kidney injury (CI-AKI; a sudden decrease in renal function) occurring 48-72 hours after injection of a contrast drug that cannot be attributed to other causes. Its existence has recently been challenged, because of some retrospective studies in which the incidence of AKI was not different between subjects who received a contrast drug and those who did not, even using propensity score matching to prevent selection bias. For some authors, only patients with estimated glomerular filtration rate <30 mL/min/1.73 m2 are at significant risk of CI-AKI. Most agree that when renal function is normal, there is no CI-AKI risk. Many experimental studies, however, are in favor of the existence of CI-AKI. Contrast drugs have been shown to cause the following changes: renal vasoconstriction, resulting in a rise in intrarenal resistance (decrease in renal blood flow and glomerular filtration rate and medullary hypoxia); epithelial vacuolization and dilatation and necrosis of proximal tubules; potentiation of angiotensin II effects, reducing nitric oxide (NO) and causing direct constriction of descending vasa recta, leading to formation of reactive oxygen species in isolated descending vasa recta of rats microperfused with a solution of iodixanol; increasing active sodium reabsorption in the thick ascending limbs of Henle's loop (increasing O2 demand and consequently medullary hypoxia); direct cytotoxic effects on endothelial and tubular epithelial cells (decrease in release of NO in vasa recta); and reducing cell survival, due to decreased activation of Akt and ERK1/2, kinases involved in cell survival/proliferation. Prevention is mainly based on extracellular volume expansion, statins, and N-acetylcysteine; conflicting results have been obtained with nebivolol, furosemide, calcium-channel blockers, theophylline, and hemodialysis.

Effectiveness of N-Acetylcysteine for the Prevention of Contrast-Induced Nephropathy: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

Conflicting results have been obtained in trials that have evaluated the prophylactic efficacy of N‐acetylcysteine (NAC) pretreatment in the prevention of contrast‐induced nephropathy (CIN). In this meta‐analysis of randomized controlled trials, we aimed to assess the effectiveness of NAC treatment for the prevention of CIN.

Methods and Results

PubMed, EMBASE, and the Cochrane Library were electronically searched from inception to January 2016 for all relevant studies. The weighted relative risk (RR) and corresponding 95% CI for incident CIN were estimated using random effects models. Standard methods for assessing statistical heterogeneity and publication bias were used. The study included 11 480 participants and 1653 cases of CIN. The incidence of CIN was 12.8% in the NAC group versus 16.0% in the control group (RR: 0.76, 95% CI: 0.66–0.88, P=0.0002). In the patients undergoing coronary angiography, the incidence of CIN in the NAC group versus the control group was 13.7% versus 17.2% (RR: 0.74, 95% CI: 0.63–0.87, P=0.0002); in those undergoing peripheral angiography, the incidence was 6.4% versus 5.8% (RR: 1.00, 95% CI: 0.42–2.40, P=1.00); in those undergoing computed tomography, the incidence was 7.7% versus 14.8% (RR: 0.51, 95% CI: 0.29–0.89, P=0.02).

Conclusions

Our meta‐analysis showed an inverse and significant association between NAC supplementation and risk of CIN in patients undergoing coronary angiography and computed tomography, while a protective role for NAC in patients undergoing peripheral angiography was not obvious.

Comparison of combination therapy of high-dose oral N-acetylcysteine and intravenous sodium bicarbonate hydration with individual therapies in the reduction of Contrast-induced Nephropathy during Cardiac Catheterisation and Percutaneous Coronary Intervention (CONTRAST): A multi-centre, randomised, controlled trial

INTRODUCTION

N-acetylcysteine (NAC) and sodium bicarbonate (SOB) therapies may prevent contrast-induced nephropathy (CIN). However, the efficacy of using combination over individual therapies was not established, and there was no large randomised study comparing abbreviated SOB therapy with conventional sustained saline pre-hydration with oral NAC.

METHODS

In a multi-centre, open-label, randomised, controlled trial (NCT00497328), we prospectively enrolled 548 patients with at least moderate renal impairment undergoing cardiac catheterisation with or without percutaneous coronary intervention. Patients were randomly assigned to 3 groups: 1) NAC: 154 mEq/L sustained sodium chloride regime (1 mL/kg/h 12 h before, during and 6h after the procedure) with oral NAC at 1.2g bid for 3 days (n=185); 2) SOB: 154 mEq/L abbreviated SOB regime at 3 mL/kg/h 1h before the procedure, and 1 mL/kg/h during and 6h after the procedure (n=182); and 3) COM: combination of abbreviated SOB regime and oral NAC (n=181). The primary end point was incidence of CIN. The secondary end points were rise in serum creatinine, hospitalisation duration, haemodialysis, morbidity and mortality within 30 days.

RESULTS

The 3 groups had similar baseline characteristics: age 68 ± 10 years, 76% male, 48% diabetic and baseline glomerular filtration rate (GFR) 47.7 ± 13.0 mL/min. There were 41 (8.8%) patients with GFR<30. The CIN incidences were NAC 6.5%, SOB 12.8% and COM 10.6%. The COM regimen was not superior to either the NAC (relative risk (RR)=1.61, 95% confidence interval (CI): 0.76 to 3.45, p=0.225) or SOB (RR=0.83, 95% CI: 0.44 to 1.56, p=0.593) regimens. The CIN incidence was lower in the NAC group than the SOB group (adjusted odds ratio (OR)=0.40, 95% CI: 0.17 to 0.92; p=0.032). Multivariate analysis showed contrast volume (OR=1.99, 95% CI: 1.33 to 2.96, p<0.001 per 100mL), female (OR=2.47, 95% CI: 1.22 to 5.00, p=0.012) and diabetes (OR=2.03, 95% CI: 1.03 to 3.99, p=0.041) were independent risk predictors. There were no differences in the secondary outcomes among the 3 groups.

CONCLUSION

The combination regimen was not superior to individual regimens in preventing CIN in patients with baseline renal impairment. There was a trend suggesting that the 12-hour sustained sodium chloride pre-hydration regimen was more protective than the 1-hour abbreviated SOB regimen.

Prevention of contrast-induced nephropathy through a knowledge of its pathogenesis and risk factors

Contrast-induced nephropathy (CIN) is an iatrogenic acute renal failure (ARF) occurring after the intravascular injection of iodinated radiographic contrast media. During the past several years, in many patients undergoing computed tomography, iodinated contrast media have not been used for the fear of ARF, thereby compromising the diagnostic procedure. But recent studies have demonstrated that CIN is rarely occurring in patients with normal renal function and that preexisting chronic renal failure and/or diabetes mellitus represent(s) predisposing condition(s) for its occurrence. After the description of CIN and its epidemiology and pathophysiology, underlying the important role played by dehydration and salt depletion, precautions for prevention of CIN are listed, suggested, and discussed. Maximum priority has to be given to adequate hydration and volume expansion prior to radiographic procedures. Other important precautions include the need for monitoring renal function before, during, and after contrast media injection, discontinuation of potentially nephrotoxic drugs, use of either iodixanol or iopamidol at the lowest dosage possible, and administration of antioxidants. A long list of references is provided that will enable readers a deep evaluation of the topic.

Acute kidney injury by radiographic contrast media: pathogenesis and prevention

It is well known that iodinated radiographic contrast media may cause kidney dysfunction, particularly in patients with preexisting renal impairment associated with diabetes. This dysfunction, when severe, will cause acute renal failure (ARF). We may define contrast-induced Acute Kidney Injury (AKI) as ARF occurring within 24-72 hrs after the intravascular injection of iodinated radiographic contrast media that cannot be attributed to other causes. The mechanisms underlying contrast media nephrotoxicity have not been fully elucidated and may be due to several factors, including renal ischaemia, particularly in the renal medulla, the formation of reactive oxygen species (ROS), reduction of nitric oxide (NO) production, and tubular epithelial and vascular endothelial injury. However, contrast-induced AKI can be prevented, but in order to do so, we need to know the risk factors. We have reviewed the risk factors for contrast-induced AKI and measures for its prevention, providing a long list of references enabling readers to deeply evaluate them both.

Side effects of radiographic contrast media: pathogenesis, risk factors, and prevention

Radiocontrast media (RCM) are medical drugs used to improve the visibility of internal organs and structures in X-ray based imaging techniques. They may have side effects ranging from itching to a life-threatening emergency, known as contrast-induced nephropathy (CIN). We define CIN as acute renal failure occurring within 24-72 hrs of exposure to RCM that cannot be attributed to other causes. It usually occurs in patients with preexisting renal impairment and diabetes. The mechanisms underlying CIN include reduction in medullary blood flow leading to hypoxia and direct tubule cell damage and the formation of reactive oxygen species. Identification of patients at high risk for CIN is important. We have reviewed the risk factors and procedures for prevention, providing a long list of references enabling readers a deep evaluation of them both. The first rule to follow in patients at risk of CIN undergoing radiographic procedure is monitoring renal function by measuring serum creatinine and calculating the eGFR before and once daily for 5 days after the procedure. It is advised to discontinue potentially nephrotoxic medications, to choose radiocontrast media at lowest dosage, and to encourage oral or intravenous hydration. In high-risk patients N-acetylcysteine may also be given.

Role of contrast media on oxidative stress, Ca(2+) signaling and apoptosis in kidney

Contrast media (CM)-induced nephropathy is a common cause of iatrogenic acute renal failure. The aim of the present review was to discuss the mechanisms and risk factors of CM, to summarize the controlled studies evaluating measures for prevention and to conclude with evidence-based strategies for prevention. A review of the relevant literature and results from recent clinical studies as well as critical analyses of published systematic reviews used MEDLINE and the Science Citation Index. The cytotoxicity induced by CM leads to apoptosis and death of endothelial and tubular cells and may be initiated by cell membrane damage together with reactive oxygen species (ROS) and inflammation. Cell damage may be aggravated by factors such as tissue hypoxia, properties of individual CM such as ionic strength, high osmolarity and/or viscosity. Clinical studies indeed support this possibility, suggesting a protective effect of ROS scavenging with the administration of N-acetylcysteine, ascorbic acid erdosteine, glutathione and bicarbonate infusion. The interaction between extracellular Ca(2+), which plays a central role in intercellular contacts and production of ROS, and the in vitro toxicity of CM was also reviewed. The current review addresses the role of oxidative stress in the pathogenesis of CM in the kidney as well as current and potential novel treatment modalities for the prevention of neutrophil activation and CM-induced kidney degeneration in patients. ROS production through CM-induced renal hypoxia may exert direct tubular and vascular endothelial injury. Preventive strategies via antioxidant supplementation include inhibition of ROS generation or scavenging.

Symmetric dimethylarginine as a proinflammatory agent in chronic kidney disease

BACKGROUND & OBJECTIVES

Chronic kidney disease (CKD) is characterized by chronic inflammation, considered a nontraditional risk factor for cardiovascular disease, the major cause of death in CKD. Symmetric dimethylarginine (SDMA) was recently demonstrated to induce reactive oxygen species in monocytes. The present study further investigates the inflammatory character of SDMA compared with its structural counterpart asymmetric dimethylarginine (ADMA).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In vitro, the effect of SDMA on intracellular monocytic expression of IL-6 and TNF-α was studied followed by an evaluation of nuclear factor (NF)-κB activation. Additionally, an association of SDMA with inflammatory parameters in consecutive stages of CKD was evaluated in vivo.

RESULTS

Monocytes incubated with SDMA showed increased IL-6 and TNF-α expression and a rise in active NF-κB. N-acetylcysteine abrogated both these effects. No significant effects were observed with ADMA. In vivo, 142 patients (67 ± 12 years) at different stages of CKD showed an inverse association between serum SDMA and ADMA and renal function. Correlations between SDMA and IL-6, TNF-α, and albumin were more significant than for ADMA, while multiple regression analysis only retained TNF-α at a high significance for SDMA (P < 0.0001). In receiver operating characteristic analysis for inflammation, defined as an IL-6 level above 2.97 pg/ml (median), the discriminative power of SDMA (area under the curve [AUC]: 0.69 ± 0.05) directly followed that of C-reactive protein (AUC: 0.82 ± 0.04) and albumin (AUC: 0.72 ± 0.05; for all, P < 0.0001) and preceded that of ADMA (P = 0.002).

CONCLUSIONS

The present study shows that SDMA is involved in the inflammatory process of CKD, activating NF-κB and resulting in enhanced expression of IL-6 and TNF-α, which is corroborated by the clinical data pointing to an in vivo association of SDMA with inflammatory markers in CKD at different stages.

Contrast induced nephropathy in urology

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

Expression of Toll-like receptor 4 on peripheral blood mononuclear cells and its effects on patients with acute myocardial infarction treated with thrombolysis

BACKGROUND AND AIMS

TLR4 has been shown to mediate inflammation in animal models of myocardial ischemia/reperfusion injury (MI/RI). Here we hypothesized that TLR4 on peripheral blood mononuclear cells (PBMCs) may be involved in the inflammatory response in this type of clinical event.

METHODS

Seventy two patients with acute myocardial infarction (AMI) who underwent thrombolysis were assigned into reperfusion group (n = 43) and non-reperfusion group (n = 29) according to recanalization of infarct-related artery (IRA) and 40 healthy volunteers were enrolled in this experiment. Eight mL of venous blood was taken from all patients 0 h before and 2, 6, 12, and 24 h after thrombolysis. Flow cytometry (FCM) was used to detect TLR4 protein expression and real-time quantitative RT-PCR was performed to determine TLR4 mRNA and myeloid differentiation protein-88 (Myd88) mRNA expression. The concentration of tumor necrosis factor-α (TNF-α) in plasma was evaluated using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared with controls, all detected indicators in AMI patients were upregulated before thrombolysis (p <0.01). After thrombolysis, they were further increased. In reperfusion group, all attained their peaks in earlier hours and the peak values were lower compared with non-reperfusion group. In both cases, either reperfusion or non-perfusion, TLR4 mRNA expression was positively correlated with the levels of Myd88 mRNA (r = 0.886 and 0.694, p <0.01), respectively.

CONCLUSIONS

TLR4 expression on PBMCs was markedly elevated in AMI patients either reperfused or non-reperfused. Inflammatory reaction by activated TLR4 in MI/RI in patients may be through TLR4-Myd88-dependent signal pathway.

Using acetaminophen's toxicity mechanism to enhance cisplatin efficacy in hepatocarcinoma and hepatoblastoma cell lines

BACKGROUND/AIMS

Acetaminophen overdose causes hepatotoxicity mediated by toxic metabolites generated through the cytochrome P450 enzyme. The objective of this study was to investigate whether acetaminophen (AAP) can enhance cisplatin (CDDP) cytotoxicity against human hepatocarcinoma and hepatoblastoma cells in vitro and whether this effect can be prevented by N-acetylcysteine (NAC).

METHODS

In vitro studies (glutathione [GSH] level, cell viability, and immunoblot assays) were performed using human hepatocarcinoma and hepatoblastoma cells cultured in AAP, CDDP, and the combination of both with or without delayed NAC administration. The pharmacology and toxicology of high-dose AAP in rats were also examined.

RESULTS

Acetaminophen decreased GSH levels in liver cancer cells in a dose- and time-dependent manner. Acetaminophen combined with CDDP had enhanced cytotoxicity over CDDP alone. The cytotoxicity caused by AAP plus CDDP was decreased by NAC, with the effectiveness being time-dependent. The GSH level was lowered in the liver but not in the blood or the brain in rats treated with a high dose of AAP (1000 mg/kg). The expression of CYP2E1 protein, a key cytochrome P450 enzyme, varies among species but is not correlated to AAP sensitivity in liver cancer cells.

CONCLUSIONS

Our results suggest that a chemotherapeutic regimen containing both AAP and CDDP with delayed NAC rescue has the potential to enhance chemotherapeutic efficacy while decreasing adverse effects. This would be a promising approach particularly for hepatoblastomas regardless of cellular CYP2E1 protein level but could also be beneficial in other malignancies.

Endovascular stenting of thoracic aortic aneurysm

In 2005, the findings of the multicenter Gore Tag study led to United States Food and Drug Administration approval for endovascular repair of thoracic aortic aneurysms (TEVAR). TEVAR provides a therapeutic option for patients who have thoracic aortic aneurysm and for the treatment of type B aortic dissection with malperfusion. Spinal cord ischemia and stroke are recognized neurologic complications of TEVAR. Identification of high-risk patients combined with targeted anesthetic and perioperative management may decrease the risk of neurologic complications after TEVAR.

Clinical outcomes of contrast-induced nephropathy in patients undergoing percutaneous coronary intervention: A prospective, multicenter, randomized study to analyze the effect of hydration and acetylcysteine

BACKGROUND

The potential role of hydration in prevention of contrast-induced nephropathy (CIN) still remains to be unclear.

METHODS

Nine-hundred and thirty-six patients scheduled for percutaneous coronary intervention (PCI) were enrolled into the present study, and divided into normal (serum creatinine<1.5 mg/dl) and abnormal (serum creatine> or =1.5 mg/dl) groups according to their baseline serum concentration of creatinine. Each group was further randomly divided into two subgroups: hydration and nonhydration. All patients in abnormal group took twice orally loading dose of 1200 mg acetylcysteine (ATLS) at 12 h before scheduled time for coronary angiogram and immediately after procedure. Creatinine concentration was remeasured at the time of admission (just before catheterization), every day for the following three days. The primary end point during 6-month follow-up included clinical driven revascularization (either PCI or CABG), death from all causes, and requiring emergency renal-replacement therapy.

RESULTS

The incidence of CIN was more commonly in abnormal group that in normal group (6.52% vs. 37.68%, p<0.001). Hydration had potentials in prevention of CIN only in patients with elevated baseline concentration of creatinine. Multivariate analysis demonstrated that the following variables remained to be significant factors correlating with CIN: age> or =70 years (odds ration [OR] 5.27, 95% confidence interval [CI] 1.94 to 13.07, p=0.0007), contrast volume> or =320 ml (OR 3.26, 95% CL 2.14 to 7.58, p=0.01), diabetes mellitus (OR 9.86, 95% CL 5.38 to 31.67, p<0.0001), and peripheral arterial disease (OR 11.25, 95% CL 5.12 to 43.19, p<0.0001). Patients with CIN in abnormal group had worse clinical outcomes, compared to patients with CIN in normal group.

CONCLUSION

Patients with CIN and preexisting renal insufficiency had worse clinical outcomes. Hydration with 0.45% sodium chloride alone had no potential effect on the occurrence of CIN in patients with normal renal function. Combination of hydration with ATLS could reduce the incidence of CIN in patients at high risk.

Nefroproteção relacionada ao uso de meio de contraste iodado: atenção de enfermagem

OBJETIVO: Analisar estudos publicados sobre Nefropatia induzida por contraste, sua prevenção e o papel do enfermeiro nesta ação, bem como, propor intervenções de enfermagem. MÉTODOS: Foi realizada revisão de literatura nas bases de dados MEDLINE, SciELO, LILACS, publicados de 1977 a 2007. RESULTADOS: Em âmbito nacional não encontramos estudos quando associamos aos descritores nefroproteção e meio de contraste iodado a palavra enfermagem. Identificamos que na prática clínica o procedimento de hidratação antes do uso de meio de contraste é o mais utilizado. CONCLUSÃO: Sabendo-se que os meios de contraste podem gerar diferentes tipos de reações adversas nos pacientes, torna-se importante o enfermeiro estar habilitado cientificamente, para reconhecer estas injúrias e, assim, implementar intervenções pertinentes, eficazes e que minimizem as complicações.

Prevention of contrast-induced nephropathy in vascular surgery patients

Presently, only hydration and N-acetylcysteine have been shown to be effective in decreasing the incidence of radiographic contrast-induced nephropathy. We investigated the role of N-acetylcysteine and various hydration protocols in vascular surgery patients undergoing angiography. A single-center, randomized, placebo-controlled trial was conducted in patients with stable, preexisting renal dysfunction undergoing elective, outpatient angiography. Patients were randomized to outpatient oral hydration and N-acetylcysteine, inpatient hydration plus N-acetylcysteine, or our standard therapy of inpatient intravenous hydration alone. Two of twenty-eight (7%) patients who received outpatient oral hydration and N-acetylcysteine developed contrast-induced nephropathy, while two of 25 (8%) who recieved inpatient hydration plus N-acetylcysteine developed contrast-induced nephropathy and two of 25 (8%) who received standard therapy of inpatient intravenous hydration alone developed contrast-induced nephropathy. There was no statistical difference in incidence of contrast-induced nephropathy between the groups. No statistically significant independent risk factors were identified among the patients who developed contrast-induced nephropathy. N-Acetylcysteine did not confer additional benefit to patients treated with inpatient intravenous hydration. Outpatient oral hydration plus N-acetylcysteine was as effective at preventing contrast-induced nephropathy as inpatient therapies and avoided costly hospital admission.

Sodium bicarbonate, N-acetylcysteine, and saline for prevention of radiocontrast-induced nephropathy. A comparison of 3 regimens for protecting contrast-induced nephropathy in patients undergoing coronary procedures. A single-center prospective controlled trial

BACKGROUND

Several protective therapies have been developed to prevent contrast-induced nephropathy (CIN). We aimed to investigate the efficacy of sodium bicarbonate by comparing 2 other regimens, including combination of N-acetylcysteine (NAC) plus sodium chloride and sodium chloride alone, to prevent CIN in patients undergoing cardiovascular procedures.

METHODS

We prospectively enrolled 264 patients who were scheduled for cardiovascular procedures and had a baseline creatinine level >1.2 mg/dL. The patients were assigned 1 of 3 prophylactic regimens: infusion of sodium bicarbonate, sodium chloride, sodium chloride plus oral NAC (600 mg bid). Contrast-induced nephropathy was defined as an increase in serum creatinine level >25% or 0.5 mg/dL after 48 hours.

RESULTS

There were no significant differences among groups regarding baseline demographic properties and nephropathy risk factors. The change in creatinine clearance was significantly better in the sodium bicarbonate group than other 2 groups (P = .007). The incidence of CIN was significantly lower in the sodium bicarbonate group (4.5%) compared with sodium chloride alone (13.6%, P = .036) and tended to be lower than in the combination group (12.5%, P = .059). After adjusting the Mehran nephropathy risk score, the risk of CIN significantly reduced with sodium bicarbonate compared with sodium chloride alone (adjusted risk ratio 0.29, P = .043).

CONCLUSIONS

Hydration with sodium bicarbonate provides better protection against CIN than the sodium chloride infusion does alone. Combination therapy of NAC plus sodium chloride did not offer additional benefit over hydration with sodium chloride alone.

Diagnosis and treatment of acute renal failure in patients with cirrhosis

In patients with cirrhosis, acute renal failure is due to prerenal failure (a result of decreased renal perfusion) and tubular necrosis. There are 3 main causes of prerenal failure: 'true hypovolemia' (which complicates hemorrhage, gastrointestinal or renal fluid losses), sepsis, and type 1 hepatorenal syndrome (HRS). Prerenal failure may also be due to the administration of non-steroidal antiinflammatory drugs, or intravascular radiocontrast agents. Prerenal failure is reversible after restoration of renal blood flow. Treatments target the cause of hypoperfusion, and fluid replacement is used to treat 'non-HRS' prerenal failure. In patients with type 1 HRS with very low short-term survival rate, liver transplantation is the ideal treatment. Systemic vasoconstrictor therapy with terlipressin (combined with intravenous human albumin), noradrenaline (combined with albumin and furosemide) or midodrine (combined with octreotide and albumin) may improve renal function in patients with type 1 HRS waiting for liver transplantation. MARS (for Molecular Adsorbent Recirculating System) and the transjugular intrahepatic portosystemic shunt may also improve renal function in these patients. In patients with cirrhosis, acute tubular necrosis is mainly due to an ischemic insult to the renal tubules. Studies are needed on the natural course and treatment (e.g., renal-replacement therapy) of acute tubular necrosis in patients with cirrhosis.

Trimetazidine in the prevention of contrast-induced nephropathy after coronary procedures

OBJECTIVE

To evaluate the efficacy of trimetazidine (TMZ) in the prevention of contrast-induced nephropathy (CIN) in patients with high serum creatinine levels undergoing coronary angiography/angioplasty.

METHODS

TMZ (20 mg thrice daily) was administered orally for 72 h starting 48 h before the procedure. All patients were given intravenous saline (0.9%) at a rate of 1 ml/kg of body weight per hour for 24 h starting 12 h beforehand. Serum creatinine levels were measured before the procedure, 48 h and 7 days after the procedure. Increase in serum creatinine level exceeding 0.5 mg/day or one quarter of the basal value is considered as CIN. Venous blood samples for serum total antioxidant capacity (TAC) measurement were drawn before and after coronary angiography.

RESULTS

Basal serum creatinine levels and TAC were similar in TMZ and control groups. Serum creatinine levels in the control group increased significantly 2 days after the procedure, and returned to the baseline values on the seventh day. However, it did not change significantly on the second day, and even significantly decreased on the seventh day in the TMZ group. CIN developed in 2.5% (1/40) of patients in the TMZ group and in 16.6% (7/42) of patients in the control group (p<0.05). TAC values were not different between treatment groups.

CONCLUSION

TMZ along with isotonic saline infusion is more effective than isotonic saline alone in reducing the risk of CIN in patients with pre-existing renal dysfunction.

Strategies to reduce the risk of contrast nephropathy: an evidence-based approach

PURPOSE OF REVIEW

Contrast nephropathy is a common complication associated with angiographic procedures that carries significant morbidity and mortality. Recent clinical trials of prophylactic strategies have reported contradictory results. This review presents recent insights into the pathophysiology of contrast nephropathy and reviews trial results in this context.

RECENT FINDINGS

A prediction rule has been developed to better identify patients at risk of developing contrast nephropathy. Factors other than osmolality play a significant role in the pathogenesis of contrast nephropathy, at least for agents with osmolalities of 800 mOsm/kg or less. New randomized trial data do not support a role for N-acetylcysteine in contrast nephropathy prophylaxis and there is additional evidence that fenoldopam is ineffective. Pooled analyses of theophylline prophylaxis trials are inconclusive. Theoretical and clinical data suggest that ascorbic acid may be renoprotective, but this requires further study.

SUMMARY

The overall incidence of contrast nephropathy remains low. Available evidence supports the use of hydration and low volumes of iso-osmolar or low-osmolar contrast in patients at risk of developing contrast nephropathy. Heterogeneity has affected interpretability of interventional trials of N-acetylcysteine or theophylline prophylaxis strategies. Future clinical trials must identify and target moderate-risk to high-risk patients and ensure that proven therapies are included in trial protocols.

Lack of protection of N-acetylcysteine (NAC) in acute renal failure related to elective aortic aneurysm repair—a randomized controlled trial

BACKGROUND

N-acetylcysteine (NAC) is an antioxidant drug largely tested in different clinical situations. Recently, NAC has been employed with variable success in the prevention of radiocontrast nephropathy. Since aortic aneurysm surgical repair is a condition that is frequently accompanied by acute renal failure (ARF), we sought to investigate whether NAC has any role in preventing ARF in this scenario.

METHODS

A randomized, placebo-controlled, double-blind trial with the following inclusion criteria: elective aortic aneurysm repair in patients with stable renal function. The groups were randomly matched for age, gender, presence of diabetes and pre-existent renal failure. NAC or placebo (control) was administered p.o. for 24 h before operation and maintained i.v. for 48 h after operation. The dose of NAC was 1200 mg b.i.d. the day before surgery and 600 mg b.i.d. after. The primary endpoint was the development of ARF up to the third post-operative day, defined as an increase in SCr > or = 25% from baseline. Secondary endpoints were: ICU mortality and ICU length of stay.

RESULTS

Forty-two patients (n = 18 for NAC group and n = 24 for control) were studied. The baseline SCr and calculated GFR did not differ between the groups (1.19 +/- 0.33 vs 1.37 +/- 0.49 mg/dl; and 64.6 +/- 26.22 vs 65.7 +/- 28.32 ml/min, NAC vs control, respectively, P = 0.17 and P = 0.90). Need for suprarenal aortic cross-clamping and its duration, occurrence of major bleeding, intra-operative hypotension and the post-operative peak of CPK did not differ between NAC and control groups. The overall incidence of ARF in the study was 36% (13/36), but it was not significantly different between groups (7/14, 50% in NAC vs 6/22, 27.3% in control, P = 0.16). The overall mortality was 23% (10/42) and was not different (P = 0.209) in NAC group (33.3%) when compared with control (16.7%), the same occurring with the length of ICU stay (2.93 +/- 1.53 vs 2.52 +/- 1.36 days, P = 0.40).

CONCLUSION

This study suggests that the putative beneficial effects of NAC on radiocontrast nephropathy might not be applicable to other situations, such as ARF associated with elective aortic aneurysm repair.

Acetazolamide for prevention of contrast-induced nephropathy: a new use for an old drug

Reactive oxygen species play a major role in the pathogenesis of contrast-induced nephropathy (CN). Hydration with sodium bicarbonate (HCO3-) can reduce the incidence of CN in high-risk patients, suggesting a direct causal relationship between low pH of tubular fluid and enhanced activity of generated reactive oxygen species to damage renal tubular cells. Whether acetazolamide (AZ), a carbonic anhydrase inhibitor, is more effective than HCO3- unknown. Ninety-six children with stable chronic renal insufficiency were randomly assigned to receive either a 154 mEq/L infusion of sodium bicarbonate (HCO3-) (n = 46) or 0.9% sodium chloride plus oral AZ (n = 50) at a rate of 3 ml/kg/hr for 1 hour before and 1 ml/kg/hr for 6 hours after the radiographic procedure. Serum creatinine concentration (Scr) was measured before and 48 hours after the procedure. The primary endpoint was an increase in the Scr concentration of > or = 25% 48 hours after the contrast administration. The baseline clinical and biochemical characteristics of the two groups were similar. The mean Scr concentration after contrast administration was significantly lower in the AZ group (p = 0.02) than in the HCO3- group (p = 0.27). The mean absolute decrease in Scr concentration at 48 hours was significantly greater in the AZ group (p < 0.01). Four of the 46 patients (8.7%) in the HCO3- group had an increase in the Scr concentration of > or = 25% compared with none of the 50 patients (0%) in the AZ group (p = 0.049). Thus, compared to HCO3-, AZ plus saline hydration was more effective for the prevention CN after radiographic procedure.

Contrast nephropathy may be partly mediated by autonomic dysfunction: renal failure considered as a modern maladaptation of the prehistoric trauma response

The mechanism behind iodinated radiocontrast nephropathy remains elusive. Direct oxidative damage is the prevailing hypothesis, but the apparent protective effect of iodine against oxidation contradicts this view. We propose that autonomic dysfunction participates in the pathogenesis of radiocontrast nephropathy and may account for other contrast-associated reactions previously attributed to allergy. Iodine, through its effects on thyroid function and chemoreceptor response to metabolic acidosis, may induce hyperadrenergia and consequently diminish renovascular flow and urine output. The renal response to adrenergia likely served an adaptive function during prehistoric evolution when trauma was a dominant source of hypovolemia and adrenergia, but the response may behave maladaptively today as evolutionarily nai ve triggers for adrenergia have emerged. Autonomic dysfunction can further impair renal function by deranging renovascular autoregulation and inducing oxidative reperfusion injury as a secondary phenomenon. Many other causes of acute renal failure such as drug toxicity, surgery, hospitalization, and diabetes may operate through hyperadrenergia, impaired renovascular autoregulation, and oxidative reperfusion injury. Dialysis, a volume reduction therapy for renal failure, can counterintuitively worsen renal dysfunction by exacerbating adrenergia, which may explain its association with accelerated atherosclerosis, inflammation, and cancer. Other examples of vicious cycles that perpetuate renal dysfunction may include renal artery stenosis, carotid stenosis, and atherosclerosis as well as the cardio-renal, hepato-renal, and pulmonary-renal syndromes. The benefits of hydration and bicarbonate in protecting renal function may operate in part through baroreceptor- and chemoreceptor-mediated reduction of sympathovagal ratio, respectively. New treatment paradigms for renal failure including pharmacologic and electro-mechanical therapies are envisioned based on autonomic remodeling, reduced sympathovagal ratio, and neuromodulation of pathways typically associated with trauma such as renin, angiotensin, vasopressin, and aldosterone.

Magnesium Supplementation Combined with N-Acetylcysteine Protects against Postischemic Acute Renal Failure

Magnesium is a potent vasodilator whose effects have not been evaluated in renal ischemia. The antioxidant properties of N-acetylcysteine (NAC) partially protect animals from ischemic/reperfusion injury. This study was designed to evaluate magnesium supplementation, alone or combined with NAC, on ischemic acute renal failure. Rats were maintained on normal diets, supplemented or not with MgCl(2).6H(2)O (1% in drinking water) for 23 d, and some rats received NAC (440 mg/kg body wt) on days 20 to 23. On day 21, ischemia was induced by clamping both renal arteries for 30 min. Five groups were studied: Normal, ischemia, ischemia+magnesium, ischemia+NAC, and ischemia+magnesium+NAC. GFR (inulin clearance), renal blood flow (RBF), FEH(2)O, and FENa were determined. Serum magnesium was decreased in ischemia-only rats. Magnesium prevented postischemia GFR and RBF decreases but did not protect against tubular damage. However, NAC completely restored the tubular damage induced by ischemia/reperfusion. Semiquantitative immunoblotting showed that NAC prevented the decreased expression of Na-K-2Cl co-transporter and aquaporin 2 after renal ischemia/reperfusion. Untreated rats with acute renal failure demonstrated markedly decreased endothelial nitric oxide synthase expression. Significantly, treatment with NAC, magnesium, or both completely inhibited downregulation of endothelial nitric oxide synthase. The tubular necrosis scores were lower in rats that were treated with NAC alone or with the magnesium-NAC combination. Magnesium prevented postischemia GFR and RBF decreases but did not protect against tubular damage. The NAC protected tubules from ischemia, decreased infiltrating macrophages/lymphocytes, and had a mild protective effect on GFR. In ischemic/reperfusion injury, renal function benefits more from the magnesium-NAC combination than from magnesium alone.

N-acetylcysteine does not prevent contrast induced nephropathy after cardiac catheterisation with an ionic low osmolality contrast medium: a multicentre clinical trial

OBJECTIVE

To evaluate oral N-acetylcysteine in the prevention of contrast induced nephropathy (CIN) in patients at low to moderate risk undergoing cardiac catheterisation with ionic low osmolality contrast medium.

METHODS

In a multicentre double blind clinical trial 156 patients undergoing coronary angiography or percutaneous coronary intervention with serum creatinine > or = 106.08 micromol/l or creatinine clearance < 50 ml/min or diabetes mellitus were randomly assigned to receive N-acetylcysteine 600 mg orally twice daily for two days or placebo. Only low osmolality ionic contrast medium was used.

RESULTS

Sixteen patients developed CIN, defined as an increase of 44.2 micromol/l in creatinine in 48 hours: eight of 77 patients (10.4%) in the N-acetylcysteine group and eight of 79 patients (10.1%) in the placebo group (p = 1.00). The mean (SD) change in serum creatinine was similar in both groups: 7.96 (35.36) micromol/l in the N-acetylcysteine group and 6.19 (25.64) micromol/l in the placebo group (p = 0.67). No difference was observed in the change in endogenous creatinine clearance (-0.54 (10.4) ml/min v -2.52 (12.3) ml/min, N-acetylcysteine and placebo, respectively, p = 0.28).

CONCLUSION

Oral N-acetylcysteine did not prevent CIN in patients at low to moderate risk undergoing cardiac catheterisation with ionic low osmolality contrast medium.

Contrast-induced nephropathy: a review

Contrast-induced nephropathy (CIN) is one of the leading causes of renal impairment in the United States and the third cause of hospital-acquired renal failure. Reduction in the incidence of CIN can lead to a decrease in the morbidity, mortality, and length of hospital stay. Although prophylactic hydration has been promising in decreasing the occurrence of CIN, other efforts such as diuretics, calcium channel blockers, theophylline, aminophylline, atrial natriuretic peptide, dopamine, and fenoldopam have been disappointing. The preventive effect of N-acetylcysteine on CIN has not been consistent in the literature. In a recent clinical trial, bicarbonate infusion was more effective than hydration in the prevention of CIN. Mechanical devices are in development to perfuse renal arteries with protective drugs during contrast exposure or for removal of contrast from coronary sinus during coronary angiography. In this article, we have reviewed available data in regards to CIN.

Current Trials of Interventions to Prevent Radiocontrast-Induced Nephropathy

Radiocontrast administration is a common cause of hospital-acquired acute renal failure. It is associated with significant in-hospital and long-term morbidity and mortality and increases the costs of medical care by at least extending the hospital stay. A variety of therapeutic interventions, including saline hydration, diuretics, mannitol, calcium channel antagonists, theophylline, endothelin receptor antagonists, and dopamine, have been employed to prevent radiocontrast-induced acute renal failure. Recent advances have examined the impact of fenoldopam (dopamine-1 receptor agonist), N-acetylcysteine (antioxidant), iso-osmolar contrast agents, hemodialysis, and hemofiltration on ameliorating radiocontrast-induced acute renal failure. Although hydration with half-normal saline had remained the gold standard for the prevention of radiocontrast-induced nephropathy, recent data have revealed the superiority of hydration with normal saline over half-normal saline. This review focuses on the most recent studies of interventions to ameliorate radiocontrast-induced acute renal failure and provides a critical analysis of some of the recent studies conducted to prevent radiocontrast-induced nephropathy.

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.

Systematic review of the impact of N-acetylcysteine on contrast nephropathy

BACKGROUND

The efficacy of N-acetylcysteine (NAC) for preventing contrast nephropathy is uncertain. We performed a systematic review and meta-analysis to assess the efficacy of NAC for preventing contrast nephropathy after administration of intravenous contrast media.

METHODS

Data were obtained from searching MEDLINE (1969-2003) and EMBASE (1988-2003), Cochrane Controlled Clinical Trial Registry (2002, Volume 3), and conference proceedings. We considered all randomized studies that compared changes in renal function between groups that received and did not receive NAC. Studies in which the control group also received active therapy were excluded, although co-intervention directed at both groups was permitted. Two reviewers independently extracted quantitative and qualitative data. Disagreements were resolved by consensus with the aid of a third party.

RESULTS

Fifteen studies with a total of 1776 patients satisfied inclusion and exclusion criteria. Contrast nephropathy was typically defined by an increase in serum creatinine of 0.5 mg/dL within 24 to 48 hours of contrast administration. The pooled random effect relative risk was 0.65 (0.43-1.00, P= 0.049), indicating that NAC significantly reduced the incidence of contrast nephropathy. However, the effect of NAC was not statistically significant in several prespecified subgroup analyses, and the results were not robust to the addition of hypothetical new or unidentified randomized trials. There was evidence of significant heterogeneity in NAC effect across studies (Q = 26.3, P= 0.02). Random effects meta-regression did not implicate identified differences in participant or study characteristics as responsible for the observed heterogeneity.

CONCLUSION

NAC may reduce the incidence of acutely increased serum creatinine after administration of intravenous contrast, but this finding was of borderline statistical significance, and there was significant heterogeneity between trials. Before NAC becomes the standard of care for all patients receiving intravenous contrast, new randomized trials evaluating its effect on clinically relevant outcomes are required.

N-acetylcysteine reduces contrast-associated nephropathy but not clinical events during long-term follow-up

BACKGROUND

Contrast-associated nephropathy (CAN) is associated with increased morbidity and mortality following percutaneous coronary intervention (PCI). N-acetylcysteine (NAC) has been shown to reduce the risk of nephropathy; however, the impact of NAC on long-term clinical outcomes has not been assessed.

METHODS

This randomized, double-blind, placebo-controlled trial enrolled 180 patients with moderate renal dysfunction undergoing PCI or coronary angiography with a high likelihood of ad hoc PCI; 171 patients completed the clinical follow-up. Patients received oral NAC (2000 mg/dose, n = 95) or placebo (n = 85) twice a day for 3 doses if randomized the night prior to the procedure, and 2 doses if randomized the day of the procedure. The primary end point was the incidence of a > or =25% increase in serum creatinine level 48 to 72 hours after PCI. Secondary end points were the inhospital incidence of death, nonfatal myocardial infarction, or urgent dialysis, and the 9-month incidence of death, nonfatal myocardial infarction, need for dialysis, or repeat hospitalization for cardiac reasons.

RESULTS

CAN occurred in 9.6% of patients assigned to NAC and 22.2% of patients assigned to placebo (P =.04); 1 patient receiving NAC required urgent dialysis. The inhospital composite end point occurred in 7 (7.4%) NAC-treated and 3 (3.5%) placebo-treated patients, P = NS. At 9 months, the composite end point occurred in 23 (24.2%) NAC-treated patients and 18 (21.2%) placebo-treated, P = NS.

CONCLUSION

Although high-dose NAC prevented periprocedural CAN, this benefit did not translate into a decrease in adverse outcomes over 9 months. Further studies to determine the clinical utility of this drug are required.

Sodium Bicarbonate: Prevention of Contrast-Agent-Induced Nephrotoxicity

Off-Label Drug Uses

This Hospital Pharmacy feature is extracted from Off-Label DrugFacts, a quarterly publication available from Facts and Comparisons. Off-Label DrugFacts is a practitioner-oriented resource for information about specific FDA-unapproved drug uses. This new guide to the literature will enable the health care professional/clinician to quickly identify published studies on off-label uses and to determine if a specific use is rational in a patient care scenario. The most relevant data are provided in tabular form so that the reader can easily identify the scope of information available. A summary of the data—including background, study design, patient population, dosage information, therapy duration, results, safety, and therapeutic considerations—precedes each table of published studies. References direct the reader to the full literature for more comprehensive information prior to patient care decisions. Direct questions or comments on “Off-Label Drug Uses” to hospitalpharmacy@drugfacts.com .

A randomized controlled trial of intravenous N-acetylcysteine for the prevention of contrast-induced nephropathy after cardiac catheterization: lack of effect

BACKGROUND

Contrast-induced nephropathy (CIN) after cardiac catheterization is common in patients with preexisting renal dysfunction. Studies of oral acetylcysteine to prevent CIN have produced conflicting results. Intravenous N-acetylcysteine (NAC) has logistic advantages in this setting. The objective of this study was to evaluate, in a blinded, randomized, placebo-controlled fashion, whether intravenous NAC reduced CIN in the setting of cardiac catheterization in patients with preexisting renal insufficiency.

METHODS

Patients with renal dysfunction undergoing cardiac catheterization were randomly assigned to intravenous NAC 500 mg immediately before the procedure or placebo. All patients received isotonic saline (200 mL) beforehand, followed by 1.5 mL/kg per hour for 6 hours, unless contraindicated. Exclusion criteria included acute renal failure, creatinine >400 micromol/L, concurrent dialysis, unstable clinical status, and prior NAC use. Baseline creatinine was obtained immediately before the procedure and repeated 2 to 8 days later. The primary end point was the occurrence of CIN defined as a reduction in creatinine clearance from baseline of >5 mL/min (Cockcroft-Gault formula).

RESULTS

The study was terminated early because of a determination of futility by the Data Safety Monitoring Committee after enrollment of 487 patients. The median baseline creatinine clearance was 44 mL/min (interquartile range, 33, 55). Median contrast received was 120 mL (interquartile range, 80, 175). Baseline characteristics were similar in the two groups. Altogether, 98 (22.0%) subjects had the primary end point: 23.3% in the NAC group and 20.7% in the placebo arm (P =.57).

CONCLUSIONS

In this large, randomized trial, enrolling a high-risk group of patients with impaired renal function, intravenous NAC was ineffective in preventing CIN.

Effect of N-acetylcysteine for prevention of contrast nephropathy in patients with moderate to severe renal insufficiency: a randomized trial

BACKGROUND

The effect of N-acetylcysteine (NAC) to prevent contrast nephropathy (CN) in patients with moderate to severe renal insufficiency undergoing coronary angiography or interventions is not clear.

METHODS

This is a prospective, open-label, randomized, controlled trial. Ninety-one consecutive patients with a serum creatinine level of 1.69 to 4.52 mg/dL (149 to 400 micromol/L) undergoing coronary procedures were recruited and randomly assigned to administration of either oral NAC, 400 mg, thrice daily the day before and day of the contrast procedure (the NAC group) or no drug (the control group). Serum creatinine was measured before and 48 hours after contrast exposure. The primary end point of this study was the development of CN, defined as an increase in serum creatinine concentration of 0.5 mg/dL or greater (> or =44 micromol/L) or a reduction in estimated glomerular filtration rate (GFR) of 25% or greater of the baseline value 48 hours after the procedure.

RESULTS

There were no significant differences between the 2 groups (46 patients, NAC group; 45 patients, control group) in baseline characteristics or mean volume of contrast agent administered. Six patients (13.3%) in the control group and 8 patients (17.4%) in the NAC group developed CN (P = 0.8). Serum creatinine levels increased from 2.27 +/- 0.54 to 2.45 +/- 0.65 mg/dL (201 +/- 48 to 217 +/- 57 micromol/L; P = 0.003) in the NAC group and 2.37 +/- 0.61 to 2.40 +/- 0.70 mg/dL (210 +/- 54 to 212 +/- 62 micromol/L; P = 0.6) in the control group. The increase in serum creatinine levels between the 2 groups had no difference (P = 0.7). Estimated GFR decreased from 30.3 +/- 8.4 to 28.1 +/- 8.4 mL/min (P = 0.01) in the NAC group and 28.4 +/- 8.6 to 27.5 +/- 8.8 mL/min (P = 0.3) in the control group. The decline in estimated GFR between the 2 groups had no difference (P = 0.7).

CONCLUSION

In the current study, oral NAC had no effect on the prevention of CN in patents with moderate to severe renal insufficiency undergoing coronary angiography or interventions. However, the sample size of our present study is small. Our findings highlight the need for a large-scale, randomized, controlled trial to determine the exact beneficial effect of NAC.

N-acetylcysteine in the prevention of radiocontrast-induced nephropathy: clinical trials and end points

N-acetylcysteine (NAC) has been suggested to prevent radiocontrast-induced nephropathy (RCIN) in patients with a reduced renal function. However, clinical studies have not been demonstrating this effect consistently. Also, reviews and meta-analyses dealing with the question of prevention of RCIN by NAC have been controversial. Nearly all investigators used serum creatinine as surrogate end point of their trials, and changes in serum creatinine concentrations are thought to reflect the extent of renal injury as primary outcome. In a recent study, an effect of NAC on creatinine values and estimated glomerular filtration rate without any effect on cystatin C levels has been shown in volunteers with a normal renal function. Therefore, before renal protective effects of NAC in RCIN are proposed, any direct effects of NAC on creatinine, urea, and estimated glomerular filtration rate should be addressed. In future trials, the glomerular filtration rate should preferentially be measured directly, or at least additional markers of the renal function (e.g., serum cystatin C) have to be assessed. Furthermore, additional 'hard' end points, i.e., hospital morbidity, mortality, or dialysis dependency, should be considered in the design of future studies of RCIN.

N-acetylcysteine for radiocontrast-induced nephropathy: Potential role in the emergency department?

Objective:

To systematically review the efficacy and safety of N-acetylcysteine (NAC) for the prevention of radiocontrast-induced nephropathy (RIN), and to discuss its potential role in the emergency department.

Methodology:

We conducted a search of MEDLINE (from 1966 to December 2003), PubMed (1966 to December 2003) and EMBASE (1988 to December 2003) for English-language, prospective, randomized, controlled trials in humans using the search terms N-acetylcysteine, acetylcysteine, radiopharmaceuticals, contrast media, and kidney failure (acute).

Results:

Five trials support and 4 trials refute the hypothesis that NAC helps prevent RIN. In 7 of 9 trials, oral NAC was administered twice daily for 2 days, on the day before and on the day of the radiocontrast study — a regime not feasible for emergent situations. More recent trials suggest that adequate hydration and lower volumes of radiocontrast, rather than NAC, are more effective ways to prevent RIN.

Conclusion:

Although further study may be indicated, current evidence does not suggest that NAC has a role in the emergency prevention of RIN.

Prevention of radiocontrast-induced nephropathy

Radiocontrast administration is a common cause of hospital-acquired acute renal failure. It is associated with significant in-hospital and long-term morbidity and mortality and increases the costs of medical care by at least extending the hospital stay. Although individuals with normal renal function generally are not considered to be at particular risk, patients with preexisting renal failure are much more likely to experience this complication after radiocontrast agent administration. Typically, serum creatinine levels begin to increase at 48 to 72 hours, peak at 3 to 5 days, and return to baseline within another 3 to 5 days. A variety of therapeutic interventions, including saline hydration, diuretics, mannitol, calcium channel antagonists, theophylline, endothelin receptor antagonists, and dopamine, have been used in an attempt to prevent radiocontrast-induced nephropathy. Of these, saline hydration is the sole efficacious therapy to protect against radiocontrast-induced nephropathy. Recent advances have examined the impact of fenoldopam (dopamine-1 [DA-1] receptor; DA-1 agonist), the antioxidant N-acetylcysteine, iso-osmolar contrast agents, hemodialysis, and hemofiltration in ameliorating radiocontrast-induced nephropathy. This review focuses on current interventions to ameliorate radiocontrast-induced acute renal failure and provides an analysis of some of the recent studies conducted to halt radiocontrast-induced nephropathy.

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.

Renal effects of N-acetylcysteine in patients at risk for contrast nephropathy: decrease in oxidant stress-mediated renal tubular injury

BACKGROUND

N-Acetylcysteine has been shown to protect against contrast nephropathy, although the mechanisms underlying such an effect are unclear. Surprisingly, studies have shown that post-radiocontrast renal function actually improves in chronic renal failure patients receiving N-acetylcysteine. However, there have been no studies investigating the cause of this improvement.

METHODS

In a double-blind, placebo-controlled study, 24 patients (aged 65+/-2 years) suffering from stable mild-to-moderate renal insufficiency and undergoing elective coronary angiography were randomized to receive either placebo or N-acetylcysteine. All received similar hydration. Renal function parameters were assessed 48 h before and 48 h after radiocontrast administration. Urinary 15-isoprostane F2(t), a specific marker of oxidative stress, was measured immediately before and after the procedure. Expression of urinary alpha-glutathione S-transferase protein, a specific proximal tubular injury marker, was assessed after the procedure.

RESULTS

Comparing creatinine clearance values before and after angiography, a significant increase was seen in N-acetylcysteine patients (44.7+/-4.2 vs 57.2+/-6.3 ml/min/1.73 m(2); P = 0.02), whereas placebo patients presented no change (46.6+/-5.0 vs 46.9+/-4.3 ml/min/1.73 m(2); P = 0.90). After radiocontrast, urinary 15-isoprostane F2(t) levels in placebo patients increased significantly over baseline values (2.9+/-0.7 vs 10.3+/-2.1 ng/mg creatinine; P = 0.007), whereas urinary 15-isoprostane F2(t) levels in N-acetylcysteine patients remained basically unchanged (3.5+/-0.5 vs 4.1+/-0.9 ng/mg creatinine; P = 0.63). Furthermore, N-acetylcysteine treatment led to lower levels of alpha-glutathione S-transferase than did placebo treatment (0.8+/-0.2 vs 2.4+/-0.7 micro g/g; P = 0.046).

CONCLUSIONS

In chronic renal failure patients, the improvement in renal function induced by post-radiocontrast administration of N-acetylcysteine is strongly associated with suppression of oxidant stress-mediated proximal tubular injury.

Prevention of radiocontrast nephropathy with N-acetylcysteine in patients with chronic kidney disease: a meta-analysis of randomized, controlled trials

BACKGROUND

Radiocontrast nephropathy (RCN) is a common cause of hospital-acquired acute renal failure. Results of several studies using N-acetylcysteine (NAC) for the prevention of RCN have yielded conflicting results. We performed a meta-analysis of group data extracted from previously published studies to assess the effect of NAC on the prevention of RCN in patients with pre-existing chronic kidney disease (CKD).

METHODS

Ovid's multidatabase search for MEDLINE, Cochrane Central Registry of Controlled Trials, Cochrane Database of Systematic Reviews, and HealthSTAR were used to identify candidate articles. Abstracts from proceedings of scientific meetings also were screened. We selected blinded and unblinded randomized controlled trials (RCTs) performed in humans 18 years and older with pre-existing CKD, defined by a mean baseline serum creatinine level of 1.2 mg/dL or greater (> or =106.1 micromol/L) or creatinine clearance less than 70 mL/min (<1.17 mL/s). The overall risk ratio (RR) for the development of RCN was computed using a random-effects model.

RESULTS

Eight RCTs (n = 885 patients) published in full-text articles were included in the primary analysis. In the control group, the overall rate of RCN was 18.5% (95% confidence interval [CI], 15 to 22). In the primary analysis, overall RR for RCN associated with the use of NAC was 0.41 (95% CI, 0.22 to 0.79; P = 0.007). In a sensitivity analysis that included 4 additional RCTs published in abstract form, RR remained significant at 0.55 (95% CI, 0.34 to 0.91; P = 0.020).

CONCLUSION

NAC reduces the risk for RCN in patients with CKD.