Prevention of radiographic-contrast-agent-induced reductions in renal function by acetylcysteine

Prevention of contrast-induced acute kidney injury after percutaneous coronary intervention for chronic total coronary occlusions

Chronic total occlusions (CTOs) represent a major challenge in percutaneous coronary revascularization. The recent advances in strategies and techniques and the development of dedicated equipment, such as microcatheters and wires, have resulted in considerably higher success rates. Although successful CTO recanalization is associated with significant clinical benefits, including improvement of angina, quality of life, reduced need for surgical revascularization, and improvement of left ventricular function, CTO procedures may require prolonged x-ray exposure and use of larger volumes of contrast compared with non-CTO procedures. Large volumes of contrast medium have been associated with increased rates of contrast-induced acute kidney injury (CI-AKI) and adverse short- and long-term outcomes. Application of specific measures and algorithms should be considered by all CTO operators to prevent CI-AKI.

Periprocedural effects of statins on the incidence of contrast-induced acute kidney injury: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The reports on the efficacy of statins for the prevention of contrast-induced acute kidney injury (CIAKI) remain controversial. The objective of this meta-analysis was to assess the effect of statins for the prevention of CIAKI.

METHODS

Comprehensive literature searches for randomized controlled trials (RCTs) of periprocedural statin treatment for prevention of CIAKI were performed using MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials Systematic Reviews and clinicaltrials.gov from inception until May 2014. The primary outcome was the incidence of CIAKI.

RESULTS

Thirteen prospective RCTs were included in our analysis. Of 5803 patients with contrast exposures, 304 patients (5.2%) had CIAKI. Patients in the statin group had an overall lower incidence of CIAKI (3.6%) compared to the control group (6.9%). Intravenous (IV) fluid hydration was used in both groups of all included studies for prevention of CIAKI. There was a significant protective effect of periprocedural statins on the incidence of CIAKI when compared to the control group [risk ratios (RRs): 0.49; 95% CI: 0.37-0.66, I(2) of 25%].

CONCLUSIONS

Our study demonstrates a statistically significant protective effect of statin treatment during procedures with contrast exposures. This finding suggests the use of statins in addition to standard IV crystalloid hydration may be beneficial in the prevention of CIAKI.

Incidence and Risk Factors for Colistin-Associated Nephrotoxicity

Polymyxins have recently reemerged as a treatment option in response to the increasing number of resistant bacterial infections seen in recent years. Therefore, the current study aimed to determine the rate of and risk factors related to colistin-associated nephrotoxicity. All adult patients who had received colistimethate sodium (CMS) between 2010 and 2012 and met the inclusion criteria were included in the study. RIFLE (Risk, Injury, Failure, Loss of renal function and End stage of renal disease) criteria were used to evaluate nephrotoxicity. Age, sex, underlying diseases presences, daily and total CMS doses, daily blood urea and creatinine levels, as well as concurrent drug use were recorded for each patient. Nephrotoxicity occurred in 48% of patients. There was a significant difference in the baseline serum urea levels of patients who experienced nephrotoxicity and those who did not (P value (P) = 0.015). Furthermore, the multivariate analysis showed that advanced age and concomitant aminoglycoside-class antibiotic use were significantly associated with nephrotoxicity. In conclusion, colistin should be used carefully, and all patients should be monitored closely for renal nephrotoxicity.

Oral hydration for prevention of contrast-induced acute kidney injury in elective radiological procedures: a systematic review and meta-analysis of randomized controlled trials

Background:

The reports on efficacy of oral hydration treatment for the prevention of contrast-induced acute kidney injury (CIAKI) in elective radiological procedures and cardiac catheterization remain controversial.

Aims:

The objective of this meta-analysis was to assess the use of oral hydration regimen for prevention of CIAKI.

Materials and Methods:

Comprehensive literature searches for randomized controlled trials (RCTs) of outpatient oral hydration treatment was performed using MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials Systematic Reviews, and clinicaltrials.gov from inception until July 4^th, 2014. Primary outcome was the incidence of CIAKI.

Results:

Six prospective RCTs were included in our analysis. Of 513patients undergoing elective procedures with contrast exposures,45 patients (8.8%) had CIAKI. Of 241 patients with oral hydration regimen, 23 (9.5%) developed CIAKI. Of 272 patients with intravenous (IV) fluid regimen, 22 (8.1%) had CIAKI. Study populations in all included studies had relatively normal kidney function to chronic kidney disease (CKD) stage 3. There was no significant increased risk of CIAKI in oral fluid regimen group compared toIV fluid regimen group (RR = 0.94, 95% confidence interval, CI = 0.38-2.31).

Conclusions:

According to our analysis,there is no evidence that oral fluid regimen is associated with more risk of CIAKI in patients undergoing elective procedures with contrast exposures compared to IV fluid regimen. This finding suggests that the oral fluid regimen might be considered as a possible outpatient treatment option for CIAKI prevention in patients with normal to moderately reduced kidney function.

Anesthesia for ambulatory diagnostic and therapeutic radiology procedures

The radiology suite presents the anesthesia provider with a unique set of challenges such as ionizing radiation, intravascular contrast, magnetic fields, physical separation and barriers from the patient, so-called borrowed space, and the large range of procedures performed. Most of these procedures will continue to be performed without the presence of an anesthesia team but, because of the ever-increasing complexity of the procedures being performed and the increasing comorbidities of patients, the anesthesia provider will likely be called more often to provide care. A thorough understanding of these challenges is essential to providing a safe anesthetic in a difficult environment.

Drug-induced impairment of renal function

Pharmaceutical agents provide diagnostic and therapeutic utility that are central to patient care. However, all agents also carry adverse drug effect profiles. While most of these are clinically insignificant, some drugs may cause unacceptable toxicity that impacts negatively on patient morbidity and mortality. Recognizing adverse effects is important for administering appropriate drug doses, instituting preventive strategies, and withdrawing the offending agent due to toxicity. In the present article, we will review those drugs that are associated with impaired renal function. By focusing on pharmaceutical agents that are currently in clinical practice, we will provide an overview of nephrotoxic drugs that a treating physician is most likely to encounter. In doing so, we will summarize risk factors for nephrotoxicity, describe clinical manifestations, and address preventive and treatment strategies.

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.

[Iodinated contrast agents used in Radiology]

Iodinated contrast media are widely used in Radiology practices with a very low rate of adverse effects, being contrast-induced nephropathy the most serious one. In the majority of cases it is temporary and reversible, even though it can increase the inhospital morbidity and mortality in patients with risk factors. We will describe the various measures of prevention, being hydration and use of non-ionic contrast low osmolality those which have demonstrated greater effectiveness. Precautions to be taken in some risk situations, as patients treated with metformin or with impaired renal function, are also discussed.

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.

A retrospective study of short- and long-term effects on renal function after acute renal infarction

PURPOSE

Acute renal infarction is often missed or diagnosed late due to its rarity and non-specific clinical manifestations. This study analyzed the clinical and laboratory findings of patients diagnosed with renal infarction to determine whether it affects short- or long-term renal prognosis.

METHODS

We retrospectively reviewed the medical records of 100 patients diagnosed as acute renal infarction from January 1995 to September 2012 at Gyeongsang National University Hospital, Jinju, South Korea.

RESULTS

Acute kidney injury (AKI) occurred in 30 patients. Infarct size was positively correlated with the occurrence of AKI (p = 0.004). Compared with non-AKI patients, AKI occurrence was significantly correlated with degree of proteinuria (p < 0.001) and the presence of microscopic hematuria (p = 0.035). AKI patients had higher levels of aspartate transaminase (p < 0.001), alanine transaminase (p < 0.001), and lactated dehydrogenase (p = 0.027). AKI after acute renal infarction was more common in patients with chronic renal failure (CRF) (eGFR < 60 mL/min), compared with non-CRF patients, whose baseline eGFR was >60 mL/min (p = 0.003). Most patients recovered from AKI, except for seven patients (7%) who developed persistent renal impairment (chronic kidney disease progression) closely correlated with magnitude of infarct size (p = 0.015). Six AKI patients died due to combined comorbidity.

CONCLUSIONS

AKI is often associated with acute renal infarction. Although most AKI recovers spontaneously, renal impairment following acute renal infarction can persist. Thus, early diagnosis and intervention are needed to preserve renal function.

Mitochondria-targeted therapies for acute kidney injury

Acute kidney injury (AKI) is a serious clinical condition with no effective treatment. Tubular cells are key targets in AKI. Tubular cells and, specifically, proximal tubular cells are extremely rich in mitochondria and mitochondrial changes had long been known to be a feature of AKI. However, only recent advances in understanding the molecules involved in mitochondria biogenesis and dynamics and the availability of mitochondria-targeted drugs has allowed the exploration of the specific role of mitochondria in AKI. We now review the morphological and functional mitochondrial changes during AKI, as well as changes in the expression of mitochondrial genes and proteins. Finally, we summarise the current status of novel therapeutic strategies specifically targeting mitochondria such as mitochondrial permeability transition pore (MPTP) opening inhibitors (cyclosporine A (CsA)), quinone analogues (MitoQ, SkQ1 and SkQR1), superoxide dismutase (SOD) mimetics (Mito-CP), Szeto-Schiller (SS) peptides (Bendavia) and mitochondrial division inhibitors (mdivi-1). MitoQ, SkQ1, SkQR1, Mito-CP, Bendavia and mdivi-1 have improved the course of diverse experimental models of AKI. Evidence for a beneficial effect of CsA on human cardiac ischaemia-reperfusion injury derives from a clinical trial; however, CsA is nephrotoxic. MitoQ and Bendavia have been shown to be safe for humans. Ongoing clinical trials are testing the efficacy of Bendavia in AKI prevention following renal artery percutaneous transluminal angioplasty.

Relation of contrast-induced nephropathy to long-term mortality after percutaneous coronary intervention

There is little information on the effect of contrast-induced nephropathy (CIN) on long-term mortality after percutaneous coronary intervention in patients with or without chronic kidney disease (CKD). Of 4,371 patients who had paired serum creatinine (SCr) measurements before and after percutaneous coronary intervention and were discharged alive in the Coronary REvascularization Demonstrating Outcome Study in Kyoto registry, the incidence of CIN (an increase in SCr of ≥0.5 mg/dl from the baseline) was 5% in our study cohort. The rate of CIN in patients with CKD was 11%, although it was 2% without CKD (p <0.0001). During a median follow-up of 42.3 months after discharge, 374 patients (8.6%) died. After adjustment for prespecified confounders, CIN was significantly correlated with long-term mortality in the entire cohort (hazard ratio [HR] 2.26, 95% confidence interval [CI] 1.62 to 2.29, p <0.0001) and in patients with CKD (HR 2.62, 95% CI 1.91 to 3.57, p <0.0001) but not in patients without CKD (HR 1.23, 95% CI 0.47 to 2.62, p = 0.6). Sensitivity analyses confirmed these results using the criteria defined as elevations of the SCr by ≥25% and 0.3 mg/dl from the baseline, respectively. In conclusion, CIN was significantly correlated with long-term mortality in patients with CKD but not in those without CKD.

Preventing amikacin related ototoxicity with N-acetylcysteine in patients undergoing peritoneal dialysis

Amikacin is a frequently used antibiotic in the treatment of peritoneal dialysis (PD)-related peritonitis. Ototoxicity is a well-known complication of amikacin for which increased oxidative stress and free oxygen radicals are thought to be responsible. In this study, the effect of N-acetyl-cysteine (NAC) on cochlear function and oxidant situation in the amikacin related ototoxicity in PD-related peritonitis patients are investigated. Forty-six patients who had their first PD-related peritonitis attacks receiving empirical amikacin treatment were enrolled in the study. The patients were randomized into two groups; the first group (n = 23) as NAC receiving and the second group (n = 23) as a placebo receiving, control group. Otoacoustic emissions were measured before, 1 week after and 4 weeks after the treatment. Oxidative stress measurements were performed concurrently in order to evaluate the effectiveness of NAC. The results of screening with otoacoustic emission testing after amikacin treatment showed that cochlear function is protected especially in higher frequencies in NAC group when compared with the control group. Evaluation of the antioxidant status of the two groups showed no differences in the basal values, but at the first week there was an increase in the NAC group compared with the control group, and this increase became significant at the fourth week. NAC is found to be safe and effective in amikacin-related ototoxicity in patients with PD-related peritonitis. We suggest a close monitoring of the patients receiving amikacin containing treatment protocols and if amikacin is administrated supplementing the treatment with NAC.

The immunological benefit of higher dose N-acetyl cysteine following mechanical ventilation in critically ill patients

BACKGROUND

Sepsis complication is a major cause of death in multiple trauma critically ill patients. Defensin (cysteine rich anti-microbial peptides), as an important component of immune system, might play an important role in this process. There is also rising data on immunological effects of N-acetyl-cysteine (NAC), a commonly used anti-oxidant in oxidative stress conditions and glutathione (GSH) deficiencies. The aim of the present study was to evaluate the potential beneficial effects of NAC administration on multiple trauma patients with sepsis.

METHODS

In a prospective, randomized controlled study, 44 multiple trauma critically ill patients who were mechanically ventilated and met the criteria of sepsis and admitted to the intensive care unit (ICU) were randomized into two groups . Control group received all standard ICU therapies and NAC group received intravenous NAC 3 gr every 6 hours for 72 hours in addition to standard therapies. Acute Physiology and Chronic Health Evaluation II (APACHE II) and Sequential Organ Failure Assessment (SOFA) scores, length of ICU stay, ICU mortality were recorded. Levels of serum Immunoglobulin M (IgM), Human β-Defensin 2 (HβD2) and GSH were assessed at baseline and 24, 72, 120 hours after intervention.

RESULTS

During a period of 13-month screening, 44 patients underwent randomization but 5 patients had to be excluded. 21 patients in NAC group and 18 patients in control group completed the study. For both groups the length of ICU stay, SOFA score and systemic oxygenation were similar. Mortality rate (40% vs. 22% respectively, p = 0.209) and ventilator days (Mean ± SD 19.82 ± 19.55 days vs. 13.82 ± 11.89 days respectively, p = 0.266) were slightly higher for NAC group. IgM and GSH levels were similar between two groups (p = 0.325, 0.125 respectively), HβD2 levels were higher for NAC group (at day 3).

CONCLUSION

High dose of NAC administration not only did not improve patients' outcome, but also raised the risk of inflammation and was associated with increased serum creatinine.

A Practical Approach to Preventing Renal Complications in the Catheterization Laboratory

Kidney injury following cardiac catheterization is an infrequent, though persistent, complication, which in some cases may be preventable. Patients at increased risk for renal complications following catheterization can be identified through individual and procedural risk factors, and several risk-prediction models are readily available. The authors advocate for the development of an easily implemented and standardized protocol, readily accessible to catheterization laboratory staff, for the identification and treatment of those patients who may be at increased risk for renal complications following cardiac catheterization.

Pharmacologic Prophylaxis for Contrast-Induced Acute Kidney Injury

In the effort to prevent contrast-induced acute kidney injury (CI-AKI), several pharmacologic agents have been tested for their single or combined nephroprotective properties. To date, however, no drug has been officially approved for this aim. This article focuses on the three agents that have been most extensively studied: statins, N-acetylcysteine, and ascorbic acid. Particular attention is paid to the impact of these drugs on the CI-AKI prevention and improved prognosis.

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.

Therapeutic approaches to diabetic nephropathy--beyond the RAS

Despite improvements in glycaemic and blood pressure control, and the efficacy of renin-angiotensin system (RAS) blockade for proteinuria reduction, diabetic nephropathy is the most frequent cause of end-stage renal disease in developed countries. This finding is consistent with the hypothesis that key pathogenetic mechanisms leading to progression of renal disease are not modified or inactivated by current therapeutic approaches. Although extensive research has elucidated molecular signalling mechanisms that are involved in progression of diabetic kidney disease, a number of high-profile clinical trials of potentially nephroprotective agents have failed, highlighting an insufficient understanding of pathogenic pathways. These include trials of paricalcitol in early diabetic kidney disease and bardoxolone methyl in advanced-stage disease. Various strategies based on encouraging data from preclinical studies that showed renoprotective effects of receptor antagonists, neutralizing antibodies, kinase inhibitors, small compounds and peptide-based technologies are currently been tested in randomized controlled trials. Phase II clinical trials are investigating approaches targeting inflammation, fibrosis and signalling pathways. However, only one trial that aims to provide evidence for marketing approval of a potentially renoprotective drug (atrasentan) is underway-further research into the potential nephroprotective effects of novel glucose-lowering agents is required.

Prediction of contrast-induced nephropathy in patients with serum creatinine levels in the upper normal range by cystatin C: a prospective study in 374 patients

OBJECTIVE

Preexisting renal impairment is a risk factor for contrast-induced nephropathy (CIN). In patients with creatinine in the upper normal level, cystatin C might be a more sensitive predictor of CIN than creatinine. Therefore, in this study, we investigated the usefulness of cystatin C to predict CIN.

SUBJECTS AND METHODS

In 400 consecutive patients with creatinine baseline levels between 0.8 and 1.3 mg/dL undergoing coronary angiography (n = 200) or CT (n = 200), baseline values of cystatin C, creatinine, blood urea nitrogen (BUN) and risk factors of CIN were determined. Creatinine was also assessed 24 and 48 hours after contrast administration.

RESULTS

Creatinine significantly (p < 0.001) increased after 24 hours and 48 hours compared with baseline (1.06 ± 0.28 and 1.07 ± 0.28 vs 0.99 ± 0.18 mg/dL). Fifty-three of 373 evaluable patients (14.2%) had an increase in creatinine of ≥ 25% or ≥ 0.5 mg/dL within 48 hours. CIN according to this definition was significantly more frequent after intraarterial contrast administration (38/190, 20%) compared with IV contrast administration (15/183, 8.2%; p = 0.001). CIN was predicted by baseline cystatin C (area under the receiver operating characteristic [ROC] curve [AUC], 0.715; p < 0.001), whereas creatinine, creatinine clearance, and BUN were not predictive. The best predictive capabilities were provided by cystatin C/creatinine-ratio (AUC, 0.826; p < 0.001). Multivariate regression analysis showed that intraarterial contrast administration (p = 0.002) and higher baseline cystatin C (p < 0.001) combined with low creatinine (p = 0.044) were independently associated with higher increases in creatinine within 48 hours after contrast administration.

CONCLUSION

CIN in patients with creatinine within the upper normal range is significantly more frequent after intraarterial than after IV contrast administration. In these patients, renal impairment after contrast administration is independently predicted by cystatin C and cystatin C/creatinine-ratio, whereas BUN and creatinine were not predictive.

Intravenous acetylcysteine for indications other than acetaminophen overdose

PURPOSE

The use of intravenous acetylcysteine for off-label indications, specifically non-acetaminophen-induced acute liver failure (NAI-ALF), severe alcoholic hepatitis, and contrast-induced nephropathy (CIN), is reviewed.

SUMMARY

I.V. acetylcysteine is most often used as an antidote for acetaminophen overdose due to its ability to increase levels of glutathione; however, it is also used to treat NAI-ALF and severe alcoholic hepatitis and to prevent CIN. Although the i.v. and oral formulations of acetylcysteine have been evaluated for these indications, most studies have examined the i.v. form. I.V. acetylcysteine is used in the treatment of NAI-ALF to improve oxygenation to the liver. One large randomized trial of 173 adults with NAI-ALF from any etiology and of any grade encephalopathy demonstrated overall improvement in transplant-free survival, particularly for patients with low-grade encephalopathy, though overall survival was not improved. When used to treat severe alcoholic hepatitis, i.v. acetylcysteine serves as an antioxidant and glutathione source. A trial of 174 patients with severe alcoholic hepatitis revealed that patients had 28-day survival benefit when treated with acetylcysteine; improvement in patients with hepatorenal syndrome was also noted. When used for the prevention of CIN, i.v. acetylcysteine provides antioxidants and vasodilation. The benefit for this indication is limited to surrogate markers such as serum creatinine and in patients with multiple risk factors for the development of CIN.

CONCLUSION

Data regarding the use of i.v. acetylcysteine for the treatment of NAI-ALF and severe alcoholic hepatitis and in the prevention of CIN are inconclusive, though some evidence supports its use in certain populations.

Carfilzomib-related acute kidney injury may be prevented by N-acetyl-L-cysteine

Carfilzomib is a second-generation epoxyketone proteasome inhibitor that is approved for treatment of relapsed and refractory multiple myeloma. Phase 2 trials have reported that 25% of treated patients have renal adverse effects. Pre-renal/vasoconstriction-related insult from this chemotherapy agent has been documented. We describe a case of a 78-year-old man with refractory multiple myeloma with acute kidney injury associated with carfilzomib treatment. We show that use of N-acetyl-l-cysteine in our patient partially mitigated the renal injury upon re-challenge. This case report hypothesizes that acute renal injury from carfilzomib is caused by vasoconstriction of the renal vessels, which may be prevented by N-acetyl-l-cysteine.

Prophylaxis of contrast-induced nephrotoxicity

Contrast-induced nephrotoxicity (CIN) is a form of acute kidney injury that follows intravascular contrast media exposure. CIN may be preventable because its risk factors are well established and the timing of renal insult is commonly known in advance. However, contrast-induced nephrotoxicity is still the third leading cause of iatrogenic renal failure. This important complication accounts up to 10% of acute renal failure cases in hospitalized patients and it is associated with increased short- and long-term morbidity and mortality. Prolonged hospitalization follows and overall increases healthcare resource utilization. This paper will discuss the various prophylactic procedures tested in clinical trials.

Contrast-induced nephropathy; A literature review

CONTEXT

Contrast-induced nephropathy (CIN) is a common cause of acute kidney dysfunction.

EVIDENCE ACQUISITIONS

Directory of Open Access Journals, Google Scholar, PubMed, EBSCO and Web of Science have been searched.

RESULTS

It is necessary to identify at risk patients at early stages to implement preventive strategies to decrease the incidence of this nephropathy. However, mechanisms of CIN have not fully explained yet. It seems that mechanisms which mediated by nitric oxide and prostaglandin-induced vasodilatation have been played a crucial role in the CIN. Hemodynamic changes of renal blood flow, which causes hypoxia in the renal medulla and direct toxic effects of contrast media on renal cells, are thought to contribute to the pathogenesis of CIN. Contrast media is normally divided into iso-osmolar, low-osmolar, and high-osmolar. N-acetylcysteine is considered as one of the best choices to prevent CIN in high-risk groups.

CONCLUSIONS

The first aim to prevent CIN is identifying high-risk subjects and controlling associate risk factors. As significant differences existed between contrasts agents due to their physicochemical properties, low-osmolar or iso-osmolar contrast media should be used to prevent CIN in at-risk patients. The volume of contrast media should be as low as possible.

Molecular mechanisms of renal cellular nephrotoxicity due to radiocontrast media

Modern iodinated radiocontrast media are all based on the triiodinated benzene ring with various chemical modifications having been made over the last few decades in order to reduce their toxicity. However, CIN remains a problem especially in patients with pre-existing renal failure. In vitro studies have demonstrated that all RCM are cytotoxic. RCM administration in vivo may lead to a decrease in renal medullary oxygenation leading to the generation of reactive oxygen species that may cause harmful effects to renal tissue. In addition, endothelin and adenosine release and decreased nitric oxide levels may worsen the hypoxic milieu. In vitro cell culture studies together with sparse in vivo rat model data have shown that important cell signalling pathways are affected by RCM. In particular, the prosurvival and proproliferative kinases Akt and ERK1/2 have been shown to be dephosphorylated (deactivated), whilst proinflammatory/cell death molecules such as the p38 and JNK kinases and the transcription factor NF- κ B may be activated by RCM, accompanied by activation of apoptotic mediators such as caspases. Increasing our knowledge of the mechanisms of RCM action may help to develop future therapies for CIN.

Pharmacological strategies to prevent contrast-induced acute kidney injury

Contrast-induced acute kidney injury (CI-AKI) is the most common iatrogenic cause of acute kidney injury after intravenous contrast media administration. In general, the incidence of CI-AKI is low in patients with normal renal function. However, the rate is remarkably elevated in patients with preexisting chronic kidney disease, diabetes mellitus, old age, high volume of contrast agent, congestive heart failure, hypotension, anemia, use of nephrotoxic drug, and volume depletion. Consequently, CI-AKI particularly in high risk patients contributes to extended hospitalizations and increases long-term morbidity and mortality. The pathogenesis of CI-AKI involves at least three mechanisms; contrast agents induce renal vasoconstriction, increase of oxygen free radicals through oxidative stress, and direct tubular toxicity. Several strategies to prevent CI-AKI have been evaluated in experimental studies and clinical trials. At present, intravascular volume expansion with either isotonic saline or sodium bicarbonate solutions has provided more consistent positive results and was recommended in the prevention of CI-AKI. However, the proportion of patients with risk still develops CI-AKI. This review critically evaluated the current evidence for pharmacological strategies to prevent CI-AKI in patients with a risk of developing CI-AKI.

Canadian Association of Radiologists consensus guidelines for the prevention of contrast-induced nephropathy: update 2012

PURPOSE

Contrast-induced acute kidney injury or contrast-induced nephropathy (CIN) is a significant complication of intravascular contrast medium (CM). These guidelines are intended as a practical approach to risk stratification and prevention. The major risk factor that predicts CIN is pre-existing chronic kidney disease.

METHODS

Members of the committee represent radiologists and nephrologists across Canada. The previous guidelines were reviewed, and an in-depth up-to-date literature review was carried out.

RESULTS

A serum creatinine level (SCr) should be obtained, and an estimated glomerular filtration rate (eGFR) should be calculated within 6 months in the outpatient who is stable and within 1 week for inpatients and patients who are not stable. Patients with an eGFR of ≥ 60 mL/min have an extremely low risk of CIN. The risk of CIN after intra-arterial CM administration appears be at least twice that after intravenous administration. Fluid volume loading remains the single most important measure, and hydration regimens that use sodium bicarbonate or normal saline solution should be considered for all patients with GFR < 60 mL/min who receive intra-arterial contrast and when GFR < 45 mL/min in patients who receive intravenous contrast. Patients are most at risk for CIN when eGFR < 30 mL/min. Additional preventative measures include the following: avoid dehydration, avoid CM when appropriate, minimize CM volume and frequency, avoid high osmolar CM, and discontinue nephrotoxic medications 48 hours before administration of CM.

Contrast-induced nephropathy in percutaneous coronary interventions: pathogenesis, risk factors, outcome, prevention and treatment

Contrast-induced nephropathy (CIN) is a well-known adverse event of therapeutic and diagnostic procedures requiring the administration of contrast medium (CM). The lack of a universal CIN definition and glomerular filtration rate markers that vary have resulted in a variety of reported incidences. The development of CIN is associated with an increase in the length of hospital stay and the risk of death. Preexisting renal dysfunction, age, diabetes, congestive heart failure and the volume of CM administered are all associated with a risk for developing CIN. The literature suggests the use of low-osmolarity CM and supports volume supplementation before administration. Moreover, other strategies to avoid CIN, including treatment with N-acetylcysteine and sodium bicarbonate have variable levels of evidence. This review examines the main components of the pathogenesis and risk factors of CIN and possible preventive measures and therapies.

The incidence of contrast-induced nephropathy (CIN) following transarterial chemoembolisation (TACE) in patients with hepatocellular carcinoma (HCC)

PURPOSE

The purpose of this retrospective study was to investigate the incidence of contrast-induced nephropathy (CIN) caused by transarterial chemoembolisation (TACE) in patients with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

One hundred forty-one patients treated between 2005 and 2008 undergoing 305 consecutive sessions of TACE were enrolled. CIN was defined as an increase in the serum creatinine level of more than 0.5 mg/dl or more than 25 % from baseline within 3 days after TACE without any other identifiable cause of acute kidney injury.

RESULTS

CIN by the present definition was observed after 2.6 % of the TACE sessions. No patient showed clinical signs or symptoms of acute renal failure, or required haemodialysis. None of the patients with an estimated glomerular filtration rate of <60 ml/min/1.73 m(2) developed CIN.

CONCLUSION

The present study suggests that TACE is a relatively safe procedure in terms of the risk of CIN under vigorous periprocedural hydration and that the incidence of CIN is comparable to that of AKI associated with intravenous CM administration.

KEY POINTS

• CIN would be lower for non-coronary arterial intervention than for coronary intervention. • The present study suggests that the CIN rates following TACE are low. • The incidence of CIN is comparable to that after intravenous CM administration.

Pre-procedural bioimpedance vectorial analysis of fluid status and prediction of contrast-induced acute kidney injury

OBJECTIVES

The aim of this study was to evaluate the relationship between pre-procedural fluid status assessed by bioimpedance vector analysis (BIVA) and development of contrast-induced acute kidney injury (CI-AKI).

BACKGROUND

Accurate fluid management in patients undergoing angiographic procedures is of critical importance in limiting the risk of CI-AKI. Therefore, establishing peri-procedural fluid volume related to increased risk of CI-AKI development is essential.

METHODS

We evaluated the fluid status by BIVA of 900 consecutive patients with stable coronary artery disease (CAD) immediately before coronary angiography, measuring the resistance/height (R/H) ratio and impedance/height (Z/H) vector. CI-AKI was defined as an increase in serum creatinine ≥0.5 mg/dl above baseline within 3 days after contrast administration (iodixanol).

RESULTS

CI-AKI occurred in 54 patients (6.0%). Pre-procedural R/H ratios were significantly higher in patients with CI-AKI than without CI-AKI (395 ± 71 Ohm/m vs. 352 ± 58 Ohm/m, p = 0.001 for women; 303 ± 59 Ohm/m vs. 279 ± 45 Ohm/m, p = 0.009 for men), indicating lower fluid volume in the patients with CI-AKI. When patients were stratified according to R/H ratio, there was an almost 3-fold higher risk in patients with higher values (odds ratio [OR]: 2.9; 95% confidence interval [CI]: 1.5 to 5.5; p = 0.002). The optimal receiver-operating characteristic curve analysis threshold values of R/H ratio for predicting CI-AKI were 380 Ohm/m for women and 315 Ohm/m for men. R/H ratio above these thresholds was found to be a significant and independent predictor of CI-AKI (OR: 3.1; 95% CI: 1.8 to 5.5; p = 0.001).

CONCLUSIONS

Lower fluid status evaluated by BIVA immediately before contrast medium administration resulted in a significant and independent predictor of CI-AKI in patients with stable CAD. This simple noninvasive analysis should be tested in guiding tailored volume repletion.

Contrast media induced nephropathy: a literature review of the available evidence and recommendations for practice

BACKGROUND

Contrast media induced nephropathy (CIN) is a sudden compromise of renal function 24-48 h after administering contrast medium during a CT scan or angiography. CIN accounts for 10% of hospital acquired renal failure and is ranked the third cause of acquiring this condition. Identifying patients at risk through proper screening can reduce the occurrence of this condition.

PURPOSE

This review paper aims to critique current evidence, provide a better understanding of CIN, inform nursing practice and make recommendations for bedside nurses and future research.

METHOD

An integrative review of the literature was made using the key terms: "contrast media", "nephritis", "nephropathy", "contrast media induced nephropathy scores", "acute kidney failure", "acute renal failure" and "acute kidney injury". MeSH key terms used in some databases were: "prevention and control", "acute kidney failure" and "treatment". Databases searched included Medline, CINAHL and Academic Search Complete, and references of relevant articles were also assessed. The search included all articles between the years 2000 and 2013.

RESULTS

Sixty-seven articles were obtained as a result of the search, including RCTs, systematic reviews, and retrospective studies.

CONCLUSION

Contrast media induced nephropathy is an iatrogenic complication occurring secondary to diagnostic or therapeutic procedures. At times it is unavoidable but a systematic method of risk assessment should be adopted to identify high risk patients for tailored and targeted approaches to management interventions.

CLINICAL IMPLICATIONS

As the use of contrast media is increasing for diagnostic purposes, it is important that nurses be aware of the risk factors for CIN, identify and monitor high risk patients to prevent deterioration in renal function when possible.

Automatic mapping extraction from multiecho T2-star weighted magnetic resonance images for improving morphological evaluations in human brain

Mapping extraction is useful in medical image analysis. Similarity coefficient mapping (SCM) replaced signal response to time course in tissue similarity mapping with signal response to TE changes in multiecho T2-star weighted magnetic resonance imaging without contrast agent. Since different tissues are with different sensitivities to reference signals, a new algorithm is proposed by adding a sensitivity index to SCM. It generates two mappings. One measures relative signal strength (SSM) and the other depicts fluctuation magnitude (FMM). Meanwhile, the new method is adaptive to generate a proper reference signal by maximizing the sum of contrast index (CI) from SSM and FMM without manual delineation. Based on four groups of images from multiecho T2-star weighted magnetic resonance imaging, the capacity of SSM and FMM in enhancing image contrast and morphological evaluation is validated. Average contrast improvement index (CII) of SSM is 1.57, 1.38, 1.34, and 1.41. Average CII of FMM is 2.42, 2.30, 2.24, and 2.35. Visual analysis of regions of interest demonstrates that SSM and FMM show better morphological structures than original images, T2-star mapping and SCM. These extracted mappings can be further applied in information fusion, signal investigation, and tissue segmentation.

Role of reactive oxygen species in pathogenesis of radiocontrast-induced nephropathy

In vitro and in vivo studies have demonstrated enhanced hypoxia and formation of reactive oxygen species (ROS) in the kidney following the administration of iodinated contrast media, which play a relevant role in the development of contrast media-induced nephropathy. Many studies indeed support this possibility, suggesting a protective effect of ROS scavenging or reduced ROS formation with the administration of N-acetylcysteine and bicarbonate infusion, respectively. Furthermore, most risk factors, predisposing to contrast-induced nephropathy, are prone to enhanced renal parenchymal hypoxia and ROS formation. In this review, the association of renal hypoxia and ROS-mediated injury is outlined. Generated during contrast-induced renal parenchymal hypoxia, ROS may exert direct tubular and vascular endothelial injury and might further intensify renal parenchymal hypoxia by virtue of endothelial dysfunction and dysregulation of tubular transport. Preventive strategies conceivably should include inhibition of ROS generation or ROS scavenging.

Role of renal biomarkers as predictors of acute kidney injury in cardiac surgery

Cardiac surgery is unique in using cardiopulmonary bypass in various clinical scenarios. Injury of vital organs is unavoidable in the perioperative period. Acute kidney injury is a consequence of the systemic inflammatory response after bypass, emboli, ischemia, and low cardiac output states, reportedly occurring in 30%–40% of open heart surgeries. Acute kidney injury is associated with increased morbidity, mortality, and cost. Many preventive measures (off-pump procedures, decreased crossclamp time, pulsatile flow, adequate hydration) are taken in the perioperative period to avoid organ injury, but in vain. Traditionally, blood urea, serum creatinine, and creatinine clearance rate were applied for prediction of acute kidney injury. The recent emergence of biomarkers such as neutrophil gelatinase-associated lipocalin, cystatin C, liver-type fatty acid binding protein, interleukin-18, kidney injury molecule-1, and tetrahydrobiopterin have helped in detecting acute kidney injury long before the rise of serum creatinine. These biomarkers can also be used as tools for predicting therapeutic effects in acute kidney injury and for monitoring drug toxicity. This review consolidates the knowledge of biomarkers and their application in acute kidney injury management.

Radiographic contrast-media-induced acute kidney injury: pathophysiology and prophylactic strategies

Contrast-induced acute kidney injury (CI-AKI) is one of the most widely discussed and debated topics in cardiovascular medicine. With increasing number of contrast-media- (CM-) enhanced imaging studies being performed and growing octogenarian population with significant comorbidities, incidence of CI-AKI remains high. In this review, pathophysiology of CI-AKI, its relationship with different types of CM, role of serum and urinary biomarkers for diagnosing CI-AKI, and various prophylactic strategies used for nephroprotection against CI-AKI are discussed in detail.