Contrast media-induced nephrotoxicity--questions and answers

Risk of Worsening Renal Function Following Repeated Exposures to Contrast Media During Percutaneous Coronary Interventions

Background

Multiple contrast media exposures are common, but their cumulative effect on renal function is unknown. We aimed to investigate the renal consequences of repeated exposures to contrast media with coronary interventions.

Methods and Results

We studied 2942 patients who underwent between 1 and 9 procedures. The primary end point was a persistent creatinine increase of ≥50% above baseline at ≥90 days after the last procedure. The effect of cumulative contrast media dose was assessed using Cox models, with cumulative exposure as a time‐dependent variable, and propensity score matching. The primary end point occurred in 190 patients (6.5%), with 6.1%, 6.8%, and 6.2% of patients with 1, 2 or 3, and ≥4 procedures, respectively (P=0.75). In the multivariable Cox model, baseline renal function, diabetes, anemia, acute coronary syndrome, and heart failure were independent predictors of the primary end point (all P≤0.01), whereas cumulative contrast dose was not (hazard ratio [HR], 1.29 [95% CI, 0.89–1.88] for the fourth contrast quartile [>509 mL] versus first contrast quartile [<233 mL]). Propensity score matching yielded 384 patient pairs with similar characteristics and either 1 or 2 to 9 contrast exposures (median cumulative dose, 160 and 480 mL, respectively). Despite large differences in the cumulative contrast exposure, there were similar rates of the primary end points (7.3% versus 6.3%, respectively; HR, 0.76 [95% CI, 0.44–1.32]).

Conclusions

In patients with multiple exposures to contrast media, worsening of renal function over time is associated with known risk factors for the progression of kidney disease but not with cumulative contrast volume.

The risk of renal function deterioration in abdominal aortic stent graft patients with and without previous kidney function failure - an analysis of risk factors

Purpose

Kidney failure influences the treatment outcomes of abdominal aortic aneurysm (AAA). A prospective study of renal function before and after aortic stent-graft treatment was performed. Special attention was paid to the influence of preoperative kidney function as well as the impact of the radiological follow-up.

Material and methods

A total of 214 endovascularly treated AAA patients were included. In all cases, pre- and postope-rative estimated glomerular filtration rate (eGFR) and serum creatinine were noted. Patients were prospectively followed up for a minimum of two years.

Results

The baseline eGFR was 69.38 ± 16.29 ml/min/1.73 m². Chronic kidney disease at baseline was noted in 29% of patients. In the direct postoperative period, acute kidney injury was identified in 8.4% of cases. Additional endo-vascular procedures within two years of observation were performed in 5.6% of cases, and over the two years of follow-up, in the study group from one to six angio-computed tomographic scans (angio-CT) per patient were performed. The mean eGFR value after the 24-month follow-up was significantly lower than the preoperative value. Among the factors influencing kidney function, an angio-CT during the same hospital stay of the primary stent-graft procedures was identified. The type of stent-graft, contrast volume during the primary procedure, need for reintervention, concomitant disease presence, and statin use did not show statistical significance.

Conclusions

Angio-CT followed by stent-graft implantation over a short time interval (within the same hospitalisation) significantly worsened renal function in the late follow-up and should be avoided in elective AAA cases.

Renin-angiotensin-aldosterone system inhibition decreased contrast-associated acute kidney injury in chronic kidney disease patients

BACKGROUND/PURPOSE

Chronic kidney disease (CKD) is a risk factor for contrast associated acute kidney injury (CA-AKI). The risk of renin-angiotensin-aldosterone system inhibitor (RASi) use in patients with CKD before the administration of contrast is not clear.

METHODS

In this nested case-control study, 8668 patients received contrast computed tomography (CT) from 2013 to 2018 during index administration in a multicenter hospital cohort. The identification of AKI is based on the Kidney Disease: Improving Global Outcomes (KDIGO) serum creatinine criteria within 48 h after contrast medium used.

RESULTS

Finally, 986 patients (age, 63.36 ± 12.22; men, 72.92%) with CKD (estimated glomerular filtration rate (eGFR) = 35.0 ± 19.8 mL/min/1.73 m²) were eligible for analysis. After the index date, RASi users (n = 315) were less likely to develop CA-AKI (13.65% vs 30.4%, p < 0.001), and had a lower hospital mortality (8.25% vs 19.23%, p < 0.001) compared with non-users. The pre-contrast use of RASi decrease the risk of AKI (OR, 0.342, p < 0.001) and hospital mortality (OR, 0.602, p = 0.045). Even a few defined daily doses (DDDs) of RASi treatment, more than 0.02 prior to contrast CT could attenuate CA-AKI. The hospital mortality was higher in RASi non-users if their eGFR value was more than 17.9 mL/min/1.73 m².

CONCLUSION

RASi use in patients with CKD prior to contrast CT has the potential to mitigate the incidence of AKI and hospital mortality. Even a low dose of RASi will noticeably decrease the risk of AKI and will not increase the risk of hyperkalemia.

Contrast Media-Different Types of Contrast Media, Their History, Chemical Properties, and Relative Nephrotoxicity

History of contrast dates back to the 1890s, with the invention of the radiograph. Nephrotoxicity has been a main limitation in ideal contrast media (CM). High-osmolar contrast media no longer are in clinical use due to overwhelming evidence supporting greater nephrotoxicity with these CM compared with current CM. Contrast-induced nephropathy (CIN) remains a common cause of in-hospital acute kidney injury. The choice contrast agent is determined mainly by cost and institution practice. This review focuses on the history, chemical properties, and experimental and clinical studies on the various groups of CM and their role in CIN.

Contrast Induced Acute Kidney Injury and Direct Cytotoxicity of Iodinated Radiocontrast Media on Renal Proximal Tubule Cells

The administration of intravenous iodinated radiocontrast media (RCM) to visualize internal structures during diagnostic procedures has increased exponentially since their first use in 1928. A serious side effect of RCM exposure is contrast-induced acute kidney injury (CI-AKI), which is defined as an abrupt and prolonged decline in renal function occurring 48-72 hours after injection. Multiple attempts have been made to decrease the toxicity of RCM by altering ionic strength and osmolarity, yet there is little evidence to substantiate that a specific RCM is superior in avoiding CI-AKI. RCM-associated kidney dysfunction is largely attributed to alterations in renal hemodynamics, specifically renal vasoconstriction; however, numerous studies indicate direct cytotoxicity as a source of epithelial damage. Exposure of in vitro renal proximal tubule cells to RCM has been shown to affect proximal tubule epithelium in the following manner: 1) changes to cellular morphology in the form of vacuolization; 2) increased production of reactive oxygen species, resulting in oxidative stress; 3) mitochondrial dysfunction, resulting in decreased efficiency of the electron transport chain and ATP production; 4) perturbation of the protein folding capacity of the endoplasmic reticulum (ER) (activating the unfolded protein response and inducing ER stress); and 5) decreased activity of cell survival kinases. The present review focuses on the direct cytotoxicity of RCM on proximal tubule cells in the absence of in vivo complications, such as alterations in renal hemodynamics or cytokine influence.

Iodixanol versus iopromide in patients with renal insufficiency undergoing coronary angiography with or without PCI

BACKGROUND

The use of contrast agents during coronary angiography can result in contrast-induced nephropathy (CIN), particularly in patients with renal dysfunction. On the contrary, different contrast agents can induce different degree of changes in cardiac function. The objective of our meta-analysis was to compare the clinical safety of iso-osmolar contrast medium iodixanol to low-osmolar contrast medium iopromide in patients with renal insufficiency undergoing coronary angiography with or without percutaneous coronary intervention (PCI).

METHODS

We searched Medline, Embase, Cochrane Library, and reference lists to identify randomized controlled trials that compared iodixanol to iopromide with the incidence of CIN as an endpoint in renal impaired patients undergoing coronary angiography. Outcome measures were the incidence of CIN, absolute peak serum creatinine (Scr) increase from baseline and a composite of cardiovascular adverse events.

RESULTS

A total of 8 trials with 3532 patients were pooled; 1759 patients received iodixanol and 1773 patients received iopromide. There was no significant difference in the incidence of CIN (summary odds ratio [OR] 0.50, 95% confidence interval [CI] 0.19-1.35, P = .17) and peak Scr increase (mean difference -0.01 mg/dL, 95% CI -0.08 to 0.05, P = .69) when iodixanol was compared with iopromide. But iodixanol was associated with a statistically significant reduction in cardiovascular adverse events when compared with iopromide (OR 0.47, 95% CI 0.30-0.73, P = .0009).

CONCLUSIONS

Analysis of pooled data from 8 randomized controlled trials of iodixanol against iopromide in patients with renal insufficiency undergoing coronary angiography with or without PCI showed that iodixanol nonsignificantly reduced the incidence of CIN, but was associated with a significantly reduced risk of cardiovascular adverse events when compared with iopromide.

Safety of Computed Tomographic Angiography in the Evaluation of Patients With Acute Stroke

Background and Purpose—

Noncontrasted head computed tomography (NCHCT) has long been the standard of care for acute stroke imaging. New guidelines recommending advanced vascular imaging to identify eligible patients for endovascular therapy have renewed safety concerns on the use of contrast in the emergent setting without laboratory confirmation of renal function.

Methods—

We compared computed tomographic angiography (CTA) versus NCHCT alone during acute stroke evaluation with focus on renal safety and timeliness of therapy delivery. We reviewed data on all emergency department patients for whom the Acute Stroke Intervention Team was activated between December 2013 and September 2014. Primary outcomes included acute kidney injury and change in serum creatinine from presentation to 24 to 48 hours (Δ serum creatinine [Cr]). We assessed therapy delay using door-to-CT and door-to-needle times.

Results—

Of 289 patients requiring Acute Stroke Intervention Team activation, 157 received CTA and 132 NCHCT only. There was no difference between groups in mean Cr at 24 to 48 hours (1.06 CTA; 1.40 NCHCT; P =0.059), ΔCr (−0.07 CTA, −0.11 NCHCT, P =0.489), or rates of acute kidney injury (5 CTA, 7 NCHCT, P =0.422). There was no significant difference in mean intravenous tissue plasminogen activator treatment times (68.11 minutes CTA, 81.36 minutes NCHCT; P =0.577). In the 157 patients who underwent CTA, 16 (10.2%) vascular anomalies and 55 (35.0%) high-grade stenoses or occlusions were identified.

Conclusions—

CTA acquisition during acute stroke evaluation was safe with regards to renal function and did not delay appropriate therapy delivery. Acute CTA acquisition offers additional clinical value in rapid identification of vascular abnormalities.

Imaging Renal Urea Handling in Rats at Millimeter Resolution using Hyperpolarized Magnetic Resonance Relaxometry

In vivo spin spin relaxation time (T₂) heterogeneity of hyperpolarized [¹³C,¹⁵N₂]urea in the rat kidney was investigated. Selective quenching of the vascular hyperpolarized ¹³C signal with a macromolecular relaxation agent revealed that a long-T₂ component of the [¹³C,¹⁵N₂]urea signal originated from the renal extravascular space, thus allowing the vascular and renal filtrate contrast agent pools of the [¹³C,¹⁵N₂]urea to be distinguished via multi-exponential analysis. The T₂ response to induced diuresis and antidiuresis was performed with two imaging agents: hyperpolarized [¹³C,¹⁵N₂]urea and a control agent hyperpolarized bis-1,1-(hydroxymethyl)-1-¹³C-cyclopropane-²H₈. Large T₂ increases in the inner-medullar and papilla were observed with the former agent and not the latter during antidiuresis. Therefore, [¹³C,¹⁵N₂]urea relaxometry is sensitive to two steps of the renal urea handling process: glomerular filtration and the inner-medullary urea transporter (UT)-A1 and UT-A3 mediated urea concentrating process. Simple motion correction and subspace denoising algorithms are presented to aid in the multi exponential data analysis. Furthermore, a T₂-edited, ultra long echo time sequence was developed for sub-2 mm³ resolution 3D encoding of urea by exploiting relaxation differences in the vascular and filtrate pools.

Contrast agents in diagnostic imaging: Present and future

Specific contrast agents have been developed for x ray examinations (mainly CT), sonography and Magnetic Resonance Imaging. Most of them are extracellular agents which create different enhancement on basis of different vascularization or on basis of different interstitial network in tissues, but some can be targeted to a particular cell line (e.g. hepatocyte). Microbubbles can be used as carrier for therapeutic drugs which can be released in specific targets under sonographic guidance, decreasing systemic toxicity and increasing therapeutic effect. Radiologists have to choose a particular contrast agent knowing its physical and chemical properties and the possibility of adverse reactions and balancing them with the clinical benefits of a more accurate diagnosis. As for any drug, contrast agents can cause adverse events, which are more frequent with Iodine based CA, but also with Gd based CA and even with sonographic contrast agents hypersensitivity reaction can occur.

Nephroprotective potential of carnitine against glycerol and contrast-induced kidney injury in rats through modulation of oxidative stress, proinflammatory cytokines, and apoptosis

OBJECTIVE

Contrast media (CM) are a major cause of nephropathy in high-risk patients. The aim of this study was to examine the effects of carnitine (CAR) in advanced nephrotoxicity due to CM administration in rats with glycerol-induced renal functional disorder.

METHODS

40 rats were divided randomly into five groups (n = 8): (1) healthy group; (2) glycerol only (GLY); (3) glycerol and CM (GLY + CM); (4) glycerol, CM and 200 mg kg(-1) carnitine (CAR200, Carnitene(®); Sigma-tau/Santa Farma, Istanbul, Turkey); and (5) glycerol, CM and 400 mg kg(-1) carnitine (CAR400). Kidney injury was induced with a single-dose, intramuscular injection of 10 ml kg(-1) body weight (b.w.) of GLY. CAR was administered intraperitoneally. CM (8 ml kg(-1) b.w. iohexol, Omnipaque™; Opakim Medical Products, Istanbul, Turkey) was infused via the tail vein to the rats in Groups 3-5.

RESULTS

l-carnitine administration significantly decreased serum creatinine and blood urea nitrogen levels. Superoxide dismutase and glutathione activity increased significantly in the treatment groups compared with the nephrotoxic groups. CAR400 significantly reduced malondialdehyde levels to healthy levels. In the treatment groups, tumour necrosis factor (TNF)-α, transforming growth factor 1β, interleukin 1β and caspase-3 gene expression decreased compared with the nephrotoxic groups. TNF-α and nuclear factor kappa-beta (NF-κB) protein expression increased after CM and CAR administration reduced both TNF-α and NF-κB expressions. Histopathologically, hyaline and haemorrhagic casts and necrosis in proximal tubules increased in the nephrotoxicity groups and decreased in the CAR groups.

CONCLUSION

The results reveal that l-carnitine protects the oxidant/antioxidant balance and decreases proinflammatory cytokines and apoptosis in CM-induced nephrotoxicity in rats with underlying pathology.

ADVANCES IN KNOWLEDGE

Depending on the underlying kidney pathologies, the incidence of CM-induced nephropathy (CIN) increases. Therefore, this is the best model to represent clinically observed CIN.

Evaluation of urine fibrinogen level in a murine model of contrast-induced nephropathy

OBJECTIVE

The mechanisms of contrast-induced nephropathy are not fully understood and sensitive biomarkers of contrast-induced nephropathy are yet to be found. We investigated whether urinary fibrinogen could be a potential biomarker for contrast-induced nephropathy.

METHODS

To create a contrast-induced nephropathy model, mice received a prostaglandin synthesis inhibitor (indomethacin) and a nitric oxide synthase inhibitor (Nω-Nitro-L-arginine methyl ester) intraperitoneally followed by a different dose of iodixanol. In the control group, normal saline was administered. Urinary fibrinogen and serum creatinine were analyzed using enzyme-linked immunosorbent assay. Kidneys were used to quantify fibrinogen using qRT-PCR and Western blot and for histopathological examination.

RESULTS

Histopathological examination demonstrated mild renal injury in the low-dose group, and moderate renal injury in the high-dose group. Urinary fibrinogen levels were significantly increased in an iodixanol dose-dependent manner (control vs. low-dose group, P < 0.05; control vs. high-dose group P < 0.01). Serum creatinine levels were only increased in the high-dose group (P < 0.01 compared to control), but not in the low-dose group. For fibrinogen-gene expression, in the low-dose group, Fgγ increased (qRT-PCR, Western blot, P < 0.05) in the high-dose group, Fgβ and Fgγ decreased (qRT-PCR, P < 0.01; Western blot, P < 0.05), and Fgα increased (qRT-PCR, P < 0.05; Western blot, P < 0.05).

CONCLUSIONS

We propose that urinary fibrinogen could be used as a potential biomarker for early contrast-induced nephropathy diagnosis.

A Retrospective Analysis of Comparison of General Versus Regional Anaesthesia for Endovascular Repair of Abdominal Aortic Aneurysm

OBJECTIVE

The aim of this study is to compare general anaesthesia (GA) versus regional anaesthesia (RA) for endovascular aneurysm repair (EVAR).

METHODS

We analysed the files of 89 patients between August 2010-August 2012 who underwent elective EVAR retrospectively.

RESULTS

We performed RA for 32 patients (36%) and GA for 57 patients (64%). The operations were completed successfully in both groups and did not require conventional surgery. The mean age of the patients was 71.5±7 (range 50-88 years). RA was preferred more than GA in the presence of advanced-stage chronic obstructive pulmonary disease statistically (p=0.032). The usage of vasodilator drug and atropine was found to be higher in the GA group than the RA group in the intraoperative period (p=0.001 and p=0.01, respectively). The intensive care unit (ICU) was necessary for 5 patients in the RA group (16%) and 13 patients for the GA group (23%) postoperatively (p=0.301). The median ICU stay in the RA group was 2 hours and 4.4 hours in the GA group (p=0.114). The median hospital stay was 2.63±1.91 days in the RA group and 2.04±1.16 days in the GA group, with no statistically significant difference between groups (p=0.120). There was no mortality of patients in either group for the peroperative period and the 30-day follow-up period.

CONCLUSION

Our present study suggests that patient characteristics are more important than the anaesthetic method on the outcomes of EVAR.

Can selective inhibitors of cyclic guanosine monophosphate (cGMP)-specific phosphadiesterase type 5 (PDE 5) offer protection against contrast induced nephropathy?

Parenchymal hypoxia within the renal outer medulla plays an important role in the pathogenesis of contrast induced nephropathy (CIN). Nitric oxide (NO) is crucial for medullary oxygenation by enhancing regional blood flow. Augmenting the effect of NO in the renal medulla by the use of selective inhibitors of cyclic guanosine monophosphate (cGMP)-specific phosphadiesterase type 5 (PDE 5) such as sildenafil (Viagra™), vardenafil (Levitra™) or tadalafil (Cialis™) could reduce the severity of the hypoxic insult induced by the contrast medium and reduce the risk of CIN. Prophylactic administration of one of these drugs particularly the long acting one tadalafil before and after the administration of CM could offer a simple and rational approach to reduce the risk of this complication. This hypothesis deserves serious investigation to determine its clinical efficacy.

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.

The role of inflammation in contrast-induced nephropathy

Objective:

Global incidence of contrast-induced nephropathy (CIN) is 2–5%, but a recent Kenyan study highlighted a local incidence of 12–14% without offering an explanation for the higher incidence. This study proposes that inflammatory states confer a higher relative risk for development of CIN. Our objective was to determine the risk of developing CIN given the presence of an inflammatory state in patients in Kenya.

Methods:

Prospective cohort study of patients undergoing a contrast-enhanced CT (CECT) scan in a private university teaching hospital in Kenya and having no known risk factors for CIN. 423 patients were recruited and grouped into those without inflammation (unexposed) having serum C-reactive protein (CRP) levels ≤5 mg dl⁻¹ and those with evidence of inflammation having CRP levels >5 mg dl⁻¹. Serum creatinine (SCr) was measured before the CECT and 48 h following the CECT with CIN diagnosed by an increase of >25% in the SCr from the baseline. Relative risk was determined and multiple logistic regression analysis performed on biophysical variables and contrast volume to assess their effect on development of CIN.

Results:

Patients with high CRP levels had a relative risk of developing CIN of 2.16 compared with those with normal levels of CRP (p = 0.016). No statistically significant association was seen between biophysical variables or volume of contrast and development of CIN.

Conclusion:

Ongoing inflammation doubles the likelihood of development of CIN.

Advances in knowledge:

This study highlights the importance of inflammation as a risk factor in the development of CIN.

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

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

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.

Acute renal injury after thoracic endovascular aortic repair of Stanford type B aortic dissection: incidence, risk factors, and prognosis

BACKGROUND/PURPOSE

Acute kidney injury (AKI) significantly increases the risk of mortality in patients following cardiovascular intervention procedures. This study was carried out to investigate the incidence, predictors, and prognostic implications of AKI after thoracic endovascular aortic repair (TEVAR) of Stanford type B aortic dissection.

METHODS

A total of 156 patients with Stanford type B aortic dissection who underwent TEVAR were retrospectively analyzed between February 1, 2004 and October 31, 2011. Multivariable regression was used to predict risk factors for AKI. Association between baseline characteristics, postoperative AKI, and mortality during follow up was evaluated.

RESULTS

AKI was identified in 48 (30.8%) of 156 patients, with seven (14.5%) patients requiring continuous renal replacement therapy. The in-hospital mortality rate was 0% in patients without AKI and 12.5% in those with AKI (p = 0.001). Univariate analysis identified preoperative chronic kidney disease, acute dissection, complicated dissection, malperfusion complications with comprehensive complications, and postoperative minimum estimated glomerular filtration rate within 48 hours as associated with AKI. Malperfusion complications [odds ratio (OR) = 4.828; 95% confidence interval (CI) = 1.163-20.03] were the only independent predictor of AKI. Patients suffering from AKI had a 14-fold increased risk for 30-day mortality (OR = 14.3; 95% CI = 1.7-118.4; p = 0.014) and a 10-fold increased risk for 1-year mortality (OR = 9.5; 95% CI = 2.02-44.9; p = 0.004).

CONCLUSION

A significant rate of AKI was observed following TEVAR and was associated with an increase in 30-day and 1-year mortality. Malperfusion complications were identified as an independent predictor of AKI.

Exposure to low- vs iso-osmolar contrast agents reduces NADPH-dependent reactive oxygen species generation in a cellular model of renal injury

Contrast-induced nephropathy represents the third cause of hospital-acquired acute renal failure. This study investigated the effects of low- vs iso-osmolar contrast medium (CM) exposure on NADPH-dependent reactive oxygen species (ROS) generation by tubular cells. X-ray attenuation of iohexol, iopamidol, and iodixanol was assessed at equimolar iodine concentrations and their effects on human renal proximal tubular cells (PTCs) were evaluated with equally attenuating solutions of each CM. Cytotoxicity, apoptosis, and necrosis were investigated by trypan blue exclusion, MTT assay, and annexin V/propidium iodide assay, respectively. ROS production was assessed by DCF assay, NADPH oxidase activity by the lucigenin-enhanced chemiluminescence method, and Nox4 expression by immunoblot. Yielding the same X-ray attenuation, CM cytotoxicity was assessed in PTCs at equimolar iodine concentrations. More necrosis was present after incubation with iohexol and iopamidol than after incubation with equal concentrations of iodixanol. Iohexol and iodixanol at low iodine concentrations induced less cytotoxicity than iopamidol. Moreover, both iohexol and iopamidol induced more apoptosis than iodixanol, with a dose-dependent effect. ROS generation was significantly higher with iopamidol and iohexol compared to iodixanol. NADPH oxidase activity and Nox4 protein expression significantly increased after exposure to iopamidol and iohexol, with a dose-dependent effect, compared with iodixanol. CM-induced Nox4 expression and activity depended upon Src activation. In conclusion, at angiographic concentrations, iodixanol induces fewer cytotoxic effects on cultured tubular cells than iohexol and iopamidol along with a lower induction of Nox4-dependent ROS generation. This enzyme may, thus, represent a potential therapeutic target to prevent iodinated CM-related oxidative stress.

Renal safety of iodixanol

Iodinated contrast is a mainstay for diagnostic and interventional procedures performed by cardiologists, radiologists and other specialists. With the emergence of computed tomographic techniques for the evaluation of cardiac disease, malignancies, trauma and a variety of other internal disorders, the use of iodinated contrast is expected to increase dramatically over the next few years. There has been considerable refinement over the past decades from ionic high-osmolar, to nonionic low-osmolar and finally to nonionic iso-osmolar contrast. Iodixanol is the only nonionic iso-osmolar contrast approved for intravascular use. This contrast agent has the lowest rates of systemic and renal adverse events. Clinical trials have demonstrated the lowest rates of contrast-induced nephropathy among all currently available forms of iodinated contrast. Specifically, iodixanol has been associated with a 71% relative risk reduction for contrast-induced nephropathy compared with low-osmolar agents in head-to-head randomized trials. This article reviews the structure, pharmacology and outcomes associated with iodixanol.

Safety of contrast-enhanced ultrasonography in dogs and cats: 488 cases (2002-2011)

OBJECTIVE

To determine the incidence of adverse events within 24 hours after contrast-enhanced ultrasonography (CEUS) in dogs and cats and compare the risk of death within 24 hours after imaging for animals that underwent ultrasonography with and without injection of a contrast agent.

DESIGN

Retrospective case-control study.

ANIMALS

750 animals (411 case dogs, 238 control dogs, 77 case cats, and 24 control cats).

PROCEDURES

At 11 institutions, medical records were reviewed of dogs and cats that had CEUS performed (cases) as were medical records of dogs and cats with clinical signs similar to those of case animals that had ultrasonography performed without injection of a contrast agent (controls). Information regarding signalment; preexisting disease; type, dose, and administration route of contrast agent used; immediate (within 1 hour after CEUS) and delayed (> 1 and ≤ 24 hours after CEUS) adverse events; and occurrence and cause of death (when available) was extracted from each medical record. Risk of death within 24 hours after ultrasonography was compared between case and control animals.

RESULTS

Of the 411 case dogs, 3 had immediate adverse events (vomiting or syncope) and 1 had a delayed adverse event (vomiting). No adverse events were recorded for case cats. Twenty-three of 357 (6.4%) clinically ill case animals and 14 of 262 (5.3%) clinically ill control animals died within 24 hours after ultrasonography; risk of death did not differ between cases and controls.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that CEUS was safe in dogs and cats.

Incidence of contrast-induced nephropathy in hospitalised patients with cancer

OBJECTIVES

To determine the frequency of and possible factors related to contrast-induced nephropathy (CIN) in hospitalised patients with cancer.

METHODS

Ninety adult patients were enrolled. Patients with risk factors for acute renal failure were excluded. Blood samples were examined the day before contrast-enhanced computed tomography (CT) and serially for 3 days thereafter. CIN was defined as an increase in serum creatinine (Cr) of 0.5 mg/dl or more, or elevation of Cr to 25 % over baseline. Relationships between CIN and possible risk factors were investigated.

RESULTS

CIN was detected in 18/90 (20 %) patients. CIN developed in 25.5 % patients who underwent chemotherapy and in 11 % patients who did not (P = 0.1). CIN more frequently developed in patients who had undergone CT within 45 days after the last chemotherapy (P = 0.005); it was also an independent risk factor (P = 0.017). CIN was significantly more after treatment with bevacizumab/irinotecan (P = 0.021) and in patients with hypertension (P = 0.044).

CONCLUSIONS

The incidence of CIN after CT in hospitalised oncological patients was 20 %. CIN developed 4.5-times more frequently in patients with cancer who had undergone recent chemotherapy. Hypertension and the combination of bevacizumab/irinotecan may be additional risk factors for CIN development.

KEY POINTS

• Contrast-induced nephropathy (CIN) is a concern for oncological patients undergoing CT. • CIN occurs more often when CT is performed <45 days after chemotherapy. • Hypertension and treatment with bevacizumab appear to be additional risk factors.

Measures used to treat contrast-induced nephropathy: overview of reviews

OBJECTIVES

Despite many interventions that have been tried, controversy remains regarding the efficacy of interventions for contrast-induced nephropathy (CIN), so we aimed to evaluate the best evidence from recent meta-analyses.

METHODS

We searched MEDLINE, EMBASE and the Cochrane library for interventions which have been used for CIN. We included only the most recent meta-analysis of each intervention. We extracted data on the methodology, quality and results of each meta-analysis. We performed narrative synthesis and adjusted indirect comparison of interventions that were shown to be statistically significant compared with a placebo.

RESULTS

We included 7 systematic reviews and meta-analyses involving 9 different interventions for CIN, with a total of 15 976 participants. A significantly decreased risk of CIN was reported in meta-analysis of the following interventions: N-acetylcysteine [odds ratio (OR) 0.65, 95% confidence interval (CI) 0.48-0.88, I(2)=64%], theophylline [relative risk (RR) 0.48, 95% CI 0.26-0.89, I(2)=44%], statins (RR 0.51, 95% CI 0.34-0.77, I(2)=0%) and sodium bicarbonate (RR 0.62, 95% CI 0.45-0.86, I(2)=49%). Furosemide was shown to increase the risk of CIN (RR 3.27, 95% CI 1.48-7.26, I(2)=0%). Other interventions such as renal replacement therapy, angiotensin-converting enzyme inhibitors, dopamine and fenoldapam failed to show any significant difference from the control group.

CONCLUSION

Although there is some evidence to suggest that N-acetylcysteine, theophylline, sodium bicarbonate and statins may reduce incidence of CIN, limitations in the study quality and heterogeneity preclude any firm recommendations.

ADVANCES IN KNOWLEDGE

N-acetylcysteine, theophylline, sodium bicarbonate and statins show some promise as potentially efficacious agents for preventing CIN, but more high-quality studies are needed before they can be recommended for use in routine practice.

Kidney Injury Biomarkers in Hypertensive, Diabetic, and Nephropathy Rat Models Treated with Contrast Media

Contrast-induced nephropathy (CIN) refers to a decline in renal function following exposure to iodinated contrast media (CM). The present study was initiated to explore the role of known human risk factors (spontaneous hypertension, diabetes, protein-losing nephropathy) on CIN development in rodent models and to determine the effect of CM administration on kidney injury biomarkers in the face of preexisting kidney injury. Spontaneously hypertensive rats (hypertension), streptozotocin-treated Sprague Dawley rats (diabetes), and Dahl salt-sensitive rats (protein-losing nephropathy) were given single intravenous injections of the nonionic, low osmolar contrast medium, iohexol. Blood urea nitrogen (BUN), serum creatinine (sCr), and urinary biomarkers; albumin, lipocalin 2 (Lcn-2), osteopontin (Opn), kidney injury molecule 1 (Kim-1), renal papillary antigen 1 (Rpa-1), α-glutathione S-transferase (α-Gst), µ-glutathione S-transferase (µ-Gst), and beta-2 microglobulin (β2m) were measured in disease models and appropriate controls to determine the response of these biomarkers to CM administration. Each disease model produced elevated biomarkers of kidney injury without CM. Preexisting histopathology was exacerbated by CM but little or no significant increases in biomarkers were observed. When 1.5-fold or greater sCr increases from pre-CM were used to define true positives, receiver–operating characteristic curve analysis of biomarker performance showed sCr was the best predictor of CIN across disease models. β2m, Lcn-2, and BUN were the best predictors of histopathology defined kidney injury.

Prevention of contrast-induced nephropathy: A randomized controlled trial of sodium bicarbonate and N-acetylcysteine

BACKGROUND

Contrast-induced nephropathy (CIN) continues to be a common cause of acute renal failure in high-risk patients undergoing radiocontrast studies. However, there is still a lack of consensus regarding the most effective measures to prevent CIN.

METHODS

ONE HUNDRED EIGHTEEN PATIENTS WITH DIABETES MELLITUS AND/OR RENAL INSUFFICIENCY, SCHEDULED FOR CORONARY ANGIOGRAPHY OR INTERVENTION, WERE RANDOMLY ASSIGNED TO ONE OF FOUR TREATMENT GROUPS: intravenous (IV) 0.9% NaCl alone, IV 0.9% NaCl plus N-acetylcysteine (NAC), IV 0.9% sodium bicarbonate (NaHCO(3)) alone or IV 0.9% NaHCO(3) plus NAC. All patients received IV hydration as a preprocedure bolus and as maintenance. Iso-osmolar contrast was used in all patients. CIN was defined as an increase of greater than 25% in the serum creatinine concentration from baseline to 72 h.

RESULTS

The overall incidence of CIN was 6%. There was no statistically significant difference in the incidence of CIN among the groups. There was a CIN incidence of 7% in the NaCl only group, 5% in the NaCl/NAC group, 11% in the NaHCO(3) only group and 4% in the NaHCO(3)/NAC group (P=0.86). The maximum increase in serum creatinine was 14.14±12.38 μmol/L in the NaHCO(3) group, 10.60±29.14 μmol/L in the NaCl only group, 9.72±13.26 μmol/L in the NaCl/NAC group and 0.177±15.91 μmol/L for the NaHCO(3)/NAC group (P=0.0792).

CONCLUSION

CIN in high-risk patients may be effectively minimized solely through the use of an aggressive hydration protocol and an iso-osmolar contrast agent. The addition of NaHCO(3) and/or NAC did not have an effect on the incidence of CIN.

Effectiveness of theophylline in preventing contrast-induced nephropathy after coronary angiographic procedures

BACKGROUND

Contrast-induced nephropathy (CIN) is the third most common cause of hospital acquired acute renal failure and is associated with increased morbidity and mortality. The use of theophylline for prevention of CIN has yielded conflicting results. This study aimed at examining the effectiveness of theophylline in prevention of CIN when added to IV hydration and N-acetylcysteine (NAC).

METHODS

Patients with stable serum creatinine and at least moderate risk for CIN according to Mehran's risk score were included in this parallel group, 1:1, single-blind, randomized controlled trial. All patients received IV hydration (1 mL/kg per hour for 24 hours) and NAC (600 mg bid for 2 days). Patients were randomized to placebo (group P) or theophylline (200 mg in 100 mL 0.9% saline, as IV infusion 30 minutes before contrast medium (CM) administration; group T). Patients underwent standard coronary angiography ± angioplasty. Serum creatinine (SCr) was assessed just before and 72 hours after contrast administration and estimated glomerular filtration rate (eGFR) was calculated.

RESULTS

This study included 60 patients with mean SCr 1.44 ± 0.7 mg/dL and eGFR 60.2 ± 29.2 mL/min. Mean SCr among group T was 1.54 ± 0.7 mg/dL with eGFR 58.6 ± 28.6 mL/min, while group P showed mean SCr of 1.34 ± 0.7 mg/dL and eGFR of 61.8 ± 30.1 mL/min. Among group P, 6 (20%) patients developed CIN while none of the patients in group T developed CIN. In comparison to placebo, theophylline significantly decreased SCr (P = 0.0001) and increased eGFR (P = 0.001) at 72 hours. Multivariate regression analysis showed that receiving placebo instead of theophylline, anemia, congestive heart failure, chronic renal impairment, and high-contrast load are all independent predictors for deteriorating renal function after CM administration.

CONCLUSION

Theophylline seems to be an effective prophylaxis against CIN for moderate- and high-risk patients undergoing coronary angiography or angioplasty. It offers additive protection when added to IV hydration and NAC.

The effects of the iodinated X-ray contrast media iodixanol, iohexol, iopromide, and ioversol on the rat kidney epithelial cell line NRK 52-E

Nephrotoxicity, associated with the administration of iodinated X-ray contrast media (ICM), continues to be a major side effect in a significant number of vulnerable patients undergoing diagnostic X-ray imaging procedures. The molecular mechanisms underlying these adverse effects on the kidneys are unclear despite several decades of investigation. Side effects are more common after exposure to high-osmolar compared with low-osmolar ICM, suggesting that osmolality may be an important physical-chemical property related to nephrotoxicity. This investigation in cultured NRK 52-E cells, a cell line of renal origin, compares the in vitro toxicity of the iso-osmolal ICM iodixanol with the low-osmolal ICM iohexol, iopromide, and ioversol. The cellular toxicity was evaluated with the trypan blue exclusion assay, the MTT assay, and incidences of cell death. A qualitative assessment of vacuolation of the cultured NRK 52-E cells was taken as a measure of intracellular uptake of ICM. A difference in cell death incidence was observed between the iso-osmolal iodixanol and the low-osmolal iohexol, iopromide, and ioversol contrast media, with the iso-osmolal iodixanol having the least effect in each of the in vitro systems tested. The osmolality of the contrast media appeared to be the major cause for the observed in vitro toxicity.

Defining Incidence and Outcome of Contrast-Induced Nephropathy Among Trauma: Is It Overhyped?

Contrast-induced nephropathy (CIN) in trauma patients is uncommon and the incidence is unknown. We studied the incidence of CIN and its outcome. A retrospective chart review of trauma patients 16 years of age and older who were admitted to our Level I trauma center during 2005 was performed. Patients who received the intravenous contrast CT scan and had their serum creatinine (Cr) monitored at admission and at 48 to 72 hours were identified. CIN was defined as a 0.5-mg/dL rise of serum Cr or a 25 per cent increase from the baseline if the baseline Cr was abnormal. We excluded patients transferred from an outside facility, patients without repeated serum Cr measurements, patients who had cardiac arrest or persistent hypotension, and patients who had received N-acetylcysteine (Mucomyst) before their CT scan. We compared CIN and non-CIN groups. During 2005, 543 fit our study criteria, of whom 19 (3.5%) had CIN. CIN (vs non-CIN) had a higher baseline serum Cr (1.48 + 0.23 vs 1.06 + 0.02, P < 0.001), a longer intensive care unit stay (17 vs 5 days, P < 0.001), and a longer hospital stay (19 vs 8 days, P < 0.001); the mortality rate was not different (10 vs 4%, P = 0.2). We found elevated baseline serum Cr (OR, 1.92; 95% CI, 1.13 to 3.27; P = 0.016) to be associated with increased risk for CIN. All but two serum Cr levels peaked within 48 hours; all returned to baseline. One patient with an underlying congenital kidney disease required temporary dialysis. CIN incidence in trauma is low and the clinical course is benign.

Determination of safe contrast media dosage to estimated glomerular filtration rate ratios to avoid contrast-induced nephropathy after elective percutaneous coronary intervention

Background and Objectives

To avoid the risk of developing contrast-induced nephropathy (CIN), it has been suggested that patients be subjected to a minimal necessary dose of contrast medium (CM-dose). However, often it is not easy to determine such a dose. This study assessed the usefulness of the ratio of CM-dose to estimated glomerular filtration rate (eGFR) in predicting the risks of CIN and sought to determine the safe level of CM-dose/eGFR in patients undergoing non-emergent percutaneous coronary intervention (PCI).

Subjects and Methods

We enrolled a total of 226 patients and calculated the ratio of CM-dose using grams of iodine (g-I) to eGFR, thus expressing it as g-I/eGFR. Among the CIN patients, those with ne-phropathy requiring dialysis (NRD) were also evaluated.

Results

Overall, there were 16 cases (7.1%) of CIN. On univariate and multivariate regression analysis, g-I/eGFR alone was found to be an independent predictor for CIN (hazard ratio=10.73, p<0.001). In an receiver operating characteristic analysis, fair discrimination for CIN was found at a g-I/eGFR level of 1.42 (C statics=0.867), and at this value, the sensitivity and specificity were 81.3% and 80%, respectively. Of patients (n=51) with g-I/eGFR ≥1.42, 23.6% (13/51) and 7.8% (4/51) developed, while those with g-I/eGFR <1.42 (n=171) had a lower incidences of CIN (1.8%, 2/171, p<0.001) and NRD (0%, 0/171, p<0.001).

Conclusion

It can be concluded that a g-I/eGFR <1.42 is a simple, useful indicator for determining the safe CM-dose based on the pre-PCI eGFR values. Furthermore, g-I/eGFR might have a close relationship with the development of NRD as well as CIN.

Contrast-induced acute kidney injury and diabetic nephropathy

Contrast-induced acute kidney injury (CIAKI) is a leading cause of iatrogenic renal failure. Multiple studies have shown that patients with diabetic nephropathy are at high risk of CIAKI. This Review presents an overview of the pathogenesis of CIAKI in patients with diabetic nephropathy and discusses the currently available and potential future strategies for CIAKI prevention.

Effect of contrast-induced nephropathy on cardiac outcomes after use of nonionic isosmolar contrast media during coronary procedure

Contrast-induced nephropathy (CIN) has been increasing and seems to be associated with clinical outcomes in ischemic heart disease. This study aimed to assess the incidence, predictors, and cardiac outcomes of CIN when nonionic isosmolar contrast media (iodixanol, Visipaque(®), GE Healthcare, Cork, Ireland) was used. Between January 2005 and July 2008, 510 patients (69.2 ± 9.0 years of age, 384 men) undergoing diagnostic coronary angiography (CAG) or percutaneous coronary intervention (PCI) were divided into two groups according to the development of CIN (CIN group: n=74; non-CIN group: n=436). CIN developed in 74 patients (14.5%). They were more likely to have diabetes (55.4% vs. 42.9%, p=0.045), decreased left ventricular ejection fraction (LVEF) (50.1 ± 12.6% vs. 57.7 ± 13.9%, p<0.001), and lower baseline hematocrit level (32.4 ± 5.3% vs. 36.6 ± 5.5%, p<0.001). Multiple logistic regression analysis revealed baseline hematocrit (odds ratio 0.900, 95% confidence interval 0.851-0.952, p<0.001), decreased LVEF (odds ratio 0.967, 95% confidence interval 0.949-0.986, p=0.001), and baseline creatinine level (odds ratio 2.317, 95% confidence interval 1.252-4.286, p=0.007) as independent predictors of CIN. At 1-year follow-up, patients with CIN were found to have more adverse outcomes than without CIN in Cox proportional hazards analysis (hazard ratio 13.068, 95% confidence interval 2.425-70.434, p=0.003). CIN was mostly associated with baseline creatinine level rather than CM amount using nonionic isosmolar CM. We found that patients with CIN had worse event-free survival than patients without CIN after multifactorial adjustment.

The effect of cardiac angiography timing, contrast media dose, and preoperative renal function on acute renal failure after coronary artery bypass grafting

OBJECTIVE

Our objective was to assess the effect of the timing of cardiac angiography, contrast media dose, and preoperative renal function on the prevalence of acute renal failure after cardiac surgery.

METHODS

Data on 395 consecutive patients who underwent coronary artery bypass grafting were prospectively collected. Creatinine clearance was estimated by the Cockcroft-Gault equation. Patients were divided into 3 groups according to the time between cardiac angiography and surgery (group A, < or = 1 day; group B, > 1 day and < or = 5 days; group C, > 5 days). Patients who underwent a salvage operation or were receiving dialysis before surgery were excluded. Acute renal failure was defined as 25% decrease from baseline of estimated creatinine clearance and estimated creatinine clearance of 60 mL/min or less on postoperative day 3. Owing to differences in preoperative characteristics between groups, propensity score analysis was used to adjust those differences.

RESULTS

Acute renal failure developed in 13.6% of patients. Hospital mortality was 3.3% and was higher in patients in whom acute renal failure developed (22%) versus those in whom it did not (0.3%; P < .001). Multivariable analysis identified preoperative estimated creatinine clearance of 60 mL/min or less (odds ratio [OR], 7.1), operation within 24 hours of catheterization (OR = 3.7), use of more than 1.4 mL/kg of contrast media (OR = 3.4), lower hemoglobin level (OR = 1.3), older age (OR = 1.1), and lower weight (OR = 0.95) as independent predictors of postoperative acute renal failure. Analysis of interaction between contrast dose and time of surgery revealed that high contrast dose (>1.4 mL/kg) predicted acute renal failure if surgery was performed up to 5 days after angiography.

CONCLUSIONS

Whenever possible, coronary bypass grafting should be delayed for at least 5 days in patients who received a high contrast dose, especially if they also have preoperative reduced renal function.

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

BACKGROUND

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

Impact of the definition utilized on the rate of contrast-induced nephropathy in percutaneous coronary intervention

Several definitions have been used to assess rates of contrast-induced nephropathy (CIN) in patients undergoing percutaneous coronary intervention (PCI). Whether the definition influences observed rates of CIN is unclear. The Oxilan Registry was the first-ever prospective analysis of the efficacy and safety of ioxilan (low-osmolar and low-viscosity contrast medium), including rates of CIN assessed by multiple definitions, in PCI. From July 2006 to June 2007, consecutive patients undergoing PCI using ioxilan were enrolled. Serum creatinine (SCr) and estimated glomerular filtration rate (eGFR) were assessed at baseline and 3 to 5 days after PCI. CIN was defined as SCr increase >or=0.5 mg/dl, eGFR decrease >or=25%, SCr increase >or=25%, or the composite. Of 400 patients (age 62 +/- 11 years), 19% were women, 37% were diabetic, 22% were anemic, and 8% had a history of congestive heart failure. Baseline SCr was 1.12 +/- 0.3 mg/dl and 24% had an eGFR <60 ml/min. CIN rates were 3.3% (SCr increase >or=0.5 mg/dl), 7.6% (eGFR decrease >or=25%), 10.2% (SCr increase >or=25%), and 10.5% (composite). Hospitalization was prolonged in 3.4% of patients with CIN and none required dialysis. There were no deaths or severe allergic reactions. Non-ST-elevation myocardial infarction and repeat revascularization each occurred in 0.8%. In conclusion, in this unselected population undergoing PCI, CIN ranged in frequency from 3.3% to 10.5% depending on the definition used and was not associated with in-hospital mortality or substantial morbidity, such as dialysis. The wide variation in CIN and its lack of association with adverse outcomes underscore the need for a standardized, clinically relevant definition.

In emergency situations, should serum creatinine be checked in all patients before performing second contrast CT examinations within 24 hours?

OBJECTIVE

The aim of this study was to determine the frequency of contrast-induced nephropathy (CIN) in patients undergoing repeat contrast-enhanced computed tomographic (CT) examinations within 24 hours, as well as associated risk factors.

MATERIALS AND METHODS

Through a search of medical and radiologic records, patients who underwent 2 contrast-enhanced CT examinations within 24 hours during a 4-year period (2003-2006), with available serum creatinine measurements before and after CT imaging were included. Medical records were reviewed for demographic data, risk factors, renal status, and CT contrast volume. The frequency of CIN was calculated, and odds ratios of risk factors were determined.

RESULTS

There were 164 patients (90 men, 74 women; mean age, 56.3 years), with an average baseline serum creatinine level of 1.02 +/- 0.73 mg/dL (range, 0.3-6.6 mg/dL). Three hundred twenty-eight CT examinations were performed: 2 in each patient, at an average interval of 11.4 hours. The mean doses of contrast medium used for the first and second CT examinations were 126.2 and 123.4 mL, respectively. Twenty-one patients (12.8%) developed CIN. Comparing patients with and without CIN, the only statistically significant risk factor for CIN was an increase in serum creatinine between the first and second CT examinations, with an odds ratio of 18 (P < .005).

CONCLUSION

The incidence of CIN in patients who underwent repeat contrast-enhanced CT examinations was 12.8%. An increase in serum creatinine between the first and second CT examinations was highly associated with CIN and may serve as a risk factor for developing CIN.

Hemodynamic and serum biochemical alterations associated with intravenous administration of three types of contrast media in anesthetized cats

OBJECTIVE

To determine the incidence and type of alterations in heart rate (HR), peak systolic blood pressure (PSBP), and serum biochemical variables (serum total bilirubin, BUN, and creatinine concentrations) associated with IV administration of ionic-iodinated contrast (IIC), nonionic-iodinated contrast (NIC), and gadolinium (GD) contrast media in anesthetized cats.

ANIMALS

220 anesthetized cats undergoing cross-sectional imaging.

PROCEDURES

HR and PSBP were recorded at 5-minute intervals for 20 minutes for untreated control cats and cats that received IIC, NIC, or GD contrast medium. The development of HR < 100 beats/min or > 200 beats/min that included a > or = 20% change from baseline was considered a response. The development of PSBP of < 90 mm Hg or > 170 mm Hg that included a > or = 20% change from baseline was considered a response. Pre- and postcontrast serum biochemical values were recorded. Results-Of cats receiving IIC medium, 2% (1/60) had a response in HR at > or = 1 time point. Of cats receiving IIC medium, 7% (4/60) had a response in PSBP. None of the cats receiving NIC medium had a response in HR; 2 of 12 had a response in PSBP. Of cats receiving GD contrast medium, 6% (5/83) had a response in HR and 8% (7/83) had a response in PSBP. None of the control cats had a response in HR or PSBP. No serum biochemical alterations were observed.

CONCLUSIONS AND CLINICAL RELEVANCE

IV administration of iodine and GD contrast media in anesthetized cats was associated with changes in HR and PSBP.