Contrast nephropathy : an evidence-based approach to prevention

Alterations of Serum Biochemical and Urinary Parameters in a Canine Population before and after Intravenous Contrast Administration

Intravenous iodinated contrast (IVIC) medium is routinely administered to dogs. Scattered information exists regarding the serum biochemical or urinary profiles associated with the administration of IVIC in dogs. The aim of the study was to describe, compare, and discuss from the perspective of previous studies the alterations in serum biochemical and urinary parameters before (T0) and within one week (T1) of the IVIC administration during routine computed tomography (CT) scan evaluation of 22 dogs. Mature dogs presenting for CT scan evaluation for preoperative oncology staging/surgical planning were included. T1 evaluation was performed within one week of IVIC administration. Statistically significant differences in serum total protein, albumin, chloride, calcium, and phosphorus concentrations, urine protein to creatinine ratio, and urine specific gravity were found between T1 and T0. At T1, the serum creatinine concentration was within reference ranges in all dogs but one. An increase in the urine protein to creatinine ratio was observed in four samples, one of which was non-proteinuric at T0. Changes in biochemistry and urine parameters between T0 and T1 were not considered clinically significant.

MicroRNA as an early diagnostic biomarker for contrast-induced acute kidney injury

Contrast-induced acute kidney injury (CI-AKI) is a common clinical complication and an important cause of increased mortality, prolonged hospitalization, and increased medical costs. For taking effective interventions in CI-AKI, early diagnosis and active prevention are of key importance. Currently, early CI-AKI detection depends on serum creatinine (Scr) levels, which lags behind the actual time of renal injury and seriously affects early diagnosis and interventions. MicroRNA (miRNA) has been found to be a useful biomarker in early CI-AKI diagnosis. Several studies have reported on tissue and time-specific miRNAs in AKI as effective diagnostic biomarkers and potential therapeutic targets, but there are only a few studies on miRNA in CI-AKI. However, these studies are preliminary exploratory investigations on changes in miRNA expression in CI-AKI, and whether these specific miRNAs can be used as biomarkers for early CI-AKI diagnosis and as clinical therapeutic targets requires systematic and in-depth studies. Therefore, more sensitive and specific miRNAs of CI-AKI could be discovered, providing newer options and development directions for early diagnosis and intervention in clinical CI-AKI practice. This review evaluates the research progress on specific miRNAs in the early diagnosis of CI-AKI with an aim of providing basic data for the clinical application of these molecular markers in CI-AKI.

The pleiotropic effects of the hydroxy-methyl-glutaryl-CoA reductase inhibitors in renal disease

It is well known that statins exert their main effect by inhibiting cholesterol synthesis through the inhibition of the 3-hydroxy-3-methyl-glutaryl-CoA reductase enzyme. The pleiotropic effects of statins, which are independent of their inhibition of cholesterol synthesis, have explained many of the beneficial effects of these drugs in a variety of disorders such as malignancies, infection, and sepsis, as well as in cardiovascular and rheumatologic disorders. However, the role of these drugs in renal disorders remains controversial. In the present review, we examine the most recent findings involving statins and renal disease among different clinical scenarios, including chronic kidney disease, contrast-induced nephropathy, renal injury after coronary artery bypass surgery, and renal transplant patients.

Pleiotropic effects of the HMG-CoA reductase inhibitors

The HMG-CoA reductase inhibitors (statins) are used extensively in the treatment of hyperlipidemia. They have also demonstrated a benefit in a variety of other disease processes. These secondary actions are known as pleiotropic effects. Our paper serves as a focused and updated discussion on the pleiotropy of statins and emphasizes the importance of randomized placebo-controlled trials to further elucidate this interesting phenomenon.

Metrically measuring liver biopsy: A chronic hepatitis B and C computer-aided morphologic description

AIM: To describe a quantitative analysis method for liver biopsy sections with a machine that we have named “Dioguardi Histological Metriser” which automatically measures the residual hepatocyte mass (including hepatocytes vacuolization), inflammation, fibrosis and the loss of liver tissue tectonics.

METHODS: We analysed digitized images of liver biopsy sections taken from 398 patients. The analysis with Dioguardi Histological Metriser was validated by comparison with semi-quantitative scoring system.

RESULTS: The method provides: (1) the metrical extension in two-dimensions (the plane) of the residual hepatocellular set, including the area of vacuoles pertinent to abnormal lipid accumulation; (2) the geometric measure of the inflammation basin, which distinguishes intra-basin space and extra-basin dispersed parenchymal leukocytes; (3) the magnitude of collagen islets, (which were considered truncated fractals and classified into three degrees of magnitude); and (4) the tectonic index that quantifies alterations (disorders) in the organization of liver tissue. Dioguardi Histological Metriser machine allows to work at a speed of 0.1 mm²/s, scanning a whole section in 6-8 min.

CONCLUSION: The results are the first standardized metrical evaluation of the geometric properties of the parenchyma, inflammation, fibrosis, and alterations in liver tissue tectonics of the biopsy sections. The present study confirms that biopsies are still valuable, not only for diagnosing chronic hepatitis, but also for quantifying changes in the organization and order of liver tissue structure.

Mortality associated with nephropathy after radiographic contrast exposure

OBJECTIVE

To define outcomes from contrast-induced nephropathy (CIN) after both intra-arterial and intravenous administration of contrast medium.

PATIENTS AND METHODS

We performed a retrospective case-matched cohort study at Mayo Clinic's site in Rochester, MN, from April 1, 2004, to March 31, 2006. All contrast procedures were evaluated for inclusion. Contrast-induced nephropathy was defined as creatinine elevation of 25% or more after contrast exposure or of more than 0.5 mg/dL within 7 days of contrast exposure. Cases of CIN were matched 1:3 with controls by age, sex, pre-procedure creatinine elevation, diabetes mellitus, and type of imaging procedure.

RESULTS

A total of 809 patients who developed CIN were matched to 2427 patients who did not develop CIN after contrast exposure. In multivariate analyses, CIN was significantly associated with 30-day mortality (odds ratio, 3.37; 95% confidence interval [CI], 2.58-4.41; P<.001) and overall mortality (hazard ratio, 1.57; 95% CI, 1.32-1.86; P<.001) after adjustment for heart failure, hypertension, medications, total hydration, iodine load, prior contrast exposure, and all matched variables during the study period. Intravenous contrast administration was a risk factor for 30-day mortality (odds ratio, 2.91; 95% CI, 1.17-7.23; P=.02) and overall mortality (hazard ratio, 3.02; 95% CI, 1.89-4.82; P<.001) compared with intra-arterial administration of contrast after adjustment for heart failure, hypertension, medications, total hydration, iodine load, prior contrast exposure, and all matched variables during the study period.

CONCLUSION

Contrast-induced nephropathy after administration of contrast medium is associated with increased mortality. This risk is higher in patients in whom contrast medium is administered intravenously than in those in whom it is administered intra-arterially.

Sodium bicarbonate is associated with an increased incidence of contrast nephropathy: a retrospective cohort study of 7977 patients at mayo clinic

BACKGROUND AND OBJECTIVES

The role of sodium bicarbonate in preventing contrast nephropathy needs to be evaluated in clinical settings.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a retrospective cohort study at Mayo Clinic in Rochester, Minnesota, to assess the risk of contrast nephropathy associated with the use of sodium bicarbonate, N-acetylcysteine, and the combination of sodium bicarbonate with N-acetylcysteine from April 2004 to May 2005. Contrast nephropathy was defined as postexposure creatinine elevation of > or =25% or >0.5 mg/dl within 7 d of contrast exposure.

RESULTS

A total of 11,516 contrast exposures in 7977 patients had creatinine values available for review before and after contrast exposure. More than 90% of exposures to agents prophylactic for contrast nephropathy were available for analysis. Sodium bicarbonate was used in 268 cases, N-acetylcysteine was used in 616 cases, and both agents were used in combination in 221 cases of contrast exposure. After adjustment for total volume of hydration, medications, age, gender, prior creatinine, contrast iodine load, prior exposure to contrast material, type of imaging study, heart failure, hypertension, renal failure, multiple myeloma, and diabetes mellitus, use of sodium bicarbonate alone was associated with an increased risk of contrast nephropathy compared with no treatment (odds ratio 3.10, 95% confidence interval 2.28 to 4.18; P < 0.001). N-acetylcysteine alone and in combination with sodium bicarbonate was not associated with any significant difference in the incidence of contrast nephropathy.

CONCLUSIONS

The use of intravenous sodium bicarbonate was associated with increased incidence of contrast nephropathy. Use of sodium bicarbonate to prevent contrast nephropathy should be evaluated further rather than adopted into clinical practice.

Determinants of amount of contrast utilized in patients undergoing percutaneous coronary procedures

OBJECTIVE

To determine predictors of contrast amount during coronary angiography and percutaneous coronary intervention.

BACKGROUND

Contrast-induced nephropathy is a leading cause of hospital-acquired acute renal insufficiency. During percutaneous coronary procedures, contrast amount is a major risk factor incriminated in development of contrast-induced nephropathy.

METHODS

Demographic and procedural details were obtained for consecutive patients undergoing percutaneous coronary procedures between January 2002 and October 2005 (N=962, mean+/-standard error of contrast amount: 216.6+/-3.0 ml) at a tertiary care hospital.

RESULTS

A significant difference (P value <0.05) in unadjusted mean contrast volume was observed between subgroups of percutaneous coronary intervention vs. coronary angiography, patients with a history of coronary artery bypass grafting, patients undergoing additional procedures and multivessel and multisite percutaneous coronary interventions. On General Linear Model analysis, independent predictors (beta coefficient, 95% confidence interval, P value) of increased contrast amount during percutaneous coronary procedures were history of coronary artery bypass grafting (44.4, 30.6-58.2, <0.001), type of coronary procedure (85.2, 73.4-97.0, <0.001 for percutaneous coronary intervention vs. coronary angiography), number of interventions and number of additional procedures performed. Among additional procedures, rotablation, intravascular ultrasound and Angiojet were associated with increased contrast use. No significant independent effect on the contrast amount was observed with percutaneous coronary intervention location (right coronary artery vs. left anterior descending artery vs. circumflex artery) site (ostial vs. proximal vs. mid vs. distal) of percutaneous coronary intervention or with interventions on chronic total occlusions on the contrast amount.

CONCLUSION

Data from our study could guide the coronary angiographer in moderating the volume of contrast utilized as well as assist with the elective planning of complex therapeutic procedures.

Emergency room management of patients with blunt major trauma: evaluation of the multislice computed tomography protocol exemplified by an urban trauma center

BACKGROUND

The early clinical management of patients with major trauma still represents a challenge. To clinically evaluate the full extent of a patient's injuries is difficult, especially when the patient is unconscious. Before December 2002, trauma patients admitted to our emergency room (ER) underwent a diagnostic protocol including physical examination, conventional radiography (CR), sonography and further procedures if necessary. After the installation of a MSCT scanner, all trauma patients underwent the "MSCT protocol" immediately after admission. The aim of the study was to compare the "MSCT-protocol" as it is performed at our institution, with the "Pre-MSCT-protocol".

METHODS

We compared 185 patients undergoing the "Pre MSCT-protocol" with 185 patients undergoing "MSCT protocol". We evaluated the efficacy, speed and accuracy of the "MSCT protocol" using several variables. Time periods from admission to the ER to admission to the intensive care unit were compared as well as outcome parameters such as length of ICU stay, ventilation period and rates of organ. Dichotomous data were analyzed by Chi-square analysis; continuous data were analyzed by Student's t test. Any values of p < 0.05 were considered significant for any test.

RESULTS

No significant differences were found regarding demographic data. The full extent of injuries was definitively diagnosed after 12 +/- 9 minutes in 92.4% of the "MSCT protocol" cohort. In only 76.2% of "Pre-MSCT protocol" cohort definitive diagnosis was possible after 41 +/- 27 minutes. Total ER time was 104 +/- 21 minutes with the "Pre-MSCT protocol" and 70 +/- 17 minutes with "MSCT protocol" (p < 0.05). "Pre-MSCT protocol" patients had a significantly longer ICU stay than "MSCT protocol" patients (p < 0.05). "MSCT protocol" patients had significantly fewer ventilation days (14.3 vs. 10.9 days). Furthermore, rates of organ failure were lower in patients undergoing the "MSCT protocol".

CONCLUSION

We could demonstrate that immediate MSCT in patients with blunt major trauma leads to more accurate and faster diagnosis, and reduction of early clinical time intervals. We also observed a reduction in ventilation, ICU, and hospital days, and in organ failure rates, though this might have been partly due to small differences in case mix. The "MSCT protocol" algorithm seems to be safe and effective.

Infrapopliteal Intervention for the Treatment of the Claudicant

As the associated risks of infrainguinal balloon angioplasty and stenting have fallen and the relative success rates have risen in recent years, the threshold for offering endovascular treatment to patients with claudication has significantly decreased. Patients once considered appropriate only for risk-factor modification, exercise therapy, and medical treatment are now increasingly being offered percutaneous revascularization as a primary treatment option. Similarly, occlusive disease of the tibial vessels, once thought to be the exclusive domain of operative bypass, is increasingly being treated percutaneously. Over this same period, results of operative infrainguinal arterial reconstruction have also considerably improved. In modern times, excellent outcomes following bypass grafting with autogenous vein to the tibial level have been demonstrated, with morbidity, mortality, and long-term patency equivalent to that of more proximal bypasses. Evidence supports the view that the anatomic level of the distal anastomosis is less critical to the long-term outcome of the procedure than factors such as operative indication and conduit quality. Within the context of this changing climate, it is an appropriate time to examine and potentially redefine the role of both endovascular and open surgical intervention for a population that has not traditionally been offered revascularization, patients with claudication secondary to infrageniculate occlusive disease.

Assessment of pulmonary thromboendarterectomy by tomographic electrocardiogram-gated equilibrium radionuclide angiocardiography compared with electron beam computed tomography

BACKGROUND

Successful thromboendarterectomy for chronic thromboembolic pulmonary hypertension promptly improves right ventricular (RV) function by decreasing RV volume and increasing ejection fraction (EF). Single photon emission computed tomography (SPECT) equilibrium radionuclide angiocardiography (ERNA) has been validated as a measure of RV and left ventricular (LV) volume and EF.

METHODS AND RESULTS

Nine patients with chronic thromboembolic pulmonary hypertension underwent electron beam computed tomography (EBCT) and SPECT ERNA cardiac studies before and after thromboendarterectomy. EBCT and SPECT ERNA measures of RV and LV volume and EF were compared. Before thromboendarterectomy, EBCT and SPECT ERNA RV and LV volumes and RV EF were similar. LV EF was within the normal range with both methods but was slightly greater (P = .004) when measured by EBCT (mean +/- SD, 0.61 +/- 0.08) compared with SPECT ERNA (0.54 +/- 0.10). Thromboendarterectomy measured by EBCT and SPECT ERNA produced marked similar and significant decreases in RV end-systolic (-72 +/- 59 mL vs -58 +/- 25 mL) and end-diastolic (-75 +/- 85 mL vs -76 +/- 32 mL) volumes and similar slight increases in RV EF (0.12 +/- 0.07 vs 0.05 +/- 0.06). Slight decreases in mean LV end-systolic (-19 +/- 23 mL vs -5 +/- 13 mL, P = .05) and end-diastolic (-32 +/- 53 mL vs -9 +/- 31 mL, P = .21) volumes occurred, with little change in mean LV EF (0.05 +/- 0.07 vs 0.00 +/- 0.10).

CONCLUSIONS

SPECT ERNA is an accurate method for measuring RV and LV volume and EF before and after thromboendarterectomy.

Thoracoabdominal-Aortoiliac MDCT Angiography Using Reduced Dose of Contrast Material

OBJECTIVE

The objective of our study was to compare the image quality of MDCT angiography studies obtained by injection of low doses of contrast medium with saline flush versus conventional doses of contrast medium.

MATERIALS AND METHODS

Seventy-one patients with pre- or postoperative aortic aneurysms underwent MDCT angiography throughout the thoracoabdominal-aortoiliac system using an 8-MDCT scanner. In 37 patients, 100 mL of contrast medium was injected at a flow rate of 3.0 mL/s (hereafter referred to as the 100-mL group). In 34 patients, 50 mL of contrast medium followed by a 20-mL saline flush was injected at a flow rate of 2.5 mL/s (the 50-mL group). For each group, quantitative analysis involved calculating the mean aortoiliac enhancement, plateau deviation, and contrast enhancement in the pulmonary trunk and superior vena cava (SVC). Qualitative analysis involved assessing the 3D postprocessing images.

RESULTS

Significant differences between the groups in mean aortoiliac enhancement (100-mL group vs 50-mL group, 337 +/- 6 H vs 319 +/- 5 H, p < 0.0001) and mean plateau deviation (51 +/- 4 H vs 58 +/- 4 H, p < 0.0001) were found. However, adequate arterial enhancement (>or= 200 H) was observed in 31 of 34 patients in the 50-mL group and uniform aortoiliac enhancement (< 50 H) was seen in 26 patients. Visual analysis showed no difference in contrast material magnitude and homogeneity between the groups. Furthermore, in the 50-mL group, the thoracic aorta was more clearly visualized because of a reduction in the opacity of the main pulmonary artery and SVC.

CONCLUSION

In our experience, administration of 50 mL of contrast medium followed by a 20-mL saline flush produces thoracoabdominal-aortoiliac MDCT angiographic examinations of effective quality in most cases.

Anästhesiologisches Management bei neuroendovaskulären Eingriffen

The endovascular treatment of diseases of intracranial and spinal vessels has become widely accepted in recent years. The patient is usually treated under general anesthesia and in choosing an appropriate anesthesia regimen and an optimized pre-interventional preparation, the anesthesiologist can influence the postinterventional result. The working environment in the angiography suite should address the requirements of a routine procedure and the necessities of complication management. Application of short-acting narcotics and relaxation of the patient if required, facilitate the intervention for both the neuroradiologist and the anesthesiologist. The patient should be supplied with everything needed before the intervention to avoid any waste of time in the case of an emergency (e.g., haemorrhage or fibrinolytic treatment). After the procedure the patient has to be monitored for at least 24 h. Peri-interventional and postinterventional complications, such as thrombo-embolism or hemorrhage, must be managed aggressively and consequently by the anesthesist to improve the postinterventional outcome. Therefore a close collaboration between the anesthesiologist and the neuroradiologist is essential.

Risk and benefit of intravenous contrast in trauma patients with an elevated serum creatinine

OBJECTIVE

Assess if the benefits outweigh the risks of intravenous (iv) contrast in trauma patients who present with an elevated serum creatinine (Cr).

BACKGROUND

Radiologic investigations with iv contrast are often used in trauma patients to rapidly assess for life threatening injuries. However, contrast nephropathy (CNP) is associated with increased morbidity and mortality. This poses a dilemma for the physician who must weigh the risks and benefits of proceeding with iv contrast versus the risks of missed injuries/delayed diagnosis.

METHODS

A 2 year (2002-2003) retrospective chart review of all trauma patients presenting with an elevated Cr(> or =1.3 mg/dL or > or =115 micromol/L). Results are mean +/- sd (p < 0.05 significant).

RESULTS

Ninety-five patients (age 51 +/- 23 years; ISS 31.7 +/- 15.6; hospital stay 29 +/- 32 days; mortality 9%) presented with a Cr > or = 1.3 mg/dL (31 with Cr > or =1.7; 3 dialysis dependent). Fifty-six (59%) were given iv contrast (C+), of which only 2 (3%) had a transient rise of 25% in Cr within 48 hours versus 6 (16%) patients not exposed to contrast (C-). No C+ patient developed CNP requiring longterm dialysis. Of the 56 undergoing C+ tests, 16 had injuries requiring urgent intervention identified; 16 had injuries that were managed nonoperatively, and 24 had serious injuries ruled out. Of the 39 C- patients, 9 had indeterminate CT's; 2 had missed injuries; and 2 had no intraabdominal injuries found at celiotomy.

CONCLUSION

This study suggests the benefits may outweight the risks for proceeding prn with iv contrast in trauma patients with an elevated creatinine. A larger study is needed to confirm these findings.

Risk factors for and economic implications of prolonged ventilation after cardiac surgery

OBJECTIVE

The study's objective was to identify predictors of prolonged ventilation and assess clinical and cost implications in patients undergoing cardiac surgery.

METHODS

Patients undergoing cardiac surgery were classified as (1) ventilated less than 96 hours or (2) ventilated 96 hours or more. Multivariate modeling was used to identify predictors of prolonged ventilation and to ascertain the impact of prolonged ventilation on in-hospital mortality and bed occupancy costs and 5-year survival.

RESULTS

A total of 7553 patients were studied; 197 (2.6%) had prolonged ventilation. Median ventilation times were 8 and 192 hours, and in-hospital mortality was 1.0% and 22.2% in the control and prolonged ventilation groups, respectively (P < .001). In-hospital mortality remained higher in the prolonged ventilation group after adjustment and when comparing propensity-matched patients (odds ratio 8.06; 95% confidence interval [CI] 4.27-15.2; P < .001 for propensity-matched groups). Independent predictors of prolonged ventilation were as follows: older age, New York Heart Association class, ejection fraction less than 50%, creatinine greater than 200 micromol/L, multiple valve replacements, aortic procedures, operative priority, reoperation for bleeding, inotropes, and preoperative intra-aortic balloon pump. Five-year survival was lower in the prolonged ventilation group (56.1% [95% CI 46.6%-64.6%] vs 88.8% [95% CI 87.9%-89.6%]) also after adjustment for imbalances and when comparing propensity-matched patients (hazard ratio 2.39; 95% CI 1.75-3.27; P < .001 for propensity-matched groups). Mean bed occupancy costs were 14,286 dollars (95% CI 12,731 dollars-15,690 dollars) and 2761 dollars (95% CI 2705 dollars-2814 dollars) in the prolonged ventilation and control groups, respectively (P < .001).

CONCLUSION

Prolonged ventilation is associated with high in-hospital mortality and costs, and poor 5-year survival. Identified predictors of prolonged ventilation might help to optimize the clinical management of these patients.

N-acetylcysteine for prevention of radiographic contrast material-induced nephropathy: is the intravenous route best?

Use of oral N-acetylcysteine for preventing radiographic contrast material-induced nephropathy (RCIN) has become widespread, despite conflicting results from clinical trials and meta-analyses. The variability in study results may reflect differences in baseline risks in study patients, hydration regimens, choice of contrast agent, definition of RCIN, and the oral dosage formulation of N-acetylcysteine used. Injectable N-acetylcysteine recently has become available in the United States. Although oral N-acetylcysteine regimens are typically administered during a 48-hour period, more rapid intravenous administration could offer an important advantage for urgent procedures such as coronary angiography. However, the three published studies in which intravenous N-acetylcysteine protocols were used have produced divergent results, likely because of substantially different dosage regimens. With few intravenous studies available, clinicians may look to more broadly studied oral regimens to estimate equivalent intravenous dosages. In the oral studies, however, a wide range of formulations were used, and the bioavailability of each product was uncertain. In addition, the intravenous route circumvents first-pass metabolism, resulting in less glutathione production, perhaps compromising the antioxidant effects of N-acetylcysteine administration. Overall, little evidence exists that any studied N-acetylcysteine protocol improves clinical outcomes in terms of reducing length of hospital stay, need for dialysis, or mortality. Furthermore, N-acetylcysteine may directly affect serum creatinine level, which all clinical trials to date have used as a primary outcome measure. If oral or intravenous N-acetylcysteine is used with the intention of preventing RCIN, more established preventive measures should not be overlooked, including adequate hydration with isotonic saline, avoidance of potentially nephrotoxic drugs, and use of iso-osmolar radiographic contrast media.