Contrast-associated Acute Kidney Injury

Biomarkers in Contrast-Induced Acute Kidney Injury: Towards A New Perspective

Contrast-Induced Acute Kidney Injury (CI-AKI) remains a frequent iatrogenic condition since radiological procedures using intra-vascular iodinated contrast media (CM) are being widely administered for diagnostic and therapeutic purposes. Despite the improvement of the medical healthcare system worldwide, CI-AKI is still associated with direct short-term and indirect long-term outcomes including increased morbidity and mortality, especially in patients with underlying pre-existing renal function impairment, cardiovascular disease, or diabetes that could rapidly progress into Chronic Kidney Disease. Although the RIFLE (Risk, Injury, Failure, Loss, End-Stage Kidney Disease), AKIN (Acute Kidney Injury Network), and KDIGO (Kidney Disease Improving Global Outcomes) clinical criteria and recommendation guidelines are based on traditional "gold standard" biomarkers known as serum creatinine, glomerular filtration rate, and urinary output, new reliable serum and urinary biomarkers are still needed for an effective unified diagnostic strategy for AKI. Starting from previous and recent publications on the benefits and limitations of validated biomarkers responding to kidney injury, glomerular filtration, and inflammation among others, this review unravels the role of new emerging biomarkers used alone or in combination as reliable tools for early diagnosis and prognosis of CI-AKI, taking into account patients and procedures-risk factors towards a new clinical perspective.

The Relationship between Rate and Volume of Intravenous Fluid Administration and Kidney Outcomes after Angiography

BACKGROUND AND OBJECTIVES

Contrast-associated AKI may result in higher morbidity and mortality. Intravenous fluid administration remains the mainstay for prevention. There is a lack of consensus on the optimal administration strategy. We studied the association of periprocedure fluid administration with contrast-associated AKI, defined as an increase in serum creatinine of at least 25% or 0.5 mg/dl from baseline at 3-5 days after angiography, and 90-day need for dialysis, death, or a 50% increase in serum creatinine.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a secondary analysis of 4671 PRESERVE participants who underwent angiographic procedures. Although fluid type was randomized, strategy of administration was at the discretion of the clinician. We divided the study cohort into quartiles by total fluid volume. We performed multivariable logistic regression, adjusting for clinically important covariates. We tested for the interaction between fluid volume and duration of fluid administration, categorized as <6 or ≥6 hours.

RESULTS

The mean (SD) age was 70 (8) years, 94% of participants were male, and median (interquartile range) eGFR was 60 (41-60) ml/min per 1.73 m2. The range of fluid administered was 89-882 ml in quartile 1 and 1258-2790 ml in quartile 4. Compared with the highest quartile (quartile 4) of fluid volume, we found a significantly higher risk of the primary outcome in quartile 1 (adjusted odds ratio, 1.58; 95% confidence interval, 1.06 to 2.38) but not in quartiles 2 and 3 compared with quartile 4. There was no difference in the incidence of contrast-associated AKI across the quartiles. The interaction between volume and duration was not significant for any of the outcomes.

CONCLUSIONS

We found that administration of a total volume of 1000 ml, starting at least 1 hour before contrast injection and continuing postcontrast for a total of 6 hours, is associated with a similar risk of adverse outcomes as larger volumes of intravenous fluids administered for periods >6 hours. Mean fluid volumes <964 ml may be associated with a higher risk for the primary outcome, although residual confounding cannot be excluded.

Safety and Efficacy of Hybrid Angiography in Chronic Lower Extremity Ischemia Patients at Risk of Contrast-Induced Acute Kidney Injury

AIM

The aim of the study was to assess the feasibility and safety of hybrid angiography consisting of carbon dioxide (CO₂) angiography supplemented by small doses of iodinated contrast medium (ICM) in the endovascular treatment of chronic limb threatening ischemia (CLTI) patients with pre-existing chronic kidney disease (CKD).

PATIENTS AND METHODS

This prospective study comprised all non-dialysis-dependent CKD patients presenting for endovascular management of CLTI. All endovascular interventions were done using CO₂ as a contrast medium whether alone or supplemented by ICM (hybrid angiography) to treat unilateral arterial steno-occlusive lesions of iliac, femoropopliteal, or BTK arteries. Study outcomes included feasibility of the device, technical success, and freedom from contrast-induced acute kidney injury (CI-AKI), renal replacement therapy, and CO₂ angiography-related complications.

RESULTS

A total of 206 CKD patients underwent endovascular intervention using CO₂ only as a contrast medium (159 patients, 77.2%), or hybrid CO₂-ICM angiography (47 patients, 22.8%). The overall technical success was 95.6%. Patients were followed up for a mean period of 17.9 ± 4.6 months. The mean volumes of CO₂, and ICM consumption were 200.7 ± 95.1 mL, and 11.8 ± 4.4 mL, respectively. The mean procedural, and fluoroscopy times were 95.6 ± 12.5 and 49.5 ± 10.8 minutes, respectively. BTK lesions were significantly associated with the need for hybrid angiography (P = <.0001). The mean pre- and postoperative serum creatinine levels were comparable (P = .08). Two patients (4.3%) showed transient manifestations of CI-AKI, but neither required renal replacement therapy. No statistically significant differences were encountered between the two study groups regarding procedure outcomes.

CONCLUSION

Hybrid CO₂-ICM angiography is safe, feasible, effective, and a fairly simple alternative during endovascular interventions to treat chronic lower extremity ischemia. Using supplemental small volumes of ICM to overcome the suboptimal images generated by CO₂ alone does not jeopardize the renal functions in CKD patients.

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.

Contrast-induced nephropathy: Basic concepts, pathophysiological implications and prevention strategies

Contrast-induced nephropathy (CIN) is reversible acute renal failure observed following administration of iodinated contrast media (CM) during angiographic or other medical procedures such as urography. There are various mechanisms through which CM develop their nephrotoxic effects, including oxidative stress and apoptosis. CIN is a real-life, albeit not very rare, entity. Exact pathophysiology remains obscure and no standard diagnostic criteria apply. The Acute Kidney Injury Network criteria was recently employed but its incidence/clinical significance warrants further clarification based on recent methodological advancements, because most published studies to date were contaminated by bias. The current study is a comprehensive review conducted to provide an overview of the basic concepts of CIN and summarize recent knowledge on its pathophysiology and the evidence supporting potential prevention strategies. CIN is expected to increase morbidity, hospital stay and mortality, while all patients scheduled to receive CM should undergo risk assessment for CIN and high-risk patients may be considered candidates for prevention strategies. The value of using compounds with antioxidant properties other than sodium bicarbonate, remains controversial, warranting further clinical investigation.