The role of dialysis in contrast-induced nephropathy: doubts and certainties

Current updates in radiocontrast-associated acute kidney injury

Contrast-associated acute kidney injury (CA-AKI) is an abrupt decline in kidney function occurring after a recent exposure to iodinated radiocontrast media. CA-AKI presents as elevated serum creatinine level or decreased urine output. CA-AKI is the third leading cause of inpatient AKI. The incidence of CA-AKI varies according to patient population characteristics, ranging from 5% in the general population to as high as 30% in special populations with preexisting comorbidities such as diabetes mellitus, cardiovascular disease, and chronic kidney disease. The development of CA-AKI places a heavy toll on patients and the healthcare system secondary to increased patient morbidity, mortality, hospital length of stay, readmission risk, and healthcare cost. Patients undergoing cardiac catheterization are of special interest, since they have higher risk of developing CA-AKI and its associated complications. The recognition, prevention, and management of CA-AKI has improved over the past few years with the introduction of fluid management guidelines, using less nephrotoxic radiocontrast media, and preprocedural CA-AKI risk assessment. Future advancements in patients' CA-AKI risk stratification and early detection will facilitate prompt initiation of mitigation treatment plans and decrease associated complications.

SIRM-SIN-AIOM: appropriateness criteria for evaluation and prevention of renal damage in the patient undergoing contrast medium examinations-consensus statements from Italian College of Radiology (SIRM), Italian College of Nephrology (SIN) and Italian Association of Medical Oncology (AIOM)

The increasing number of examinations and interventional radiological procedures that require the administration of contrast medium (CM) in patients at risk for advanced age and/or comorbidities highlights the problem of CM-induced renal toxicity. A multidisciplinary group consisting of specialists of different disciplines—radiologists, nephrologists and oncologists, members of the respective Italian Scientific Societies—agreed to draw up this position paper, to assist clinicians increasingly facing the challenges posed by CM-related renal dysfunction in their daily clinical practice.

The major risk factor for acute renal failure following CM administration (post-CM AKI) is the preexistence of renal failure, particularly when associated with diabetes, heart failure or cancer.

In accordance with the recent guidelines ESUR, the present document reaffirms the importance of renal risk assessment through the evaluation of the renal function (eGFR) measured on serum creatinine and defines the renal risk cutoff when the eGFR is < 30 ml/min/1.73 m2 for procedures with intravenous (i.v.) or intra-arterial (i.a.) administration of CM with renal contact at the second passage (i.e., after CM dilution with the passage into the pulmonary circulation).

The cutoff of renal risk is considered an eGFR < 45 ml/min/1.73 m2 in patients undergoing i.a. administration with first-pass renal contact (CM injected directly into the renal arteries or in the arterial district upstream of the renal circulation) or in particularly unstable patients such as those admitted to the ICU.

Intravenous hydration using either saline or Na bicarbonate solution before and after CM administration represents the most effective preventive measure in patients at risk of post-CM AKI. In the case of urgency, the infusion of 1.4% sodium bicarbonate pre- and post-CM may be more appropriate than the administration of saline.

In cancer patients undergoing computed tomography, pre- and post-CM hydration should be performed when the eGFR is < 30 ml/min/1.73 m2 and it is also advisable to maintain a 5 to 7 days interval with respect to the administration of cisplatin and to wait 14 days before administering zoledronic acid.

In patients with more severe renal risk (i.e., with eGFR < 20 ml/min/1.73 m2), particularly if undergoing cardiological interventional procedures, the prevention of post-CM AKI should be implemented through an internal protocol shared between the specialists who treat the patient.

In magnetic resonance imaging (MRI) using gadolinium CM, there is a lower risk of AKI than with iodinated CM, particularly if doses < 0.1 mmol/kg body weight are used and in patients with eGFR > 30 ml/min/1.73 m2. Dialysis after MRI is indicated only in patients already undergoing chronic dialysis treatment to reduce the potential risk of systemic nephrogenic fibrosis.

Continuous venovenous hemofiltration after coronary procedures for the prevention of contrast-induced acute kidney injury in patients with severe chronic renal failure

Continuous venovenous hemofiltration (CVVH) is a renal replacement therapy that has been successfully used in patients with severe chronic renal failure to prevent contrast-induced acute kidney injury (CI-AKI). In this study, we present a consecutive experience using a new CVVH protocol that has also been applied to patients with acute coronary syndrome (ACS). CVVH was performed in consecutive patients with estimated glomerular filtration rate <30 ml/min/1.73 m(2) (mean ± SD, 21.1 ± 7.3 ml/min/1.73 m(2)) undergoing diagnostic or interventional coronary procedures starting after the angiographic procedures. Iopamidol was used as a contrast agent. In the first 6 patients, iopamidol removal by the CVVH hemofilter and kidney was calculated by measuring iopamidol concentrations in the blood, urine, and ultrafiltrate collected during the 6-hour CVVH session. In the second phase, the protocol was applied to 47 additional patients meeting the inclusion criteria. Six-hour CVVH resulted in iopamidol removal comparable with that of 12-hour diuresis (43 ± 12% vs 42 ± 15% of administered, p = NS). CI-AKI occurred in 7.5% of patients in the whole population and no patients had acute pulmonary edema, need for dialysis, or any major bleeding. In conclusion, in a population including patients with ACS with severe chronic renal failure undergoing coronary angiographic procedures, 6-hour CVVH performed only after contrast medium exposure was able to remove an amount of contrast medium similar to that removed by the kidneys in 12 hours and resulted in a low rate of CI-AKI.