[Pathophysiology and prevention of contrast-induced acute renal failure]. / Fisiopatologia e prevenzione della insufficienza renale acuta da mezzo di contrasto.

Although the infusion of iodinated contrast media in diagnostic and interventional procedures may cause acute renal failure (ARF) especially in older or diabetic patients with preexisting nephropathy, these procedures are often unavoidable. Contrast medium-induced ARF is defined as an increase in serum creatinine of 0.5 mg/dL or a 25% or greater relative increase from baseline within 72 hours of iodinated contrast medium infusion. Because it is often very difficult to employ alternative diagnostic procedures, it is mandatory to adopt prophylactic protocols to prevent radiocontrast nephropathy. Renal hemodynamic lesions leading to medullary hypoxia, oxygen free radicals inducing tubular cell alterations, and parenchymal vasoconstriction are the main factors in the pathogenesis of contrast-induced ARF. Among the many proposed protocols to prevent contrast-induced renal toxicity, the most effective procedure is hydration with 1 mL/kg/h of isotonic saline solution in the 12 hours before and after contrast medium infusion. Promising results in terms of cardiac and renal protection have been reported in a recent trial with the use of high-dose N-acetylcysteine acting as an oxygen free radical scavenger: an intravenous bolus of 1200 mg N-acetylcysteine was given before coronary angiography followed by 1200 mg orally twice a day for 48 hours after the procedure. The protective effect seemed to involve not only the kidney: the drug was found to induce a significant reduction of the necrotic area in myocardial infarction.

[Sepsis, acute renal failure and multiple organ dysfunction syndrome]. / Sepsi, insufficienza renale acuta e "multiple organ dysfunction syndrome".

The so-called systemic inflammatory response syndrome (SIRS ) represents the cellular inflammatory and neuroendocrine systemic reaction in response to many adverse events. epsis is defined as IR induced by bacterial, mycotic or viral toxins. The circulating toxins deriving from the bacterial wall can activate the septic cascade that induces many systemic reactions involving the activation of the cellular immunity, complement and coagulation system. The endothelial cell is the target of the systemic phlogistic reaction; its stimulation is followed by the production of many vasoactive paracrine and systemic agents. In this context, local and systemic cytokine production plays a major role in inducing the septic cascade, which although meant to be a phlogistic defense reaction, can often become an uncontrolled and dangerous inflammatory reaction. The sepsis-derived lesions can involve many organs and apparatus leading to the picture of sepsis syndrome. Sepsis syndrome often induces severe pulmonary lesions with a picture of acute respiratory distress syndrome (ARDS ). The combination of acute renal failure and sepsis is associated with a high mortality rate, namely in patients with a nitric oxide-induced systemic reduction in peripheral vascular resistances and septic shock. The toxinemia can also induce myocardial damage with a reduction in cardiac performance. Therefore, septic patients who have a combination of pulmonary, cardio-vascular, renal and cerebral lesions present with the picture of multiple organ dysfunction syndrome, that can increase mor-tality to > 0%.