Nephropathy In High-risk Patients Research Articles

Ascorbic Acid Prevents Contrast-Mediated Nephropathy in Patients With Renal Dysfunction Undergoing Coronary Angiography or Intervention

Contrast agents can cause a reduction in renal function that may be due to the generation of reactive oxygen species. Conflicting evidence suggests that administration of the antioxidant acetylcysteine prevents this renal impairment. The action of other antioxidant agents has not been investigated. We conducted a randomized, double-blind, placebo-controlled trial of ascorbic acid in 231 patients with a serum creatinine concentration > or =1.2 mg/dL who underwent coronary angiography and/or intervention. Ascorbic acid, 3 g at least 2 hours before the procedure and 2 g in the night and the morning after the procedure, or placebo was administered orally. Contrast-mediated nephropathy was defined by an absolute increase of serum creatinine > or =0.5 mg/dL or a relative increase of > or =25% measured 2 to 5 days after the procedure. Contrast-mediated nephropathy occurred in 11 of the 118 patients (9%) in the ascorbic acid group and in 23 of the 113 patients (20%) in the placebo group (odds ratio [OR], 0.38; 95% confidence interval [CI], 0.17 to 0.85; P=0.02). The mean serum creatinine concentration increased significantly in the placebo group (from 1.36+/-0.50 to 1.50+/-0.54 mg/dL, P<0.001) and nonsignificantly in the ascorbic acid group (from 1.46+/-0.52 to 1.52+/-0.64 mg/dL, P=0.07). The mean increase in serum creatinine concentration was greater in the placebo group than in the ascorbic acid group (difference of 0.09 mg/dL; 95% CI, 0.00 to 0.17; P=0.049). Prophylactic oral administration of ascorbic acid may protect against contrast-mediated nephropathy in high-risk patients undergoing a coronary procedure.

Low risk of contrast nephropathy in high-risk patients undergoing spiral computed tomography angiography with the contrast medium iopromide and prophylactic oral hydratation.

Spiral computed tomography angiography (CTA) is a sensitive and specific technique for visualizing renal arteries and diagnosing renal artery stenosis (RAS). Whether spiral CTA is associated with increased risk of contrast nephropathy (CN) in patients with impaired renal function is unknown. We prospectively studied 50 patients with chronic renal insufficiency (serum creatinine concentration greater than 1.58 mg/dl) who underwent spiral CTA with iopromide, a nonionic, low-osmolar contrast agent. Fourteen patients had diabetes mellitus. Patients were encouraged to drink 1 l of water 12 hours before and 2 l over 24 hours after the procedure. The presence of CN was defined by an increase of 20% or more in the baseline serum creatinine level within or 72 hours after administration of the radio-contrast agent. In the entire group, mean serum creatinine levels increased significantly from 2.92 +/- 1.39 to 3.06 +/- 1.55 mg/dl (p = 0.02) and mean creatinine clearance decreased from 29.8 +/- 12.9 to 28.9 +/- 12.8 ml/min (p = 0.009) 72 h after administration of the contrast medium. Two patients experienced an increase in serum creatinine level of 20%. Renal function returned to baseline within seven days in the 2 patients. Absolute changes in creatinine clearance after the administration of radiocontrast medium were similar in nondiabetic and diabetic patients and in the subgroup of patients, with a baseline serum creatinine of < 3 mg/dl and > or = 3 mg/dl. In patients with chronic renal insufficiency, spiral CTA performed with iopromide, a nonionic, low-osmolar contrast medium and a prophylactic oral hydratation, is a minimally invasive technique with low risk of contrast nephropathy.

Diabetes mellitus and hypertension: a mandate for intense treatment according to new guidelines.

Diabetics without a prior myocardial infarction have the same risk of a future myocardial infarction as nondiabetics with a prior myocardial infarction; however, epidemiologic studies suggest that lower blood pressure treatment goals may have potential benefit for diabetics with hypertension. Low-dose diuretics, beta-blockers, angiotensin-converting enzyme inhibitors, and dihydropyridine calcium antagonists have reduced cardiovascular events in patients with diabetes. Angiotensin receptor blockers with diabetic renal disease have reduced the rate of end-stage renal disease, whereas dihydropyridine calcium antagonists show no benefit. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers reduce overall mortality, cardiovascular events, and the development of the overt nephropathy in high-risk patients with diabetes without advanced renal disease. The blood pressure treatment goal for patients with diabetes without macroalbuminuria is less than 130/80 mm Hg and less than 125/75 mm Hg for patients with diabetes and nephrotic syndrome. To achieve these goals, multiple antihypertensive drugs are required.

N-acetylcysteine ameliorates renal microcirculation: Studies in rats

N-acetylcysteine (NAC) administration has been shown to ameliorate experimental acute renal failure induced by ischemia-reflow, and was found to prevent radiocontrast nephropathy in high-risk patients. While the protective effect of NAC has been primarily attributed to scavenging oxygen free radicals, improving renal microcirculation also may play a role in the prevention of acute renal failure. This study was designed to explore the effect of NAC on renal microcirculation. Blood pressure, total renal blood flow and selective regional cortical and outer medullary blood flow were continuously monitored in anesthetized Sprague Dawley rats with ultrasonic and laser-Doppler probes during the infusion of NAC (60 mg/kg). In control intact rats blood pressure and renal microcirculation were unaffected by NAC. By contrast, following renal vasoconstriction induced by the radiocontrast agent iothalamate meglumine, NAC decreased total, cortical and medullary vascular resistance by 7 to 10% (P < 0.05). NAC also reduced renal vascular resistance by 16% when given during angiotensin II infusion (P < 0.05). Altered renal microcirculation, induced by the cyclooxygenase inhibitor indomethacin, by the nitric oxide synthase-inhibitor, Nomeganitro-l-arginine (L-NAME), or with their combination was partially restored by NAC. Nevertheless, NAC administration failed to attenuate renal function and morphology in a rat model of acute renal failure with selective outer medullary hypoxic injury, induced by indomethacin, L-NAME and iothalamate. NAC ameliorates renal vasoconstriction, an effect that seems to be mediated by mechanisms other than prostaglandins and nitric oxide. The potential renoprotective outcome of NAC and the role of its vasodilating effect on the pre-constricted renal vasculature should be evaluated further.

Use of fenoldopam to prevent radiocontrast nephropathy in high-risk patients.

We evaluated the ability of fenoldopam, a newly available renal vasodilator, to prevent radiocontrast nephropathy in high-risk patients undergoing interventional diagnostic and therapeutic angiographic procedures. We reviewed the results from 46 consecutive procedures in patients with serum creatinine > or = 1.5 mg/dL if diabetic and > or = 1.7 mg/dL if nondiabetic. We compared our results to a previously published cohort of similarly at-risk patients. The incidence of radiocontrast nephropathy, defined as an increase in serum creatinine of > or = 25% at 48 hr following the procedure, was 13% in the group treated with fenoldopam, compared to an expected 38%. The percentage change in serum creatinine at 48 hr was +16% vs. +118%, respectively, in the two groups. In this preliminary experience, the use of fenoldopam in high-risk patients appears to minimize the likelihood of radioncontrast nephropathy. Cathet Cardiovasc Intervent 2001;53:341-345.

Spiral computed tomography angiography (CTA): technique for renal artery stenosis not associated with increased risk of contrast nephropathy in patients with renal insufficiency

Spiral CTA is a sensitive and specific technique for visualizing renal arteries and diagnosing renal artery stenosis. One of the disadvantages of this method is the need to administer a large volum of iodine contrast and the theorical risk of nephrotoxicity, specially in high risk patients for contrast nephropathy. Nevertheless, studies analysing the nephrotoxicity of spiral CTA are lacking. This study was designed to test if spiral CTA is associated with increased risk of contrast nephropathy in high-risk patients with renal insufficiency. We prospectively studied 43 patients with chronic renal insufficiency (serum creatinine >140 μmol/l), who were undergoing an spiral CTA for evaluating renal artery stenosis. Twelve patients (28%) had diabetes mellitus and renal failure. A monomeric, nonionic, low-osmolar, Iopromide, 300 mg of iodine per milliliter, (Ultravist 300, Schering, The Netherlands) was administered in all patients. The mean dose of contrast injected was 160 ±10 ml. Serum creatinine was measured immediately before and 24 and 72 hours after administration of the contrast agent. Radiocontrast nephropathy was defined as an increase in serum creatinine of at least 20% over baseline within 24 or 72 hours after administration of the contrast. All patients were encouraged to drink 1 liter of water during the 12 hours before and 2 liters during the 24 hours after the procedure. Mean serum creatinine was 250,5 μmol/l ±110,6 (149-705) before, 255,2 ±114,9 (148-698) 24 hours and 263,0 ±124,3 (141-724) 72 hours after administration of the contrast ( p=0,03). Nevertheless, only two patients (4,6%) experienced an increase of 20% in serum creatinine levels. On 7th day, there was return to baseline creatinine level in the two patients. When patients with diabetes mellitus were analysed separately, the baseline creatinine level was 259,5 ±150,1 μmol/l (164-705), at 24 hours was 279,0 ± 158,8 (148-698), and 283,5 ± 172,1 (164-724) at 72 hours after (p=0,05). Spiral CTA is a minimally invasive procedure without substancial risk of contrast material-induced nephrotoxicity, even in high-risk patients with preexisting renal insufficiency and diabetes mellitus.

N-Acetyl cysteine for prevention of contrast induced nephropathy

The antioxidant N-acetyl Cysteine prevents contrast induced nephropathy in patients with impaired renal function who undergo coronary angiogeaphy. However its role in Bangladeshi population is not clear. This study was done determine whether oral acetylcysteine prevents contrast induced nephropathy in high risk patients.100 patients with mild to moderate renal insufficiency who are undergoing elective coronary angiography with or without intervention.50 patients were randomy assigned to receive oral N acetyl cysteine (600mg) twice daily on the day before and on the day of procedure. All patients received low osmolar contrast agent.10 (20%) control patients (no premedicationgroup) and none of acetyl cysteine (0%) group developed a more than 25% increase in serum creatinine level within 48 hours after contrast exposure. Acetyl cysteine prevents contrast induced nephropathy. Keywords : Anti Oxidant; contrast induced nephropathy. DOI: 10.3329/uhj.v5i2.4554 University Heart Journal Vol.5(2) July 2009 pp.56-58