***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: OBJECTIVES Prophylactic acetylcysteine along with hydration seems to be better than hydration alone in preventing the reduction in renal function induced by a contrast dye . BACKGROUND Contrast media can lead to acute renal failure that may occasionally require hemodialysis . METHODS One hundred eighty-three consecutive patients with impairment of renal function , undergoing coronary and /or peripheral angiography and /or angioplasty , were r and omly assigned to receive 0.45 % saline intravenously and acetylcysteine ( 600 mg orally twice daily ; group A , n = 92 ) or 0.45 % saline intravenously alone ( group B , n = 91 ) before and after nonionic , low-osmolality contrast dye administration . RESULTS The baseline serum creatinine concentrations were similar ( 1.5 + /- 0.4 mg/dl in group A vs. 1.5 + /- 0.4 mg/dl in group B ; p = 0.37 ) . An increase of > or = 25 % in the baseline creatinine level 48 h after the procedure occurred in 6 ( 6.5 % ) of 92 patients in group A and in 10 ( 11 % ) of 91 patients in group B ( p = 0.22 ) . In the subgroup with a low ( < 140 ml ) contrast dose , renal function deterioration occurred in 5 ( 8.5 % ) of 60 patients in group B and in 0 of 60 patients in group A ( p = 0.02 ; odds ratio [ OR ] 0.44 , 95 % confidence interval [ CI ] 0.35 to 0.54 ) . In the subgroup with a high contrast dose , no difference was found ( 5/31 vs. 6/32 patients , p = 0.78 ) . By multivariate analysis , the amount of contrast agent , but not the treatment strategy , was a predictor of the occurrence of contrast dye-associated nephrotoxicity ( OR 2.58 , 95 % CI 1.1 to 4.9 ; p = 0.035 ) . CONCLUSIONS In patients with reduced renal function undergoing angiography and /or angioplasty , the amount of contrast agent , but not the administration of prophylactic acetylcysteine , was a predictor of renal function deterioration .  Prophylactic acetylcysteine might provide better protection than hydration alone , only when a small volume of contrast agent is used The nephroprotective role of N-acetylcysteine ( NAC ) against contrast-induced nephropathy ( CIN ) in patients undergoing peripheral arterial angiography remains unclear . A total of 40 patients undergoing peripheral arterial angiography were r and omized to receive intravenous ( iv ) hydration only ( group 1 ) or oral NAC in addition to iv hydration ( group 2 ; IS RCT N : 35882618 ) . Primary outcome was reduction in the elevation of urinary retinol binding protein ( RBP ) , albumin — creatinine ratio ( ACR ) , and serum creatinine ( serC ) . Groups 1 and 2 had equivocal percentage reduction in RBP and ACR levels from baseline ( P = .80 and .30 ) . A significant reduction in serC was , however , observed with NAC by third postprocedure day ( P = .04 ) . One patient in the treatment arm developed CIN compared with 3 patients in the control group ( P = .33 ) . Equivocal changes in RBP and ACR levels by both treatments seem to indicate that either is equally effective in affording renal protection Purpose To determine the role of prophylactic N-acetylcysteine in the prevention of contrast-induced nephrotoxicity . Methods One hundred and sixteen patients undergoing noncoronary angiography , with or without pre-existing renal impairment , were r and omly assigned to receive prophylactic oral N-acetylcysteine or no treatment .  Serum creatinine ( sCr ) was measured prior to angiography and 48 hr after the procedure . Urine sample s were collected before and after the examination for measurement of malondialdehyde ( MDA ) concentration . Contrast-induced nephrotoxicity ( CIN ) was defined as a rise in serum creatinine of 0.5 mg/dl ( 44 mmol/l ) at 48 hr . Results Complete data were available on 106 patients , 53 of whom had received N-acetylcysteine . There were no significant differences between the two groups in baseline characteristics , type of angiogram , or volume and concentration of contrast used . Three patients ( 2.8 % ) , all of whom had received N-acetylcysteine , developed CIN . In the N-acetylcysteine group , the mean serum creatinine in patients with renal impairment was 151.0 ± 44.2 μmol/l prior to the procedure and 155.6 ± 48.6 μmol/l ( p = 0.49 ) after the procedure . Respective values for those without renal impairment were 79.6 ± 15.1 μmol/l and 81.2 ± 20.0 μmol/l ( p = 0.65 ) . In the group that had not received N-acetylcysteine , the mean serum creatinine levels before and after the procedure were 150.0 ± 58.1 and 141.4 ± 48.0 μmol/l ( p = 0.17 ) in patients with renal impairment and 79.7 ± 14.2 and 81.4 ± 15.4 μmol/l ( p = 0.34 ) in those without renal impairment . In both groups , no significant change in urinary MDA concentration was observed . Conclusion There is no benefit to the prophylactic administration of N-acetylcysteine in patients undergoing peripheral angiography using current contrast media BACKGROUND Radiographic contrast agents can cause a reduction in renal function that may be due to reactive oxygen species . Whether the reduction can be prevented by the administration of antioxidants is unknown . METHODS We prospect ively studied 83 patients with chronic renal insufficiency ( mean [ + /-SD ] serum creatinine concentration , 2.4+/-1.3 mg per deciliter [ 216+/-116 micromol per liter ] ) who were undergoing computed tomography with a nonionic , low-osmolality contrast agent . Patients were r and omly assigned either to receive the antioxidant acetylcysteine ( 600 mg orally twice daily ) and 0.45 percent saline intravenously , before and after administration of the contrast agent , or to receive placebo and saline . RESULTS Ten of the 83 patients ( 12 percent ) had an increase of at least 0.5 mg per deciliter ( 44 micromol per liter ) in the serum creatinine concentration 48 hours after administration of the contrast agent : 1 of the 41 patients in the acetylcysteine group ( 2 percent ) and 9 of the 42 patients in the control group ( 21 percent ; P=0.01 ; relative risk , 0.1 ; 95 percent confidence interval , 0.02 to 0.9 ) . In the acetylcysteine group , the mean serum creatinine concentration decreased significantly ( P<0.001 ) , from 2.5+/-1.3 to 2.1+/-1.3 mg per deciliter ( 220+/-118 to 186+/-112 micromol per liter ) 48 hours after the administration of the contrast medium , whereas in the control group , the mean serum creatinine concentration increased nonsignificantly ( P=0.18 ) , from 2.4+/-1.3 to 2.6+/-1.5 mg per deciliter ( 212+/-114 to 226+/-133 micromol per liter ) ( P<0.001 for the comparison between groups ) . CONCLUSIONS Prophylactic oral administration of the antioxidant acetylcysteine , along with hydration , prevents the reduction in renal function induced by contrast agents in patients with chronic renal insufficiency Despite myriad improvements in the care of hospitalized patients , a decline in renal function remains a common event . Renal function in 4,622 consecutive patients admitted to the medical and surgical services of an urban tertiary care hospital was followed up prospect ively from the time of admission . Some degree of renal insufficiency developed in 7.2 % of patients . Decreased renal perfusion , medications , surgery , and radiographic contrast media were the most common causes of hospital-acquired renal insufficiency ( HARI ) . The overall mortality rate was 19.4 % and was similar among patients for all causes of renal insufficiency , except sepsis . For patients with a greater than 3.0-mg/dL increase in serum creatinine level , the mortality rate was 37.8 % . As shown by previous investigators , age and preexisting renal insufficiency were risk factors for HARI . Women and blacks had less hospital-acquired renal failure . The increasing acuity of hospital admissions has been accompanied by a greater incidence of acute renal insufficiency in patients admitted to hospitals . There is a trend toward better survival in patients with a severe deterioration in renal function AIMS Prophylactic administration of N-acetylcysteine ( NAC ) ( 600 mg orally twice daily ) , along with hydration , prevents contrast agent-associated nephrotoxicity ( CAN ) induced by a low dose of non-ionic , low-osmolality contrast dye . We tested whether a double dose of NAC is more effective to prevent CAN . METHODS AND RESULTS Two-hundred-twenty-four consecutive patients with chronic renal insufficiency ( creatinine level > or = 1.5mg/dl and /or creatinine clearance < 60ml/min ) , referred to our institution for coronary and /or peripheral procedures , were r and omly assigned to receive 0.45 % saline intravenously and NAC at the st and ard dose ( 600 mg orally twice daily ; SD Group ; n=110 ) or at a double dose ( 1200 mg orally twice daily ; DD Group ; n=114 ) before and after a non-ionic , low-osmolality contrast dye administration . Increase of at least 0.5mg/dl of the creatinine concentration 48h after the procedure occurred in 12/109 patients ( 11 % ) in the SD Group and 4/114 patients ( 3.5 % ) in the DD Group ( P=0.038 ; OR=0.29 ; 95 % CI=0.09 - 0.94 ) . In the subgroup with low ( < 140ml , or contrast ratio < = 1 ) contrast dose , no significant difference in renal function deterioration occurred between the 2 groups . In the subgroup with high ( > or = 140ml , or contrast ratio > 1 ) contrast dose , the event was significantly more frequent in the SD Group . Conclusions Double dose of NAC seems to be more effective than the st and ard dose in preventing CAN , especially with high volumes of non-ionic , low-osmolality contrast agent OBJECTIVE ( S ) Apart from proper hydration , only oral N-acetylcysteine ( NAC ) has shown efficacy in reducing radiographic contrast media (RCM)-induced acute renal failure , though its benefit has been challenged . We investigated the effect of intravenous ( i.v . ) NAC on renal function in patients with vascular disease receiving RCM for angiography . METHODS Single-center , r and omized , double-blind , placebo-controlled trial . Based on a previous study , a trial with 44 patients each in placebo and treatment arms would give at least 80 % power to show a statistically significant difference at the 5 % level . Vascular patients undergoing angiography were consented and segregated into those whose serum creatinine ( SC ) level was normal or raised ( men > 1.32 mg/dl ; women > 1.07 mg/dL ) . All patients received 500 mL i.v . normal saline 6 to 12 hours prior to and then after angiography . Groups with normal SC and raised SC were r and omly assigned to either 1 g of NAC with normal saline before and after angiography or nothing ( placebo ) . Main outcome measures were change in SC and creatinine clearance ( CrCl ) as measured 1 , 2 , and 7 days postangiography ( with comparison between active and placebo groups using unpaired t test ) and incidence of acute renal decline ( > 25 % or 0.5 mg/dL rise in SC ) at 48 hours ( with comparison between active and placebo using the Fisher exact test ) . RESULTS Forty-six patients received  NAC ( 29 normal SC , 17 raised SC ) , and 48 received placebo ( 27 normal SC , 21 raised SC ) . There was no significant difference in postangiography SC or CrCl at any of the time points measured between NAC and placebo in patients with either normal or raised SC . In the raised SC group , 3 patients from both the NAC and placebo groups suffered acute renal declines . Importantly , at 48 hours , the impaired SC group had a significant reduction in CrCl ( -14 % + /- 41 % vs + 18 % + /- 58 % : P = .0142 ) and a significant rise in SC ( +  
    Output:
    
In conclusion , insufficient evidence exists to recommend NAC for the prevention of CIN in patients undergoing peripheral angiography