***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVES Cardiopulmonary bypass ( CPB ) is widely regarded as an important contributor to renal failure , a well recognized complication following coronary artery surgery ( coronary artery bypass grafting ( CABG ) ) . Anecdotally off-pump coronary surgery ( OPCAB ) is considered renoprotective . We examine the extent of renal glomerular and tubular injury in low-risk patients undergoing either OPCAB or on-pump coronary artery bypass ( ONCAB ) .  METHODS Forty low-risk patients with normal preoperative cardiac and renal functions awaiting elective CABG were prospect ively r and omized into those undergoing OPCAB ( n=20 ) and ONCAB ( n=20 ) . Glomerular and tubular injury were measured respectively by urinary excretion of microalbumin and retinol binding protein ( RBP ) indexed to creatinine ( Cr ) . Daily measurements were taken from admission to postoperative day 5 . Fluid balance , serum Cr and blood urea were also monitored . RESULTS No mortality or renal complication were observed . Both groups had similar demographic makeup , Parsonnet score , functional status and extent of coronary revascularization ( 2.1+/-1.0 vs. 2.5+/-0.7 grafts ; P=0.08 ) . Serum Cr and blood urea remained normal in both groups throughout the study . A significant and similar rise in urinary RBP : Cr occurred in both groups peaking on day 1 ( 3183+/-2534 vs. 4035+/-4079 ; P=0.43 ) before reapproximating baseline levels . These trends were also observed with urinary microalbumin : Cr ( 5.05+/-2.66 vs. 6.77+/-5.76 ; P=0.22 ) . Group B patients had a significantly more negative fluid balance on postoperative day 2 ( -183+/-1118 vs. 637+/-847 ml ; P=0.03 ) . CONCLUSIONS Although renal complication or serum markers of kidney dysfunction were absent , sensitive indicators revealed significant and similar injury to renal tubules and glomeruli following either OPCAB or ONCAB . These results suggest that avoidance of CPB does not offer additional renoprotection to patients at low risk of perioperative renal insult during CABG OBJECTIVES We aim ed to evaluate the renoprotective role of renal-dose dopamine on cardiac surgical patients at high risk of postoperative renal dysfunction . The latter included older patients or those with pre-existing renal disease , elevated preoperative serum creatinine ( Cr ) , poor ventricular function , hypertension , diabetes mellitus and unstable angina requiring intravenous therapy . METHODS Fifty patients undergoing cardiopulmonary bypass ( CPB ) who fulfilled the entry criteria were prospect ively r and omized into two groups : Group 1 received a ' renal-dose ' ( 3 microg kg(-1 ) min(-1 ) ) dopamine infusion starting at anaesthetic induction for 48 h whilst saline infusion acted as placebo in Group 2 . The anaesthetic and CPB regimes were st and ardized . Urinary excretion of retinol binding protein ( RBP ) indexed to Cr , an accurate and sensitive marker of early renal tubular damage , was assessed daily for 6 days . Additional outcome measures included daily fluid balance , blood urea and serum Cr . Statistical comparisons were made using ANOVA and Mann-Whitney U-test . RESULTS No significant difference was found between the groups in their age , gender , preoperative NYHA class , ejection fraction , baseline serum Cr and duration of CPB and aortic cross-clamping . Renal replacement therapy was not required in any instance . Both groups demonstrated a similar and significant rise in urinary RBP throughout the study period . Dopamine-treated patients achieved more negative average fluid balance than those on placebo ( 5 vs. 229 ml , P<0.05 ) . CONCLUSIONS Renal-dose dopamine therapy failed to offer additional renoprotection to patients considered at increased risk of renal dysfunction after CPB Activation of the renin-angiotensin system during open heart surgery may have consequences both beneficial in sustaining blood pressure and deleterious in compromising renal hemodynamics . The influence of short-term pretreatment with captopril on blood pressure and renal function was assessed double-blind versus placebo in 18 patients without pre-existing cardiac or renal failure , and undergoing coronary artery bypass . No difference in blood pressure and fluid requirement during the surgical period was observed between groups receiving captopril or placebo .  Effective renal plasma flow and glomerular filtration rate decreased in the placebo group whereas they remained unaltered in the captopril group ; during cardiopulmonary bypass , urinary excretion of sodium was greater in patients receiving captopril than those receiving placebo . These results suggest that captopril pretreatment does not compromise the control of blood pressure and renal function during open heart surgery ; additional studies on the protective value of angiotensin-converting enzyme inhibitors are warranted in patients at higher risk for developing renal failure Between August 2004 and May 2006 , 124 patients undergoing coronary artery bypass grafting with ejection fractions ≤ 35 % were r and omly assigned to off-pump or conventional procedures . Preoperative characteristics were the same in both groups , except for age and degree of mitral regurgitation . Off-pump coronary artery grafting was carried out using a tissue stabilizer and a single-suture technique ; conventional coronary bypass employed cardiopulmonary bypass , moderate hypothermia , and ante grade -retro grade cold blood cardioplegic arrest . There were significantly fewer vessels grafted ( 3.09 ± 0.41 ) in the off-pump group than in those who had a conventional procedure ( 3.42 ± 0.86 ) . The rates of mortality , morbidity , balloon pump support , inotropic usage , gastrointestinal bleeding , renal dysfunction , reintubation , as well as intensive care and hospital stay , were significantly lower in the off-pump group . The incidence of perioperative myocardial infa rct ion did not differ significantly between groups . The results of this study indicate that beating-heart coronary bypass is safe and effective in patients with left ventricular dysfunction AIM Renal function is one of the most important prognostic factors following cardiac surgery . Whether aspirin affects cardiopulmonary bypass related renal injury is investigated in this study . METHODS Ninety-four patients with impaired renal function ( creatinine = or > 1.5 mg/dl ) undergoing coronary artery bypass grafting ( CABG )  were categorized into 2 groups according to aspirin administration before surgery . Serum creatinine , urinary output and creatinine clearance along with other perioperative factors were compared between the 2 groups prior to surgery , 24 hours and 48 hours following cardiopulmonary bypass . RESULTS Creatinine levels increased significantly in the second postoperative day only in the non-aspirin ( control ) group ( 3.7+/-1.6 vs 2.9+/-1.7 mg/dl , p=0.03 ) . Aspirin ( study ) group had lower creatinine levels in day 1 ( p=0.03 ) and day 2 ( p=0.001 ) . Furthermore , in the study group creatinine clearance was higher in day 1 ( 34.3+/-14.3 vs 30.9+/-13.1 ml/min , p=0.01 ) and in day 2 ( 32.6+/-13.8 vs 26.4+/-9.8 ml , p<0.0001 ) . Creatinine levels at discharge were elevated compared to the preoperative levels in the control group ( p=0.01 ) . However , the study group had lower creatinine levels at discharge ( 2.6+/-1.4 vs 3.8+/-1.6 mg/dl , p<0.0001 ) . Urinary output was higher in the study group in the first postoperative day compared to the control group ( p=0.01 ) . Postoperative bleeding was slightly increased in the study group compared to the control group ( 760+/-230 ml vs 530+/-210 ml , p=0.01 ) . CONCLUSIONS Continuation of aspirin administration until the day of surgery may have a protective effect against renal injury result ing from cardiopulmonary bypass , with only a negligible increase in bleeding . Possible explanations for this effect are antiplatelet activity of aspirin during cardiopulmonary bypass causing inhibition of vasoconstrictive agents like thromboxane , and improvement of renal perfusion by reducing blood viscosity Mannitol is often added to the cardiopulmonary bypass pump prime to reduce the incidence of renal dysfunction , but studies so far have been inconclusive . Urinary excretion of microalbumin and retinol binding protein are more sensitive than routine biochemical tests of renal function after cardiac surgery . We performed a double‐blind , r and omised , controlled trial in cardiac surgical patients with pre‐operative plasma creatinine < 130 μmol.l−1 . Twenty patients received 0.5 g.kg−1 of mannitol in the pump prime , whereas 20 control patients received an equivalent volume of Hartmann ’s solution .  Blood and urine sample s were taken on the day before surgery and daily for 5 days postoperatively for measurement of plasma urea and creatinine , urinary creatinine , retinol binding protein and microalbumin . We found no differences between the mannitol and control patients for any measured variable , and conclude that mannitol has little impact on renal function in patients with normal pre‐operative plasma creatinine concentrations Thirty-six patients with preoperative renal dysfunction were studied to evaluate the effects of dopamine ( D ) and dopamine-nitroprusside ( DN ) on renal function during cardiopulmonary bypass ( CPB ) . No differences from the control group ( C ) were found in creatinine clearance , fractional sodium excretion , osmolarity and free-water clearance . Sodium output/intake ratio during CPB was higher in group D than in groups C and DN ( P less than 0.05 ) ; water output/intake ratio was higher in group D than in group C ( P less than 0.05 ) . Urine lysozime levels and alpha-glycosidase/creatinine ratios increased similarly in the three groups , suggesting ischemic tubular cell damage . No patients showed acute postoperative renal failure or a worsening of their renal dysfunction . The data suggest an increased water and sodium excretion during CPB with a dopamine infusion , possibly result ing from a renal vasodilator effect that was abolished by simultaneous nitroprusside administration Impairment of renal and splanchnic perfusion during and after cardiopulmonary bypass may be responsible for acute renal failure and endotoxin‐mediated systemic inflammation , respectively . We hypothesised that fenoldopam , a selective dopamine receptor agonist , would preserve renal function after cardiopulmonary bypass through its selective renal vasodilatory and natriuretic effects , and increase gastrointestinal mucosal perfusion by selective splanchnic vasodilation . We examined the effects of fenoldopam on haemodynamic parameters , creatinine clearance , fractional excretion of sodium , urine output , free water clearance and gastric mucosal pH in 31 patients undergoing elective coronary revascularisation . Patients were r and omly assigned to receive continuous infusions of fenoldopam 0.1 µg.kg−1.min−1 ( n = 16 ) or placebo ( n = 15 ) . Renal parameters were measured : during a 24‐h period before hospital admission , during cardiopulmonary bypass , from completion of cardiopulmonary bypass until 4 h later , from 4 to 8 h after cardiopulmonary bypass , and from 8 to 14 h after cardiopulmonary bypass . Gastric intramucosal pH was measured using a gastric tonometer before , during and after cardiopulmonary bypass . In the placebo group , but not the fenoldopam group , mean ( SD ) creatinine clearance decreased after separation from cardiopulmonary bypass , from 107 ( 36 ) to 71 ( 22 ) ml.min−1 ( p < 0.01 ) and from 107 ( 36 ) to 79 ( 26 ) ml.min−1 ( p < 0.01 ) for the 0–4 h and 4–8 h intervals after cardiopulmonary bypass , respectively . Changes in intramucosal pH were similar in both groups . The findings are consistent with the hypothesis that fenoldopam possesses a renoprotective effect in patients undergoing cardiopulmonary bypass OBJECTIVES The purpose of this study was to determine the role nesiritide might play in patients with left ventricular dysfunction undergoing coronary artery bypass grafting ( CABG ) using cardiopulmonary bypass ( CPB ) .  BACKGROUND Given the hemodynamic , neurohormonal , and renal effects of natriuretic peptides , nesiritide might be useful in the management of patients undergoing cardiac surgery . METHODS This prospect i ve , double-blind , exploratory evaluation r and omly assigned patients with ejection fraction < /=40 % who were undergoing CABG with anticipated use of CPB to receive either nesiritide or placebo  , in addition to usual care , for 24 to 96 h after induction of anesthesia . Postoperative renal function , hemodynamics , and 
    Output:
    
When analyzed separately , dopamine and N-acetylcysteine did not reduce the risk for AKI .
The results advocate large , good- quality , multicenter studies to determine whether promising interventions reliably reduce rates of acute renal replacement therapy and mortality in the cardiac surgery setting