***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: CONTEXT Although acute renal failure ( ARF ) is believed to be common in the setting of critical illness and is associated with a high risk of death , little is known about its epidemiology and outcome or how these vary in different regions of the world . OBJECTIVES To determine the period prevalence of ARF in intensive care unit ( ICU ) patients in multiple countries ; to characterize differences in etiology , illness severity , and clinical practice ; and to determine the impact of these differences on patient outcomes . DESIGN , SETTING , AND PATIENTS Prospect i ve observational study of ICU patients who either were treated with renal replacement therapy ( RRT ) or fulfilled at least 1 of the predefined criteria for ARF from September 2000 to December 2001 at 54 hospitals in 23 countries . MAIN OUTCOME MEASURES Occurrence of ARF , factors contributing to etiology , illness severity , treatment , need for renal support after hospital discharge , and hospital mortality . RESULTS Of 29 269 critically ill patients admitted during the study period , 1738 ( 5.7 % ; 95 % confidence interval [ CI ] , 5.5%-6.0 % ) had ARF during their ICU stay , including 1260 who were treated with RRT . The most common contributing factor to ARF was septic shock ( 47.5 % ; 95 % CI , 45.2%-49.5 % ) . Approximately 30 % of patients had preadmission renal dysfunction . Overall hospital mortality was 60.3 % ( 95 % CI , 58.0%-62.6 % ) . Dialysis dependence at hospital discharge was 13.8 % ( 95 % CI , 11.2%-16.3 % ) for survivors . Independent risk factors for hospital mortality included use of vasopressors ( odds ratio [ OR ] , 1.95 ; 95 % CI , 1.50 - 2.55 ; P<.001 ) , mechanical ventilation ( OR , 2.11 ; 95 % CI , 1.58 - 2.82 ; P<.001 ) , septic shock ( OR , 1.36 ; 95 % CI , 1.03 - 1.79 ; P = .03 ) , cardiogenic shock ( OR , 1.41 ; 95 % CI , 1.05 - 1.90 ; P = .02 ) , and hepatorenal syndrome ( OR , 1.87 ; 95 % CI , 1.07 - 3.28 ; P = .03 ) . CONCLUSION In this multinational study , the period prevalence of ARF requiring RRT in the ICU was between 5 % and 6 % and was associated with a high hospital mortality rate BACKGROUND Continuous veno-venous haemofiltration is increasingly used to treat acute renal failure in critically ill patients , but a clear definition of an adequate treatment dose has not been established . We undertook a prospect i ve r and omised study of the impact different ultrafiltration doses in continuous renal replacement therapy on survival . METHODS We enrolled 425 patients , with a mean age of 61 years , in intensive care who had acute renal failure . Patients were r and omly assigned ultrafiltration at 20 mL h(-1 ) kg(-1 ) ( group 1 , n=146 ) , 35 mL h(-1 ) kg(-1 ) ( group 2 , n=139 ) , or 45 mL h(-1 ) kg(-1 ) ( group 3 , n=140 ) . The primary endpoint was survival at 15 days after stopping haemofiltration . We also assessed recovery of renal function and frequency of complications during treatment . Analysis was by intention to treat . RESULTS Survival in group 1 was significantly lower than in groups 2 ( p=0.0007 ) and 3 ( p=0.0013 ) . Survival in groups 2 and 3 did not differ significantly ( p=0.87 ) . Adjustment for possible confounding factors did not change the pattern of differences among the groups . Survivors in all groups had lower concentrations of blood urea nitrogen before continuous haemofiltration was started than non-survivors . 95 % , 92 % , and 90 % of survivors in groups 1 , 2 , and 3 , respectively , had full recovery of renal function . The frequency of complications was similarly low in all groups . INTERPRETATION Mortality among these critically ill patients was high , but increase in the rate of ultrafiltration improved survival significantly . We recommend that ultrafiltration should be prescribed according to patient 's bodyweight and should reach at least 35 mL h(-1 ) kg(-1 ) Introduction The optimal dialysis dose for the treatment of acute kidney injury ( AKI ) is controversial . We sought to evaluate the relationship between renal replacement therapy ( RRT ) dose and outcome . Methods We performed a prospect i ve multicentre observational study in 30 intensive care units ( ICUs ) in eight countries from June 2005 to December 2007 . Delivered RRT dose was calculated in patients treated exclusively with either continuous RRT ( CRRT ) or intermittent RRT ( IRRT ) during their ICU stay . Dose was categorised into more-intensive ( CRRT ≥ 35 ml/kg/hour , IRRT ≥ 6 sessions/week ) or less-intensive ( CRRT < 35 ml/kg/hour , IRRT < 6 sessions/week ) . The main outcome measures were ICU mortality , ICU length of stay and duration of mechanical ventilation . Results Of 15,200 critically ill patients admitted during the study period , 553 AKI patients were treated with RRT , including 338 who received CRRT only and 87 who received IRRT only . For CRRT , the median delivered dose was 27.1 ml/kg/hour ( interquartile range ( IQR ) = 22.1 to 33.9 ) . For IRRT , the median dose was 7 sessions/week ( IQR = 5 to 7 ) . Only 22 % of CRRT patients and 64 % of IRRT patients received a more-intensive dose . Crude ICU mortality among CRRT patients were 60.8 % vs. 52.5 % ( more-intensive vs. less-intensive groups , respectively ) . In IRRT , this was 23.6 vs. 19.4 % , respectively . On multivariable analysis , there was no significant association between RRT dose and ICU mortality ( Odds ratio ( OR ) more-intensive vs. less-intensive : CRRT OR = 1.21 , 95 % confidence interval ( CI ) = 0.66 to 2.21 ; IRRT OR = 1.50 , 95 % CI = 0.48 to 4.67 ) . Among survivors , shorter ICU stay and duration of mechanical ventilation were observed in the more-intensive RRT groups ( more-intensive vs. less-intensive for all : CRRT ( median ) : 15 ( IQR = 8 to 26 ) vs. 19.5 ( IQR = 12 to 33.5 ) ICU days , P = 0.063 ; 7 ( IQR = 4 to 17 ) vs. 14 ( IQR = 5 to 24 ) ventilation days , P = 0.031 ; IRRT : 8 ( IQR = 5.5 to 14 ) vs. 18 ( IQR = 13 to 35 ) ICU days , P = 0.008 ; 2.5 ( IQR = 0 to 10 ) vs. 12 ( IQR = 3 to 24 ) ventilation days , P = 0.026 ) . Conclusions After adjustment for multiple variables , these data provide no evidence for a survival benefit afforded by higher dose RRT . However , more-intensive RRT was associated with a favourable effect on ICU stay and duration of mechanical ventilation among survivors . This result warrants further exploration . Trial Registration Cochrane Renal Group ( CRG110600093 ) Objectives : To determine whether continuous venovenous hemofiltration leads to extraction of tumor necrosis factor alpha ( TNFα ) and cytokines from the circulation of critically ill patients with sepsis and acute renal failure and to quantitate the clearance and the removal rate of these cytokines and their effect on serum cytokine concentrations . Design : Prospect i ve , controlled study in patients with continuous venovenous hemofiltration ( 24 l/24 h ) using a polysulphone membrane in patients with acute renal failure . Patients : 33 ventilated patients with acute renal failure of septic ( n = 18 ) and cardiovascular origin ( n = 15 ) were studied . Interventions : Hemodynamic monitoring and collection of blood and ultrafiltrate sample s before and during the first 72 h of continuous hemofiltration . Measurements and main results : Cardiovascular hemodynamics ( Swan-Ganz catheter ) , Acute Physiology and Chronic Health Evaluation II score , creatinine , electrolytes , and blood urea nitrogen were recorded daily . Cytokines ( TNFα , TNFα-RII , interleukin ( IL ) 1β , IL1RA , IL2 , IL2R , IL6 , IL6R , IL8 , IL10 ) were measured in prefilter blood and in ultrafiltrate immediately preceding and 12 , 24 , 48 , and 72 h after initiating continuous venovenous hemofiltration ( CVVH ) . Septic patients showed elevated cardiovascular values for cardiac output ( 7.2 ± 2.1 l/min ) , cardiac index ( 4.2 ± 1.3 l/min per m2 ) , and stroke volume ( 67 ± 23 ml ) and reduced values for systemic vascular resistance ( 540 ± 299 dyn · s · cm− 5 ) . All hemodynamic values normalized within the first 24 h after initiating CVVH treatment . TNFα was 1833 ± 1217 pg/ml in septic patients and 42.9 ± 6.3 pg/ml in nonseptic patients ( p < 0.05 ) prior to CVVH . TNFα was detected in ultrafiltrate but did not decrease in blood during treatment with CVVH . There was no difference in IL 1β between septic ( 3.8 ± 1.9 pg/ml ) and nonseptic patients ( 1.7 ± 0.5 pg/ml ) . No significant elimination of cytokines was achieved in the present study by CVVH treatment . Conclusions : These findings demonstrate that CVVH can remove TNFα and special cytokines from the circulation of critically ill patients . Cardiovascular hemodynamics seemed to improve in septic patients after induction of hemofiltration treatment , although there was no evidence that extracorporeal removal of cytokines achieved a reduction in blood levels . The study indicates that low volume continuous hemofiltration with polysulphone membranes in patients with acute renal failure is not able to induce significant removal of cytokines Objectives To determine whether continuous veno-venous hemofiltration with dialysis leads to extraction of tumor necrosis factor-α ( TNF-α ) and interleukin-1β ( IL-1β ) from the circulation of critically ill patients with sepsis and acute renal failure and to quantitate the clearance and removal rates of these cytokines and their effect on serum cytokine concentrations . Design Prospect i ve , controlled study of TNF-α and IL-1β extraction by continuous veno-venous hemofiltration with dialysis in patients with septic acute renal failure . Setting Intensive care unit of a tertiary institution . Patients Eighteen critically ill patients with sepsis and acute renal failure . Control group of six patients experiencing an acute illness while undergoing chronic hemodialysis .  Interventions Collection of blood sample s before continuous veno-venous hemofiltration with hemodialysis . Simultaneous collection of prefilter blood and ultradiafiltrate after 4 and 24 hrs of treatment . Measurements and Main Results TNF-α and IL-1β concentrations were measured in blood and ultradiafiltrate . Their clearances and daily extraction were calculated and compared with a control group . TNF-α was detected in 66.6 % of serum sample s of patients with septic acute renal failure ; IL-1β was detected in 55 % of patients ' sera sample s. Both TNF-α and IL-1β were cleared by the hemofilter during continuous veno-venous hemofiltration with dialysis . The mean clearance for TNF-α was 30.7 L/day ( 95 % confidence interval 22.4 to 39 ) with a daily mean excretion of 14.1 μg ( 95 % confidence interval 1.7 to 26.5 ) . Mean IL-1β clearance was 36.1 L/day ( 95 % confidence interval 25.4 to 46.8 ) equivalent to a mean daily IL-1β excretion of 1 μg ( 95 % confidence interval 0.9 to 1.1 ) . No measurable concentrations of TNF-α or IL-1β were found in the serum or ultrafiltrate specimens of control patients . Conclusions These findings demonstrate that continuous veno-venous hemofiltration with dialysis can remove both TNF-α and IL-1β from the circulation of septic , critically ill patients . This cytokine extraction may prove to be of benefit in attenuating the progression of multiple organ dysfunction in patients with sepsis-associated renal failure , who are receiving continuous veno-venous hemofiltration with dialysis . 
    Output:
    
Meta-regression analysis indicated that the results were not affected by the percentage of patients with sepsis or septic shock .