***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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    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 Objective To evaluate the effect of high-volume hemofiltration ( HVHF ) with lactate-buffered replacement fluids on acid-base balance . Design R and omized crossover study . Setting Intensive Care Unit of Tertiary Medical Center Participants Ten patients with septic shock and acute renal failure . Interventions R and om allocation to 8 h of isovolemic high-volume hemofiltration ( ultrafiltration rate : 6 l/h ) or 8 h of isovolemic continuous venovenous hemofiltration ( ultrafiltration rate : 1 l/h ) with lactate-buffered replacement fluid with subsequent crossover . Measurements and results We measured blood gases , electrolytes , albumin , and lactate concentrations and completed quantitative biophysical analysis of acid-base balance changes . Before high-volume hemofiltration , patients had a slight metabolic alkalosis [ pH : 7.42 ; base excess ( BE ) 2.4 mEq/l ] despite hyperlactatemia ( lactate : 2.51 mmol/l ) . After 2 h of high-volume hemofiltration , the mean lactate concentration increased to 7.30 mmol/l ( p=0.0001 ) . However , a decrease in chloride , strong ion difference effective , and strong ion gap ( SIG ) compensated for the effect of iatrogenic hyperlactatemia so that the pH only decreased to 7.39 ( p=0.05 ) and the BE to −0.15 ( p=0.001 ) . After 6 h , despite persistent hyperlactatemia ( 7 mmol/l ) , the pH had returned to 7.42 and the BE to 2.45 mEq/l . These changes remained essentially stable at 8 h. Similar but less intense changes occurred during continuous venovenous hemofiltration . Conclusions HVHF with lactate-buffered replacement fluids  induces iatrogenic hyperlactatemia . However , such hyperlactatemia only has a mild and transient acidifying effect . A decrease in chloride and strong ion difference effective and the removal of unmeasured anions all rapidly compensate for this effect BACKGROUND Acute renal failure is a serious complication in critically ill patients and frequently requires renal replacement therapy , which alters trace element and vitamin metabolism . OBJECTIVE The objective was to study trace element balances during continuous renal replacement therapy ( CRRT ) in intensive care patients . DESIGN In a prospect i ve r and omized crossover trial , patients with acute renal failure received CRRT with either sodium bicarbonate ( Bic ) or sodium lactate ( Lac ) as a buffering agent over 2 consecutive 24-h periods .  Copper , selenium , zinc , and thiamine were measured with highly sensitive analytic methods in plasma , replacement solutions , and effluent during 8-h periods . Balances were calculated as the difference between fluids administered and effluent losses and were compared with the recommended intakes ( RI ) from parenteral nutrition . RESULTS Nineteen sessions were conducted in 11 patients aged 65 + /- 10 y.  Baseline plasma concentrations of copper were normal , whereas those of selenium and zinc were below reference ranges ; glutathione peroxidase was in the lower range of normal . The replacement solutions contained no detectable copper , 0.01 micromol Se/L ( Bic and Lac ) , and 1.42 ( Bic ) and 0.85 ( Lac ) micromol Zn/L. Micronutrients were detectable in all effluents , and losses were stable in each patient ; no significant differences were found between the Bic and Lac groups . The 24-h balances were negative for selenium ( -0.97 micromol , or 2 times the daily RI ) , copper ( -6.54 micromol , or 0.3 times the daily RI ) , and thiamine ( -4.12 mg , or 1.5 times the RI ) and modestly positive for zinc ( 20.7 micromol , or 0.2 times the RI ) . CONCLUSIONS CRRT results in significant losses and negative balances of selenium , copper , and thiamine , which contribute to low plasma concentrations . Prolonged CRRT is likely to result in selenium and thiamine depletion despite supplementation at recommended amounts UNLABELLED Clinical experience with two physiologic bicarbonate/lactate peritoneal dialysis solutions in automated peritoneal dialysis . BACKGROUND Patients on automated peritoneal dialysis ( APD ) usually receive larger volumes of dialysis solution and more frequent , shorter exchanges than patients on continuous ambulatory peritoneal dialysis ( CAPD ) , and therefore are likely to derive greater benefit from more physiologic solutions . METHODS Peritoneal dialysis solutions containing 25 mmol/L bicarbonate and either 10 or 15 mmol/L lactate were compared with st and ard lactate solutions ( 35 or 40 mmol/L ) in two prospect i ve , open-label studies of patients on APD . Each study included a 2-week baseline period ( lactate solution ) , a 6-week treatment period ( bicarbonate/lactate solution ) , and a 2-week follow-up period ( same lactate solution as baseline ) . Biochemical analyses and assessment s of vital signs and safety parameters were conducted at baseline , every 2 weeks during treatment , and at the end of the follow-up period . A product use question naire was administered in one study at the end of treatment . RESULTS A statistically significant rise in plasma bicarbonate ( approximately 2 mmol/L ) occurred when patients switched from a lactate solution to the bicarbonate/lactate solution with equimolar buffer concentration ( P < 0.001 for each solution ) . Plasma bicarbonate decreased by 1.16 mmol/L after a switch from lactate 40 mmol/L to bicarbonate/lactate 35 mmol/L ( P < 0.001 ) . When patients switched to bicarbonate/lactate 35 , the majority of individual venous plasma bicarbonate values were in the normal range . A switch from a lower calcium ( 1.25 mmol/ L ) lactate solution to a higher calcium ( 1.75 mmol/L ) lactate/bicarbonate solution result ed in a statistically significant rise in serum calcium ( 0.06 mmol/L , P < 0.018 ) . The product use question naire revealed improvements in symptoms , including reduced pain on infusion . CONCLUSION Bicarbonate/lactate solutions may be used safely and effectively in patients on APD . The availability of 2 formulations with different buffer and calcium content provides flexibility for the control of acidosis as well as calcium balance Objective We evaluated the variable Kt/V , which has become established in the therapy of end-stage renal disease in acute renal failure , to assess the influence of the filtration volume of continuous venovenous hemofiltration on Kt/V. We measured the variables of acid-base balance and uremia control . Design Prospect i ve interventional pilot study . Setting Medical intensive care unit of a university hospital . Patients Fifty-six patients with acute renal failure and continuous venovenous hemofiltration treatment . Interventions The patients were consecutively treated with a filtration volume of either 1 L/hr ( group 1 ) or 1.5 L/hr ( group 2 ) . Measurements and Main Results Patients with a filtration volume of 1.5 L/hr achieved a Kt/V of 0.8 per day , which was significantly higher than in the patient group treated with 1 L/hr ( 0.53 , p < .05 ) . The filtration volume of 1.5 L/hr led to a markedly better control of blood urea nitrogen concentrations , 69.3 ± 6.6 mg/dL vs. 52.1 ± 5.2 ( p < .05 ) , and to a much quicker and longer lasting compensation of acidosis . Both groups had acidotic pH at the beginning of therapy ( group 1 , 7.29 ± 0.02 ; group 2 , 7.29 ± 0.02 , nonsignificant ) . In group 2 , a significantly higher pH value than in group 1 was measured after 24 hrs of continuous venovenous hemofiltration ( p < .001 ; 7.39 ± 0.02 vs. 7.31 ± 0.02 ) . The pH values in group 1 did not normalize until after 4 days . The filtration volume of 1.5 L/hr led to a quicker increase in bicarbonate concentrations after 24 hrs of therapy ( group 1 , 2.8 ± 3.2 mmol/L ; group 2 , 6.5 ± 3.1 mmol/L , p < .001 ) . Conclusions The st and ardized urea clearance Kt/V is a valuable tool in the treatment of acute renal failure . Higher Kt/V levels were associated with a better control of uremia and acid-base balance . However , there were no differences in the clinical course , patient survival , percentage of patients with or without renal failure who were transferred from the intensive care unit , or Acute Physiology and Chronic Health Evaluation III scores The characteristics of acetate-free biofiltration ( AFB ) are now well documented in patients with chronic renal failure : hemodynamic tolerance , correction of acid-base imbalance , buffer-free dialysate ( without acetate ) and absence of backfiltration . This hemodialysis technique can be beneficial to patients with acute renal failure ( ARF ) . In our intensive care unit , we prospect ively studied 29 patients with isolated ARF or ARF associated with failure of other organs . All eligible patients were r and omly assigned to undergo dialysis with bicarbonate hemodialysis ( BH ) or with ( AFB ) .  All used the same high flux biocompatible dialysis membranes . Effectiveness and hemodynamic tolerance of hemodialysis sessions and evolution of patients were analyzed . Correction of metabolic disorders , although better in the AFB group was not statistically different from that in the BH group . Re-equilibration of acid-base balance was also similar , with or without mechanical ventilation . Heparin consumption was significantly higher in the AFB group , with no effect on haemorrhagic complications . Analysis of hypo- and hypertensive episodes , defined as arterial pressure ( AP ) variations 20 % greater than initial pressure , showed no difference in terms of number or degree of AP variation . However , weight loss and the rate of ultrafiltration led to a higher hypotensive risk in the BH group ( p < 0.05 ) . Finally , the clinical course and prognosis was similar in both groups . In summary , AFB may be considered as effective a hemodialysis technique as BH in patients with ARF . Weight loss was better tolerated in the AFB group and can be a favorable factor considering the deleterious effect of overhydration in patients admitted to an intensive care unit . This 
    Output:
    
There were no significant different between bicarbonate- and lactate-buffered solutions for mortality , serum bicarbonate levels , serum creatinine , serum base excess , serum pH , carbon dioxide partial pressure , central venous pressure and serum electrolytes .
Patients treated with bicarbonate-buffered solutions may experience fewer cardiovascular events , lower serum lactate levels , higher mean arterial pressure and less hypotensive events .
With the exception of mortality , we were not able to assess the main primary outcomes of this review - length of time in ICU , total length of hospital stay and relapse