***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: Summary Background Infusion therapy is one of the most frequently prescribed medications in hospitalized patients . Currently used crystalloid solutes have a variable composition and may therefore influence acid-base status , intracellular and extracellular water content and plasma electrolyte compositions and have a major impact on organ function and outcome . The aim of our study was to investigate whether use of acetate-based balanced crystalloids leads to better hemodynamic stability compared to 0.9 % saline . Methods We performed a sub- analysis of a prospect i ve , r and omized , controlled trial comparing effects of 0.9 % saline or an acetate-buffered , balanced crystalloid during the perioperative period in patients with end-stage renal disease undergoing cadaveric renal transplantation .  Need for catecholamine therapy and blood pressure were the primary measures . Results A total of 150 patients were included in the study of which 76 were r and omized to 0.9 % saline while 74 received an acetate-buffered balanced crystalloid . Noradrenaline for cardiocirculatory support during surgery was significantly more often administered in the normal saline group , given earlier and with a higher cumulative dose compared to patients receiving an acetate-buffered balanced crystalloid ( 30 % versus 15 % , p = 0.027 ; 68 ± 45 µg/kg versus 75 ± 60 µg/kg , p = 0.0055 and 0.000492 µg/kg body weight/min , ±0.002311 versus 0.000107 µg/kg/min , ±0.00039 , p = 0.04 , respectively ) . Mean minimum arterial blood pressure was significantly lower in patients r and omized to 0.9 % saline than in patients receiving the balanced infusion solution ( 57.2 [ SD 8.7 ] versus 60.3 [ SD 10.2 ] mm Hg , p = 0.024 ) . Conclusion The use of an acetate-buffered , balanced infusion solution results in reduced need for use of catecholamines and cumulative catecholamine dose for hemodynamic support and in less occurrence of arterial hypotension in the perioperative period . Further research in the field is strongly encouraged A prospect i ve r and omized double-blind study was performed to determine the effects of three colloids , Haemaccel , Gelofusine and albumin , and also saline on platelet activation , platelet aggregation ( induced by adenosine diphosphate ( ADP ) , epinephrine , collagen ) platelet agglutination by ristocetin and other hemostatic variables in 55 patients undergoing primary unilateral total hip replacement . The fluids were administered according to normal clinical practice and assessment s were made immediately before , at the end , and 2 h after the end of surgery . Surgery was accompanied by thrombin generation ( increases in thrombin/antithrombin III complex , prothrombin F1 + 2 fragment ) platelet activation ( betaTG ) and compromised coagulation . Generally , the platelet activation appeared to result in platelet desensitization and brought about a persistent reduction in platelet aggregation to ADP and epinephrine , irrespective of the fluid used . Additionally , Haemaccel and Gelofusine inhibited ristocetin-induced platelet agglutination and albumin inhibited collagen-induced platelet aggregation . Gross inhibitory effects of Haemaccel that had been predicted from an earlier in vitro study did not occur . Particular fluids had selective additional effects on the hemostatic system . Albumin infusion served to maintain plasma albumin at normal concentrations postsurgery . The two gelatin preparations , Haemaccel and Gelofusine , maintained plasma viscosity . All three colloids led to a transient increase in activated partial thromboplastin time postsurgery and also a transient fall in the concentration of factor VIII , which were accompanied by a transient increase in bleeding time , but there was no measurable increase in blood loss . Inhibition of platelet aggregation by certain colloids may provide additional protection against the increased thrombotic risk in patients following major surgery Metabolic acidosis and changes in serum osmolarity are consequences of 0.9 % normal saline ( NS ) solution administration . We sought to determine if these physiologic changes influence patient outcome . Patients undergoing aortic reconstructive surgery were enrolled and were r and omly assigned to receive lactated Ringer ’s ( LR ) solution ( n = 33 ) or NS ( n = 33 ) in a double-blinded fashion . Anesthetic and fluid management were st and ardized . Multiple measures of outcome were monitored . The NS patients developed a hyperchloremic acidosis and received more bicarbonate therapy ( 30 ± 62 mL in the NS group versus 4 ± 16 mL in the LR group ; mean ± sd ) , which was given if the base deficit was greater than −5 mEq/L. The NS patients also received a larger volume of platelet transfusion ( 478 ± 302 mL in the NS group versus 223 ± 24 mL in the LR group ; mean ± sd ) . When all blood products were summed , the NS group received significantly more blood products ( P = 0.02 ) . There were no differences in duration of mechanical ventilation , intensive care unit stay , hospital stay , and incidence of complications . When NS was used as the primary intraoperative solution , significantly more acidosis was seen on completion of surgery . This acidosis result ed in no apparent change in outcome but required larger amounts of bicarbonate to achieve predetermined measurements of base deficit and was associated with the use of larger amounts of blood products . These changes should be considered when choosing fluids for surgical procedures involving extensive blood loss and requiring extensive fluid administration Study Design . Prospect i ve , r and omized , double blind , clinical study . Objective . To compare the hemostatic and electrolyte effects of 2 commonly administered hydroxyethyl starches ( HES ) in patients undergoing posterior lumbar interbody fusion ( PLIF ) . Summary of Background Data . HES are commonly administered colloid solutions to restore and maintain intravascular volume before transfusion is initiated . However , infusion of HES itself can impair coagulation . HES-induced coagulopathy could be a serious problem in PLIF which involves continuous bone bleeding and oozing . Voluven ( Fresenius Kabi , Germany ) , previously regarded as the least coagulopathic due to its low molecular weight ( MW ) and degree of substitution ( DS ) , is a saline-based HES . Hextend ( Biotime , United States ) is a new type of HES with physiologic pH and balanced electrolytes , including calcium , which is beneficial to coagulation . Studies comparing the coagulopathy of Hextend and Voluven are rare . Therefore , coagulation , pH/electrolyte changes , and blood loss using Hextend and Voluven in patients undergoing PLIF were compared . Methods . Fifty-four patients scheduled for PLIF involving 3 vertebrae or less were r and omly assigned to the Voluven or the Hextend group . Of each solution 15 mL/kg was administered during surgery . Blood loss , coagulation , and electrolyte profiles were checked before infusion and 5 minutes , 3 hours , and 24 hours after the end of infusion . Results . The Hextend group showed slightly better electrolyte balance , however , more coagulation impairment and postoperative transfusion ( 37 % vs. 11 % ) compared with the Voluven group . The effect of Hextend on coagulation lasted until 24 hours after infusion . Conclusion . If coagulopathy is a concern during PLIF , then , a HES with low MW/DS in a saline-based medium ( Voluven ) may be a better alternative than a HES with high MW/DS in a balanced salt medium ( Hextend ) UNLABELLED Animal studies have shown that large volumes of IV lactated Ringer 's solution ( LR ) decrease serum osmolality , thereby increasing cerebral water . These studies have led to recommendations to limit LR to avoid cerebral edema in neurosurgical patients . Eighteen healthy human volunteers aged 20 - 48 yr received 50 mL/kg LR over 1 h on one occasion and 0.9 % sodium chloride ( NS ) on another . Venous sample s were taken at baseline ( T1 ) , at infusion end ( T2 ) , and 1 h after T2 ( T3 ) . Time until first urination was noted . With LR , serum osmolality decreased by 4+/-3 mOsm/kg from T1 to T2 and increased insignificantly with NS . At T3 , osmolality returned almost to baseline in the LR group . Blood pH increased from T1 to T2 with LR by 0.04+/-0.04 and decreased with NS by 0.04+/-0.04 . These pH changes persisted at T3 . Subjective mental changes occurred only with NS . Abdominal discomfort was more common with NS . Time until first urination was longer with NS ( 106+/-11 min ) than with LR ( 75+/-10 min ) ( P < 0.001 ) . In healthy humans , an infusion of large volumes of LR , but not NS , transiently decreased serum osmolality , whereas acidosis associated with NS persisted and urinary output was slower with NS . IMPLICATION S Large volumes of lactated Ringer 's solution administered to healthy humans produced small transient changes in serum osmolality . Large volumes of sodium chloride did not change osmolality but result ed in lower OBJECTIVES To compare the effects of lactated Ringer 's solution ( LR ) , 6 % hetastarch in a balanced-saline vehicle ( HS-BS ) , and 6 % hetastarch in normal saline ( HS-NS ) on coagulation using thromboelastography . DESIGN Prospect i ve , r and omized double-blinded evaluation of previously published clinical trial . SETTING Tertiary-care medical center . PARTICIPANTS Patients undergoing elective noncardiac surgery with an anticipated blood loss > 500 mL. A total of 90 patients were enrolled with 30 patients in each group . INTERVENTIONS Patients received a st and ardized anesthetic . LR , HS-BS , and HS-NS were administered intraoperatively based on a fluid administration algorithm . Hemodynamic targets included maintenance of arterial blood pressure , heart rate , and urine output within a predefined range . MEASUREMENTS AND MAIN RESULTS Thromboelastography variables for r time , k time , maximum amplitude , and alpha angle ( mean + /- SD ) were recorded at induction of anesthesia , at the end of surgery , and 24 hours postoperatively . Patients in the LR group showed a state of hypercoagulation at the end of surgery with reductions ( p < 0.005 ) in r time ( -3.8 + /- 6.7 mm ) and k time ( -1.7 + /- 2.5 mm ) . This state of hypercoagulation continued into the postoperative period . Patients in the HS-NS group showed a state of hypocoagulation with increases ( p < 0.05 ) in r time ( + 6.2 + /- 8.5 mm ) and k time ( + 1.7 + /- 3.9 mm ) and a reduction in maximum amplitude ( -8.0 + /- 9.8 mm ) at the end of surgery . This state of hypocoagulation was reduced in the postoperative period . Patients in the HS-BS group showed no significant changes in coagulation status at end of surgery , with the smallest changes in r time ( -0.3 + /- 4.1 mm ) , k time ( + 0.1 + /- 3.1 mm ) , maximum amplitude ( -5.4 + /- 12.3 mm ) , and alpha angle ( 0.3 + /- 12.5 degrees ) . CONCLUSION LR-treated patients exhibited a hypercoagulative profile that persisted into the postoperative period . HS-BS administration was associated with a lesser change in the coagulation profile compared with HS-NS , which was associated with a hypocoagulative state Normal saline ( NS ; 0.9 % NaCl ) is administered during kidney transplantation to avoid the risk of hyperkalemia associated with potassium-containing fluids . Recent evidence suggests that NS may be associated with adverse effects that are not seen with balanced-salt fluids , e.g. , lactated Ringer ’s solution ( LR ) . We hypothesized that NS is detrimental to renal function in kidney transplant recipients . Adults undergoing kidney transplantation were enrolled in a prospect i ve , r and omized , double-blind clinical trial of NS versus LR for intraoperative IV fluid therapy . The primary outcome measure was creatinine concentration on postoperative Day 3 . The study was terminated for safety reasons after interim analysis of data from 51 patients . Forty-eight patients underwent living donor kidney transplants , and three patients underwent cadaveric donor transplants . Twenty-six patients received  NS , and 25 patients received LR . There was no difference between groups in the primary outcome measure . Five ( 19 % ) patients in the NS group versus zero ( 0 % ) patients in the LR group had potassium concentrations > 6 mEq/L and were treated for hyperkalemia ( P = 0.05 ) . Eight ( 31 % ) patients in the NS group versus zero ( 0 % ) patients in the LR group were treated for metabolic acidosis ( P = 0.004 ) . NS did not adversely affect renal function .  LR was associated with less hyperkalemia and acidosis compared with NS . LR may be a safe choice for IV fluid therapy in patients undergoing 
    Output:
    
Current evidence is insufficient to show effects of perioperative administration of buffered versus non-buffered crystalloid fluids  on mortality and organ system function in adult patients following surgery .
Benefits of buffered fluid were measurable in biochemical terms , particularly a significant reduction in postoperative hyperchloraemia and metabolic acidosis .
Small effect sizes for biochemical outcomes and lack of correlated clinical follow-up data mean that robust conclusions on major morbidity and mortality associated with buffered versus non-buffered perioperative fluid choices are still lacking .