***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: 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 ) 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 kidney transplantation Purpose A balanced fluid replacement strategy appears to be promising for correcting hypovolemia . The benefits of a balanced fluid replacement regimen were studied in elderly cardiac surgery patients . Methods In a r and omized clinical trial , 50 patients aged > 75 years undergoing cardiac surgery received a balanced 6 % HES 130/0.42 plus a balanced crystalloid solution ( n = 25 ) or a non-balanced HES in saline plus saline solution ( n = 25 ) to keep pulmonary capillary wedge pressure/ central venous pressure between 12–14 mmHg . Acid-base status , inflammation , endothelial activation ( soluble intercellular adhesion molecule-1 , kidney integrity ( kidney-specific proteins glutathione transferase-alpha ; neutrophil gelatinase-associated lipocalin ) were studied after induction of anesthesia , 5 h after surgery , 1 and 2 days thereafter . Serum creatinine ( sCr ) was measured approximately 60 days after discharge . Results A total of 2,750 ± 640 mL of balanced and 2,820 ± 550 mL of unbalanced HES were given until the second POD . Base excess ( BE ) was significantly reduced in the unbalanced ( from + 1.21 ± 0.3 to −4.39 ± 1.0 mmol L−1 5 h after surgery ; P < 0.001 ) and remained unchanged in the balanced group ( from 1.04 ± 0.3 to −0.81 ± 0.3 mmol L−1 5 h after surgery ) . Evolution of the BE was significantly different . Inflammatory response and endothelial activation were significantly less pronounced in the balanced than the unbalanced group . Concentrations of kidney-specific proteins after surgery indicated less alterations of kidney integrity in the balanced than in the unbalanced group . Conclusions A total balanced volume replacement strategy including a balanced HES and a balanced crystalloid solution result ed in moderate beneficial effects on acid-base status , inflammation , endothelial activation , and kidney integrity compared to a conventional unbalanced volume replacement regimen The IV administration of sodium chloride solutions may produce a metabolic acidosis and gastrointestinal dysfunction . We design ed this trial to determine whether , in elderly surgical patients , crystalloid and colloid solutions with a more physiologically balanced electrolyte formulation , such as Hartmann ’s solution and Hextend ® , can provide a superior metabolic environment and improved indices of organ perfusion when compared with saline-based fluids . Forty-seven elderly patients undergoing major surgery were r and omly allocated to one of two study groups . Patients in the Balanced Fluid group received an intraoperative fluid regimen that consisted of Hartmann ’s solution and 6 % hetastarch in balanced electrolyte and glucose injection ( Hextend ) . Patients in the Saline group were given 0.9 % sodium chloride solution and 6 % hetastarch in 0.9 % sodium chloride solution ( Hespan ® ) . Biochemical indices and acid-base balance were determined . Gastric tonometry was used as a reflection of splanchnic perfusion . Postoperative chloride levels demonstrated a larger increase in the Saline group than the Balanced Fluid group ( 9.8 vs 3.3 mmol/L , P = 0.0001 ) . Postoperative st and ard base excess showed a larger decline in the Saline group than the Balanced Fluid group ( −5.5 vs −0.9 mmol/L , P = 0.0001 ) . Two-thirds of patients in the Saline group , but none in the Balanced Fluid group , developed postoperative hyperchloremic metabolic acidosis ( P = 0.0001 ) . Gastric tonometry indicated a larger increase in the CO2 gap during surgery in the Saline group compared with the Balanced Fluid group ( 1.7 vs 0.9 kPa , P = 0.0394 ) . In this study , the use 
    Output:
    
There was no difference in intraoperative blood loss nor the volumes of intraoperative red cell or fresh frozen plasma transfused between groups .
The non-buffered fluid group also had significantly greater base deficit , serum sodium and chloride levels .
There was no difference demonstrated in length of hospital stay and no data were reported on cost or quality of life .
AUTHORS ' CONCLUSIONS The administration of buffered fluids to adult patients during surgery is equally safe and effective as the administration of non-buffered saline-based fluids .
The use of buffered fluids is associated with less metabolic derangement , in particular hyperchloraemia and metabolic acidosis .