***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: Colloids are useful in cardiac surgery to increase preload and improve cardiac output without the risks associated with blood transfusions . Pentastarch is a new low-molecular weight hydroxyethyl starch compound under investigation for this purpose . The authors compared , in a r and omized fashion , 12 patients who received pentastarch and 17 patients who received albumin for volume expansion after open-heart surgery . During the 24-hour study period there was no significant difference between the two groups with respect to systemic blood pressure , mean arterial pressure , cardiac index , right atrial pressure , and pulmonary capillary wedge pressure , with the exception of a higher mean arterial pressure and systolic blood pressure at 4 hours in the albumin group and higher heart rate at 12 hours in the pentastarch group . In addition , postoperative prothrombin time , partial thromboplastin time , fibrinogen , platelets , and factor VIII levels were not significantly different between the two groups . There were no complications attributed to colloid administration . The hemodynamic parameters were further evaluated in a subset of 6 pentastarch and 9 albumin patients who received the first 500 mL of colloid in a similar time frame and under similar clinical conditions . The patients who received pentastarch showed a significantly greater increase in cardiac index than did the patients who received albumin . No significant change in other parameters were noted between the two groups . The authors conclude that pentastarch is as safe as albumin and may be a more effective volume exp and er than albumin when used in open-heart surgery patients Changes in transfusion behaviour induce a widespread use of colloid plasma substitutes , the range of which has recently been enlarged by the marketing of starch derivatives . The product chosen depends , at least in part , on its adverse effects , anaphylactoid reactions being a part of these . This study aim ed to discover the frequency and severity of these reactions according to the type of substitute available in France , to look for possible risk factors , and determine the mechanisms involved . A prospect i ve inquiry was carried out in 49 public and private hospitals spread throughout France . It lasted for 15 months , between June 1991 and October 1992 . A data sheet was filled in for each patient who was given a plasma substitute  , whether or not there was an incident . When a reaction did occur , an assessment was carried out in two stages : straightaway , with the measurement of the concentrations of serum tryptase , antigelatin antibodies , urinary methylhistamine ; and four to six weeks later , with skin tests .  A series of 19.593 patients was thus collected : 48.1 % were given gelatins , 26.7 % starches , 15.7 % albumin , and 9.5 % dextrans . 43 anaphylactoid reactions were recorded , giving an overall frequency of 0.219 % , or 1 reaction for 456 patients . The frequency differed according to the substitute considered : 0.345 % for gelatins , 0.273 % for dextrans , 0.099 % for albumin , and 0.058 % for starches . These reactions ( grade s III and IV ) were serious in 20 % of cases . Multivariate analysis revealed four independent risk factors : giving gelatins ( odds ratio : 4.81 ) , giving dextrans ( odds ratio : 3.83 ) , a history of drug allergy ( odds ratio : 3.16 ) , and being male ( odds ratio : 1.98 ) . The relative risks of anaphylactoid reactions due to one type of substitute with respect to another were estimated to be 6 times less for starches with respect to gelatins , and 4.7 times less than with dextrans . The relative risk of albumin is 3.4 times less than that of gelatins , and almost identical to that of the starches . An immuno-allergological assessment was only carried out in 15 patients who had been given a gelatin ( Plasmion ) . IgE-dependent anaphylaxis was proven in 7 of these . To conclude , it was shown that gelatins and dextrans should be avoided in patients with a known history of drug allergy . When a reaction does occur , an allergological assessment must be carried out , as this may be due to specific antibodies . Should this prove to be the case , that particular substitute would be contraindicated for the rest of the patient 's life Hydroxyethyl starch ( HES ) is efficacious as a volume exp and er in cardiac surgical patients , but it may impair the haemostatic mechanisms . However , this latter effect may be less conspicuous with low molecular weight ( LMW ) solutions than with high molecular weight ( HMW ) solutions . Therefore , LMW- and HMW-HES solutions were evaluated as priming solutions for cardiopulmonary bypass ( CPB ) with respect to their effect on haemostasis . Forty-five patients undergoing coronary bypass grafting were prospect ively r and omised to three groups and received in a double-blind manner as their CPB prime either 20 ml.kg-1 LMW-HES ( Mw 120,000 ) , 20 ml.kg-1 HMW-HES ( Mw 400,000 ) or Ringer 's acetate 2000 ml . The final volume of the prime was completed to 2000 ml with Ringer 's acetate in the HES groups . Anaesthesia and CPB management were st and ardised . Plasma levels of von Willebr and factor antigen and factor VIII procoagulant activity were significantly more depressed after CPB in both HES-groups as compared with the crystalloid prime group . In addition , APTT was more prolonged and the maximal amplitude of thromboelastographic tracing was more decreased in the HES-groups . It is concluded that it may be advisable to avoid HES solutions in the CPB prime , especially in patients with an increased risk for bleeding after cardiac operations In this prospect i ve , r and omized , open controlled study we compared the effects on net red blood cell loss of 6 % hydroxyethyl starch 130/0.4 ( HES : n = 64 ) and 3 % modified fluid gelatin ( GEL : n = 68 ) administered for intravascular volume management in patients undergoing coronary surgery .  Blood losses were calculated from determination of circulating blood volume and measurement of preoperative and postoperative hematocrit . Amount of colloids that could be administered was limited to 50 mL/kg . If additional fluids were required , balanced crystalloid solution was used . Anesthetic and surgical techniques were st and ardized . Both groups were similar with regard to demographic and intraoperative variables . Total study drug was 48.9 ± 17.2 mL/kg in the HES group and 48.9 ± 14.6 mL/kg in the GEL group . Total red blood cell loss was 544 ± 305 mL in the HES group and 504 ± 327 mL the GEL group . Measured blood losses were also similar in both groups ( HES , 19.4 ± 12.3 mL/kg ; GEL , 19.2 ± 14.5 mL/kg ) . Exposure to allogeneic blood product was comparable in both groups . In the conditions of the present study , HES 130/0.4 up to 50 mL/kg is a valuable alternative to modified fluid gelatin for plasma volume expansion during and after cardiac surgery Background Hydroxyethyl starch ( HES ) 130/0.4 may impair blood coagulation less than other HES solutions and , thus , may be used at larger doses without increasing the risk of postoperative bleeding . This study tested the hypothesis that volume replacement with 6 % HES 130/0.4 at a dose of up to 50 ml/kg does not increase blood loss and transfusion requirements in elective coronary artery bypass surgery compared with 6 % HES 200/0.5 at a dose of up to 33 ml/kg . Methods One hundred twenty adult patients scheduled for elective coronary artery bypass surgery were r and omized to receive up to 50 ml/kg of 6 % HES 130/0.4 or up to 33 ml/kg of 6 % HES 200/0.5 for volume replacement during surgery and until 24 h thereafter . Volume requirements in excess of the respective maximum dose of HES were treated with gelatin . Colloid use was at the discretion of the attending physicians and not dictated by protocol . The primary outcome variable was chest tube drainage volume during the first 24 h after surgery . Results The data from 117 patients ( HES 130/0.4 , 59 patients ; HES 200/0.5 , 58 patients ) who completed the study according to protocol were analyzed . The median volumes of HES administered were 49 and 33 ml/kg in the HES 130/0.4 and HES 200/0.5 groups , respectively ( P < 0.001 ) . Consequently , patients in the HES 130/0.4 group required less  gelatin  in addition to HES than those in the HES 200/0.5 group ( medians : 7 ml/kg vs. 20 ml/kg , P < 0.001 ) . The combined volumes of HES and gelatin were similar for both groups ( P = 0.21 ) . The 24-h chest tube drainage ( medians : 660 ml vs. 705 ml , P = 0.60 ) did not differ significantly between the groups , nor did transfusion outcome . Conclusion Six percent HES 130/0.4 at a median dose of 49 ml/kg did not increase blood loss and transfusion requirements in coronary artery bypass surgery compared with 6 % HES 200/0.5 at a median dose of 33 ml/kg Objectives : To determine whether a starch solution for volume resuscitation in a flow-based protocol improves circulatory status better than a crystalloid solution , as defined by the need for catecholamines in patients the morning after cardiac surgery , and whether this can be performed without increased morbidity . Design : Concealed , r and omized , double-blind , controlled trial . Participants : Two hundred sixty-two patients who underwent cardiac surgery at a tertiary care hospital . Interventions : Based on predefined criteria indicating a need for fluids , and a nurse-delivered algorithm that used central venous pressure and cardiac index obtained from a pulmonary artery catheter , patients were allocated to receive 250-mL boluses of 0.9 % saline or a 250-molecular weight 10 % solution of pentastarch . Results : Two hundred thirty-seven patients received volume boluses : 119 hydroxyethyl starches and 118 saline . Between 8:00 am and 9:00 am the morning after surgery , 13 ( 10.9 % ) of hydroxyethyl starch patients and 34 ( 28.8 % ) saline patients were using catecholamines ( p = .001 ) . Hydroxyethyl starch patients had less pneumonia and mediastinal infections ( p = .03 ) and less cardiac pacing ( p = .03 ) . There were two deaths in each group . There was no difference in the daily creatinine , development of RIFLE risk criteria during hospital stay , or new dialysis . The numbers and volumes of packed red blood cells were similar in the two groups , but more hydroxyethyl starch patients received plasma transfusions ( p = .05 ) . Conclusions : Use of a colloid solution for volume resuscitation in a nurse-delivered flow-based algorithm , which included a pulmonary artery catheter , significantly improved hemodynamic status , an important factor for readiness for discharge from the intensive care unit We investigated the effect of postoperative administration of colloids on hemostasis in 45 patients after cardiac surgery . Patients were r and omized to receive 15 mL kg−1 of either 4 % albumin , 4 % succinylated gelatin , or 6 % hydroxyethyl starch ( molecular weight of 200 kDa/degree of substitution 0.5 ) as a short-term infusion . There was a comparable decrease in maximum clot firmness of thromboelastometry tracings in gelatin and hydroxyethyl starch groups immediately after completion of the infusion , whereas these values remained unchanged in the albumin group . The impairment in clot strength persisted up to 2 h , although the values partly recovered . Postoperative bleeding correlated inversely with the clot strength in pooled data of the artificial colloids . Fibrin formation ( clot formation time , & agr;-angle ) and fibrinogen-dependent clot strength ( maximum clot firmness and shear elastic modulus ) were more disturbed in the hydroxyethyl starch group than in the gelatin group . We conclude that after cardiopulmonary bypass surgery , both gelatin and hydroxyethyl starch impair clot strength and fibrin buildup , which may predispose patients to increased blood loss . The greatest impairment in hemostasis was seen after hydroxyethyl starch administration , whereas albumin appeared to have the least effect on hemostatic variables Objective : To evaluate the magnitude and cause of metabolic acidosis after infusion of 7.5 % sodium chloride 6 % dextran 70 . Design : R and omized , prospect i ve clinical study . Setting : University hospital . Patients : Two groups of 14 patients each , undergoing repair of abdominal aortic aneurysm . Interventions : Patients were r and omly assigned to receive either 250 mL of hypertonic saline dextran ( HSD ) or a conventional fluid regimen with 250 mL of hydroxyethyl starch in normal saline solution ( H-NS ) during the period of aortic clamping . Additionally , normal sal 
    Output:
    
No difference was found in terms of complications , renal failure , or reoperation .
Conclusions Perioperative administration of HES preparations is comparatively safe .
As the third generation of HES preparations , HES 130 kD showed a trend toward lower blood loss and transfusion rates and is a suitable choice for cardiovascular surgery