***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: BACKGROUND Goal directed fluid therapy ( GDFT ) has been shown to improve outcomes in moderate to high-risk surgery . However , most of the present GDFT protocol s based on cardiac output optimization use invasive devices and the protocol s may require significant practitioner attention and intervention to apply them accurately . The aim of this prospect i ve pilot study was to evaluate the clinical feasibility of GDFT using a closed-loop fluid administration system with a non-invasive cardiac output monitoring device ( Nexfin ™ , BMEYE , Amsterdam , Netherl and s ) . METHODS Patients scheduled for elective moderate risk surgery under general anaesthesia were enrolled . The primary anaesthesia team managing the case selected GDFT targets using the controller interface and all patients received a baseline 3 ml kg(-1 ) h(-1 ) crystalloid infusion . Colloid solutions were delivered by the closed-loop system for intravascular volume expansion using data from the Nexfin ™ monitor . Compliance with GDFT management was defined as acceptable when a patient spent more than 85 % of the surgery time in a preload independent state ( defined as pulse pressure variation < 13 % ) or when average cardiac index during surgery was > 2.5 litre min(-1 ) m(-2 ) . RESULTS A total of 13 patients were included in the study group . All patients met the established criteria for delivery of GDFT  for greater than 85 % of case time . The median length of stay in the hospital was 5 [ 3 - 6 ] days . CONCLUSION In this pilot study , GDFT management using the closed-loop fluid administration system with a non-invasive CO monitoring device was feasible and maintained a high rate of protocol compliance . CLINICAL TRIAL REGISTRATION NCT02020863 UNLABELLED The effects of intravascular volume replacement regimens on tissue oxygen tension ( ptiO(2 ) ) are not definitely known . Forty-two consecutive patients scheduled for elective major abdominal surgery were prospect ively r and omized to receive either 6 % hydroxyethyl starch ( HES ) ( mean molecular weight 130 kd , degree of substitution 0.4 , n = 21 ) or lactated Ringer 's solution ( RL , n = 21 ) for intravascular volume replacement . Fluids were administered perioperatively and continued for 24 h on the intensive care unit to keep central venous pressure between 8 and 12 mm Hg . The ptiO(2 ) was measured continuously in the left deltoid muscle by using microsensoric implantable partial pressure of oxygen catheters after the induction of anesthesia ( baseline , T0 ) , 60 min ( T1 ) and 120 min thereafter ( T2 ) , at the end of surgery ( T3 ) , and on the morning of the first postoperative day on the intensive care unit ( T4 ) . HES 130/0.4 2920 + /- 360 mL and 11,740 + /- 2,630 mL of RL were given to the patients within the study period . Systemic hemodynamics and oxygenation ( PaO(2 ) , PaCO(2 ) ) did not differ significantly between the two volume groups throughout the study . From similar baseline values , ptiO(2 ) increased significantly in the HES-treated patients ( a maximum of 59 % at T4 ) , whereas it decreased in the RL group ( a maximum of -23 % at T4 , P < 0.05 ) . The largest differences of ptiO(2 ) were measured on the morning of the first postoperative day . We conclude that intravascular volume replacement with 6 % HES 130/0.4 improved tissue oxygenation during and after major surgical procedures compared with a crystalloid-based volume replacement strategy . Improved microperfusion and less endothelial swelling may be responsible for the increase in ptiO(2 ) in the HES 130/0.4-treated patients . IMPLICATION S In patients undergoing major abdominal surgery , a colloid-based ( with hydroxyethyl starch [ HES ] 130/0.4 ) and a crystalloid-based ( with lactated Ringer 's solution [ RL ] ) volume replacement regimen was compared regarding tissue oxygen tension ( ptiO(2 ) ) measured continuously by microsensoric implantable catheters . The ptiO(2 ) increased in the HES-treated ( + 59 % ) but decreased in the RL-treated ( -23 % ) patients . Improved microcirculation may be the mechanism for the better ptiO(2 ) in the HES group Background : An individualized fluid optimization strategy , based on maximization of cardiac stroke volume ( SV ) with colloid boluses ( goal ‐directed therapy ) , improves outcome after surgery .  Oesophageal Doppler ( OD ) is used for SV maximization in most r and omized studies , but evidence ‐based guidelines for the SV maximization procedure are lacking and variation in SV may influence the indication for fluid administration . We measured beat‐to‐beat OD SV before and after  fluid optimization  in order to estimate the number of heartbeats for which SV needs to be averaged to provide an acceptable accuracy for goal ‐directed therapy with this technology OBJECTIVES To study the impact of different adherence levels to the enhanced recovery after surgery ( ERAS ) protocol and the effect of various ERAS elements on outcomes following major surgery . DESIGN Single-center prospect i ve cohort study before and after reinforcement of an ERAS protocol . Comparisons were made both between and across periods using multivariate logistic regression . All clinical data ( 114 variables ) were prospect ively recorded . SETTING Ersta Hospital , Stockholm , Sweden . PATIENTS Nine hundred fifty-three consecutive patients with colorectal cancer : 464 patients treated in 2002 to 2004 and 489 in 2005 to 2007 . MAIN OUTCOME MEASURES The association between improved adherence to the ERAS protocol and the incidence of postoperative symptoms , complications , and length of stay following major colorectal cancer surgery was analyzed . RESULTS Following an overall increase in preoperative and perioperative adherence to the ERAS protocol from 43.3 % in 2002 to 2004 to 70.6 % in 2005 to 2007 , both postoperative complications ( odds ratio , 0.73 ; 95 % confidence interval , 0.55 - 0.98 ) and symptoms ( odds ratio , 0.53 ; 95 % confidence interval , 0.40 - 0.70 ) declined significantly . Restriction of intravenous fluid and use of a preoperative carbohydrate drink were major independent predictors . Across periods , the proportion of adverse postoperative outcomes ( 30-day morbidity , symptoms , and readmissions ) was significantly reduced with increasing adherence to the ERAS protocol ( > 70 % , > 80 % , and > 90 % ) compared with low ERAS adherence ( < 50 % ) . CONCLUSION Improved adherence to the st and ardized multimodal ERAS protocol is significantly associated with improved clinical outcomes following major colorectal cancer surgery , indicating a dose-response relationship Introduction Perioperative hypovolemia arises frequently and contributes to intestinal hypoperfusion and subsequent postoperative complications . Goal -directed fluid therapy might reduce these complications . The aim of this study was to compare the effects of goal -directed administration of crystalloids and colloids on the distribution of systemic , hepatosplanchnic , and microcirculatory ( small intestine ) blood flow after major abdominal surgery in a clinical ly relevant pig model . Methods Twenty-seven pigs were anesthetized and mechanically ventilated and underwent open laparotomy .  They were r and omly assigned to one of three treatment groups : the restricted Ringer lactate ( R-RL ) group ( n = 9 ) received 3 mL/kg per hour of RL , the goal -directed RL ( GD-RL ) group ( n = 9 ) received 3 mL/kg per hour of RL and intermittent boluses of 250 mL of RL , and the goal -directed colloid ( GD-C ) group ( n = 9 ) received 3 mL/kg per hour of RL and boluses of 250 mL of 6 % hydroxyethyl starch ( 130/0.4 ) . The latter two groups received a bolus infusion when mixed venous oxygen saturation was below 60 % ( ' lockout ' time of 30 minutes ) . Regional blood flow was measured in the superior mesenteric artery and the celiac trunk . In the small bowel , microcirculatory blood flow was measured using laser Doppler flowmetry . Intestinal tissue oxygen tension was measured with intramural Clark-type electrodes . Results After 4 hours of treatment , arterial blood pressure , cardiac output , mesenteric artery flow , and mixed oxygen saturation were significantly higher in the GD-C and GD-RL groups than in the R-RL group . Microcirculatory flow in the intestinal mucosa increased by 50 % in the GD-C group but remained unchanged in the other two groups . Likewise , tissue oxygen tension in the intestine increased by 30 % in the GD-C group but remained unchanged in the GD-RL group and decreased by 18 % in the R-RL group . Mesenteric venous glucose concentrations were higher and lactate levels were lower in the GD-C group compared with the two crystalloid groups . Conclusions Goal -directed colloid administration markedly increased microcirculatory blood flow in the small intestine and intestinal tissue oxygen tension after abdominal surgery . In contrast , goal -directed crystalloid and restricted crystalloid administrations had no such effects . Additionally , mesenteric venous glucose and lactate concentrations suggest that intestinal cellular substrate levels were higher in the colloid-treated than in the crystalloid-treated animals . These results support the notion that perioperative goal -directed therapy with colloids might be beneficial during major abdominal surgery Introduction Little is known about mortality rates following  general surgical procedures  in the United Kingdom . Deaths are most common in the ' high-risk ' surgical population consisting mainly of older patients , with coexisting medical disease , who undergo major surgery . Only limited data are presently available to describe this population . The aim of the present study was to estimate the size of the high-risk general surgical population and to describe the outcome and intensive care unit ( ICU ) re source use . Methods Data on inpatient general surgical procedures and ICU admissions in 94 National Health Service hospitals between January 1999 and October 2004 were extracted from the Intensive Care National Audit & Research Centre data base and the CHKS data base . High-risk surgical procedures were defined prospect ively as those for which the mortality rate was 5 % or greater . Results There were 4,117,727 surgical procedures ; 2,893,432 were elective ( 12,704 deaths ; 0.44 % ) and 1,224,295 were emergencies ( 65,674 deaths ; 5.4 % ) . A high-risk population of 513,924 patients was identified ( 63,340 deaths ; 12.3 % ) , which accounted for 83.8 % of deaths but for only 12.5 % of procedures . This population had a prolonged hospital stay ( median , 16 days ; interquartile range , 9–29 days ) . There were 59,424 ICU admissions ( 11,398 deaths ; 19 % ) . Among admissions directly to the ICU following surgery , there were 31,633 elective admissions with 3,199 deaths ( 10.1 % ) and 24,764 emergency admissions with 7,084 deaths ( 28.6 % ) . The ICU stays were short ( median , 1.6 days ; interquartile range , 0.8–3.7 days ) but hospital admissions for those admitted to the ICU were prolonged ( median , 16 days ; interquartile range , 10–30 days ) . Among the ICU population , 40.8 % of deaths occurred after the initial discharge from the ICU . The highest mortality rate ( 39 % ) occurred in the population admitted to the ICU following initial postoperative care on a st and ard ward . Conclusion A large high-risk surgical population accounts for 12.5 % of surgical procedures but for more than 80 % of deaths . Despite high mortality rates , fewer than 15 % of these patients are admitted to the ICU BACKGROUND A prospect i ve , r and omized controlled trial comparing conventional intraoperative fluid management with two differing methods of invasive haemodynamic monitoring to optimize intraoperative fluid therapy , in patients undergoing proximal femoral fracture repair under general anaesthesia . METHODS Ninety patients r and omized to three groups ; conventional intraoperative fluid management ( Gp CON  , n=29 ) , and two groups receiving additional repeated colloid fluid challenges guided by central venous pressure ( Gp CVP , n=31 ) or oesophageal Doppler ultrasonography ( Gp DOP , n=30 ) . Primary outcome measures were time to medical fitness to discharge , hospital stay and postoperative morbidity . RESULTS The fluid challenge result ed in significantly greater perioperative changes in central venous pressure between Gp CVP and Gp CON ( mean 5 ( 95 % confidence interval 3 - 7 ) mm Hg ) ( P<0.0001 ) . Important perioperative changes were also shown in Gp DOP with increases of 49.4 ms ( 19.7 - 79.1 ms ) in the corrected flow time , 
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No differences were found in secondary outcomes , neither in other subgroups .
CONCLUSIONS GDHT guided by EDM decreases postoperative complications , especially in patients undergoing colorectal surgery and high-risk surgery .
However , no differences versus restrictive fluid therapy and in intermediate-risk patients were found