***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: AIM To investigate the effect of low central venous pressure ( LCVP ) on blood loss during hepatectomy for hepatocellular carcinoma ( HCC ) . METHODS By the method of sealed envelope , 50 HCC patients were r and omized into LCVP group ( n=25 ) and control group ( n=25 ) . In LCVP group , CVP was maintained at 2 - 4 mmHg and systolic blood pressure ( SBP ) above 90 mmHg by manipulation of the patient 's posture and administration of drugs during hepatectomy , while in control group hepatectomy was performed routinely without lowering CVP . The patients ' preoperative conditions , volume of blood loss during hepatectomy , volume of blood transfusion , length of hospital stay , changes in hepatic and renal functions were compared between the two groups . RESULTS There were no significant differences in patients ' preoperative conditions , maximal tumor dimension , pattern of hepatectomy , duration of vascular occlusion , operation time , weight of resected liver tissues , incidence of post-operative complications , hepatic and renal functions between the two groups . LCVP group had a markedly lower volume of total intraoperative blood loss and blood loss during hepatectomy than the control group , being 903.9+/-180.8 mL vs 2 329.4+/-2 538.4 ( W=495.5 , P<0.01 ) and 672.4+/-429.9 mL vs 1 662.6+/-1 932.1 ( W=543.5 , P<0.01 ) . There were no remarkable differences in the pre-resection and post-resection blood losses between the two groups . The length of hospital stay was significantly shortened in LCVP group as compared with the control group , being 16.3+/-6.8 d vs 21.5+/-8.6 d ( W=532.5 , P<0.05 ) . CONCLUSION LCVP is easily achievable in technique . Maintenance of CVP < or= 4 mmHg can help reduce blood loss during hepatectomy , shorten the length of hospital stay , and has no detrimental effects on hepatic or renal function Objective This prospect i ve r and omized study determined the influence of closed-suction drainage on the incidence of postoperative complications after elective hepatic resection . Summary Background Data Routine drainage is no longer advocated after several intra-abdominal surgical procedures . Methods A series of 81 patients who underwent elective hepatic resection were r and omly allocated to either a nondrainage group ( n = 39 ) and a drainage group with closed-suction drainage ( n = 42 ) . Indications for resection were 42 benign lesions and 39 malignant tumors , including 19 with cirrhosis . Major hepatic resection was performed in 25 patients and minor resection , in 56 . All patients underwent ultrasonography with puncture for bacteriologic cultures of all fluid collection s within the first 5 postoperative days . Results One patient died in each group . Ultrasonography found a significantly higher rate of subphrenic collection s in the drainage group compared with the nondrainage group ( respectively , 36 % vs. 15 % , p < 0.05 ) . These collection s were more frequently infected in the drainage group ( n = 6 ) than in the nondrainage group ( n = 2 ) . After major liver resection , the rate of intra-abdominal postoperative complications ( i.e. , subphrenic fluid collection s , hematomas , and bilomas ) was similar between the two groups . Conclusion Minor liver resection is safer without drainage . Major liver resection can be performed with or without abdominal drainage BACKGROUND Two r and omized prospect i ve studies suggested that ischemic preconditioning ( IP ) protects the human liver against ischemia-reperfusion injury after hepatectomy performed under continuous clamping of the portal triad . The primary goal of this study was to determine whether IP protects the human liver against ischemia-reperfusion injury after hepatectomy under continuous vascular exclusion with preservation of the caval flow . STUDY DESIGN Sixty patients were r and omly divided into two groups : with ( n=30 ; preconditioning group ) and without ( n=30 ; control group ) IP ( 10 minutes of portal triad clamping and 10 minutes of reperfusion ) before major hepatectomy under vascular exclusion of the liver preserving the caval flow .  Serum concentrations of aspartate transferase , alanine transferase , glutathione-S-transferase , and bilirubin and prothrombin time were regularly determined until discharge and at 1 month . Morbidity and mortality were determined in both groups . RESULTS Peak postoperative concentrations of aspartate transferase were similar in the groups with and without IP ( 851 + /- 1,733 IU/L and 427 + /- 166 IU/L respectively , p=0.2 ) . A similar trend toward a higher peak concentration of alanine transferase and glutathione-S-transferase was indeed observed in the preconditioning group compared with the control group . Morbidity and mortality rates and lengths of ICU and hospitalization stays were similar in both groups . CONCLUSIONS IP does not improve liver tolerance to ischemia-reperfusion after hepatectomy under vascular exclusion of the liver with preservation of the caval flow . This maneuver does not improve postoperative liver function and does not affect morbidity or mortality rates . The clinical use of IP through 10 minutes of warm ischemia in this technique of hepatectomy is not currently recommended OBJECTIVES To analyze sources search ed in Cochrane review s , to determine the proportion of trials included in review s that are indexed in major data bases , and to compare the quality of these trials with those from other sources . METHODS All new systematic review s in the Cochrane Library , Issue1 2001 , that were restricted to r and omized controlled trials ( RCTs ) or quasi- RCTs were selected . The sources search ed in the review s were recorded , and the trials included were checked to see whether they were indexed in four major data bases . Trials not indexed were checked to determine how they could be identified . The quality of trials found in major data bases was compared with those found from other sources . RESULTS The range in the number of data bases search ed per review ranged between one and twenty-seven . The proportion of the trials in the four data bases were Cochrane Controlled Trials Register = 78.5 % , MEDLINE = 68.8 % , Embase = 65.0 % , and Science/Social Sciences Citation Index = 60.7 % . Search ing another twenty-six data bases after Cochrane Controlled Trials Register ( CCTR ) , MEDLINE , and Embase only found 2.4 % additional trials . There was no significant difference between trials found in the CCTR , MEDLINE , and Embase compared with other trials , with respect to adequate allocation concealment or sample size . CONCLUSIONS There was a large variation between review s in the exhaustiveness of the literature search es . CCTR was the single best source of RCTs . Additional data base search ing retrieved only a small percentage of extra trials . Contacting authors and manufacturers to find unpublished trials appeared to be a more effective method of obtaining the additional better quality trials Background / Aims : Degradation of adenine nucleotides to adenosine has been suggested to play a critical role in ischemic preconditioning ( IPC ) . Thus , we question ed in patients undergoing partial hepatectomy whether ( i ) IPC will increase plasma purine catabolites and whether ( ii ) formation of purines in response to vascular clamping ( Pringle maneuver ) can be attenuated by prior IPC . Methods : 75 patients were r and omly assigned to three groups : group I underwent hepatectomy without vascular clamping ; group II was subjected to the Pringle maneuver during resection , and group III was preconditioned ( 10 min ischemia and 10 min reperfusion ) prior to the Pringle maneuver for resection .  Central , portal venous and arterial plasma concentrations of adenosine , inosine , hypoxanthine and xanthine were determined by high-performance liquid chromatography . Results : Duration of the Pringle maneuver did not differ between patients with or without IPC . Surgery without vascular clamping had only a minor effect on plasma purine concentrations . After IPC , plasma concentrations of purines transiently increased . After the Pringle maneuver alone , purine plasma concentrations were most increased . This strong rise in plasma purines caused by the Pringle maneuver , however , was significantly attenuated by IPC . When portal venous minus arterial concentration difference was calculated for inosine or hypoxanthine , the respective differences became positive in patients subjected to the Pringle maneuver and were completely prevented by preconditioning . Conclusion : These data demonstrate that ( i ) IPC increases formation of adenosine , and that ( ii ) the unwanted degradation of adenine nucleotides to purines caused by the Pringle maneuver can be attenuated by IPC . Because IPC also induces a decrease of portal venous minus arterial purine plasma concentration differences , IPC might possibly decrease disturbances in the energy metabolism in the intestine as well Objective : To st and ardize the definition of postoperative liver failure ( PLF ) for prediction of early mortality after hepatectomy . Summary Background Data : The definition of PLF is not st and ardized , making the comparison of innovations in surgical techniques and the timely use of specific therapeutic interventions complex . Methods : Between 1998 and 2002 , 775 elective liver resections , including 69 % for malignancies and 60 % major resections , were included in a prospect i ve data base . The nontumorous liver was abnormal in 43 % with steatosis > 30 % in 14 % , noncirrhotic fibrosis in 43 % , and cirrhosis in 12 % . The impact of  prothrombin time ( PT ) < 50 % and serum bilirubin ( SB ) > 50 & mgr;mol/L on postoperative days ( POD ) 1 , 3 , 5 , and 7 was analyzed . Results : The lowest PT level was observed on postoperative day ( POD ) 1 , while the peak of SB was observed on POD 3 . These 2 variables tended to return to preoperative values by POD 5 . The median interval between hepatectomy and postoperative death was 15 days ( range , 5–39 days ) . Postoperative mortality significantly increased in patients with PT < 50 % and SB > 50 & mgr;ml/L. The conjunction of PT < 50 % and SB > 50 & mgr;mol/L on POD 5 was a strong predictive factor of mortality . In patients with significant morbidity , this “ 50 - 50 criteria ” was met 3 to 8 days before clinical evidence of complications . Conclusions : The association of PT < 50 % and SB > 50 & mgr;ml/L on POD 5 ( the 50 - 50 criteria ) was a simple , early , and accurate predictor of more than 50 % mortality rate after hepatectomy . This criteria could be identified early enough , before clinical evidence of complications , for specific interventions to be applied in due time BACKGROUND The Pringle manoeuvre and ischaemic preconditioning are applied to prevent blood loss and ischaemia-reperfusion injury , respectively , during liver surgery . In this prospect i ve clinical trial we report on the intraoperative haemodynamic effects of the Pringle manoeuvre alone or in combination with ischaemic preconditioning . METHODS Patients ( n=68 ) were assigned r and omly to three groups : ( i ) resection with the Pringle manoeuvre ; ( ii ) with ischaemic preconditioning before the Pringle manoeuvre for resection ; ( iii ) without pedicle clamping .  RESULTS Following the Pringle manoeuvre the mean arterial pressure increased transiently , but significantly decreased after unclamping as a result of peripheral vasodilation . Ischaemic preconditioning improved cardiovascular stability by lowering the need for catecholamines after liver reperfusion without affecting the blood sparing benefits of the Pringle manoeuvre . In addition , ischaemic preconditioning protected against reperfusion-induced tissue injury . CONCLUSIONS Ischaemic preconditioning provides both better intraoperative haemodynamic stability and anti-ischaemic effects thereby allowing us to take full advantage of blood loss reduction by the Pringle manoeuvre HYPOTHESIS Blood loss in hepatic resection is an important determinant of operative outcome . OBJECTIVE To clarify whether reducing the tidal volume would be effective in decreasing blood loss during liver transection . DESIGN R and omized controlled trial . SETTING University hospital . PATIENTS Eighty patients scheduled to undergo hepatic resection were r and omly assigned to receive liver transection under normoventilation ( n = 40 ) or hypoventilation ( n = 40 ) . INTERVENTIONS During liver transection , in the normoventilation group , the tidal volume was 10 mL/kg and the respiratory rate was 10/min ; in the hypoventilation group , the tidal volume was reduced to 4 mL/kg and respiratory rate was increased to 15/min . Liver transection was performed under total or selective inflow occlusion . MAIN OUTCOME MEASURE Blood loss . RESULTS Between the 
    Output:
    
There was no difference in mortality , liver failure , or other morbidities .
The blood loss was significantly lower in vascular occlusion compared with no vascular occlusion .
Intermittent vascular occlusion seems safe in liver resection .
However , it does not seem to decrease morbidity .