***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: The actual incidence of neurologic dysfunction result ing from hemorrhagic complications associated with neuraxial blockade is unknown . Although the incidence cited in the literature is estimated to be less than 1 in 150,000 epidural and less than 1 in 220,000 spinal anesthetics , recent epidemiologic surveys suggest that the frequency is increasing and may be as high as 1 in 3000 in some patient population s. Overall , the risk of clinical ly significant bleeding increase with age , associated abnormalities of the spinal cord or vertebral column , the presence of an underlying coagulopathy , difficulty during needle placement , and an indwelling neuraxial catheter during sustained anticoagulation ( particularly with st and ard heparin or low-molecular weight heparin ) . The need for prompt diagnosis and intervention to optimize is also consistently reported . In response to these patient safety issues , the American Society of Regional Anesthesia and Pain Medicine ( ASRA ) convened its Third Consensus Conference on Regional Anesthesia and Anticoagulation . Practice guidelines or recommendations summarize evidence -based review s. However , the rarity of spinal hematoma defies a prospect i ve r and omized study , and there is no current laboratory model . As a result , the ASRA consensus statements represent the collective experience of recognized experts in the field of neuraxial anesthesia and anticoagulation . These are based on case reports , clinical series , pharmacology , hematology , and risk factors for surgical bleeding . An underst and ing of the complexity of this issue is essential to patient management Background Delirium is a common complication in elderly patients after surgery and associated with increased morbidity and mortality . Studies suggest that deep anesthesia and intense pain are important precipitating factors of postoperative delirium . Neuraxial block is frequently used in combination with general anesthesia for patients undergoing major thoracic and abdominal surgery . Compared with general anesthesia alone and postoperative intravenous analgesia , combined epidural-general anesthesia and postoperative epidural analgesia decreases the requirement of general anesthetics during surgery and provided better pain relief after surgery . However , whether combined epidural-general anesthesia plus epidural analgesia is superior to general anesthesia plus intravenous analgesia in decreasing the incidence of postoperative delirium remains unknown . Methods / design This is a multicenter , open-label , r and omized , parallel-controlled clinical trial . One thous and eight hundred elderly patients ( age range 60–90 years ) who are scheduled to undergo major thoracic or abdominal surgery are r and omized to receive either general anesthesia plus postoperative intravenous analgesia or combined epidural-general anesthesia plus postoperative epidural analgesia . The primary outcome is the 7-day incidence of postoperative delirium . Secondary outcomes include the duration of postoperative delirium , the intensity of pain during the first three days after surgery , the 30-day incidences of postoperative non-delirium complications , the length of stay in hospital after surgery and 30-day all-cause mortality . Discussion Results of the present study will provide information to guide clinical practice in choosing appropriate anesthesia-analgesia method for elderly patients undergoing major thoracic and abdominal surgery . Trial registration The study is registered on Clinical Trials.gov NCT01661907 and Chinese Clinical Trial Registry ChiCTR-TRC-12002371 The effects of thoracic epidural anesthesia ( TEA ) on total body oxygen supply-dem and ratio are complex due to potential influences on both O2 delivery ( & OV0422;O2 ) and consumption ( & OV0312;O2 ) . One hundred and five patients undergoing abdominal aortic surgery were r and omly assigned to one of three groups to compare the cardiovascular and metabolic responses associated with ( 1 ) thoracic epidural anesthesia plus light general anesthesia ( group TEA ) ; ( 2 ) general anesthesia with halothane ( group H ) ; and ( 3 ) neuroleptanalgesia ( group NLA ) . Values of cardiac index ( CI ) and & OV0422;O2 were less intra operatively in the TEA group than in the H or NLA groups , while & OV0312;O2 values were similar . & OV0312;O2 during recovery was greater in both the TEA and NLA groups than in the H group . Consequently the oxygen supply-dem and ratio ( & OV0422;O2/&OV0312;O2 ) was less in the TEA group throughout the perioperative period and about 30 % below baseline values during early recovery . At comparable & OV0312;O2 , CI and mixed venous O2 saturation were always less in the TEA group than in the NLA group . Heart rate was slowest intra operatively during TEA , and stroke work was less with TEA than with NLA . As cardiac filling pressure and systemic vascular resistance did not differ among the three groups , reduced adaptation of CI to tissue O2 needs during TEA was attributed to negative inotropic and chronotropic effects of the sympathetic blockade . We conclude that in patients undergoing abdominal aortic surgery , TEA has no apparent advantage over general anesthesia Purpose To determine the effect of epidural anesthesia ( EP ) on oxygenation of the chronically ischemic limb in patients undergoing aorto-femoral bypass grafting and to assess whether it produces an alteration of lipid peroxidation and antioxidant status following revascularization . Methods In this prospect i ve , r and omized , single-blinded study 40 ASA II or III patients undergoing elective aorto-femoral bypass grafting were allocated to receive general anesthesia ( group GA , n = 20 ) , or epidural + GA ( group EP , n = 20 ) during surgery . Femoral venous blood-gas status , activities of the protecting antioxidant enzymes superoxide dismutase ( SOD ) , glutathione peroxidase ( GSH-px ) , glutathione reductase ( GSH-rd ) , glutathione ( GSH ) and thiobarbituric acid-reactive substances ( TBARS ) as a marker of lipid peroxidation were determined in blood sample s taken from the femoral vein at different intervals before and after revascularization . Results Before the induction of anesthesia in group EP , femoral venous PO2 [ mean ( st and ard deviation ) , 95 % confidence interval ] increased after achieving an adequate level of blockade by EP extending to the dermatomal level of T6 - 8 [ 29.32 ( 4.6 ) , 26.34–32.30 to 36.29 ( 4.6 ) , 33.37–39.22 mmHg , P < 0.05 ] . Femoral venous PO2 was similar in both groups thereafter . In the GA group a significant increase in erythrocyte TBARS was observed immediately after restoration of blood flow when compared with baseline values [ 221.32 ( 102 ) , 148.35 - 294 - 29 to 337.26 ( 123 ) 248.99 - 425.53 nmol·g−1 hemoglobin , P < 0.01 ] but not at any other moment . In the EP group TBARS did not increase throughout the study . Within group comparisons revealed no significant differences in GSH , GSH-px , GSH-rd and SOD . Conclusion In patients with atherosclerotic aorto-iliac occlusive disease EP may possibly attenuate lipid peroxidation following revascularization but has no effect on antioxidant enzyme activities . RésuméObjectifDéterminer l’effet de l’anesthésie péridurale ( AP ) sur l’oxygénation du membre soumis à l’ischémie chez les patients qui subissent un pontage aorto-fémoral et évaluer si elle produit une altération de la peroxydation lipidique et de l’état antioxydant à la suite de la revascularisation . MéthodeUne étude prospect i ve , r and omisée et à simple insu a été menée auprès de 40 patients d’état physique ASA II ou III qui devaient subir un pontage aorto-fémoral sous anesthésie générale ( groupe AG , n = 20 ) ou anesthésie péridurale + AG ( groupe AP , n = 20 ) . La gazométrie du sang veineux fémoral , les activités des enzymes protecteurs antioxydants superoxyde dismutase ( SOD ) , glutathion peroxydase ( GSH-px ) , glutathion réductase ( GSH-rd ) , glutathion ( GSH ) et les substances réactives à l’acide thiobarbiturique  ( SRATB ) , comme marqueur de la peroxydation lipidique , ont été mesurés dans les échantillons sanguins prélevés de la veine fémorale à différents intervalles avant et après la revascularisation . RésultatsAvant l’induction de l’AP , la PO2 veineuse fémorale [ moyenne ( écart type ) , intervalle de confiance de 95 % ] s’est élevée après le blocage péridural adéquat s’étendant au niveau du dermatome T6 - 8 [ 29,32 ( 4,6 ) 26,34 - 32,30 à 36,29 ( 4,6 ) 33,37 - 39,22 mmHg , P < 0,05 ] . La PO2 veineuse fémorale a été similaire dans les deux groupes par la suite . Dans le groupe AG , une hausse significative d’érythrocyte SRATB , en comparaison avec les valeurs de base , a été notée immédiatement et seulement après la restauration du débit sanguin [ 221,32 ( 102 ) 148,35 - 294 - 29 à 337,26 ( 123 ) 248,99 - 425,53 nmol·g−1 hémoglobine , P < 0,01 ] . Dans le groupe AP , les SRATB n’ont pas augmenté pendant l’étude . Aucune différence intragroupe significative de GSH , GSH-px , GSH-rd et SOD n’a été notée . Conclusion Chez les patients atteints d’occlusion aorto-iliaque , l’AP peut atténuer la peroxydation lipidique à la suite de la revascularisation , mais n’a pas d’effet sur les activités antioxydantes des enzymes UNLABELLED It has been shown that the stress response to lower abdominal surgery can be inhibited by epidural analgesia ( EA ) . But EA seems to have little influence on the stress reaction to major abdominal surgery . The purpose of our study was to find out whether EA is able to diminish the cortisol and glucose response to major transabdominal surgery . METHODS 31 patients undergoing elective surgery of the abdominal aorta were subdivided at r and om into 3 different anaesthesia groups : 1 . halothane anesthesia , 2 . neuroleptanalgesia ( NLA ) and 3 . thoracic EA with bupivacaine ( 0.5 % ) in combination with a light general anesthesia . Some patients of each group received an intravenous infusion of 5 % glucose . Blood sample s were drawn before anesthesia , after intubation , 5 times during surgery and at the end of the operation and were analysed for cortisol and glucose . During the early postoperative period , 1 , 2 and 24 h after surgery , only cortisol was measured . RESULTS Only the glucose levels of patients who received no carbohydrate-containing infusion fluids were used for evaluation of the stress response . In the halothane group , there was a significant increase of the mean cortisol and glucose levels after the start of surgery . No intraoperative elevations of blood glucose and cortisol were seen in the EA group . Patients of the NLA group showed no hyperglycaemia and only mild elevations of the cortisol levels during the intraoperative period . ( ABSTRACT TRUNCATED AT 250 WORDS The Multicenter Australian Study of Epidural Anesthesia and Analgesia in Major Surgery ( The MASTER Trial ) was design ed to evaluate the possible benefit of epidural block in improving outcome in high-risk patients . The trial began in 1995 and is scheduled to reach the planned sample size of 900 during 2001 . This paper describes the trial design and presents data comparing 455 patients r and omized in 21 institutions in Australia , Hong Kong , and Malaysia , with 237 patients from the same hospitals who were eligible but not r and omized . Nine categories of high-risk patients were defined as entry criteria for the trial . Protocol s for ethical review , informed consent , r and omization , clinical anesthesia and analgesia , and perioperative management were determined following extensive consultation with anesthesiologists throughout Australia . Clinical and research information was collected in participating hospitals by research staff who may not have been blind to allocation . Decisions about the presence or absence of endpoints were made primarily by a computer algorithm , supplemented by blinded clinical experts . Without unblinding the trial , comparison of eligibility criteria and incidence of endpoints between r and omized and nonr and omized patients showed only small differences . We conclude that there is no strong evidence of important demographic or clinical differences between r and omized 
    Output:
    
The level of evidence was low for mortality and time before tracheal extubation ; moderate for myocardial infa rct ion , respiratory failure and intensive care unit length of stay ; and high for gastrointestinal bleeding and VAS scores .
AUTHORS ' CONCLUSIONS Epidural analgesia provided better pain management , reduced myocardial infa rct ion , time to tracheal extubation , postoperative respiratory failure , gastrointestinal bleeding , and intensive care unit length of stay compared with systemic opioid-based drugs .
For mortality , we did not find a difference at 30 days