***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: OBJECTIVE To eluci date the time course and magnitude of hemodynamic and fibrinolytic changes associated with sequential gradient intermittent pneumatic compression ( SGIPC ) . DESIGN Two-phase , intervention and response investigation in normal volunteers . MATERIAL S AND METHODS Subjects were assigned to  control ( phase I ) or compression ( phase II ) groups . Serial blood sample s were obtained via femoral venous catheters for tissue plasminogen activator ( tPA ) , plasminogen activator inhibitor ( PAI-1 ) , tPA-PAI-1 complex ( tPA-PAI ) , and euglobulin lysis time ( ELT ) from all subjects and for fibrin degradation products ( FbDP ) and fibrinogen degradation products ( FgDP ) from phase II subjects . Duplex venous scanning was carried out on phase II subjects before and during SGIPC . RESULTS Catheter placement caused elevations in PAI-1 and tPA-PAI , which stabilized within 4 hours of catheter insertion . In phase II , SGIPC induced significant increases in FbDP , FgDP , and tPA-PAI and decreases in ELT and PAI-1 , all of which quickly reverted to baseline on termination of compression . Femoral venous blood flow increased by more than 100 % with SGIPC . CONCLUSIONS Sequential gradient intermittent pneumatic compression induces prompt , but short-lived , alterations in both fibrinolytic and hemodynamic function . Noncontinuous SGIPC may result in suboptimal thromboembolic prophylaxis BACKGROUND Current treatment regimens that are design ed to prevent deep venous thrombosis in patients undergoing orthopaedic procedures rely predominantly on drug prophylaxis alone . The purpose of this r and omized clinical study was to evaluate the effectiveness of a mechanical adjunct to chemoprophylaxis that involves intermittent compression of the legs . METHODS During a twenty-two month period , 1803 patients undergoing a variety of orthopaedic procedures were prospect ively r and omized to receive either chemoprophylaxis alone or a combination of chemoprophylaxis and mechanical prophylaxis .  Nine hundred and two patients were managed with low-molecular-weight heparin alone , and 901 were managed with low-molecular-weight heparin and intermittent pneumatic compression of the calves for varying time periods . Twenty-four percent of the patients underwent total hip or knee joint replacement . Screening for deep venous thrombosis was performed on the day of discharge with duplex-color-coded ultrasound . RESULTS In the chemoprophylaxis-only group , fifteen patients ( 1.7 % ) were diagnosed with a deep venous thrombosis ; three thromboses were symptomatic . In the chemoprophylaxis plus intermittent pneumatic compression group , four patients ( 0.4 % ) were diagnosed with deep venous thrombosis ; one thrombosis was symptomatic . The difference between the groups with regard to the prevalence of deep venous thrombosis was significant ( p = 0.007 ) . In the chemoprophylaxis plus intermittent pneumatic compression group , no deep venous thromboses were found in patients who received more than six hours of intermittent pneumatic compression daily . CONCLUSIONS Venous thrombosis prophylaxis with low-molecular-weight heparin augmented with a device that delivers rapid-inflation intermittent pneumatic compression to the calves was found to be significantly more effective for preventing deep venous thrombosis when compared with a treatment regimen that involved low-molecular-weight heparin alone BACKGROUND The benefit of combined mechanical and pharmacologic methods for venous thromboembolism prevention after abdominal surgery has not been clearly established . OBJECTIVES To compare the efficacy and safety of fondaparinux in conjunction with intermittent pneumatic compression vs. intermittent pneumatic compression alone in this context . PATIENTS AND METHODS This was a r and omized , double-blind , placebo-controlled superiority trial . Patients aged at least 40 years undergoing abdominal surgery were r and omized to receive either fondaparinux 2.5 mg or placebo  s.c . for 5 - 9 days , starting 6 - 8 h postoperatively . All patients received intermittent pneumatic compression . The primary efficacy outcome was venous thromboembolism up to day 10 . The main safety outcomes were major bleeding and all-cause mortality . Follow-up lasted 32 days . RESULTS Of the 1309 patients r and omized , 842 ( 64.3 % ) were evaluable for efficacy . The venous thromboembolism rate was 1.7 % ( 7/424 ) in the fondaparinux-treated patients and 5.3 % ( 22/418 ) in the placebo-treated patients ( odds ratio reduction 69.8 % ; 95 % confidence interval 27.9 - 87.3 ; P = 0.004 ) . Fondaparinux significantly reduced the proximal deep vein thrombosis rate from 1.7 % ( 7/417 ) to 0.2 % ( 1/424 ; P = 0.037 ) . Major bleeds occurred in 1.6 % ( 10/635 ) and 0.2 % ( 1/650 ) of fondaparinux-treated and placebo-treated patients , respectively ( P = 0.006 ) , none being fatal or involving a critical organ . By day 32 , eight patients ( 1.3 % ) receiving fondaparinux and five ( 0.8 % ) receiving placebo had died . CONCLUSIONS In patients undergoing abdominal surgery and receiving intermittent pneumatic compression , fondaparinux 2.5 mg reduced the venous thromboembolism rate by 69.8 % as compared to pneumatic compression alone , with a low bleeding risk as compared to placebo Deep-vein thrombosis ( DVT ) and pulmonary embolism ( PE ) represent life-threatening postoperative complications frequently responsible for in-hospital mortality following total knee arthroplasty ( TKA ) . Mechanical prophylaxis in the form of a foot pump offers an alternative to pharmacological and physical therapy . The aim of this prospect i ve and r and omised study was to examine the clinical efficacy of the A-V Impulse ( AVI ) system in reduction of soft-tissue swelling of the lower limb following a TKA . A total of 80 patients undergoing cemented TKA between September 2005 and December 2006 were r and omised into two groups of 40 patients ( n¹ = 40 , n² = 40 ) during the 16-month study period . All patients received a subcutaneous dose of low molecular weight heparin ( LMWH ) ( Enoxaparin/Clexane ® 40 mg ) once daily beginning 24 hours prior to the operation . The mean age for the groups n¹ and n² were 68.93 and 68.15 years , respectively .  The reduction of soft-tissue swelling in the n¹ group was significantly higher ( p < 0.05 ) compared with n² . Evaluation of body mass index ( BMI ) with regard to the average reduction of soft-tissue swelling showed no significant influence ( p < 0.05 ) . The better function of the operated knee in group AVI was a significant predictor for improved agility and mobility ( p < 0.01 ) . No complications were reported for the application of the AVI . No ultrasonographic evidence of DVT or PE was found in any of the 80 patients during the investigative time period of eight days . After three months , there was no evidence of a symptomatic DVT BACKGROUND Patients undergoing neurosurgical procedures are at risk of venous thromboembolism ( VTE ) , but often have contraindications for anticoagulant prophylaxis . OBJECTIVES To assess the efficacy and tolerability of a new , lightweight , portable , battery-powered , intermittent calf compression device , Venowave , for the prevention of VTE in neurosurgical in patients . PATIENTS / METHODS We performed an open r and omized controlled trial comparing Venowave with control for the prevention of VTE in patients undergoing neurosurgery . The primary outcome was the composite of asymptomatic deep vein thrombosis ( DVT ) detected by screening venography or compression ultrasound  performed on day 9 ( ± 2 days ) and symptomatic VTE . RESULTS We r and omized 75 patients to receive Venowave devices and 75 to the control group . All patients were prescribed graduated compression stockings and physiotherapy . VTE occurred in three patients r and omized to Venowave and in 14 patients r and omized to control ( 4.0 % vs. 18.7 % , relative risk 0.21 ; 95 % confidence interval 0.05 - 0.75 , P = 0.008 ) . Similar reductions were seen for proximal DVT ( 2.7 % vs. 8.0 % ) and symptomatic VTE ( 0 % vs. 2.7 % ) , and the results were consistent in all subgroups examined . CONCLUSIONS Venowave devices are effective in preventing VTE in high-risk neurosurgical patients Context The decision to discontinue anticoagulation for venous thromboembolism ( VTE ) should depend in part on the subsequent risk for a fatal recurrence . Previous studies have measured fatality rates in patients still receiving anticoagulant drugs .  Contribution In a cohort from 2 source studies that had monitored 2052 patients for an average of 4.5 years after discontinuing anticoagulation for a first episode of VTE , the annual risk for any fatal pulmonary embolism ( PE ) was 0.43 events per 100 patient-years . The risk for definite or probable fatal recurrent PE was 0.17 events per 100 patient-years . Implication Although these rates seem low , decision makers must also take into account the rates of fatal PE recurrence and fatal hemorrhage if anticoagulant therapy is continued . The Editors When deciding whether to discontinue anticoagulant therapy for venous thromboembolism ( VTE ) , the subsequent risk for fatal pulmonary embolism ( PE ) is an important prognostic consideration . This risk can be expressed in absolute terms as the annual risk for fatal PE and in conditional terms as the risk that recurrent disease will be fatal ( case-fatality rate ) ( 1 , 2 ) . Knowledge of the annual risk for fatal PE may influence decisions about discontinuing anticoagulation , depending on the comfort level of clinicians and patients about an acceptably low risk for fatal PE . The case-fatality rate measures the clinical impact of disease recurrence if anticoagulation is discontinued , which can be weighed against the case-fatality rate of bleeding if anticoagulation is continued ( 3 , 4 ) . Past studies do not adequately address these issues . They include meta-analyses , which are retrospective and potentially unreliable ( 2 ) ; patient registry or population -based cohort studies that did not st and ardize anticoagulant therapy ( 59 ) ; or studies from linked administrative data bases , which rely on secondary data sources that may be inaccurate ( 1012 ) . Furthermore , these studies did not monitor patients for recurrent disease for long enough ( usually 1 year ) to assess long-term risk for fatal PE . Finally , these studies provide limited data on the risk for fatal PE after anticoagulation is discontinued in patient subgroups , such as persons presenting with PE or idiopathic VTE ( 2 , 512 ) . Therefore , we studied an inception cohort of patients who , after a first episode of VTE , had discontinued anticoagulant therapy and underwent clinical follow-up . We created the inception cohort by pooling data from 2 source studies ( 1315 ) . Our objective was to provide reliable and precise estimates of the annual risk for fatal PE and the case-fatality rate of recurrent PE . We also assessed these outcomes according to patients ' initial presentation ( deep venous thrombosis [ DVT ] , PE , or both ) and VTE etiology ( secondary or idiopathic ) . Methods Inception Cohort We studied an inception cohort of patients who completed at least 3 months of anticoagulant therapy after a first episode of symptomatic VTE . The observation period for the inception cohort began when the patient discontinued anticoagulant therapy , and it ended when the patient had nonfatal DVT or PE , fatal PE , or death from another cause . If 1 of these outcomes did not occur , patients were observed until the study ended or for a maximum of 120 months , whichever came first . Inception Cohort Subgroups We placed patients in subgroups according to initial presentation of VTE ( DVT alone , PE alone , or DVT and PE ) and VTE etiology ( secondary or idiopathic ) . We defined secondary VTE as occurring in the presence of 1 or more transient risk factors , such as surgery , leg trauma , leg fracture , or childbirth ( within 3 months of presentation ) , or if the patient was bedridden for more than 1 week because of a medical illness , rheumatologic illness , pregnancy , or hormonal therapy use . We defined idiopathic VTE as occurring in the absence of any of the aforementioned risk factors . Clinical Outcomes During follow-up of the inception cohort , we assessed the following outcomes : recurrent nonfatal DVT ( defined as a new noncompressible vein segment , an increase of the vein diameter by > 4 mm compared with the last available measurement on venous ultrasonography , or a new intraluminal filling defect on venography ) ; recurrent nonfatal PE ( defined as a new ventilationperfusion mismatch on lung scan or a new intral 
    Output:
    
Use of an intermittent pneumatic compression device alone is neither superior nor inferior to chemoprophylaxis .
CONCLUSIONS In the absence of large r and omized multicenter trials comparing the use of intermittent pneumatic compression or chemoprophylaxis alone to a combination of both treatments , the current evidence supports the use of a combined approach in high-risk surgical patients