***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 Introduction This prospect i ve study was design ed to confirm risk factors and to assess the incidence of deep vein thrombosis after total hip and surface replacement arthroplasty in Korean patients not receiving anticoagulation prophylaxis and to determine efficacy of plasma D-dimer levels as a screening test . Material s and methods From May 2003 to August 2004 , 221 consecutive patients undergoing unilateral total hip arthroplasty and hip resurfacing were evaluated . All patients underwent ultrasonography preoperatively and venography and /or ultrasonography on postoperative day 7 . Plasma D-dimer levels were estimated by latex immuno-assay preoperatively and on days 3 and 7 postoperatively . Results Of the 221 patients in our cohort , 23 developed deep vein thrombosis ( 10.4 % ) . Age ( r = 0.245 , P < 0.001 ) and gender ( r = 0.155 , P = 0.021 ) significantly correlated with deep vein thrombosis . Rise in incidence paralleled increase in age ( X2 = 32.860 , P < 0.001 ) . D-dimer levels on postoperative days 3 ( γ = 0.364 , P < 0.001 ) and 7 ( γ = 0.470 , P < 0.001 ) were significantly correlated to the development of DVT . Conclusion While incidence of deep vein thrombosis in Korean population after THA was lower than that in the West ; it increased with age , and in female gender . Significant correlation was found between D-dimer levels and the development of deep vein thrombosis D-dimers may be elevated after surgery . However , the kinetics of postoperative D-dimers remains unknown hampering the use of D-dimer testing in surgical patients with suspected venous thromboembolism .  D-dimer levels  were prospect ively measured in 154 patients after general surgery at predefined time points ( kinetics were determined in an initial cohort of 108 patients ; for validation , these findings were applied to a second cohort of 46 patients ) . Clinical factors influencing the peak of D-dimers were analyzed using multivariate regression . Surgical operations were stratified based on severity ( type I : not entering abdominal cavity ; type II : intraabdominal ; type III : retroperitoneal/liver surgery ) . D-dimer levels increased postoperatively reaching a peak on day 7 . After type I surgery , peak D-dimer levels did not exceed normal range ( 300 ng/ml , 100–500 ) . After type II procedures , peak D-dimer level was 1500 ng/ml ( 200–7800 ) and returned to normal values after 25 days ( ±14 ) . Peak level was 4000 ng/ml ( 500–14 400 ) after type III surgery normalizing within 38 days ( ±11 ) . Clearance of D-dimer was exponential after having reached the peak with 6.0 % per day ( 95 % confidence interval 4.8–7.1 % ) . By this clearance , D-dimer values could be adequately predicted in the validation cohort after day 7 ( r2 = 0.63 ) . Peak D-dimer levels were independently influenced by the type of surgery ( P < 0.001 ) , the operation time ( P < 0.001 ) and by preoperatively elevated D-dimer levels ( P < 0.001 ) . Based on this data , duration of postoperative D-dimer elevation after abdominal surgery is predictable . This study indicates for the first time when D-dimers may be used again in the diagnostic algorithm for venous thromboembolism exclusion after surgery in patients with low or moderate clinical probability The WizAir-DVT is a miniature , lightweight ( 690 g ) , battery-operated and mobile intermittent pneumatic compression device ( ICD ) , which enables continuous intraoperative use and immediate patient mobilization postoperatively . We compared its efficacy with a commonly used ICD , the Kendall SCD . Peak femoral vein flow velocity was measured in 20 apparently healthy volunteers at rest and with each device : we found no significant differences between them . A second prospect i ve , r and omized , clinical trial was used to compare the efficiency of the device in preventing deep venous thrombosis ( DVT ) after joint replacement in 50 patients ( n=25/group ) . None developed DVT . Doppler ultrasonography revealed no significant differences . The WizAir-DVT antithrombotic compression device is as safe and effective as the Kendall SCD Background : Intermittent pneumatic foot compression ( IPC ) is a useful technique for prophylaxis of  peri‐operative venous thromboembolism .  The aim of this study was to determine the effect of  IPC on blood coagulation/fibrinolysis and platelet function using a blood viscometer ( SonoclotTM ) and a platelet aggregation monitor ( WBA analyzerTM ) , respectively . Using the same blood sample s , serum levels of tissue‐type plasminogen activator ( t‐PA ) , thrombomodulin ( TM ) and activated protein C ( APC ) were also measured The purpose of this study was to evaluate the efficacy of two intermittent pneumatic compression devices as prophylaxis against intravascular coagulation and leg swelling following total hip arthroplasty . We studied 121 patients by assessing thrombogenesis using the D-dimer level before and after total hip arthroplasty . In addition , the patients ’ postoperative swelling was evaluated by measuring the thigh and lower leg circumference . Altogether , 58 patients were assigned to the calf-thigh pneumatic compression group , and the other 63 were assigned to the plantar compression group ; the two pneumatic compression devices were compared to evaluate which was more effective for reducing thrombogenesis . At 7 days postoperatively , the mean D-dimer levels of the calf-thigh compression group and the plantar compression group were 8.86 and 9.26 µg/ml , respectively . There was no significant difference ( P = 0.697 ) between the two groups . However , the increased ratio of the circumference of the thigh , which was compared after arthroplasty , averaged 1.22 % in the calf-thigh compression group and 3.19 % in the plantar compression group , which was significantly different ( P ≪ 0.01 ) . Calf-thigh pneumatic compression was found to be more effective than plantar compression for reducing thigh swelling during the early postoperative stage A crossover study was performed to evaluate the effect of several pneumatic compression devices and active dorsoplantar flexion in 10 patients who underwent total hip arthroplasty . Using the Acuson 128XP/10 duplex ultrasound unit with a 5-MHz linear array probe , peak venous velocity and venous volume were assessed above and below the greater saphenous vein and common femoral vein junction . A computer generated r and omization table was used to determine the order of the test conditions . The pneumatic compression devices evaluated included two foot pumps , one foot and calf pump , one calf pump , and three calf and thigh pumps . Statistical analyses included analysis of variance and analysis of variance with covariance between devices and patients . The covariates tested were the baseline measurements and the order in which the devices were tested . Differences between devices relate in part to the frequency and rate of inflation and the location and type of compression . Pulsatile calf and foot and calf pneumatic compression with a rapid inflation time produced the greatest increase in peak venous velocity , whereas compression of the calf and thigh showed the greatest increase in venous volume . Because patient and nursing compliance is essential to the success of mechanical prophylaxis for thromboembolic disease , the more simple , yet efficacious , devices that are easier to apply and less cumbersome appear to have a greater likelihood of success . In the active and alert patient , active dorsoplantar flexion should be encouraged BACKGROUND AND OBJECTIVES Intermittent pneumatic compression ( IPC ) is an effective form of deep vein thrombosis prophylaxis for general surgery patients . The antithrombotic effect of IPC is thought to be the result of increased venous velocity and stimulation of endogenous fibrinolysis . However , the mechanism of enhanced fibrinolytic activity and the relative effects on normal and postthrombotic veins have not been defined . The purpose s of this study are 1 ) to quantify changes in fibrinolytic activity with IPC ; 2 ) to study the mechanism of fibrinolytic enhancement with IPC ; and 3 ) to evaluate whether postthrombotic patients have the same capacity for fibrinolytic enhancement with IPC as do normal subjects . METHODS Twelve volunteers ( 6 normal and 6 postthrombotic ) had 5 IPC devices applied for 120 minutes in r and om fashion , 1 per week x 5 weeks . The devices included single-chamber , sequential , foot , calf , and long-leg compression . Subjects had an indwelling antecubital venous cannula placed for blood drawn at baseline , 60 , 120 , and 180 minutes after IPC devices were applied . Global fibrinolytic activity ( euglobulin fraction , fibrin plate assay ) , tissue plasminogen activator ( tPA ) antigen ( Ag ) and activity ( Act ) , plasminogen activator inhibitor-1 ( PAI-1 ) Ag and Act , alpha-2-antiplasmin-plasmin complexes , and von Willebr and factor ( vWF ) antigen were assayed . RESULTS A striking elevation in fibrinolytic activity was noted at 180 minutes with all devices in normal subjects and postthrombotic patients ( p = 0.01 - 0.0001 ) ; however , baseline and stimulated fibrinolytic activity was attenuated in postthrombotic patients ( < 0.03 ) . The tPA-Act increased only in normal subjects ( 3.8 + /- 1.9 % ) ( p = 0.057 ) , despite a decrease in plasma tPA-Ag , which was observed in both normal subjects ( -12.4 + /- 3.8 % ) ( p = 0.009 ) and patients ( -17.2 + /- 3.1 % ) ( p = 0.001 ) . PAI-1-Ag decreased in both normal subjects ( -13.4 + /- 3.8 % ) ( p = 0.007 ) and patients ( -12.0 + /- 3.1 % ) ( p = 0.013 ) with a marked reduction in PAI-1-Act in both normal subjects ( p = 0.003 ) and patients ( p = 0.004 ) . There were no changes in vWF , and alpha-2-antiplasmin-plasmin complexes increased only in postthrombotic patients ( p = 0.021 ) . CONCLUSIONS Stimulation of endogenous fibrinolytic activity occurs after IPC , both in normal subjects and postthrombotic patients ; however , baseline and overall fibrinolytic response in postthrombotic patients is reduced . The mechanism of increased fibrinolytic activity is likely because of a reduction in PAI-1 , with a result ing increase of tPA activity After total hip ( THR ) or knee replacement ( TKR ) , there is still an appreciable risk of developing deep-vein thrombosis despite prophylaxis with low-molecular-weight heparin ( LMWH ) . In a prospect i ve , r and omised study we examined the efficacy of LMWH in combination with intermittent pneumatic compression in patients undergoing primary unilateral THR or TKR . We administered 40 mg of enoxaparin daily to 131 patients combined with either the use of intermittent pneumatic compression or the wearing of graduated compression stockings . Compression ultrasonography showed no evidence of thrombosis after LMWH and intermittent pneumatic compression . In the group with LMWH and compression stockings the prevalence of thrombosis was 28.6 % ( 40 % after TKR , 14 % after THR ) . This difference was significant ( p < 0.0001 
    Output:
    
The authors found no cases of symptomatic DVT or PE in either the calf-thigh compression group or the plantar compression group during the first three weeks after the THR .
The calf-thigh pneumatic compression was more effective than plantar compression for reducing thigh swelling during the early postoperative stage .
There is a lack of evidence from r and omized controlled trials to make an informed choice of IPC device for preventing venous thromboembolism ( VTE ) following total hip replacement .