***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 
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    Input: BACKGROUND Unfractionated heparin and the low molecular weight heparin , dalteparin , are used for prophylaxis against venous thromboembolism in patients undergoing craniotomy . These drugs were compared in a r and omized , prospect i ve pilot study comparing intermittent pneumatic compression devices plus dalteparin to intermittent pneumatic compression devices plus heparin . METHODS One hundred patients undergoing craniotomy were r and omly allocated to receive perioperative prophylaxis with subcutaneous ( SC heparin , 5000 units every 12 hours , or dalteparin , 2,500 units once a day , begun at induction of anesthesia and continued for 7 days or until the patient was ambulating . Entry criteria were age over 18 years , no deep vein thrombosis ( DVT ) preoperatively as judged by lower limb duplex ultrasound and no clinical evidence of pulmonary embolism preoperatively . Patients with hypersensitivity to heparin , penetrating head injury or who refused informed consent were excluded . Patients underwent a duplex study 1 week after surgery and 1 month clinical follow-up . All patients were treated with lower limb intermittent pneumatic compression devices . RESULTS There were no differences between groups in age , gender , and risk factors for venous thromboembolism . There were no differences between groups in intraoperative blood loss , transfusion requirements or postoperative platelet counts . Two patients receiving dalteparin developed DVT ( one symptomatic and one asymptomatic ) . No patient treated with heparin developed DVT and no patient in either group developed pulmonary embolism . There were two hemorrhages that did not require repeat craniotomy in patients receiving dalteparin and one that did require surgical evacuation in a patient treated with heparin . Drug was stopped in two patients treated with dalteparin because of thrombocytopenia . None of these differences were statistically significant . CONCLUSION There was no significant difference in postoperative hemorrhage , venous thromboembolism or thrombocytopenia between heparin and dalteparin . The results suggest that , given the small sample size of this trial , both drugs appear to be safe and the incidence of venous thromboembolism by postoperative screening duplex ultrasound appears to be low when these agents are used in combination with intermittent pneumatic compression devices 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 Objective To compare the effectiveness and safety of low-dose unfractionated heparin and a low-molecular-weight heparin as prophylaxis against venous thromboembolism after colorectal surgery . Methods In a multicenter , double-blind trial , patients undergoing resection of part or all of the colon or rectum were r and omized to receive , by subcutaneous injection , either calcium heparin 5,000 units every 8 hours or enoxaparin 40 mg once daily ( plus two additional saline injections ) . Deep vein thrombosis was assessed by routine bilateral contrast venography performed between postoperative day 5 and 9 , or earlier if clinical ly suspected . Results Nine hundred thirty-six r and omized patients completed the protocol and had an adequate outcome assessment . The venous thromboembolism rates were the same in both groups . There were no deaths from pulmonary embolism or bleeding complications . Although the proportion of all bleeding events in the enoxaparin group was significantly greater than in the low-dose heparin group , the rates of major bleeding and reoperation for bleeding were not significantly different . Conclusions Both heparin 5,000 units subcutaneously every 8 hours and enoxaparin 40 mg subcutaneously once daily provide highly effective and safe prophylaxis for patients undergoing colorectal surgery . However , given the current differences in cost , prophylaxis with low-dose heparin remains the preferred method at present We initiated a prospect i ve , partially r and omized trial of the effects of perioperative prophylactic mini-dose heparin on the incidence of clinical ly evident pulmonary emboli , intraoperative blood loss , blood transfusions , duration of postoperative pelvic drainage , and lymphocele formation in 68 consecutive patients undergoing radical retropubic prostatectomy . We treated 32 patients with mini-dose heparin and 36 without it . We detected pulmonary emboli in 4 ( 11 % ) patients not treated with mini-dose heparin and in none treated with heparin ( p = 0.052 ) . Anesthesiologists estimated a mean intraoperative blood loss of 2,152 cc in the heparinized patients compared with 1,886 cc in controls ( p = 0.2 ) . At a time when our policy was to replace all blood loss , we transfused a mean of 3.9 units to heparinized patients and 3.2 units to controls ( p = 0.1 ) . Persistent lymphatic drainage requiring more than six days of closed suction drainage occurred in 12 of 32 ( 38 % ) heparinized patients as compared with 4 of 36 ( 11 % ) controls ( p = 0.01 ) . We discontinued the study after 68 patients because of the morbidity associated with mini-dose heparin . Because of the associated morbidity we do not recommend the routine use of mini-dose heparin in patients undergoing radical prostatectomy The possible benefits of adding a low-dose heparin regimen to the technique of peroperative intermittent calf compression for preventing  deep vein thrombosis  ( D.V.T. ) were assessed in a r and omized trial in 84 surgical patients . The efficacy of peroperative intermittent calf compression  was not enhanced by a low-dose heparin regimen , but neither was it worsened . Age , weight , duration , operation , and malignant disease did not affect the relative effectiveness of the two regimens of prophylaxis . The results confirmed that venous stasis is the principal cause of INTRODUCTION Pneumatic compression stocking ( PCS ) devices have been introduced to decrease the incidence of postoperative deep venous thrombosis ( DVT ) . However , their role in the prophylaxis against pulmonary embolism ( PE ) remains unclear . This study was undertaken to compare the prophylactic effectiveness of subcutaneous heparin ( SCH ) alone vs the combined use of PCS and SCH in the prevention of PE following cardiac surgery . METHODS We studied 2,551 consecutive patients who underwent cardiac surgery over a 10-year period . They were r and omly allocated to two groups . Group A included 1,196 patients who were treated with 5,000 U of SCH every 12 h and group B included 1,355 patients treated with a combined prophylactic regimen of PCS and SCH . RESULTS The diagnosis of PE was established in 69 patients by either high-probability ventilation perfusion scan , pulmonary angiogram , or autopsy . The incidence of PE in group A patients was 4 % ( 48/1,196 ) and in group B was 1.5 % ( 21/1,355 ) . The concomitant use of bilateral PCS and SCH reduced the frequency of postoperative PE in 62 % in comparison to the prophylaxis with SCH alone ( p < 0.001 ) . CONCLUSIONS These data suggest that the combined prophylactic method of bilateral PCS and SCH is superior to SCH alone in the prevention of PE after cardiac surgery OBJECTIVE It has been previously shown that the SCD Response Compression System , by sensing the postcompression refill time of the lower limbs , delivers more compression cycles over time , result ing in as much as a 76 % increase in the total volume of blood expelled per hour . Extended indications for pneumatic compression have necessitated the introduction of portable devices . The aim of our study was to test the hemodynamic effectiveness of a new portable sequential compression system ( the SCD Express ) , which has the ability to detect the individual refill time of the two lower limbs separately . METHODS This was an open , controlled trial with 30 normal volunteers . The new SCD Express was compared with the SCD Response Compression System in the supine and semirecumbent positions . The refilling time sensed by the device was compared with that determined from velocity recordings of the superficial femoral vein using duplex ultrasonography . Baseline and augmented flow velocity and volume flow , including the total volume of blood expelled per hour during compression with the SCD Express , were compared with those produced by the SCD Response compression system in the same volunteers and positions . RESULTS Both devices significantly increased venous flow velocity as much as 2.26 times baseline in supine position and 2.67 times baseline in semirecumbent position ( all P < .001 ) . There was a linear relationship between duplex ultrasonography-derived refill time and the SCD Express-derived refill time in both the supine ( r = 0.39 , P = .03 ) and semirecumbent ( r = 0.71 , P < .001 ) positions but not with the SCD Response . Refill time measured by the SCD Express device was significantly shorter and the cycle rate higher in comparison with the SCD Response in both positions . The single-cycle flow velocity and volume flow parameters generated by the two devices were similar in both positions . However , median ( interquartile range ) total volume of blood expelled per hour was slightly higher with the SCD Express device in the supine position ( 7206 mL/h [ range , 5042 - 8437 ] vs 6712 mL/h [ 4941 - 10,676 ] ; P = .85 ) and semirecumbent position ( 4588 mL/h [ range , 3721 - 6252 ] vs 4262 mL/h [ 3520 - 5831 ] ; P = .22 ) . Peak volume of blood expelled per hour by the SCD Express device in the semirecumbent position was significantly increased by 10 % in comparison with the SCD Response ( P = .03 ) . CONCLUSIONS Flow velocity and volume flow enhancement by the SCD Response and SCD Express were essentially similar . The latter , a portable device with optional battery power that detects the individual refill time of the lower limbs separately , is anticipated to be associated with improved overall compliance and therefore optimized thromboprophylaxis . Studies testing its potential for improved efficacy in preventing deep vein thrombosis are justified Summary . Two hundred and thirty-eight patients with femoral neck fractures were entered into a r and omised pilot study comparing the use of sequential treatment by ‘ Flowtron DVT ’ garments in the perioperative period followed by Enoxaparin ( Clexane-Rhône-Poulenc Rorer ) , and Enoxaparin alone .  One hundred and ninety-three patients were excluded indicating the difficulty of achieving pure comparisons in this population . The remaining 44 were r and omised : 21 received Enoxaparin from the time of admission , and 23 had sequential treatment  . There was no statistically significant difference in the incidence of thromboembolism . Patient preference did not indicate a favoured treatment subjectively . The operation field was drier in the sequential group , although this did not reach significance . Sequential treatment was not shown to be better or worse than treatment with Enoxaparin , but the trends favoured sequential treatment rather than drug treatment alone . The technique allows the operation to be carried out without the problems produced by low dose heparins and mobilisation is not hindered by compression garments . Résumé . 238 patients présentant une fracture du col du fémur ont fait l’objet d’une étude pour comparer un traitement séquentiel avec utilisation d’une compression intermittente du mollet en période péri-opératoire ( Flowtron DVT ) suivie d’un traitement par Enoxaparin ( Clexane – Rhône Poulenc Rorer ) et un traitement habituel 
    Output:
    
The comparison of compression plus pharmacological prophylaxis versus compression plus aspirin showed a non-significant reduction in PE and DVT in favor of the former group .
Compared with compression alone , combined prophylactic modalities decrease significantly the incidence of venous thromboembolism .
Compared with pharmacological prophylaxis alone , combined modalities reduce significantly the incidence of DVT but the effect on PE is unknown .
The results of the current review support , especially in high-risk patients , the use of combined modalities .