Incidence of humoral risk factors in silent postoperative thrombosis of deep calf veins

Disturbances of fibrinolysis and a decreased amount of antithrombin III-activity are of high interest as dispositional factors.     

Failure of low-dose heparin to improve efficacy of peroperative intermittent calf compression in preventing postoperative deep vein thrombosis.

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 randomized 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 D.V.T.     

Low-molecular-weight heparin and prevention of postoperative deep vein thrombosis.

The efficacy of low-molecular-weight heparin as a prophylactic agent was assessed in 150 consecutive patients over the age of 40 undergoing major abdominal surgery. Fifty of these patients received 1250 activated partial thromboplastin time (APTT) units of low-molecular-weight heparin every 12 hours: three developed isotopic deep vein thrombosis, which was confirmed by phlebography in two cases. The other 100 patients received a single injection of 1850 APTT units of low-molecular-weight heparin. Three of them developed isotopic deep vein thrombosis; phlebography failed to confirm the presence of thrombi in each case. None of the 150 patients studied died from fatal or contributory pulmonary emboli. Low-molecular-weight heparin was not associated with any increase in preoperative or postoperative bleeding. The effect of equal amounts of postoperative bleeding. The effect of equal amounts of low-molecular-weight heparin and unfractionated heparin on the coagulation mechanism during surgery was investigated in another 30 patients. The clotting assays and results of in-vivo platelet function tests indicated that both preparations produced similar effect. Intragroup comparisons, however, showed significant differences in the anti-factor Xa activity, lipoprotein lipase release, and plasma prekallikrein concentrations. A single injection of low-molecular-weight heparin daily is a convenient way of preventing deep vein thrombosis in high-risk patients undergoing major abdominal surgery.     

Dextran and intermittent pneumatic compression in prevention of postoperative deep vein thrombosis: multiunit trial.

Seven general surgical units co-operated in a clinical trial of dextran 70 and pneumatic calf compression alone and in combination in the preventing of 125I-fibrinogen-detectable deep vein thrombosis in 305 patients. Both dextran regimens were significantly more effective than pneumatic compression alone. Pulmonary embolism was diagnosed in 14 patients, but there was no significant difference in incidence among the three treatment groups. In patients receiving dextran there was no greater median operative blood loss but there was a significantly greater incidence of postoperative bleeding complications.     

Prophylaxis of postoperative deep vein thrombosis: selective use of low-dose heparin in high-risk patients.

Administration of prophylactic low-dose subcutaneous heparin to prevent postoperative deep vein thrombosis is expensive, entails treating many patients unnecessarily, and causes some side effects. By using a predictive index a population of patients who are at particularly high risk of developing postoperative deep vein thrombosis may be identified preoperatively. Prophylaxis was given only to these patients, resulting in an incidence of deep vein thrombosis of 3.8% compared with 16.1% in previous studies in which no specific prophylaxis was given. By limiting prophylaxis to the group of patients identified by the predictive index as being at high risk of developing postoperative deep vein thrombosis results may be obtained that are as good as those expected from treating the whole population. Thus many patients are saved from exposure to low-dose subcutaneous heparin.