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Query: UMLS:C0034065 (pulmonary embolism)
 14,979 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Heparin remains the most effective antithrombotic drug. It acts by combining with plasma antithrombin, thereby accelerating the neurtalisation of thrombin and other acitvated coagulation factors. Full-dose intravenous heparin is indicated in all cases of pulmonary embolism and established deep venous thrombosis, unless there exist compelling contraindications. Continuous intravenous infusion of heparin appears to be safer than intermittent injection. Low-dose subcutaneous heparin is effective in preventing the initial occurrence of thigh vein thrombi and in reducing the incidence of fatal pulmonary embolism in general surgical patients over the age of 40. The efficacy of low-dose heparin in preventing pulmonary emboli following hip surgery has not been established. The incidence of severe heparin-induced thrombocytopenia appears to be rising. Platelet counts should be performed in all patients receiving heparin by any mode of administration.
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PMID:Heparin Therapy: regimens and management. 31 90

Heparin is an anticoagulant drug which is used for the prophylaxis and treatment of venous thromboembolism and for the treatment of some cases of arterial thromboembolism. Venous thromboembolism is the commonest preventable cause of death in hospitalized patients, and the best approach to reduce its morbidity and mortality is the use of safe, effective, prophylaxis in patients at high risk. The use of low doses of heparin given s.c. (5000 units, 8 hourly)) has been shown in prospective clinical trials to be effective prophylaxis against venous thrombosis and nonfatal and fatal pulmonary embolism in patients undergoing general abdominothoracic surgery, without producing dangerous bleeding. Low-dose heparin, however, is not totally effective in patients undergoing hip surgery and suprapubic prostatectomy. The lack of benefit in these patients may be related to the intensity of the provocation to thrombosis. The use of heparin in large doses to treat thrombosis is associated with hemorrhagic complications in up to 30% of patients. There is evidence that continuous i.v. heparin is associated with fewer hemorrhagic complications than intermittent i.v. heparin, but the frequency is not related to the dose or to the use of laboratory monitoring. Hemorrhagic complications occur more frequently in elderly patients and in females and is more common following surgical operations. The frequency of recurrent venous thromboembolism is low in patients on therapeutic doses of heparin, and there is no difference in the frequency of recurrence in patients receiving heparin by continuous i.v. or intermittent i.v. administration.
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PMID:Prophylaxis and therapy of venous thromboembolism. 38 Sep 2

The efficacy of a six-month course of low-dose heparin therapy was compared to a conventional warfarin regimen by a prospective, controlled trial in 48 patients with pulmonary embolism or deep venous thrombosis of the legs. All subjects had complicated medical illnesses and a high risk of recurrent thromboembolism. Bleeding complications were virtually negligible during heparin therapy and occurred significantly more frequently in patients receiving warfarin. Heparin was as effective as warfarin in the prevention of recurrent thromboembolism. Patient compliance with the two treatment regimens was comparable. Self-administered, low-dose heparin therapy is a useful alternative to warfarin in the long-term management of complicated thromboembolic disorders.
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PMID:Low-dose heparin therapy in the long-term management of venous thromboembolism. 38 91

The physician frequently encounters the problems of deep vein thrombosis and pulmonary embolism. Recently, a number of studies have been published which are of considerable help in the management of these disorders. It has been shown that in many cases, low-dose heparin is effective in the prevention of both venous thrombosis and pulmonary embolism. However, once venous thrombosis has already occurred, it is necessary to use full-dose heparin, preferably by the continuous intravenous route, with maintenance of the partial thromboplastin time (PTT) at 1 1/2 times the control at all times. Although monitoring the PTT may not prevent hemorrhage, it will help prevent further thrombosis. Heparin is generally continued for seven to ten days. During this time warfarin is generally begun, and it is important to continue the patient on warfarin for five to seven days while the patient is receiving intravenous heparin therapy. After stopping heparin, oral anticoagulation with warfarin should be continued for six weeks. Then, in the absence of a previous history of venous thromboembolism or a known predisposing condition, it is safe to abruptly discontinue anticoagulation in most patients.
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PMID:Heparin and warfarin: use of anticoagulants in the prevention and treatment of venous thrombosis and pulmonary embolism. 43 53

Heparin is a naturally occurring anticoagulant drug that combines with anti-thrombin III to inhibit many steps of the coagulation pathway. Clinically, heparin is used in small doses to prevent venous thrombosis and pulmonary embolism; in large doses, it is the treatment of choice in acute venous thromboembolism. Heparin also is used to treat some acute arterial thromboembolic episodes. Heparin may be given by intermittent intravenous injection or continuous intravenous infusion, usually in doses of approximately 30,000 units per day. Hemorrhage, the main side effect of heparin, appears to be less frequent when therapeutic doses are given by continuous intravenous infusion rather than by intermittent intravenous injection.
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PMID:When and how to use heparin prophylaxis and treatment. 44 77

A perspective study by the Royal College of General Practitioners reported that the risk of developing deep venous thrombosis of the legs in women taking oral contraceptives was 5.66 times higher than women not on medication. Estrogen-progestogen compounds are highly potent hormones that produce alterations in metabolic and endocrine functions. Clinical examination of the leg is the most reliable method of determining the earliest indication of thrombophlebitis even with the latest diagnostic tools of venography. The key to diagnosis and treatment of pulmonary embolism, which often occurs with patients with thrombophlebitis, is a patient's complaint of leg pains. Those who have undergone surgery, especially abdominal and pelvic, are bedridden, and those who are taking oral contraceptives are at risk of thrombophlebitis. Deep thrombophlebitis of the leg is not recognized clinically in 50-80% of those with venographically documented thrombophlebitis because the signs and symptoms are so protean. Treatment with heparin and leg bandages is most common. Heparin is often followed with coumarin therapy. Some methods of diagnosis are calf tenderness, edema, skin temperature, Homan's Sign, Lowenberg's Sign, Pratt's Sign, cyanosis, systemic signs, and contrast venogram.
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PMID:A review of the birth control pill and its relationship to thrombophlebitis. 44 35

In postoperative and posttraumatic states, thromboembolic prophylaxis results in tenfold lower occurrence of pulmonary embolism and venous thrombisis--on which the postthrombotic syndrome is based--without a determinable increase of bleeding risk. Heparin is the treatment of choice. The dosage should be calculated on the basis of body weight. A minimal laboratory program of control measurements can diminish side effects.
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PMID:[Anticoagulant-induced prophylaxis of thrombosis (author's transl)]. 59 88

Heparin disappearance after injection and plasma levels during continuous infusion were studied in normal subjects and patients with thrombophlebitis, pulmonary embolism, renal failure, and liver failure. Heparin removal in normal subjects after 75 u/kg was nearly linear with a clearance of 0.64 ml/min/kg, SD +/- 0.11. Clearance varied inversely with dose. Heparin clearance in pulmonary embolism (0.80 ml/min/kg +/- 0.23) was significantly accelerated compared both to normals (P less than 0.005) and to thrombophlebitis patients (0.55 ml/min/kg +/- 0.19, P less than 0.01); the disappearance was more curvilinear in thrombophlebitis and pulmonary embolism than in normal subjects (P less than 0.025). Continuous infusion heparin requirements were greater in pulmonary embolism than in thrombophlebitis, in accordance with pharmacokinetic predictions. The pattern and rate of disappearance in renal disease was similar to normal subjects; in liver disease clearance was accelerated (0.86 ml/min/kg +/- 0.28) and disappearance curvilinear. Because of accelerated clearance, the initial dose of heparin in pulmonary embolism should be greater (25 u/kg/h) than in thrombophlebitis (10-15 u/kg/h). Variability within patient groups necessitates some laboratory control of dosage.
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PMID:Heparin pharmacokinetics: increased requirements in pulmonary embolism. 66 73

Pulmonary thromboembolism is a widespread problem and is an important cause of death in patients with a variety of medical and surgical conditions. There have been few significant advances in the understanding of the aetiology beyond additional evidence confirming the importance of Virchow's triad. An impressive list of epidemiological associations has been compiled, however. Some knowledge of the natural progression of the disease is required as an aid in the understanding of the application of the therapeutic and prophylactic measures available in the management of pulmonary embolism. It would seem that at least two-thirds of pulmonary emboli are non-fatal, and in these cases the natural resolution, even of comparatively large embolic masses, is very efficient in patients without pre-existing cardiopulmonary disease. Diagnosis may prove difficult and most ancillary investigations are of questionable value. On the other hand, pulmonary radio-isotope scanning is far more specific and pulmonary angiography is a comparatively simple and complication-free diagnostic procedure. Prophylaxis is a real and practical aim, especially following surgery or myocardial infarction. In these groups widespread clinical trials of prophylactic measures have been made possible by the objective radio-iosotope screening techniques. Mechanical means of preventing venous stasis and anticoagulation appear effective. In addition, low-dose subcutaneous heparin seems to be as useful as heparin in conventional dosage. Apart from conventional supportive therapy, there are three major approaches to the treatment of pulmonary embolism. Heparin remains the mainstay, particularly in the less severe cases, hopefully preventing propogation of thrombosis and recurrence of embolism, thus allowing resolution to take place. Thrombolytic therapy with streptokinase or urokinase is capable of producing far more rapid dissolution of pulmonary emboli with consequent theoretical advantages over heparin. No reduction in mortality has been shown using thrombolytic therapy. Patients who fail to respond satisfactorily to acute resuscitative measures may require pulmonary embolectomy.
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PMID:Pulmonary embolism: current therapeutic concepts. 77 78

There are three categories of antithrombotic agents: drugs which prevent fibrin fromation (the anticoagulants and defibrinating enzymes), drugs which prevent platelet adhesion or aggregation (the antiplatelet drugs), and thrombolytic drugs which induce fibrin degradation. Clinical studies have now led to a better understanding of the relative value of these drugs in different thrombotic disorders. In addition, knowledge of the mechanism of action of some of these drugs has recently been much advanced. The anticoagulant drugs in clinical use are heparin and the oral anticoagulants. Heparin is a potent inhibitor of several steps on the intrinsic coagulation pathway through its effect on a plasma cofactor, antithrombin III. its action is immediate, but heparin must be given parenterally. Oral anticoagulants act more slowly, by reducing the hepatic synthesis of biologically active factors II, VII, IX and X, but can be given by mouth. Heparin is therefore most suitable for starting anticoagulant treatment, while oral anticoagulants are generally used for prolonged therapy. The value of the anticoagulants as antithrombotic agents has been best assessed by studying their effectiveness in preventing and treating venous thromboembolic disease. Oral anticoagulants have been repeatedly shown to prevent venous thrombosis and pulmonary embolism in patients at high risk of developing these complications. However, the increased risk of postoperative bleeding has prevented their widespread use for this purpose in surgical patients. Recently, the use of low doses of heparin, given subcutaneously before and after surgery, has been shown to markedly reduce the incidence of venous thrombosis and pulmonary embolism (including fatal pulmonary embolism) after major elective abdominal surgery, and to produce only a slight increase of postoperative bleeding. This represents a major advance in anticoagulant prophylaxis of venous thromboembolism insurgical patients. However, low dose heparin prophylasix is relatively ineffective in patients having hip surgery, and has not been evaluated in patients having other types of orthopaidic surgery. There is direct evidence that antocoagulant therapy prevents death and recurrent embolism in patients who have developed pulmonary embolism, and considerable indirect evidence that it prevents pulmonary embolism, and considerable indirect evidence that it prevents pulmonary embolism (and death from pulmonary embolism) in patients who have venous thrombosis. The incidence of further venous thromboembolism or bleeding during treatment appears to be minimised when heparin is given by continuous intravenous infusion in a dose sufficient to produce a moderate, but no excessive, prolongation of a heparin-sensitive, in vitro coagulation test. The tests most commonly used to monitor heparin therapy was based on either the whole blood clotting time or the activated partial thromboplastin time...
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PMID:Antithrombotic drugs: part I. 78 43


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