Prevention of venous thromboembolism

The aim of prophylaxis in venous thromboembolism is firstly to prevent fatal pulmonary embolism and secondly to reduce the morbidity associated with deep vein thrombosis and the post-phlebitic limb. Particularly high-risk groups are identifiable and include those over 60 years of age undergoing major surgery, patients with malignancy and those undergoing hip operations. Low-dose subcutaneous heparin (5000 U s.c. commenced two hours preoperatively and continued eight to twelve hourly until the patient is fully mobile) is unequivocally effective in preventing deep vein thrombosis in medical and surgical patients and, most importantly, significantly reduces the incidence of fatal postoperative pulmonary embolism and total mortality. Furthermore, in established deep vein thrombosis, low-dose heparin limits proximal clot propagation, which is the prelude to pulmonary embolism. Despite this, surveys have demonstrated an alarming deficiency amongst clinicians in the application of measures to prevent venous thromboembolism. Heparin prophylaxis carries a small risk of increased bleeding complications, mostly evidenced by the frequency of wound haematoma rather than major haemorrhage. Low molecular heparin fragments (e.g. Fragmin, Choay, Enoxaprin) are now emerging as useful alternative agents, having the advantage of once daily administration and yet providing similar efficacy in the prevention of deep vein thrombosis. However, protection against fatal pulmonary embolism has yet to be demonstrated. Mechanical methods of prophylaxis designed to counteract venous stasis, such as graduated elastic compression stockings, are also beneficial in protection against deep vein thrombosis but by themselves do not achieve such consistently good prophylaxis as low-dose heparin. However, clinical trials with combinations of mechanical methods and low-dose heparin indicate that this may be the optimum approach to very high-risk patients. In the presence of established acute deep vein thrombosis, anticoagulant therapy is the mainstay in preventing pulmonary embolism. Vena caval interruption procedures should be reserved for patients in whom anticoagulation is contraindicated or for those who develop recurrent pulmonary embolism despite adequate anticoagulation.     

Prevention of venous thromboembolism

Recognition of the patient at risk and delivery of appropriate prophylaxis are imperative to reduce the incidence of VTE (including fatal PE) in hospitalized patients. This article provides estimates of risk and a summary of effective prophylaxis methods such that physicians can tailor an individual patient's prophylaxis regimen to maximize DVT risk reduction in the safest and most cost-effective manner.     

Prevention of venous thromboembolism

Patients with clinical conditions such as surgery, trauma, and acute medical illness have a transiently increased risk of venous thromboembolism and merit consideration for adequate thromboprophylaxis. The choice of an appropriate pharmacologic or physical means of prophylaxis should be made taking into account both the thrombotic and bleeding risk associated with patient-related factors and the type of surgery or other disease state involved. A large number of randomized clinical trials, meta-analyses, and guidelines developed by scientific societies worldwide have addressed this issue and have provided information and recommendations that should be considered carefully. The aim of this review is to provide the practicing physician with a brief updated summary of the subject, stratifying those patients at low thrombotic risk who do not require specific thromboprophylaxis apart from early ambulation, from those at moderate or higher thrombotic risk. Patients at moderate thrombotic risk face a 10 to 20% risk of deep vein thrombosis (DVT) and require prophylaxis with low-dose unfractionated heparin or low molecular weight heparins (LMWHs) at a dosage < 3400 U once daily, or with graduated elastic stockings if their bleeding risk is high. Patients with an expected 20 to 40% DVT rate without prophylaxis are considered at high thrombotic risk and should be treated preferentially with LMWHs at high prophylactic dosage (> 3400 U). Patients undergoing major orthopedic surgery face a DVT rate > 40%, are considered at very high risk of venous thromboembolism, and should be given either LMWHs at high prophylactic dosage, fondaparinux, or vitamin K antagonists--either alone or in association with intermittent pneumatic compression devices.     

Prevention of venous thromboembolism.

Venous thromboembolism is a preventable cause of morbidity and death in hospitalized patients. In addition to administering correct and effective prophylaxis to the various treatment groups, therapy should be tailored to the individual based on the identification of baseline risk factors. No patient at significant risk for venous thrombosis should be left unprotected.     

肿瘤相关性静脉血栓栓塞症的预防

恶性肿瘤是静脉血栓栓塞症（VTE）的高危因素之一。最近一项尸检报告约80％的致命性肺栓塞发生在内科肿瘤患者;外科患者中VTE已成为肿瘤术后患者30d内的首要死亡原因,远远超过术后出血所致的死亡。FRONTLINE研究表明只有50％的肿瘤外科医师和5％的肿瘤内科医师对肿瘤患者实施了VTE预防,而我国肿瘤相关VTE的预防则处于刚刚起步阶段。推动肿瘤患者院内、院外规范化的血栓预防是目前我国肿瘤内、外科医师所面临的紧迫问题。本文就肿瘤合并VTE的流行病学、风险评估和院内、院外肿瘤患者VTE预防的具体措施做了系统阐述。     

肿瘤相关性静脉血栓栓塞症的预防

恶性肿瘤是静脉血栓栓塞症（venousthrombosisembolism,VTE）的高危因素之一。最近一项尸检报告显示约80％的致命性肺栓塞（pulmonaryembolism,PE）发生在内科肿瘤患者;外科患者中VTE已成为肿瘤术后患者30d内的首要死亡原因,远远超过术后出血所致的死亡。我国肿瘤相关VrI＇E的预防则处于刚刚起步阶段,推动肿瘤患者院内、院外规范化的血栓预防是目前我国肿瘤内、外科医生所面临的紧迫问题。现就肿瘤合并VTE的流行病学、风险评估和院内、院外肿瘤患者VTE预防的具体措施做一系统阐述。     

Prevention of venous thromboembolism in psychiatry

The hospitalized patients of the psychiatric wards represent a risk group for the development of venous thromboembolism. Apart from sedative administration, total movement reduction, bad life style and daily routine and increased body weight, there is negative impact of dehydration, prolonged hospitalization and sometimes immobilisation in consequence of mechanical restraints. A large amount of patients are treated with antipsychotics that have a series of adverse effects. Depending of the drug used, the most frequent of them are somnolence, fatigue, extrapyramidal syndrome, hypotension, hepatotoxicity, increased body weight, prolongation of the QT interval of the ECG with a risk of ventricular arrhythmias, hematopoietic disorders, lipid or glycide metabolism disorders or hyperprolactinemia. Another potential adverse effect of these drugs is the heightened risk of venous thromboembolism development (deep vein thrombosis and/or pulmonary embolism). There is the risk of a pathological blood clotting event in psychiatric patients, especially those treated with antipsychotics. Although it is not high, it can have fatal consequences when combined with a relatively frequent pulmonary embolism and difficult diagnostics of thromboembolism. An algorithm for thromboembolism prevention has been developed. It involves important general risk factors of venous thrombosis (VTE history, immobilisation, malignancy, age over 75 years etc.) and also markers (physical restraints, dehydration, obesity, antipsychotics use) that can participate in the pathogenesis of venous thrombosis in the hospitalized psychiatric patients with limited motility. The authors believe that this prophylaxis is indicated, safe, effective and that it improves the quality of life at relatively low costs.     

Prevention of venous thromboembolism in pregnancy

Pulmonary thromboembolism, rising from deep venous thrombosis (DVT), is a major cause of maternal death in the developed World. DVT is a significant source of morbidity in pregnancy and the puerperium with long-term sequelae such as post-thrombotic syndrome. The major risk factors for venous thromboembolism (VTE) are: increasing age, particularly over 35 years; operative vaginal delivery; Caesarean section, especially emergency Caesarean section in labour; high body mass index; previous VTE, especially if idiopathic or thrombophilia-associated; thrombophilia; and a family history of thrombosis suggestive of an underlying thrombophilia. Thromboprophylaxis centres largely on the use of low-molecular-weight heparin (LMWH). LMWHs, such as enoxaparin and dalteparin, have substantial clinical and practical advantages compared with unfractionated heparin, particularly in terms of improved safety with a significantly lower incidence of heparin-induced osteoporosis and thrombocytopenia. Such agents should be used in women with significant risk factors for VTE both antenatally and post-partum.     

Prevention of venous thromboembolism in orthopaedics

The incidence of venous thromboembolism in orthopaedic patients is high and its prevention deserves special attention. In patients with total hip and knee replacements and with the proximal femur fractures, low molecular weight heparin should be administered at higher prophylactic dosages. Following its approval, pentasaccharide (fondaparinux) should become the drug of choice, especially in patients with proximal femur fractures. Pharmacological prophylaxis should take at least 10 days in case of total knee replacements and longer in patients with increased risk of venous thromboembolism. In patients with total hip replacements or with proximal femur fractures, LMWH or pentasaccharide prophylaxis is indicated over a period of 28-35 days. Under the conditions of well working infrastructure for anticoagulation treatment, there is an alternative of warfarin treatment, lasting consequently 6-8 weeks. In patients with proximal femur fracture that bleed or are in a very increased risk of bleeding, a possible alternative is represented by intermittent pneumatic compression and shift to antithrombotic treatment after bleeding stops. In patients with knee arthroscopies displaying no risk factors of venous thromboembolism where tourniquet was used no longer than 60 minutes, pharmacological prophylaxis is not necessary. Only timely mobilisation is recommended. In patients displaying risk factors of venous thromboembolism or with tourniquet use surpassing 60 minutes, it is advisable to administer low molecular weight heparin in lower prophylactic dosage. In patients with lower extremity fractures treated with osteosynthesis, LMWH administration of 7-10 days is indicated. In patients with lower extremity injuries requiring plaster casting or other type of fixation reaching below the knee, LMWH administration is indicated over the whole period of fixation in persons with higher risk (people with venous thromboembolism in their histories, in direct relative's histories, people with thrombophilic conditions including poeple with malignancies, women using hormonal contraceptives or their substitutions). Aspirin is not a suitable drug for separate administration in the prophylaxis of venous thromboembolism in orthopaedic patients.     

Prevention of venous thromboembolism in paediatry

Data in Canadian registry for VTE in children show, that incidence of VTE in children is 0.07/10 000. The situation in adults--with incidence of VTE 37/10 000--is however completely different. Only 5% of VTE in children are idiopathic and less then 10% are related to hereditary prothrombotic risk factors only. In other words, more than 80% of VTE in children are somehow related to acquired prothrombotic risk factors. Despite of this, there have not been found any measures, that would be able to further decrease significantly this very low incidence of VTE in children. This is probably the reason, why to date there are no evidence based recommendations for primary prophylaxis of VTE in children and also there is no valid reason for non-selective screening for hereditary prothrombotic risk factors in population of children, who have not suffered VTE.     

Prevention of venous thromboembolism after surgery

Venous thromboembolism, including deep vein thrombosis and pulmonary embolism, is the third leading cause of cardiovascular death after myocardial infarction and stroke in the United States. Recommendations regarding the type and duration of prophylaxis for the various conditions are summarized herein.     

The prevention of venous thromboembolism in older adults: guidelines

The rationale for thromboprophylaxis is based on the high prevalence of venous thromboembolism (VTE), a disorder involving deep vein thrombosis (DVT) and pulmonary embolism (PE), among hospitalized patients, the clinically silent nature of VTE in most patients, and the morbidity, cost, and potential mortality associated with unprevented thromboembolism. Both DVT and PE cause few specific symptoms, and the clinical diagnosis is unreliable. Since the first clinical manifestation of VTE may be fatal PE, it is inappropriate to wait for symptoms before treatment. Unrecognized and untreated DVT may also cause the postphlebitic syndrome and predispose patients to subsequent episodes of recurrent VTE. Routine screening for VTE has also not been shown to reduce the incidence of symptomatic VTE or fatal PE. Use of effective methods of prophylaxis is more cost effective and is safer than selective, intensive screening for VTE. This article reviews current recommendations for the prevention of VTE as they apply to older adults. The recommendations discussed are based on the Sixth American College of Chest Physicians Consensus Conference on Antithrombotic Therapy reported in Chest. 2001;119:132S-175S.     

Treatment of venous thromboembolism: guidelines translated for the clinician

Venous thromboembolism is a major cause of morbidity and mortality affecting over 2 million people in the United States each year. The American College of Chest Physicians (ACCP) published their first consensus statement on antithrombotic therapy in 1986, and the most recent guidelines from the ACCP on this topic were released in 2008. We aim to summarize the most recent ACCP guidelines on therapy for venous thromboembolism with practical application and interpretation for the practicing physician. We will briefly review the rating system used in the guidelines for the level of evidence and the strength of the recommendation. We will then discuss the recommendations for initial anticoagulant therapies including low molecular weight heparin, unfractionated heparin, and fondaparinux for patients with both deep vein thrombosis (DVT) and pulmonary embolism (PE). A discussion of the guidelines on duration of anticoagulant therapy with a vitamin K antagonist is also included. In addition, we will address the use of thrombolytic therapy and inferior vena cava filter placement for DVT and PE. Prevention of postphlebitic syndrome is discussed as well. We will conclude with a brief discussion of future directions including several novel therapeutic anticoagulants.     

Prevention of venous thromboembolism: focus on mechanical prophylaxis

Venous thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism, is a leading health-care problem whose pathogenesis is usually related to the so-called Virchow's triad and involves a variety of factors classified as inherited or acquired, predisposing, or triggers. The main goal of thromboprophylaxis is to reduce mortality and morbidity associated with VTE risk factors. Although striking evidence now indicates that the various pharmacological anticoagulant therapies can substantially lower the risk, this benefit might be offset by a small but definite risk of hemorrhage in some circumstances. Mechanical prophylaxis methods have been suggested because they counteract most of the components of the Virchow's triad and are not associated with any bleeding risk. Although early and frequent ambulation has been historically advised for preventing VTE, this measure is inadequate per se and frequently not feasible as the sole means of mechanical thromboprophylaxis. Accordingly, additional measures are being used in clinical practice, including graded compression stockings, intermittent pneumatic compression devices, and venous foot pumps. Although the efficiency of these measures has been extensively assessed in several clinical studies, there remain unanswered questions, including their suboptimal use and the lack of unequivocal clinical evidence supporting real benefits for preventing VTE. Overall, mechanical compression methods can reduce the risk of VTE by nearly two thirds when used as the only form of thromboprophylaxis and by about half when combined with a pharmacological approach. The main mechanism of action appears to be related to a milking (wavelike) effect to evacuate leg veins and reduce venous stasis because an effect on the enhancement of fibrinolysis remains unproven. Although the biological and clinical evidence suggests that graduate compression stockings are an effective, relatively cheap, and more comfortable thromboprophylactic measure, they appear less effective overall than intermittent pneumatic compression. In conclusion, although the preventive benefits of mechanical prophylaxis on VTE might be circumscribed to select medical and surgical settings, there appears to exist no clinical reason to discourage adoption of these measures when indicated.     

Prevention of venous thromboembolism in neurosurgery: a metaanalysis

BACKGROUND: Venous thromboembolism (VTE) is an important complication of neurosurgery. Current guidelines recommend pharmacologic prophylaxis in this setting with either unfractionated heparin or low-molecular-weight heparin (LMWH). We conducted a systematic review asking, "Among patients undergoing neurosurgical procedures, how safe and effective is the prophylactic use of heparin and mechanical devices?" METHODS: We searched the medical literature to identify prospective trials reporting on VTE prevention (either mechanical or pharmacologic). The rates of VTE and bleeding were our primary end points and were pooled using a random-effects model. RESULTS: We identified 30 studies reporting on 7,779 patients. There were 18 randomized controlled trials and 12 cohort studies. The results of pooled relative risks (RRs) showed LMWH and intermittent compression devices (ICDs) to be effective in reducing the rate of deep vein thrombosis (LMWH: RR, 0.60; 95% confidence interval [CI], 0.44 to 0.81; ICD: RR, 0.41; 95% CI, 0.21 to 0.78). Similar results were seen when pooled rates from all 30 trials were analyzed. In head-to-head trials, there was no statistical difference in the rate of intracranial hemorrhage (ICH) between therapy with LMWH and nonpharmacologic methods (RR, 1.97; 95% CI, 0.64 to 6.09). The pooled rates of ICH and minor bleeding were generally higher with heparin therapy than with non-heparin-based prophylactic modalities. CONCLUSIONS: In a mixed neurosurgical population, LMWH and ICDs are both effective in the prevention of VTE. Sensitivity analyses have suggested that isolated high-risk groups, such as those with patients undergoing craniotomy for neoplasm, may benefit from a combination of prophylactic methods, suggesting the need for a more individualized approach to these patients.     

Prophylaxis for venous thromboembolism: guidelines translated for the clinician

Venous thromboembolism is a major cause of morbidity and mortality worldwide and most often affects hospitalized postoperative surgical and medical patients. Venous thromboembolism prophylaxis undoubtedly improves the care of these patients, as demonstrated by the current literature and guidelines. Failure to prescribe prophylaxis when indicated, however, remains a vital health care concern. The American College of Chest Physicians (ACCP) published their most recent guidelines regarding venous thromboembolism prophylaxis in 2008. In this review, we aim to summarize the most recent ACCP prophylaxis guidelines with practical application and interpretation for the practicing physician. Here we present the most practical information from these guidelines and summarize essential recommendations in key tables. We will briefly review the grading system used in the guidelines for the level of evidence and the strength of the recommendation. We will then discuss the recommendations for prophylaxis in the various patient populations described in these guidelines including general and orthopedic surgery, gynecologic surgery, urologic surgery, thoracic surgery, neurosurgery, trauma, medical conditions, cancer patients, and critical care. In addition, we will discuss recent clinical trials regarding novel anticoagulants for venous thromboembolism prophylaxis and share some conclusions.