Prevention of deep vein thrombosis and pulmonary embolism

Venous thromboembolism is a major cause of perioperative morbidity and mortality. Immobilized medical patients are also at risk. Long-term sequelae represent a significant chronic health burden. Hospitalized patients should be assessed for their risk of thromboembolism and bleeding at regular intervals. Risk stratification using recommended models can be used to guide the choice of thromboprophylaxis. Both mechanical and pharmacological interventions reduce the incidence of venous thromboembolism. Extended prophylaxis is now recommended following high-risk orthopaedic and cancer surgeries and a number of newer oral antithrombotic agents are now available for this. Anaesthesia should be tailored to minimize the risk of venous stasis and maximize early postoperative mobilization.     

Risk Stratification for Recurrent Venous Thromboembolism in Unprovoked Venous Thromboembolism Patients

Unprovoked venous thromboembolism (VTE) patients are at much higher risk of a recurrent VTE event than provoked VTE patients. Oral anticoagulation therapy (OAT) after a first unprovoked VTE has proved to effectively reduce the risk of recurrence during therapy however this benefit is lost after discontinuing OAT. A minimum of 6 to 12 months of OAT is recommended for first unprovoked VTE patients to prevent recurrence. However, there is evidence indicating that some patients are at ongoing high risk of recurrent VTE after discontinuation of therapy and that these patients may need indefinite anticoagulation to effectively prevent recurrences. Several risk factors for recurrent VTE have been identified that may be helpful to physicians when deciding whether OAT should be continued or discontinued in unprovoked VTE patients after initial therapy. The present article reviews risk factors for recurrent VTE including D-Dimer levels after discontinuation of OAT, elevated levels of Factor VIII, residual venous obstruction, post-throm-botic syndrome, male gender, and older age. Research is also underway to determine the predictive ability of these known VTE recurrence risk factors, combinations of these risk factors and their interrelationships as well as to actively search for additional potential predictors.     

Insufficient duration of venous thromboembolism prophylaxis after total hip or knee replacement when compared with the time course of thromboembolic events: findings from the Global Orthopaedic Registry

Patients who have undergone total hip or knee replacement (THR and TKR, respectively) are at high risk of venous thromboembolism. We aimed to determine the time courses of both the incidence of venous thromboembolism and effective prophylaxis. Patients with elective primary THR and TKR were enrolled in the multi-national Global Orthopaedic Registry. Data on the incidence of venous thromboembolism and prophylaxis were collected from 6639 THR and 8326 TKR patients. The cumulative incidence of venous thromboembolism within three months of surgery was 1.7% in the THR and 2.3% in the TKR patients. The mean times to venous thromboembolism were 21.5 days (sd 22.5) for THR, and 9.7 days (sd 14.1) for TKR. It occurred after the median time to discharge in 75% of the THR and 57% of the TKA patients who developed venous thromboembolism. Of those who received recommended forms of prophylaxis, approximately one-quarter (26% of THR and 27% of TKR patients) were not receiving it seven days after surgery, the minimum duration recommended at the time of the study. The risk of venous thromboembolism extends beyond the usual period of hospitalisation, while the duration of prophylaxis is often shorter than this. Practices should be re-assessed to ensure that patients receive appropriate durations of prophylaxis.     

Current status of anticoagulants

INDICATIONS: Direct inhibitors of thrombin, such as hirudin, are directed against the active site and the recognition site of thrombin. Because of their low-molecular-weight, they can inactivate thrombin bound to fibrin. Prevention of thromboembolic complications in patients undergoing primary total hip or knee replacement is now an authorized indication of desirudin in France. The recommended treatment for heparin-induced thrombocytopenia is lepirudin when there is a clinically evident thrombosis and danaparoid sodium, a mixture of anticoagulant glycosaminoglycans in an antithrombotic prophylaxis setting. LMWH: Low-molecular weight heparins are not yet authorized in France for the treatment of pulmonary embolism. However, deep venous thrombosis can be securely treated with one daily fixed dose of nadroparin or tinzaparin. ORAL ANTICOAGULATION: The duration of anticoagulation therapy in patients with venous thromboembolism remains controversial. Three to six months of therapy is recommended after a first episode of venous thromboembolism; the shorter regimen may be chosen when there is an identifiable and transient risk factor, and the longer when the thrombosis is idiopathic. In the context of primary prevention of ischaemic heart disease low intensity oral anticoagulation could be recommended in men at high risk.     

Primary prophylaxis of venous thromboembolism in surgical patients

Venous thromboembolism is a major risk for surgical patients during the perioperative period. Prevention of perioperative venous thromboembolism remains a critical component of surgical patient care. The risk for venous thromboembolism in surgical patients can be stratified by their risk factors and by the type of operation. Pharmacological prophylaxis for venous thromboembolism includes unfractionated heparin, low-molecular weight heparin, fondaparinux, warfarin, antiplatelet therapy, and direct thrombin inhibitors. Mechanical devices such as graduated compression stockings, intermittent pneumatic compressions, and venous foot pumps are also effective modalities for venous thromboembolism prophylaxis. The optimal preventive measure of venous thromboembolism should be based on the degree of risk for venous thromboembolism with the intensity of prophylaxis while balancing potential treatment benefits and risks in each individual patient. The epidemiology of venous thromboembolism, the methods for achieving venous thromboembolism prophylaxis, and the approach to institute venous thromboembolism prophylaxis in surgical patients undergoing various operative interventions are reviewed in this article.     

Perioperative management of chronic anticoagulation in orthopaedic surgery

The orthopaedic patient on chronic anticoagulation therapy is at risk of thromboembolism and hemorrhage in the perioperative period. To establish the most effective anticoagulation regimen, patients should be stratified according to the risk of arterial or venous thromboembolism. Timing of surgery, thromboembolic risk, and bleeding risk should be considered when developing an anticoagulation protocol. Retrievable inferior vena cava filters may be a viable alternative to bridging therapy in patients at high risk of venous thromboembolism and/or bleeding.     

出凝血异常普通外科病人围手术期静脉血栓栓塞症防治策略

易栓症是外科围手术期静脉血栓栓塞症(VTE)的防治重点。对于接受手术的止凝血障碍病人,需要谨慎评估VTE的个体风险,同时兼顾手术和麻醉的性质、出血障碍类型和严重程度、年龄、体重指数(BMI)、血栓形成史、恶性肿瘤和其他高危共患病。VTE风险应与已知出血障碍病人使用抗凝相关的出血风险平衡。实验室检查有助于发现和判断血栓与出血的病因,对病人的止凝血代偿能力作出评估,并对抗凝药物的合理使用提供依据。对上述病人,建议术后不常规使用药物预防血栓,尤其是血友病病人,但围手术期因子替代和止血药物的过度应用仍存在导致血栓的风险。使用低分子肝素(LMWH)和直接口服抗凝剂前应评估肾小球滤过率。当血小板计数<50×109/L,LMWH短期减量应用可能相对安全,监测抗Хa水平可用于调整中重度血小板减少症病人LMWH的剂量。主要消化道出血停止和重新使用华法林应至少相隔7 d。对于高血栓栓塞风险和术后高出血风险病人,术后当晚和术后第1天减量应用直接口服抗凝剂是一种可取的做法。     

Venous thromboembolism following major orthopedic surgery: what is the risk after discharge?

Guidelines recommend thromboprophylaxis for at least 10 days to prevent venous thromboembolism in patients undergoing high-risk orthopedic surgery, such as total hip arthroplasty (THA) or total knee arthroplasty (TKA). Furthermore, the recently updated ACCP guidelines also recommend extending the duration of thromboprophylaxis for 28 to 35 days following THA or hip fracture surgery as the risk for venous thromboembolism persists for up to 3 months after surgery. Extended-duration thromboprophylaxis (up to 6 weeks) with low-molecular-weight heparin is significantly more effective in preventing venous thromboembolism in orthopedic surgery patients than the recommended practice of at least 10 days. Extended-duration thromboprophylaxis may require risk stratification to identify high-risk patients. Current risk-assessment models have limitations and are not specific to orthopedic surgery patients; therefore, improvements may facilitate the use of extended-duration thromboprophylaxis in high-risk patients, thereby reducing the burden of venous thromboembolism.     

Pharmacological prophylaxis of venous thromboembolism in contemporary radical retropubic prostatectomy: Does concomitant pelvic lymphadenectomy matter?

The prevention of venous thromboembolism is a major concern in cancer patients undergoing pelvic surgery. Radical retropubic prostatectomy is a common treatment for localized prostate cancer and has been identified as a high risk procedure for postoperative venous thromboembolism. However, most patients diagnosed with prostate cancer in the current era have clinically localized, low volume disease and the risk of venous thromboembolism is very low. Multiple guidelines exist for the prevention of venous thromboembolism in patients undergoing radical retropubic prostatectomy and pharmacological venous thromboembolism prophylaxis is recommended. Most urological surgeons in the USA however, do not routinely utilize pharmacological prophylaxis. A major concern arises when radical retropubic prostatectomy is performed with a concomitant pelvic lymphadenectomy. Pharmacological prophylaxis is known to increase the rate of lymph drainage and the rate of lymphocele formation. Evidence suggests that lymphocele may be an independent risk factor for venous thromboembolism in the postoperative period. These factors raise concern over current guidelines calling for routine use of pharmacological venous thromboembolism prophylaxis in radical retropubic prostatectomy especially when lymphadenectomy is performed simultaneously.     

Deep vein thrombosis/pulmonary embolism: prophylaxis, diagnosis, and management

Thoracic surgery patients should be regarded at high risk for postoperative venous thromboembolism (VTE). VTE mechanical and pharmacologic prophylaxis with low molecular weight heparin, or low-dose unfractionated heparin or fondaparinux (Arixtra) is therefore strongly recommended. Pharmacologic prophylaxis should be extended to 4 weeks after major cancer surgery. Pulmonary embolism should be always managed with anticoagulation, in addition to thrombolytic therapy, in patients presenting with cardiogenic shock or persistent arterial hypotension.     

Thromboprohylaxis in orthopedic surgery and traumatology

Orthopaedic and trauma surgery are classified according 3 groups of venous thromboembolic risk. Elective total hip replacement (THR) or total knee replacement (TKR), hip fracture surgery or trauma patients are at high risk. Isolated lower extremity injury with fracture is at moderate risk whereas this risk is low without fracture as well as with knee arthroscopy. In THR and TKR, low molecular weight heparin (LMWH), fondaparinux or melagatran-ximelagatran are strongly recommended. The routine use of other anticoagulants, in particular vitamin K antagonist are not recommended. In patients at high risk of venous thromboembolism as for example trauma patients, optimal use of intermittent pneumatic compression is an alternative option in case of contra-indication to anticoagulant prophylaxis. Graduated compression stockings enhance the efficacy of pharmacological methods. In schedule surgery, initiation of prophylaxis with LMWH may be started postoperatively. To reduce the haemorrhagic risk of anticoagulants, timing of first postoperative dose is essential and is proper to each drug. Duration of prophylaxis depends on the surgical and the individual patients' risk. Extended prophylaxis in THR for up to 42 days with LMWH and up to 35 days with fondaparinux in hip fracture surgery is recommended. However extended prophylaxis after 14 days in TKR has not demonstrated a higher efficacy and should only be considered for patients with additional risk factors. In patients with isolated lower extremity injury or undergoing knee arthroscopy, LMWH should not be routinely used according to a low or a moderate risk and/or the duration of prophylaxis required. But LMWH has to be considered for patients with additional risk factors. Prophylaxis in other orthopedic procedures has not been assessed and will be extrapolated from the above recommendations.     

Caprini风险评估模型在静脉血栓栓塞症护理中的研究进展

综述Caprini风险评估模型在静脉血栓栓塞症护理中的研究进展。建议静脉血栓栓塞症诊疗模式逐渐向医护共同决策的分级护理模式转变，健全信息化风险预警系统，提升静脉血栓栓塞症的护理水平。     

Perioperative deep vein thrombosis prevention: what works, what does not work and does it improve outcome?

PURPOSE OF REVIEW: To critically evaluate the benefit/risk ratio of some strategies for venous thromboembolism prophylaxis (VTE) RECENT FINDINGS: A growing body of evidence shows that graduated elastic stockings are not effective in medical patients. Special surgical settings as bariatric surgery deserve attention with a high VTE risk and no evidence-based data with regard to prophylaxis. Extended prophylaxis is being evaluated in these patients, whereas its efficacy has been demonstrated in abdominal and pelvic surgery for cancer. New oral anticoagulants are about to change the clinical landscape but yet some issues are not solved: no antidote, no monitoring, no standardization for the perioperative bridging in patients with therapeutic doses. In addition, they have not been tested in fragile patients in whom an increased bleeding risk could be feared. Finally, a large bunch of guidelines are now available to help the physician in the decision-making process. SUMMARY: Studies evaluating the benefit/risk ratio of graduated elastic stockings should now take place in surgery. Increasing and splitting the anticoagulant dose (mainly low molecular weight heparins) by two injections a day could be recommended in bariatric surgery and morbidly obese patients. New anticoagulant agents should also be tested in special populations, following the European Medicines Agency guidance. The methodology of clinical trials in VTE prophylaxis has to be moved forward, pending the choice of debatable surrogate end-points as asymptomatic venous thrombosis and disputed issues on the assessment of major bleeding.     

重视腹部外科手术后下肢深静脉血栓形成和肺栓塞的防治

肺栓塞是下肢深静脉血栓形成最严重的并发症,对部分病人而言是一种隐匿性威胁。腹部外科手术后下肢深静脉血栓形成和肺栓塞并不少见,应该引起临床医生的足够重视。应建立以“防”为主的观念,对具有危险因素的病人采取积极的预防措施。同时临床医生应熟悉下肢深静脉血栓形成和肺栓塞的早期临床表现,结合病史和易患因素综合分析,提高警惕,及时诊断,减少误诊和漏诊。一旦明确诊断,则应积极采取各种有效措施进行合理治疗,将快速康复外科的理念应用于治疗过程中,争取达到更快更好的恢复。     

Venous thromboembolism prevention in surgery and obstetrics: clinical practice guidelines

BACKGROUND AND OBJECTIVE: To produce up-to-date clinical practice guidelines on the prevention of venous thromboembolism in surgery and obstetrics. METHODS: A Steering Committee defined the scope of the topic, the questions to be answered, and the assessment criteria. Eight multidisciplinary working groups (total of 70 experts) performed a critical appraisal of the literature in the following disciplines: pharmacology of antithrombotic agents, orthopaedics; general surgery (gastrointestinal (GI) and varicose vein surgery); urology; gynaecology and obstetrics; thoracic, cardiac and vascular surgery; surgery of the head, neck and spine; and surgery of burns patients. The resultant reports and guidelines were submitted for comment and completion of the Appraisal of Guidelines Research & Evaluation questionnaire to a total of 150 peer reviewers, before producing definite guidelines. RESULTS: The report answers the following questions for each type of surgery: (i) What is the venous thromboembolism incidence according to clinical and/or paraclinical criteria in the absence of prophylaxis? (with stratification of venous thromboembolism risk into low, moderate and high categories); (ii) What is the efficacy and safety of the prophylactic measures used? (iii) When should prophylaxis be introduced and how long should it last? (iv) Does ambulatory surgery affect efficacy and safety of prophylaxis? CONCLUSIONS: Apart from answering the above questions, the guidelines provide a summary table for each discipline. This table stratifies types of surgery into the three risk categories, specifies the recommended prophylaxis for venous thromboembolism (pharmacological and/or mechanical) and grades each recommendation. In addition, whenever appropriate, the recommended prophylaxis is adjusted to low- and high-risk patients.     

SARS-CoV-2 infection and venous thromboembolism after surgery: an international prospective cohort study

SARS-CoV-2 has been associated with an increased rate of venous thromboembolism in critically ill patients. Since surgical patients are already at higher risk of venous thromboembolism than general populations, this study aimed to determine if patients with peri-operative or prior SARS-CoV-2 were at further increased risk of venous thromboembolism. We conducted a planned sub-study and analysis from an international, multicentre, prospective cohort study of elective and emergency patients undergoing surgery during October 2020. Patients from all surgical specialties were included. The primary outcome measure was venous thromboembolism (pulmonary embolism or deep vein thrombosis) within 30 days of surgery. SARS-CoV-2 diagnosis was defined as peri-operative (7 days before to 30 days after surgery); recent (1–6 weeks before surgery); previous (≥7 weeks before surgery); or none. Information on prophylaxis regimens or pre-operative anti-coagulation for baseline comorbidities was not available. Postoperative venous thromboembolism rate was 0.5% (666/123,591) in patients without SARS-CoV-2; 2.2% (50/2317) in patients with peri-operative SARS-CoV-2; 1.6% (15/953) in patients with recent SARS-CoV-2; and 1.0% (11/1148) in patients with previous SARS-CoV-2. After adjustment for confounding factors, patients with peri-operative (adjusted odds ratio 1.5 (95%CI 1.1–2.0)) and recent SARS-CoV-2 (1.9 (95%CI 1.2–3.3)) remained at higher risk of venous thromboembolism, with a borderline finding in previous SARS-CoV-2 (1.7 (95%CI 0.9–3.0)). Overall, venous thromboembolism was independently associated with 30-day mortality (5.4 (95%CI 4.3–6.7)). In patients with SARS-CoV-2, mortality without venous thromboembolism was 7.4% (319/4342) and with venous thromboembolism was 40.8% (31/76). Patients undergoing surgery with peri-operative or recent SARS-CoV-2 appear to be at increased risk of postoperative venous thromboembolism compared with patients with no history of SARS-CoV-2 infection. Optimal venous thromboembolism prophylaxis and treatment are unknown in this cohort of patients, and these data should be interpreted accordingly.     

Risk stratification for recurrent venous thromboembolism in unprovoked venous thromboembolism patients

Unprovoked venous thromboembolism (VTE) patients are at much higher risk of a recurrent VTE event than provoked VTE patients. Oral anticoagulation therapy (OAT) after a first unprovoked VTE has proved to effectively reduce the risk of recurrence during therapy however this benefit is lost after discontinuing OAT. A minimum of 6 to 12 months of OAT is recommended for first unprovoked VTE patients to prevent recurrence. However, there is evidence indicating that some patients are at ongoing high risk of recurrent VTE after discontinuation of therapy and that these patients may need indefinite anticoagulation to effectively prevent recurrences. Several risk factors for recurrent VTE have been identified that may be helpful to physicians when deciding whether OAT should be continued or discontinued in unprovoked VTE patients after initial therapy. The present article reviews risk factors for recurrent VTE including D-Dimer levels after discontinuation of OAT, elevated levels of Factor VIII, residual venous obstruction, post-thrombotic syndrome, male gender, and older age. Research is also underway to determine the predictive ability of these known VTE recurrence risk factors, combinations of these risk factors and their interrelationships as well as to actively search for additional potential predictors.     

Spinal hematoma associated with heparin therapy for venous thromboembolism prophylaxis

Spinal hematoma is a rare and serious complication anesthesia. Risk factors for spinal hematoma during neuraxial anesthesia are anatomic abnormalities, impaired hemostasis and difficult needle placement. Japanese guideline for prevention of venous thromboembolism recommends low-dose unfractionated heparin (LDUH) to patients with moderate and high risk in perioperative period. LDUH is not contraindication for neuraxial anesthesia in this guideline. In order to reduce the risk of spinal hematoma in patients receiving heparin, it is recommended that the needle placement and catheter removal should be done when the anticoagulant effect of heparin is at the minimum. Postoperative evaluation of the neurological status is also important for early detection of a spinal hematoma.     

Thrombosis and coagulation: deep vein thrombosis and pulmonary embolism prophylaxis

Venous thromboembolism (deep venous thrombosis and pulmonary embolism, VTE) is a common complication in surgical patients and is the primary cause of preventable deaths in hospitalized patients. Despite well-known risk factors, VTE prophylaxis is frequently not practiced according to recommended guidelines.Patients can readily be stratified according to their risk of perioperative VTE, and mechanical and pharmacologic prophylactic regimens can be tailored to their individual risk. Pharmacologic VTEprophylaxis should be the standard of care in most clinical settings given its ease of administration, low risk, and cost-effectiveness.     

Internal jugular vein thrombosis associated with venous hypoplasia and protein S deficiency revealed by ultrasonography

A 41-year-old woman, who had no thrombotic risk factors and past history except congenital scoliosis, underwent central venous catheterization (CVC) before correction of the scoliosis. When internal jugular vein (IJV) catheterization using the anatomical landmark technique failed, CVC under ultrasound guidance was tried. As a consequence, thrombosis and hypoplasia of the right IJV were incidentally detected by ultrasonography. Central venous catheters were then successfully placed in other veins under ultrasound guidance. Also, after examinations to rule out the possibility of pulmonary embolism and to clarify the causes of the IJV thrombosis, the patient was found to have protein S deficiency. CVC under ultrasound guidance should be recommended to prevent the failure of cannulation and complications such as thromboembolism in patients who could possibly have anomalies of vessels as a result of anatomical deformities caused by severe scoliosis, even if patients do not have thrombotic risk factors such as a history of central catheter insertion or intravenous drug abuse, cancer, advanced age, cerebral infarction, and left ventricular dysfunction. Also, if venous thrombosis is found in patients without predisposing risk factors, one should ascertain the cause of the hypercoagulable state, for example protein S deficiency, and perform appropriate treatment and prevention of venous thromboembolism.