Patients with acute respiratory distress syndrome due to infection with the novel coronavirus SARS-COV2 are currently considered at high risk of developing thromboembolic complications in both venous and arterial vessels. The use of anticoagulants for preventive or curative purposes should be considered to reduce the risk of thromboembolic events. We report a case of a patient with severe COVID-19 acute respiratory distress syndrome who consecutively developed a right femoral deep vein thrombosis related to the femoral central line and acute ischemia of the left upper limb related to a radial arterial line. He was under a therapeutic dose of low molecular weight heparin twice a day three days before. The femoral vein was free of thrombosis while the central line was placed under a duplex ultrasound. Thromboembolic events can occur in patients with severe COVID-19 despite therapeutic anticoagulants. Close monitoring of vascular access with duplex ultrasound may be required.

Summary.  A variety of definitions of major bleeding have been used in published clinical studies, and this diversity adds to the difficulty in comparing data between trials and in performing meta‐analyses. In the first step towards unified definitions of bleeding complications, the definition of major bleeding in non‐surgical patients was discussed at the Control of Anticoagulation Subcommittee of the International Society on Thrombosis and Haemostasis. Arising from that discussion, a definition was developed that should be applicable to studies with all agents that interfere with hemostasis, including anticoagulants, platelet function inhibitors and fibrinolytic drugs. The definition and the text that follows have been reviewed and approved by the cochairs of the subcommittee and the revised version is published here. The intention is to also seek approval of this definition from the regulatory authorities.

For the treatment of acute venous thromboembolism, a fixed dose of dabigatran is as effective as warfarin, has a safety profile that is similar to that of warfarin, and does not require laboratory monitoring. (ClinicalTrials.gov number, NCT00291330.)

Background: VTE is a serious, but decreasing complication following major orthopedic surgery. This guideline focuses on optimal prophylaxis to reduce postoperative pulmonary embolism and DVT. Methods: The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement. Results: In patients undergoing major orthopedic surgery, we recommend the use of one of the following rather than no antithrombotic prophylaxis: low-molecular-weight heparin; fondaparinux; dabigatran, apixaban, rivaroxaban (total hip arthroplasty or total knee arthroplasty but not hip fracture surgery); low-dose unfractionated heparin; adjusted-dose vitamin K antagonist; aspirin (all Grade 1B); or an intermittent pneumatic compression device (IPCD) (Grade 1C) for a minimum of 10 to 14 days. We suggest the use of low-molecular-weight heparin in preference to the other agents we have recommended as alternatives (Grade 2C/2B), and in patients receiving pharmacologic prophylaxis, we suggest adding an IPCD during the hospital stay (Grade 2C). We suggest extending thromboprophylaxis for up to 35 days (Grade 2B). In patients at increased bleeding risk, we suggest an IPCD or no prophylaxis (Grade 2C). In patients who decline injections, we recommend using apixaban or dabigatran (all Grade 1B). We suggest against using inferior vena cava fi lter placement for primary prevention in patients with contraindications to both pharmacologic and mechanical thromboprophylaxis (Grade 2C). We recommend against Doppler (or duplex) ultrasonography screening before hospital discharge (Grade 1B). For patients with isolated lowerextremity injuries requiring leg immobilization, we suggest no thromboprophylaxis (Grade 2B). For patients undergoing knee arthroscopy without a history of VTE, we suggest no thromboprophylaxis (Grade 2B). Conclusions: Optimal strategies for thromboprophylaxis after major orthopedic surgery include pharmacologic and mechanical approaches. CHEST 2012; 141(2)(Suppl):e278S-e325SAbbreviations: DUS 5 Doppler (or duplex) ultrasonography; GCS 5 graduated compression stockings; HFS 5 hip fracture surgery; INR 5 international normalized ratio; IPCD 5 intermittent pneumatic compression device; IVC 5 inferior vena cava; LDUH 5 low-dose unfractionated heparin; LMWH 5 low-molecular-weight heparin; PE 5 pulmonary embolism; PEP 5 Pulmonary Embolism Prevention trial; RCT 5 randomized controlled trial; RR 5 risk ratio; THA 5 total hip arthroplasty; TKA 5 total knee arthroplasty; UFH 5 unfractionated heparin; VFP 5 venous foot pump; VKA 5 vitamin K antagonist