Introduction Incidence DVT pulmonary embolism 700,000 symptomatic PE/yr in USA of these 200,000 are fatal Risk factors for thromboembolism Virchow's triad venous stasis hypercoagulable state intimal injury primary hypercoagulopathies (inherited) MTHFR/C677T/TT gene mutation carries highest risk factor V Leiden mutation antithrombin III deficiency protein C deficiency protein S deficiency activated protein C resistance secondary factors (acquired) malignancy recently been associated with up to 20% of all new diagnoses of VTE elevated hormone conditions recombinant erythropoeitin hormone replacement oral contraceptive therapy late pregnancy elevated antiphospholipid antibody conditions lupus anticoagulant anticardiolipin antibody history of thromboembolism obesity aging CHF varicose veins smoking general anesthetics (vs. epidural and spinal) immobilization increased blood viscosity Pathophysiology Mechanism of clot formation stasis fibrin formation thromboplastin (aka Tissue Factor (TF), platelet tissue factor, factor III, or CD142) is released during dissection which leads to activation of the extrinsic pathway and fibrin formation clot retraction propagation Prophylaxis Overview prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE) is most important factor in decreasing morbidity and mortality prophylaxis treatment should be determined by weighing risk of bleeding vs risk of pulmonary embolus AAOS risk factors for major bleeding bleeding disorders history of a recent gastrointestinal bleed history of a recent hemorrhagic stroke AAOS risk factors for pulmonary embolus hypercoagulable state previous documented pulmonary embolism Prophylaxis in hip & knee replacement mechanical prophylaxis compressive stockings recommended pneumatic compression devices are recommended by the AAOS across all risk (low to high risk of either bleeding or pulmonary embolism) groups undergoing total hip or total knee arthroplasty increase venous return and endothelial-derived fibrinolysis decrease venous compliance and venous stasis chemical prophylaxis American Academy of Orthopaedic Surgeons (AAOS) and American College of Chest Physicians (ACCP) support ASA as a monotherapy medical treatment see anticoagulation section below Deep Venous Thrombosis Introduction procedures associated with greater frequency of DVT spine fracture with paralysis elective total knee arthroplasty 2-3X greater rate of DVT than THA elective total hip arthroplasty hip fracture polytrauma based on AAOS review, the rate of DVT does not correlate with PE or death following THA or TKA Physical exam often more helpful than imaging pain and swelling Homan's sign is not very specific Imaging venography is gold standard for proximal DVTs (proximal to trifurcation) venous duplex ultrasound is 96% sensitive, 98% specific plethysmography is 75% sensitive, 90% specific CT is 90% sensitive, 95% specific Treatment heparin therapy followed by long term coumadin indications postoperative DVT above knee treatment for DVT below knee is controversial vena cava filter placement indications preoperative identification of DVT in a patient with lower extremity or pelvic trauma who is high risk for DVT development see anticoagulation Pulmonary Embolism Introduction 700,000 asymptomatic PE/yr in USA of these 200,000 are fatal procedures associated with pulmonary embolism hip fracture elective total hip arthroplasty the greatest risk of activation of the clotting cascade during total hip arthroplasty occurs during insertion of the femoral component elective total knee arthroplasty spine fracture with paralysis early diagnosis and treatment is most important factor for survival Presentation PE should be suspected in postoperative patients with acute onset pleuritic pain and dyspnea tachypnea tachycardia Evaluation EKG ABG Imaging CXR nuclear medicine ventilation-perfusion scan (V/Q) pulmonary angiography is gold standard helical chest CT widely considered first line imaging modality Treatment continuous IV heparin infusion followed by warfarin therapy indications in most cases as first line treatment technique continuous IV heparin infusion typically given for 7-10 days warfarin therapy typically given for 3 months monitor heparin therapy with PTT (partial thromboplastin time) monitor coumadin therapy with INR (international normalized ratio) thrombolytics indications in specific cases technique see anticoagulation the greatest risk of activation of the clotting cascade during total hip arthroplasty occurs during insertion of the femoral component;
QUESTIONS 1 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ10.67) A 67-year-old man complains of low-grade fevers and calf pain 2 weeks following a total knee arthroplasty. What is the next appropriate step in management of this patient? Review Topic QID: 3154 1 Plethysmography of lower extremity 1% (18/2658) 2 MRI of lower extremity 0% (9/2658) 3 CT angiography of lower extremity 1% (18/2658) 4 Venous ultrasonography 95% (2530/2658) 5 Knee aspiration to evaluate for septic joint 3% (78/2658) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 4 (OBQ08.144) Which of the following is NOT a component of Virchow's triad? Review Topic QID: 530 1 Thrombocytopenia 7% (90/1224) 2 Platelet dysfunction 2% (21/1224) 3 Hypercoagulability 0% (5/1224) 4 Venous stasis 1% (14/1224) 5 Neither thrombocytopenia (answer 1) nor platelet dysfunction (answer 2) are components of Virchow's triad 89% (1091/1224) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 5 (OBQ09.265) The 2009 AAOS Clinical Guideline on prevention of pulmonary embolism in patients undergoing total hip or knee arthroplasty recommends classifying patients as having either a "standard" or "elevated" risk of bleeding complications. The presence of all of the following qualify a patient as having an "elevated" risk of major bleeding EXCEPT? Review Topic QID: 3078 1 History of hemophilia 2% (24/1485) 2 History of protein C deficiency 84% (1241/1485) 3 History of a recent gastrointestinal bleed 6% (95/1485) 4 History of a recent hemorrhagic stroke 3% (49/1485) 5 History of Von Willebrand's Disease 5% (71/1485) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 2 (OBQ13.244) A 59-year-old patient undergoing total hip arthroplasty has a genetically inherited thrombophilia disorder. In this disorder, a variant co-factor cannot be inhibited by activated protein C causing overproduction of thrombin. What is this patients clotting disorder? Review Topic QID: 4879 1 Factor V Leiden 71% (2292/3243) 2 Antithrombin III deficiency 13% (422/3243) 3 Familial dysfibrinogenemia 2% (80/3243) 4 Protein S deficiency 12% (378/3243) 5 Congenital deficiency of plasminogen 1% (38/3243) ML 3 Select Answer to see Preferred Response PREFERRED RESPONSE 1 (OBQ12.206) A 52-year-old male underwent a right total knee arthroplasty 3 days ago and reports new onset dyspnea. His vitals signs include a temperature of 98.8, pulse of 133, blood pressure of 130/77, respiratory rate of 28, and oxygen saturation of 91% on room air. A chest radiograph shows atelectasis. Which of the following findings is most likely also present? Review Topic QID: 4566 1 Hyperchloremic metabolic acidosis 7% (274/3709) 2 Jugular venous distention with tracheal deviation 3% (124/3709) 3 EKG demonstrating S-wave in lead I Q-wave in lead III T-wave inversion in lead III 74% (2731/3709) 4 Pleural effusion with pleural/serum protein >0.5 and pleural/serum LDH > 0.6 5% (179/3709) 5 Increased carbon monoxide diffusing capacity (DLCO) 10% (363/3709) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (OBQ05.27) During total hip arthroplasty, which of the following interventions increases the risk of pulmonary ventilation-perfusion mismatch the greatest? Review Topic QID: 64 1 Acetabular reaming 3% (49/1754) 2 Cement pressurization of the femoral canal 94% (1643/1754) 3 Use of a modular femoral stem 2% (30/1754) 4 Intra-operative sequential compressive device on the non-operative leg 1% (9/1754) 5 Posterior approach 1% (16/1754) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 2 (OBQ10.189) A 30-year-old male with Protein C deficiency sustains a large subarachnoid hemorrhage and bilateral calcaneus fractures after falling off of a roof. The patient has been in the intensive care unit for 5 days for monitoring of his head injury. All of the following factors are appropriate reasons to obtain a helical chest CT scan EXCEPT: Review Topic QID: 3282 1 Elevated alveolar-arterial gradient (> 20 mm Hg) on arterial blood gas 10% (265/2765) 2 Pulse oximetry reading of 99% with respiratory rate of 35 breaths/min 27% (756/2765) 3 Pulse rate of 125 beats/min with new onset right bundle branch block 9% (247/2765) 4 Paco2 > 35 mm Hg on arterial blood gas 48% (1315/2765) 5 Pao2 < 80 mm Hg on arterial blood gas 6% (160/2765) ML 4 Select Answer to see Preferred Response PREFERRED RESPONSE 4 (OBQ04.224) A 25-year-old healthy male is scheduled to undergo a a nine-level posterior spinal fusion for scoliosis. Administering preoperative recombinant erythropoietin would place the patient at increased risk of developing which of the following complications? Review Topic QID: 1329 1 Acute renal failure 6% (35/577) 2 Increased bleeding time 4% (22/577) 3 Thrombotic event 81% (470/577) 4 Wound complications 3% (16/577) 5 Delayed spinal fusion 5% (30/577) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (OBQ04.273) A 65-year-old female undergoes a total knee arthroplasty. In addition to chemoprophylaxis for deep vein thrombosis (DVT) prevention she is given pneumatic compression devices. Which of the following is associated with pneumatic compression devices? Review Topic QID: 1378 1 Increased endothelial fibrinogenesis 6% (38/621) 2 Decreased bleeding times 0% (2/621) 3 Increased endothelial injury 2% (15/621) 4 Increased venous compliance 9% (55/621) 5 Increased venous blood flow 82% (509/621) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 5 (OBQ05.172) A 65-year-old man undergoes total knee replacement and is found to have deep vein thrombosis two days later. What molecule is thought to be involved in this process when it is released during surgical dissection? Review Topic QID: 1058 1 Prothrombin 36% (596/1639) 2 RANKL 1% (18/1639) 3 IL-1b 12% (197/1639) 4 Thromboplastin 46% (753/1639) 5 Factor XI 4% (72/1639) ML 4 Select Answer to see Preferred Response PREFERRED RESPONSE 4 Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK
pdf Prevention of VTE in orthopedic surgery patients: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Basic Science - Journal Club Falck-Ytter Y1, Francis CW, Johanson NA, Curley C, Dahl OE, Schulman S, Ortel TL, Pauker SG, Colwell CW Jr; American College of Chest Physicians. Chest. 2012 Feb;141(2 Suppl):e278S-325S. doi: 10.1378/chest.11-2404. PMID: 22315265 (Link to Abstract)