Chapter 28 DVT Flashcards
Describe the mechanism of action for Low-Dose Unfractionated Heparin (LDUH) – LDUH binds with __________ to inhibit factor __________ (__________) and factor __________ (__________ clotting pathway).
Describe the mechanism of action for Low-Dose Unfractionated Heparin (LDUH) – LDUH binds with antithrombin III to inhibit factor Ha (thrombin) and factor Xa (intrinsic clotting pathway).
Describe the mechanism of action for Low-Molecular-Weight Heparin (LMWH) – Mechanism of action is similar to __________, but the reduced binding with plasma proteins results in a __________ and more __________ half-life. It is contraindicated in __________ (__________).1Enoxaparin (Lovenox), 30 mg SC bid or 40 mg qd, is FDA-approved for s/p THA; 30 mg bid is approved for s/p TKA. Dalteparin (Fragmin), 5,000 U SC qd, is FDA-approved for s/p THA.
Describe the mechanism of action for Low-Molecular-Weight Heparin (LMWH) – Mechanism of action is similar to LDUH, but the reduced binding with plasma proteins results in a longer and more predictable half-life. It is contraindicated in heparin-induced thrombocytopenia (HIT).1Enoxaparin (Lovenox), 30 mg SC bid or 40 mg qd, is FDA-approved for s/p THA; 30 mg bid is approved for s/p TKA. Dalteparin (Fragmin), 5,000 U SC qd, is FDA-approved for s/p THA.
Describe the mechanism of action for Vitamin K antagonist (VKA or __________) – It inhibits the vitamin K–mediated production of procoagulant factors X, IX, VII, and II (extrinsic pathway) and anticoagulant proteins __________ and __________. There is an initial paradoxical procoagulant effect since proteins __________ and __________ are depleted first (thus, initiating therapy with “loading” doses >5 mg qd is not usually recommended).
For INRs 5 to 9 w/o significant bleeding, give 1 to 2.5 mg po vitamin K or follow INRs w/o vitamin K. For INRs > 9 w/o significant bleeding, give 3 to 5 mg po vitamin K and monitor INRs (repeat vitamin K if necessary). For elevated INRs with serious bleeding, give 10 mg vitamin K by slow IV infusion (repeat q12h if necessary) and supplement with plasma or prothrombin complex concentrate.
Describe the mechanism of action for Vitamin K antagonist (VKA or Warfarin1) – It inhibits the vitamin K–mediated production of procoagulant factors X, IX, VII, and II (extrinsic pathway) and anticoagulant proteins C and S. There is an initial paradoxical procoagulant effect since proteins C and S are depleted first (thus, initiating therapy with “loading” doses >5 mg qd is not usually recommended).
For INRs 5 to 9 w/o significant bleeding, give 1 to 2.5 mg po vitamin K or follow INRs w/o vitamin K. For INRs > 9 w/o significant bleeding, give 3 to 5 mg po vitamin K and monitor INRs (repeat vitamin K if necessary). For elevated INRs with serious bleeding, give 10 mg vitamin K by slow IV infusion (repeat q12h if necessary) and supplement with plasma or prothrombin complex concentrate.
Describe the mechanism of action for Fondaparinux, 2.5 mg SC qd (Arixtra) – This is a heparin derivative that selectively inhibits factor __________ and is FDA-approved for s/p hip fracture surgery (HFS), THA, and TKA.
Describe the mechanism of action for Fondaparinux, 2.5 mg SC qd (Arixtra) – This is a heparin derivative that selectively inhibits factor Xa and is FDA-approved for s/p hip fracture surgery (HFS), THA, and TKA.
Hirudins (e.g., lepirudin, 15 mg SC bid) are direct __________ inhibitors indicated in the setting of __________. Heparinoids (e.g., danaparoid, no longer available for nonmedical reasons) have a similar mechanism of action as that of UH, but do not contain __________ and are also used in the setting of __________.
Hirudins (e.g., lepirudin, 15 mg SC bid) are direct thrombin inhibitors indicated in the setting of HIT. Heparinoids (e.g., danaparoid, no longer available for nonmedical reasons) have a similar mechanism of action as that of UH, but do not contain heparin and are also used in the setting of HIT.
ASA inhibits __________ __________, but is not recommended by the American College of Chest Physicians (ACCP) for DVT prophylaxis because other measures are more efficacious.
ASA inhibits platelet aggregation, but is not recommended by the American College of Chest Physicians (ACCP) for DVT prophylaxis because other measures are more efficacious.
Inferior vena cava filters are used for __________ __________ (not DVT) prophylaxis.
Inferior vena cava filters are used for pulmonary embolism (not DVT) prophylaxis.
Orthopedic surgery: THA or TKA – _________, fondaparinux, or _________ (INR _________ to _________).
Orthopedic surgery: THA or TKA – LMWH, fondaparinux, or VKA (INR 2 to 3).
HFS – _________, LMWH, VKA, or LDUH.
HFS – Fondaparinux, LMWH, VKA, or LDUH.
Duration – THA/HFS 10 to 35 days, TKA at least 10 days. Optimal use of _________ or _________ may provide additional efficacy.
Duration – THA/HFS 10 to 35 days, TKA at least 10 days. Optimal use of intermittent pneumatic compression or graduated compression stockings may provide additional efficacy.
Medical/Neuro Patients – _________, _________, or fondaparinux is recommended for patients with general medical issues (e.g., cancer and bed rest) or following ischemic stroke with impaired mobility. The ideal time to start anticoagulation after hemorrhagic stroke has not been determined.
Medical/Neuro Patients – LMWH, LDUH, or fondaparinux is recommended for patients with general medical issues (e.g., cancer and bed rest) or following ischemic stroke with impaired mobility. The ideal time to start anticoagulation after hemorrhagic stroke has not been determined.
SCI – Mechanical and anticoagulation treatment should be initiated as early as possible, provided there is no active bleeding or coagulopathy. Compression hose and boots should be applied for _________ weeks (r/o DVT first if thromboprophylaxis has been delayed >72 hours).
For American Spinal Injury Association (ASIA) A, B – UH adjusted to high-normal aPTT (activated PTT) or LMWH for ≥8 weeks. For ASIA A, B with other risk factor(s) (e.g., LEx fracture, cancer, previous thrombosis, heart failure, obesity, and age >70 years) – UH adjusted to high-normal aPTT or LMWH for 12 weeks or discontinue from rehabilitation. ASIA C – UH 5,000 U q12h or LMWH for up to 8 weeks. ASIA D – UH 5,000 U q12h or LMWH while in hospital. The ACCP recommends against the use of inferior vena cava filters as thromboprophylaxis following acute SCI.
SCI – Mechanical and anticoagulation treatment should be initiated as early as possible, provided there is no active bleeding or coagulopathy. Compression hose and boots should be applied for 2 weeks (r/o DVT first if thromboprophylaxis has been delayed >72 hours).
For American Spinal Injury Association (ASIA) A, B – UH adjusted to high-normal aPTT (activated PTT) or LMWH for ≥8 weeks. For ASIA A, B with other risk factor(s) (e.g., LEx fracture, cancer, previous thrombosis, heart failure, obesity, and age >70 years) – UH adjusted to high-normal aPTT or LMWH for 12 weeks or discontinue from rehabilitation. ASIA C – UH 5,000 U q12h or LMWH for up to 8 weeks. ASIA D – UH 5,000 U q12h or LMWH while in hospital. The ACCP recommends against the use of inferior vena cava filters as thromboprophylaxis following acute SCI.
In the absence of contraindications, initial treatment is typically _________. _________ is usually started within 24 hours of DVT diagnosis, once the heparin is therapeutic. A 5-mg initial dose of _________ is preferred over a 10-mg dose due to early paradoxical hypercoagulability. _________ is discontinued when the INR has been ≥2 for two consecutive days. _________ is typically instituted for _________ to _________ months.
LMWH (e.g., enoxaparin, 1 mg/kg SC bid, or dalteparin, 200 U/kg SC qd) + warfarin is an alternative for the outpatient treatment of uncomplicated DVT; LMWH can be discontinued after 5 days and when INR > 2.
Thrombolytics may have a role in patients with extensive proximal DVT and low bleed risk. The treatment of isolated calf DVT remains controversial.
In the absence of contraindications, initial treatment is typically IV heparin. Warfarin is usually started within 24 hours of DVT diagnosis, once the heparin is therapeutic. A 5-mg initial dose of warfarin is preferred over a 10-mg dose due to early paradoxical hypercoagulability. Heparin is discontinued when the INR has been ≥2 for two consecutive days. Warfarin is typically instituted for 3 to 6 months.
LMWH (e.g., enoxaparin, 1 mg/kg SC bid, or dalteparin, 200 U/kg SC qd) + warfarin is an alternative for the outpatient treatment of uncomplicated DVT; LMWH can be discontinued after 5 days and when INR > 2.
Thrombolytics may have a role in patients with extensive proximal DVT and low bleed risk. The treatment of isolated calf DVT remains controversial.
