Deep Venous Thrombosis (DVT) - Risk Reduction : Wheeless' Textbook of Orthopaedics

Procedure-specific risk reduction

Specific agents for risk reduction

apixaban (oral factor Xa inhibitor)
- Apixaban for Extended Treatment of Venous Thromboembolism
aspirin (see role of ASA for DVT prophylaxsis)
danaparoid
- low molecular wt glycosaminoglycan with potent anti factor Xa activity
fondaparinux
low molecular weight heparins
- may be more effective in total hip arthroplasty as compared to total knee arthroplasty
- typically LMWH are administered 12-24 hours following surgery and is continued for 14 days
recombinant hirudin desirudin
- may offer up to 86% risk reduction of DVT
- direct inhibitor of thrombin
rivaroxaban (Xarelto)
- highly selective direct factor Xa inhibitor with oral bioavailability and rapid onset of action
- availability – 10 mg, 15 mg, and 20 mg tablets
- indications (non-comprehensive)
  - prophylaxis of deep vein thrombosis (DVT) in adults undergoing hip and knee replacement
  - treatment of patients with DVT and pulmonary embolism (PE)
  - long-term treatment to prevent recurrence of DVT and PE
- references
SQ heparin
thrombolytic therapy
warfarin

Bleeding complications

difficulty in assessing the risk of bleeding complications among various agents depends mainly on dose of meds used and amount of monitoring
- i.e., to achieve the desired anticoagulation effect (and DVT prophylaxsis), how much bleeding are we willing to accept?
- published bleeding complications note 5% bleeding from LMWH, 3% bleeding from coumadin, and 2.5% from SQ heparin
- in contrast, the bleeding complications from ASA is approximately 0.4%

Mechanical methods for risk reduction

note that there is a large venous plexus in the foot which is compressed when the foot is flattened with wt bearing
- wt bearing compresses about 30 ml out of the foot and flushes it into the deep venous system
- foot pump systems attempt to reproduce this effect
- TED hose (compression stockings) are recommended when using mechanical devices in order to help control venous capacitance
compression stockings
- note that mechanical compression devices that wrap around the leg cannot be used in total knee patients
- in the study by Warwick, et al. (1998), DVT was noted in 18% of foot pump patients vs 13% of enoxaparin patients (no sig difference)
  - patients in the enoxaparin group had significantly more bruising, thigh swelling, and wound oozing
  - the authors used venography to evaluate DVT formation
  - the authors concluded that foot pump devices had comprable efficacy to low molecular wt heparin
  - reference - Comparison of the use of a foot pump with the use of low-molecular-weight heparin for the prevention of deep-vein thrombosis after total hip replacement. A prospective, randomized trial.
foot movement
- sustained movement of the foot (30 cycles for one minute) will produce a sustained increase in the venous outflow (22 % greater than baseline) which gradually returns to the base line after 30 min
- reference - The effect of active movement of the foot on venous blood flow after after total hip replacement.

Epidural anesthesia

epidural anesthesia has clearly been shown to reduce prevalence of DVT
potential problem is that blood thinning agents cannot be used as long as the epidural catheter is in place (due to the risk of epidural hematoma and resulting neurologic deficit)
reference: The prevalence of deep venous thrombosis after total hip arthroplasty with hypotensive epidural anesthesia