Changing Trends In DVT prophylaxis in Orthopedics
Venous thromboembolism (VTE) has been identified as an immediate threat to patients undergoing major orthopedic procedures such as total hip arthroplasty (THA) and total knee arthroplasty (TKA). Given the known dangers of VTE, arthroplasty surgeons are sensitive to the need for VTE thromboprophylaxis. However, the modalities of thromboprophylaxis used to minimize the risks to patients have been variable. Clinical practice guidelines have been published by several professional organizations, while some hospitals have established their own protocols. The 2 most popular guidelines are those published by the Academy of Orthopaedic Surgeons (AAOS) and American College of Chest Physicians (ACCP), both from North America.
Key Points Before Following the Guidelines
- With all due respect to the members of the associations Of the 71 trials that were used in formulating the guidelines out of which 52 were funded by pharma companies 5 didn’t disclose funding sources only 14 were non funded trials. Thus there are a lot of conflict of interest in trials and the data extracted for recommendation may not be accurate.
- All Studies used demonstration of DVT by venogram or ultrasound as end point. Numerous studies have shown presence of asymptomatic or symptomatic DVT may not correlate with occurrence of Pulmonary embolism.
- All prophylaxis have a inherent risk of bleeding in trials only life threatening bleeds were included. But effect of anti coagulant on minor bleeding, wound complications, infection rates need for re operation have not been considered.
- Strict following of guidelines may be option in insured patients. But in resource restricted areas many chose not give any prophylaxis due to financial constraints. Thus more than risk reduction alone cost benefit must also be considered while forming guidelines.
” Strict following of guidelines may not be feasible for all practices. Thrombo Prophylaxis is a must for all major orthopedic surgeries and must be customized to individuals practice and resources, based on risk and cost efficacy”
Mechanical prophylaxis is any compressive device applied to an affected limb. It can be a compressive stockings, Intermittent Pneumatic Compression Devices (IPCD), or similar working devices.ACCP guidelines suggest the use of IPCD be at least 18 hours a day as an adjunct to chemoprophylaxis, or in patient with high risk of bleeding. The AAOS guidelines recommend use of mechanical compressive devices in patients with known bleeding disorders, such as hemophilia or active liver disease or as with chemoprophylaxis in patient with previous VTE.
” Some form of mechanical prophylaxis in form of crepe bandage/ stockings/ Pneumatic compression device intra operative further decreases DVT risk”
VTE prophylaxis for THA and TKA patients are available in chemical and/or mechanical forms. Chemical prophylaxis agents included in the clinical guidelines were aspirin, warfarin, LMWH, fondaparinux, dabigatran, rivaroxaban, and apixaban.
Low Molecular Weight Heparin (LMWH)
Low molecular weight heparin is generated from unfractionated heparin either through physical, chemical, or enzymatic depolarization . Some of the available LMWHs are enoxaparin, dalteparin, and tinzaparin. Among these 3, only (enoxaparin and dalteparin) are indicated in major orthopedic surgery.
“ Though the newer Fac Xa inhibitors are more efficient in anticoagulation they have increased bleeding complications. Thus Enoxaparin is still the best form of prophylaxis. A dose of 40mg sc once daily and increase to 1.5mg/Kg if DVT develops”
Factor Xa Inhibitor (Fondaparinux, Rivaroxaban, Apixaban)
There are 2 types of factor Xa inhibitors, the indirect and direct. Fondaparinux and idraparinux are examples of indirect factor Xa inhibitors. They are synthetic, highly selective factor Xa inhibitors that work in a pentasaccharide form.On the other hand, direct factor Xa inhibitors work by binding to the active site of factor Xa, thus, blocking the interaction with its substrate. Examples of oral direct factor Xa inhibitors are rivaroxaban, apixaban, edoxaban, and betrixaban.
” Oral anticoagulants like Rivaroxaban, apixaban. and aspirin are more cost effective than Enoxaparin”
Timing of Thrombo prophylaxis
“For patients undergoing major orthopedic surgery (THA, TKA, HFS) and receiving LMWH as thromboprophylaxis, its recommend starting either 12 h or more preoperatively or 12 h or more postoperatively rather than within 4 h or less preoperatively or 4 h or less postoperatively to prevent bleeding complications intraop”
Duration Thrombo prophylaxis
For patients undergoing major orthopedic surgery, its suggested to extending thromboprophylaxis in the outpatient period for up to 35 days from the day of surgery rather than for only 10 to 14 days.
” Enoxaparin can be given till discharge of patient and at home oral Apixaban 2.5mg twice daily eliminates the need for nurse or attendant to administer Enoxaparin injections. The Apixaban is way cheaper than enoxaparin and may be continued till 14 days in minor cases and upto 35 days in major cases. Alternatively aspirin 325mg may also be used.”
Isolated Lower-Leg Injuries Distal to the Knee
“Its suggest no prophylaxis rather than pharmacologic thromboprophylaxis in patients with isolated lower-leg injuries requiring leg immobilization”
“Compression stockings should be continued in post operative period up to 1 month along with anticoagulants”