VENOUS THROMBOEMBOLIC DISEASE

The risk of new or recurrent Venous Thromboembolism (VTE) versus the risk of perioperative bleeding while on anticoagulation should always be discussed with the surgeon.

Preoperative evaluation:

Assessment: patients without prior VTE:

• Risk factors:  Previous VTE, malignancy, hereditary thrombophilias, pregnancy. 
• Meds:  Hormone replacement therapy or oral contraceptives should be stopped if possible (see “Perioperative Medication Management”).
• Exam:  Assess for signs or symptoms of VTE.
• Imaging:  There is no data to support screening imaging studies prior to surgery.
• Surgery type:  Certain procedures confer greater VTE risk.

For patients with recent VTE (Ref 1,2,3): 

Time of VTE prior to surgery	Risk of recurrent VTE after stopping anticoagulation	Management
		Preop	Postop
Within 1 month	Approaching 50% if stopped prior to 1 month.	*Avoid surgery if possible.* Consider IVC filter. Bridge with IV heparin.	Bridge with IV heparin.
1-3 months prior	The risk decreases sharply after 1 month. At 1 month about 8%. At 3 months about 4%.	Avoid surgery if possible. Consider bridge therapy with IV heparin. If hospitalized, give prophylaxis-dose LDUH or LMWH (if not bridging).	Bridge with IV heparin.
>3 months prior	3 months of anticoagulation is a reasonable amount of time prior to surgery	No bridging unless severe hypercoagulable state present. If hospitalized, give prophylaxis-dose LDUH or LMWH.	Prophylaxis-dose LDUH or LMWH until on therapeutic anticoagulation (if this is being continued for an extended duration)

LDUH=low dose unfractionated heparin; LMWH=low molecular weight heparin

• Bridging:
• IV heparin:  If used preop, stop heparin infusion 4-6 hours prior to surgery. Postop check with surgeon for when bleeding risk is acceptable and consider giving without bolus.
• LMWH: last dose usually given in AM the day prior to surgery (ie >24 hours prior).  Postop given when surgical bleeding risk is acceptable, or use IV heparin.
• IVC filters:  Exist only to prevent PE.  Anticoagulation is still indicated once surgical bleeding risk is low enough.  Possible indications for IVC filters:
• Acute proximal DVT with an absolute contraindication to therapeutic anticoagulation due to bleeding. (Ref 6)
• Acute VTE within 2 weeks of surgery AND high risk of bleeding while on IV heparin. (Ref 1,4)
• Large PE and poor baseline cardiopulmonary reserve such that another embolic event would be poorly tolerated (even if able to be anticoagulated). (Ref 5)
• Potentially retrievable IVC filters:  May be considered when the contraindication to anticoagulation is likely to be temporary, e.g. <2 wks.  Ability to remove a filter decreases with time—retrieval should generally occur by 3 months (Ref 7,8).  A time course for possible retrieval should always be discussed with the proceduralist.

Postoperative management:
Recommended VTE prophylaxis (Ref 9)

Risk Category*	Type of Surgery	Recommended Prophylaxis10
		1st line	2nd line
Low Risk	Minor surgery in mobile patients (e.g. gyn laparoscopic procedures, transurethral surgeries, outpatient spine procedures in low risk patients)	Early ambulation	None
Moderate Risk	General surgery Open gynecologic Open urologic surgery	LDUH Q12 or Q8 hours	LMWH
		For higher risk patients (e.g.prior VTE, extensive surgery for malignancy):  Use LMWH (1st list) or LDUH Q8H dosing (2nd line) +/- IPC/GCS.  Consider extending prophylaxis for up to 28 days.
	Bariatric surgery	LMWH high dose prophylaxis (e.g. enoxaparin 40 mg SQ Q12H for BMI >40) +/- IPC/GCS	LDUH Q8H +/- IPC/GCS.  Consider higher doses e.g. 7500 units SQ Q8H.
	Intracranial neurosurgical procedure	IPC/GCS	LDUH SQ Q8H or Q12H, or LMWH
	Elective spine surgery with additional VTE risk factors (advanced age, malignancy, neurologic deficit, previous VTE, anterior surgical approach)	LDUH Q8H +/- IPC/GCS	LMWH +/- IPC/GCS
High Risk	Hip or knee arthroplasty	LMWH (enoxaparin 30 mg SQ Q12H or dalteparin 5000 units SQ daily) started either 12 hrs preop or 12-24 hours post op.  Cont for a total of 10-35 days.	Warfarin (INR 2-3) started either night before or evening of surgery. Cont for a total of 10-35 days.
	Hip fracture surgery	LMWH (enoxaparin 30 SQ Q12H or dalteparin 5000 units SQ daily) +/- GCS/IPC.  Cont for a total of 10-35 days.	Warfarin (INR 2-3) initiated either night before or evening of surgery.  Cont for a total of 10-35 days.
	Spinal cord injury	LMWH (enoxaparin 30 SQ Q12H or dalteparin 5000 units SQ daily) +/- GCS/IPC.  Initiate when bleeding risk acceptable. Continue LMWH or convert to warfarin if going to inpatient rehab.	LDUH Q8H + IPC/GCS
	Trauma	LMWH (enoxaparin 30 mg SQ Q12H or dalteparin 5000 units SQ daily) as soon as bleeding risk is low enough. For major trauma in immobile pts going to inpatient rehab, can continue LMWH/warfarin.	IPC/GCS

LDUH=low dose unfractionated heparin 5000 units subcutaneous
LMWH=low molecular weight heparin, enoxaparin 40 mg or dalteparin 5000 units subcutaneous, unless otherwise specified.
IPC=intermittent pneumatic compression,
GCS=graded compression stockings
*assumes patients with average risk of venous thromboembolism at baseline, not those with hypercoagulable states, and average risk of bleeding, not those with bleeding diatheses.

Notes on prophylaxis:

• In the table above, the suitable types of pharmacologic prophylaxis for each type of surgery are outlined by 2008 American College of Chest Physicians (ACCP) guidelines, while the specific dosing recommendations are from the UWMC anticoagulation website. Regardless, be aware that decisions regarding timing and method of prophylaxis are usually at the discretion of the surgeon with consideration to the risk of surgical bleeding.
• Aspirin:  The American Academy of Orthopedic Surgeons (Ref 11) guidelines allow for the use of aspirin 325 mg bid as prophylaxis. However, the ACCP guidelines do not recommend this. (Ref 9)
• Knee arthroscopy: generally considered low-risk and pharmacologic prophylaxis with LMWH is only recommended if there are additional VTE risk factors.
• GCS/IPC:  If pharmacologic prophylaxis is indicated but not possible due to bleeding risk, then GCS/IPC is recommended. When the bleeding risk has subsided, pharmacologic prophylaxis should be added.
• Combination therapy: For patients with high VTE risk, there may be benefit to using pharmacologic and mechanical prophylaxis together.
• Neuraxial anesthesia:  The use of neuraxial anesthesia may complicate use of LMWH and warfarin. (Ref 10)  Generally use LDUH instead.  See “Pain Management”
• Body weight:  Dose adjustment of LMWH is often needed in the very obese (e.g. the bariatric surgery patient) and those with very low body weight—check with your clinical pharmacist.  Although dalteparin is currently the UWMC formulary LMWH agent, enoxaparin at the above dosing is recommended for patients with BMI>40.
• Chronic kidney disease: For VTE prophylaxis, dalteparin does not typically need dose adjustment. However, other LMWH (enoxaparin) may need dose adjustment or additional monitoring with factor Xa levels—discuss with clinical pharmacist.
• Vascular surgery: Unless other risk factors present, no pharmacologic prophylaxis recommended.  Most patients receive either heparin or antiplatelet agents. 
• Burns:  If additional risk factors (advanced age, morbid obesity, extensive or lower-extremity burns, lower extremity trauma, femoral venous catheter, prolonged immobility) then use LMWH or LDUH when surgically acceptable.  Most burns patients are treated at Harborview.
• Fondaparinux: is an equally weighted option in multiple categories in the current ACCP guidelines; however its cost in our opinion does not currently justify its use over that of LDUH or LMWH. 
• New anticoagulants:  Not yet on formulary at UWMC. Dabigatran, a direct IIa (thrombin) inhibitor, has been approved in the US for stroke prevention in atrial fibrillation, and rivaroxaban, a direct Xa inhibitor, has been submitted in US for approval for stroke prevention in atrial fibrillation. These medications have been studied for VTE prevention in hip and knee arthroplasty and have been approved in Europe and Canada for this indication. (Ref 14)

 

Postoperative VTE
Despite best efforts, postoperative VTE still occurs.  Patients may present with acute hypoxia, dyspnea, tachycardia, limb edema.  Keep in mind patients in the postoperative state may have other explanations for symptoms of VTE, so clinical suspicion remains vital that VTE is not missed. 

Test	Notes
Chest CT, PE protocol	Requires 18 gauge antecubital IV, power PICC, or power port to deliver an adequately timed contrast bolus for the study to be properly interpreted.  Uses IV contrast—caution in patients with kidney disease.
V/Q scan	Consider if contraindication to CT. May be difficult to interpret in patients with underlying lung disease.
Lower extremity duplex	Use if suspected DVT, or if suspected PE and unable to perform Chest CT or V/Q scan. A single negative lower extremity duplex does not rule out PE.
D-dimer	Do not use—not useful in patients with moderate to high pre-test probability of DVT or PE.

Immediate Management:

• Stabilization of patient, assessment of severity of VTE.  Treat with therapeutic dose anticoagulation as soon as able.  Must discuss bleeding risk with surgery team.

Bleeding risk	Management of DVT/PE
Anticoagulation unacceptable	IVC filter until able to anticoagulate. Consider potentially retrievable IVC filter Give prophylactic dose LDUH or LMWH if possible.
Anticoagulation acceptable, but high risk	IV heparin.  Consider using “no-bolus” protocol.
Anticoagulation acceptable, low risk	IV heparin or LMWH (therapeutic dose). Begin warfarin.

• IV heparin and LMWH have been found to be equal in efficacy for VTE.  A systematic review found that LMWH had a significant reduction in thrombotic complications, hemorrhage, and mortality compared to UFH in patients with DVT. (Ref 12) However, IV heparin is advantageous postoperatively because of its short half-life and is reversible.    
• Thrombolytics are indicated for massive PE (SBP <90). (Ref 15) Contraindications include intracranial neoplasm, history of intracranial hemorrhage/hemorrhagic stroke, internal bleeding within 6 months.  Due to bleeding risk, this option must always be discussed with the surgeon.
• Catheter embolectomy is an option in centers with appropriate expertise for patients with massive PE. (Ref 15)
• Upper extremity and catheter-associated DVT:  Current recommendations favor treating as you would a lower extremity DVT, although definitive data is lacking.  Either LMWH or IV heparin are appropriate initial management strategies. (Ref 6)

 

 

 

Subacute and long term management:

• For acute VTE, administer IV heparin/LMWH for at least 5 days total and until the INR is ≥ 2.0 for at least 24 hours.  (i.e. usually need to give additional heparin after the first INR is in target range)
• If using dalteparin as a LMWH agent, dosing is typically 200 U/kg SQ daily. Discuss with your clinical pharmacist for dose adjustments that may need to be made for CrCl<30, weight >98 kg, and pregnancy.
• Consider LWMH alone if VTE in association with malignancy13.  However, cost is a concern.
• Duration of therapy for VTE is 3 months if there was a reversible, transient risk factor (e.g. recent surgery, immobilization). (Ref 6)
• Duration of therapy is at least 3 months for unprovoked VTE. After 3 months, risk-benefit of further anticoagulation should be assessed. If proximal DVT with no bleeding and good monitoring while on anticoagulation, long-term therapy is recommended. For 2nd unprovoked VTE, long-term therapy is also recommended. (Ref 6)
• Use compression stockings for DVT to reduce risk of post-thrombotic syndrome.

References

• 1. Lip G.  Management of anticoagulation before and after elective surgery.  UptoDate.  Article revision date 9/2010.
• 2. [no authors listed].  Optimum duration of anticoagulation for deep-vein thrombosis and pulmonary embolism.  Research Committee of the British Thoracic Society.  Lancet.  1992;340:873-876.
• 3. Kearon C, Hirsh J. Management of anticoagulation before and after elective surgery.  N Engl J Med.  1997;336: 1506-1511.
• 4. Geerts WH, et al. http://www.tigc.org/clinical-guides/Inferior-Vena-Cava-Filters.aspx accessed May 2011.
• 5. Fedullo P, et al. Inferior Vena Cava Filters. UptoDate.  Article revision date 12/8/08.
• 6. Kearon C, Kahn SR, Agnelli G, et al.  Antithrombotic Therapy for Venous Thromboembolic Disease. Chest.  2008;133:454-545.
• 7. Imberti D Biachi M, Farina A, et al.  Clinical experience with retrievable vena cava filters: results of a prospective observational multicenter study.  J Thromb Haemost.  2005;3:1370–75.
• 8. Mismetti P, Rivron-Guillot K, Quenet S, et al. A prospective long-term study of 220 patients with a retrievable vena cava filter for secondary prevention of venous thromboembolism. Chest.  2007;131:223-229.
• 9. Geerts WH, Bergqvist D, Pineo GF. et al.Prevention of Venous Thromboembolism.  Chest.  2008;133;381S-453S.
• 10. University of Washington Medical Center Anticoagulation Services. www.uwmcacc.org . Last update 5/10, accessed February 2011.
• 11. American Academy of Orthopaedic Surgeons - Medical Specialty Society.  2007 May. American Academy of Orthopaedic Surgeons clinical guideline on prevention of symptomatic pulmonary embolism in patients undergoing total hip or knee arthroplasty .  Accessed online at:  http://www.ngc.gov/summary/summary.aspx?ss=15&doc_id=10850&nbr=005665&string=aaos
• 12. Erkens P, Prins M.  Fixed dose subcutaneous low molecular weight heparins versus adjusted dose unfractionated heparin for venous thromboembolism.  Cochrane Database Syst Rev.  2010; CD001100.
• 13. Lee AY, Levine MN, Baker RI, et al.  Low-Molecular-Weight Heparin versus a Coumarin for the Prevention of Recurrent Venous Thromboembolism in Patients with Cancer.  N Engl J Med.  2003;349:146-153.
• 14. Galanis T, Thomson L, Palladino M, et al. New oral anticoagulants. J Throm Thrombolysis. Feb 2011.
• 15. Jaff MR, McMurtry S, Archer SL, et al.  Management of Massive and Submassive Pulmonary Embolism, Iliofemoral Deep Vein Thrombosis, and Chronic Thromboembolic Pulmonary Hypertension: A Scientific Statement From the American Heart Association.  Circulation.  2011; 123: 1788-1830.

 

Updated May 2011