1. What You Need to Know about Venous Thromboembolism
By Bill Pruitt, RRT, AE-C, CPFT, MBA
and Robin Lawson, RN, DNP
Nursing2009, April 2009
2.3 ANCC contact hours
Online:
© 2009 by Lippincott Williams & Wilkins. All world rights reserved.

2. What is venous thromboembolism (VTE)?
An occlusion in a vein caused by a thrombus (most common)
An embolus of an air bubble, fat droplets, amniotic fluid, clumps of parasites, tumor cells (less common)
In I.V. drug users, a foreign substance such as talc can lead to VTE

3. Where does VTE occur? Typically in leg veins 2% to 3% occur in arms
Pulmonary embolism can occur when part of a deep vein thrombosis (DVT) breaks loose and travels through the right side of the heart into pulmonary artery

4. Pulmonary embolism (PE)
PE occludes blood flow to part of the lung and impairs gas exchange
Affected portion of lung becomes necrotic and impairs oxygen delivery to other body tissues
90% of all PEs come from thrombi in the popliteal vein and larger veins above it

5. What happens in DVT and PE
When DVT obstructs venous circulation in a leg, collateral circulation may develop rapidly
Patient may have few signs and symptoms; when they develop, are related to local inflammation and local tissue ischemia as well as degree of venous outflow obstruction

6. What happens in DVT and PE
Complications of DVT include venous valvular damage, chronic venous insufficiency (chronic pain, swelling, cramping, skin discoloration, ulceration in affected limb), PE
PE obstructs blood flow in pulmonary arterial system

7. What happens in DVT and PE
Pathologic changes depend on degree of obstruction and patient’s condition
If blood flow is obstructed in gas exchange areas of lung (alveoli and respiratory bronchioles), you’ll see V/Q mismatch and increased physiologic dead space ventilation

8. What happens in DVT and PE
Extensive PE causes large area of dead space ventilation, imposing increased work on right ventricle as a result of obstructed right ventricular outflow and pulmonary vasoconstriction from release of vasoactive mediators

9. What happens in DVT and PE
Increased right ventricular afterload results in right ventricular hypertrophy and decreased right ventricular ejection fraction. Ventricle becomes ischemic and may eventually progress to right ventricular failure

10. Risk factors
Hereditary: deficiency in antithrombin, protein C, protein S, or plasminogen
Acquired: surgery, trauma, advanced age, cancer, reduced mobility, smoking, use of oral contraceptives, pregnancy

11. Assessing a patient’s VTE risk
Scoring systems based on patient’s clinical characteristics can estimate patient’s likelihood of developing VTE
Wells prediction rule for DVT, Wells and Geneva prediction rules for PE provide probability ranking for VTE based on history of DVT or PE, cancer, recent surgery/immobilization, age, heart rate

12. Assessing a patient’s VTE risk
Based on type and number of risk factors, patient’s level of risk can be classified as low, moderate, or high as stipulated in 2008 ACCP guidelines
Appropriate prophylactic treatment can start based on ACCP recommendations. Risk assessment is ideally incorporated into initial assessment form

13. Comparing VTE Risk Level of risk
Low: mobile patients undergoing minor surgery; medical patients who are fully mobile
Moderate: patients undergoing general surgery or open gynecologic or urologic surgery; medical patients who are sick or on bed rest

14. Comparing VTE Risk Level of risk
High: patients undergoing hip or knee arthroplasty or hip fracture surgery; patients with major trauma or spinal cord injury

15. Comparing VTE Risk Risk of DVT if no prophylaxis is given
Low: less than 10%
Moderate: 10% to 40%
Moderate plus high bleeding risk: 10% to 40%
High: 40% to 80%
High plus high bleeding risk: 40% to 80%

16. Comparing VTE Risk Suggested prophylaxis
Low: no specific prophylaxis; early and aggressive ambulation
Moderate: low-molecular-weight heparin (LMWH) at recommended doses, low-dose unfractionated heparin 2 or 3 times/day, or fondaparinux

17. Comparing VTE Risk
Moderate plus high bleeding risk: mechanical prophylaxis with intermittent pneumatic compression,venous foot pump, graduated compression stockings
High: LMWH at recommended doses, fondaparinux, oral vitamin K antagonists to maintain INR between 2 and 3
High, plus high bleeding risk: mechanical prophylaxis as above

18. Recognizing VTE
Patient with DVT: edema, pain, warmth in one leg, venous stasis ulcers, venous varicosities, venous insufficiency
Patient with PE: dyspnea, hemoptysis, cough, wheezes, tachypnea, pulmonary crackles, chest pain, palpitations, tachycardia, lightheadedness; suspect massive PE with sudden hypotension, syncope, severe hypoxemia, cardiac arrest

19. Diagnosing VTE
Based on patient’s risk factors, physical assessment findings, diagnostic study results
Physical assessment for DVT: examine patient’s legs, noting erythema, tenderness, pain; palpation could dislodge and cause PE

20. Diagnosing VTE
D-dimer: normal value less than 500 ng/mL; if high, needs duplex ultrasound
Duplex ultrasound: two-dimensional ultrasound with Doppler; provides vein images, blood flow measurements; loses accuracy in calf vein
Contrast venography: gold standard; invasive with potential complications

21. Is it PE? Diagnostic testing aimed at: - confirming condition
- defining severity
- ruling out conditions that mimic PE (pneumonia, myocardial infarction)
If massive PE suspected, treatment takes priority over testing

22. Diagnosing PE Chest X-ray: helps rule out other causes
ECG: useful for ruling out cardiac causes; may show ST, T wave changes
Arterial blood gases: will show ventilation perfusion mismatch

23. Diagnosing PE D-dimer: can help rule out PE
Spiral computed tomography pulmonary angiography; can help confirm diagnosis of PE and rule out other causes

24. Preventing VTE after surgery
Risk depends on type of surgery, presence of other risk factors
Procedures with prolonged immobility are at highest risk: orthopedic, neurosurgery, major vascular surgery, major abdominal or pelvic surgery

25. Preventing VTE after surgery
Latest guidelines from ACCP recommend all hospitals develop formal prevention strategy to include:
- computerized decision support
- preprinted or standing orders
- regular audits to monitor adherence
Guidelines recommend against using aspirin alone and early ambulation in low-risk general surgery patients

26. Treating VTE
Anticoagulants, warm compresses, leg elevation are first-line treatment
Oxygen, ventilation, I.V. fluids, fibrinolytics may be ordered for PE
Vena cava filter may stop traveling thrombi
Embolectomy: for patients with massive PE who don’t respond to fibrinolytics

27. Inferior vena cava (IVC) filter
Some newer filters are called retrievable or optional filters
Can be retrieved after a period or left in permanently
Recommended for patients with documented VTE who have difficulty receiving full-dose anticoagulation

28. Prevention
Hospitalized patients should be routinely assessed for VTE risk
Measure and use graduated compression stockings correctly
Make sure pneumatic compression devices function properly

29. Prevention Explain importance of these devices to patient
Encourage early ambulation after surgery
Surgical patients on unfractionated heparin will need baseline aPTT, hematocrit, and platelet counts

30. Prevention
If long-term anticoagulation is needed, warfarin will be started for 4 to 5 days before heparin is discontinued
Heparin discontinued when INR is in therapeutic range (2.0 to 3.0) on two consecutive measurements 24 hrs apart
Monitor patient for signs of bleeding

31. Educating your patient
Teach patient risk factors for DVT
Teach preventive measures
Instruct patient to call HCP if signs and symptoms of DVT develop

32. Warfarin therapy patient education
Eat limited foods high in vitamin K
Keep blood work appointments
Check with HCP or pharmacist before taking vitamin supplements

33. Warfarin therapy patient education
Limit alcohol intake
Alert HCP about anticoagulant therapy before undergoing medical procedures
Protect from injury (soft toothbrushes, electric razors) due to bleeding/bruising

34. Warfarin therapy patient education
Stop smoking, lose weight, drink lots of fluids
Women should not use oral contraceptives if history of DVT/PE

35. Travel Long air flights, car rides linked to DVT/PE
ACCP recommends anyone sitting for more than 8 hours avoid constrictive clothing and stay hydrated
For patients at high risk for DVT, wear graduated compression stockings or receive single dose of LMWH before departure