What You Need to Know aboutVenous Thromboembolism

By Bill Pruitt, RRT, AE-C, CPFT, MBA and Robin Lawson, RN, DNP

Nursing2009, April 20092.3 ANCC contact hours

Online: www.nursingcenter.com

© 2009 by Lippincott Williams & Wilkins. All world rights reserved.

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

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

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

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

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

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

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

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

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

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

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

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

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

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%

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

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

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

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

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

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

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

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

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

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

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

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

Prevention Hospitalized patients should be routinely

assessed for VTE risk

Measure and use graduated compression stockings correctly

Make sure pneumatic compression devices function properly

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

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

Educating your patient Teach patient risk factors for DVT

Teach preventive measures

Instruct patient to call HCP if signs and symptoms of DVT develop

Warfarin therapy patient education Eat limited foods high in vitamin K

Keep blood work appointments

Check with HCP or pharmacist before taking vitamin supplements

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

Warfarin therapy patient education Stop smoking, lose weight, drink lots of

fluids

Women should not use oral contraceptives if history of DVT/PE

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