Deep vein thrombosis secondary prevention

Editors-in-Chief: C. Michael Gibson, M.S., M.D. Associate Editor-In-Chief: Ujjwal Rastogi, MBBS [mailto:urastogi@perfuse.org]

Overview
The U.S. Preventive Services Task Forces’ describes secondary prevention measures as those that “identify and treat asymptomatic persons who have already developed risk factors or preclinical disease but in whom the condition is not clinically apparent.”

Clinical practice guidelines by the American College of Chest Physicians (ACCP) provide recommendations on DVT prophylaxis in hospitalized patients.

General Medical Inpatients
Regarding general medical inpatients the guidelines state, "In acutely ill medical patients who have been admitted to the hospital with congestive heart failure or severe respiratory disease, or who are confined to bed and have one or more additional risk factors, including active cancer, previous VTE, sepsis, acute neurologic disease, or inflammatory bowel disease, we recommend prophylaxis with LDUH (Grade 1A) or LMWH (Grade 1A) ." Enoxaparin or unfractionated heparin may be used. LMWH may be more effective than UFH. If UFH heparin is used, 5000 U 3 times daily may be more effective.

Since publication of the ACCP guidelines, an additional randomized controlled trial and meta-analysis including the trial have been published. The meta-analysis concluded " Anticoagulant prophylaxis is effective in preventing symptomatic venous thromboembolism during anticoagulant prophylaxis in at-risk hospitalized medical patients. Additional research is needed to determine the risk for venous thromboembolism in these patients after prophylaxis has been stopped." With regards to which patients are at risk, most studies in the meta-analysis were of patients with New York Heart Association Functional Classification (NYHA) III-IV heart failure. Regarding patients at lesser risk of DVT, the trial above and an earlier trial are relevant yet inconclusive.

Chronic renal dialysis patients may be at increased risk of thromboembolism, but randomized controlled trials have not addressed the risk benefit of prophylaxis.

Surgery Patients
In patients who have undergone surgery, low molecular weight heparins (LMWH) are routinely administered to prevent thrombosis. LMWH can only currently be administered subcutaneously by injection. Prophylaxis for pregnant women who have a history of thrombosis may be limited to LMWH injections or may not be necessary if their risk factors are mainly temporary.

Early and regular ambulation (walking) is a treatment that predates anticoagulants and is still recognized and used today. Walking activates the body's muscle pumps, increasing venous velocity and preventing stasis. Intermittent pneumatic compression (IPC) machines have proven protective in bed- or chair-ridden patients at very high risk or with contraindications to heparins. IPC machines use air bladders that are wrapped around the thigh and/or calf. The bladders alternately inflate and deflate, squeezing the muscles and increasing blood velocity by as much as 500%. IPC machines have been proven effective on knee and hip surgery patients (a population with a risk as high as 80% with no prophylactic treatment) of developing DVT and PE. Alternatively, between 150-300mg of aspirin can be taken.

In knee replacement patients, the timing of perioperative LMWH was recorded as the main risk factor of postoperative knee prosthesis infection.

Living With Deep Vein Thrombosis
Patients who have had deep vein thrombosis, are at greater risk for recurrence. It's important to:
 * Take steps to prevent deep vein thrombosis (DVT).
 * Check your legs for signs and symptoms of DVT. These include
 * swollen areas
 * pain or tenderness
 * increased warmth in swollen or painful areas
 * Red or discolored skin on the legs.
 * Contact your doctor right away if you have signs and symptoms of DVT.