Air travel and venous thromboembolism: Minimizing the risk
ABSTRACTFor those traveling on long flights, the risk of deep vein thrombosis or pulmonary embolism, generally referred to as venous thromboembolism (VTE), is real and dangerous if left unrecognized or untreated. The goal of this publication is to provide an overview of how best to prevent VTE during travel, and how to diagnose and treat it.
KEY POINTS
- The risk of VTE is about three times higher in passengers on long-distance flights than in the general population, although the absolute risk is still low.
- All long-distance air passengers should perform stretching exercises once an hour while in flight to prevent VTE. They should also stay hydrated.
- For patients at higher risk due to hypercoagulable conditions, physicians can consider prescribing compression stockings or an anticoagulant drug (a low-molecular-weight heparin or a factor Xa inhibitor) to be taken before the flight, or both.
- The evaluation of a patient with suspected VTE should include an estimation of the pretest probability of disease. If symptoms dictate, duplex ultrasonography of the upper or lower extremity to detect deep vein thrombosis or spiral computed tomography, ventilation-perfusion lung scan, or pulmonary angiography (where available) to diagnose an acute pulmonary embolism should be ordered.
Editor’s Note: The views expressed in this article are solely those of the authors and do not reflect the official policy or position of the Department of State or the United States Government. This version of the article was peer-reviewed.
Venous thromboembolism (VTE) associated with travel has emerged as an important public health concern over the past decade. Numerous epidemiologic and case control studies have reported air travel as a risk factor for the development of VTE and have attempted to determine who is at risk and which precautions need to be taken to prevent this potentially fatal event.1–7 Often referred to as “traveler’s thrombosis” or “flight-related deep vein thrombosis,” VTE can also develop after long trips by automobile, bus, or train.8,9 Although the absolute risk is very low, this threat appears to be about three times higher in travelers and increases with longer trips.3
This article focuses on defining VTE and recognizing its clinical features, as well as providing recommendations and guidelines to prevent, diagnose, and treat this complication in people who travel.
WHAT IS VENOUS THROMBOEMBOLISM?
Deep vein thrombosis and pulmonary embolism represent different manifestations of the same clinical entity, ie, VTE. VTE is a common, lethal disease that affects hospitalized and nonhospitalized patients, frequently recurs, is often overlooked, may be asymptomatic, and may result in long-term complications that include pulmonary hypertension and the postthrombotic syndrome.
Deep vein thrombosis of the upper extremities is generally related to an indwelling venous catheter or a central line being used for long-term administration of antibiotics, chemotherapy, or nutrition. A condition known as Paget-Schroetter syndrome or “effort thrombosis” may be seen in younger or athletic people who have a history of strenuous or unusual arm exercise.
RISK FACTORS FOR VTE
Common inherited risk factors include:
- Factor V Leiden mutation
- Prothrombin gene mutation G20210A
- Hyperhomocysteinemia
- Deficiency of the natural anticoagulant proteins C, S, or antithrombin
- Elevated levels of factor VIII (may be inherited or acquired).
Acquired risk factors include:
- Older age
- Immobilization or stasis (such as sitting for long periods of time while traveling)
- Surgery (most notably orthopedic procedures including hip and knee replacement and repair of a hip fracture)
- Trauma
- Stroke
- Acute medical illness (including congestive heart failure, chronic obstructive pulmonary disease, pneumonia)
- The antiphospholipid syndrome (consisting of a lupus anticoagulant, anticardiolipin antibodies, or both)
- Pregnancy and the postpartum state
- Use of oral contraceptives or hormone replacement therapy
- Cancer (including the myeloproliferative disorders) and certain chemotherapeutic agents
- Obesity (a body mass index > 30 kg/m2, see www.nhlbisupport.com/bmi/)
- Inflammatory bowel disease
- Previous VTE
- A central venous catheter or pacemaker
- Nephrotic syndrome.
In addition, emerging risk factors more recently recognized include male sex, persistence of elevated factor VIII levels, and the continued presence of an elevated D-dimer level or deep vein thrombosis on duplex ultrasonography once anticoagulation treatment is completed. There is also evidence of an association between VTE and risk factors for atherosclerotic arterial disease such as smoking, hypertension, hyperlipidemia, and diabetes.
CLINICAL MANIFESTATIONS OF VTE
Patients with deep vein thrombosis may complain of pain, swelling, or both in the leg or arm. Physical examination may reveal increased warmth, tenderness, erythema, edema, or dilated (collateral) veins, most notable on the upper thigh or calf (for deep vein thrombosis in the lower extremity) or the chest wall (for upper-extremity deep vein thrombosis). The examiner may also observe a tender, palpable cord, which represents a superficial vein thrombosis involving the great and small saphenous veins (Figure 1). In extreme situations, the limb may be cyanotic or gangrenous.
