Guideline Development Group

Background and Need for a CPG on Venous Thromboembolism

Venous thromboembolism is a life-threatening disorder that ranks as the third most common cardiovascular illness after acute coronary syndrome and stroke.⁴ VTE consists of DVT and PE, two inter-related primary conditions caused by venous blood clots, along with several secondary conditions including PTS and CTEPH.⁵ From a primary and secondary prevention perspective, the seriousness of VTE development related to mortality, morbidity, and diminished life-quality is a world-wide concern.⁶ The incidence of VTE differs greatly among countries. For example, the United States ranges from 70 to 120 cases/100,000 habitants per year, and in Europe there are between 140 and 240 cases/100.000 habitants per year, with sudden death being a frequent outcome.⁷

Deep vein thrombosis is a serious yet potentially preventable medical condition that occurs when a blood clot forms in a deep vein, most commonly in the calf, thigh, or pelvis. A life threatening, acute complication of LE DVT is PE. This occurs when the clot dislodges, travels through the venous system and causes a blockage in the pulmonary circulatory system. A proximal LE DVT, defined as occurring in the popliteal vein or veins more cephalad, is associated with an estimated 50% risk of PE if not treated as compared to approximately 20% to 25% of LE DVTs below the knee (Heit 2001). Approximately one in five individuals with acute PE die almost immediately, while 40% will die within three months.⁸ In those who survive PE, significant cardiopulmonary morbidity can occur, most notably CTEPH.

CTEPH can be the result of a single PE, multiple PEs, or recurrent PEs. Acutely, PE causes an obstruction of flow. This narrowing of the lumen may lead to reduced oxygenation and pulmonary hypertension. Chronically, the infarction of lung tissue following PE may result in a reduction of vascularization and concomitant pulmonary hypertension. Over time, the workload imposed on the right heart increases and contributes to right heart dysfunction and then failure.⁹ A new syndrome, post-PE syndrome, has more recently been proposed to capture those patients with persistent abnormal cardiac and pulmonary function that do not meet the criteria for CTEPH.⁵ These conditions are associated with diminished function and lowered quality of life.¹⁰

Beyond the threat of PE and its sequelae, LE DVT may lead to the long-term complications. PTS is the most frequent complication and develops in up to 50% of these patients even when an appropriate anticoagulant is used.^{11, 12} A clot remaining in the vein of the LE can obstruct blood flow leading to venous hypertension. Additionally, damage to the vein itself occurs and leads to inflammation and necrosis of the vein which eventually is removed by phagocytic cells, leading to venous hypertension. This impaired blood flow can lead to classic symptoms of PTS which often includes chronic aching pain, intractable edema, limb heaviness, and leg ulcers.¹⁰ This chronic pathology can cause serious long-term ill health, impaired functional mobility, poor quality of life, and increased costs for the patient and the healthcare system.

Across various practice settings, physical therapists encounter patients who are at risk for VTE, may have an undiagnosed LE DVT, or have recently been diagnosed with a LE DVT. The physical therapist's responsibility to every patient is five-fold: 1. prevention of VTE; 2. screening for LE DVT; 3. contributing to the healthcare team in making prudent decisions regarding safe mobility for these patients; 4. patient education and shared decision-making; and 5. prevention of long term consequences of LE DVT. Such decisions should always be made in collaboration with the referring physician and other members of the healthcare team, i.e., it is assumed that such decisions will not be made in isolation, and that the physical therapist will communicate with the medical team.

Due to the long standing controversy regarding mobilization versus bed rest following VTE diagnosis and with the development of new anticoagulation medications, the physical therapy community needs evidence based guidelines to assist in clinical decision making. This clinical practice guideline is intended to be used as a reference document to guide physical therapy practice in the prevention of, screening for, and management of patients at risk for or diagnosed with LE DVT. This CPG is based upon a systematic review of published studies on the risks of early ambulation in patients with diagnosed DVT and on other established clinical guidelines on prevention, risk factors, and screening for VTE and PTS. In addition to providing practice recommendations, this guideline also addresses gaps in the evidence and areas that require further investigation.