Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Deep Vein Thrombosis


Related Terms

  • Peripheral Arterial Thrombosis
  • Peripheral Thrombosis
  • Venous Thrombosis

Differential Diagnosis

Specialists

  • Emergency Medicine Physician
  • Internal Medicine Physician
  • Pulmonologist
  • Radiologist
  • Vascular Surgeon

Comorbid Conditions

Factors Influencing Duration

Duration depends on the severity of symptoms, the presence of emboli, and the type of treatment (medical or surgical). Disability can range from a few weeks to several months, depending on how quickly symptoms resolve, the number and severity of complications, and the progression of coexisting chronic diseases. Factors that may influence the length of disability include surgical complications that can delay recovery, cigarette smoking, and a sedentary lifestyle.

Medical Codes

ICD-9-CM:
453 - Venous Embolism and Thrombosis, Other
453.4 - Acute venous Embolism and Thrombosis of Deep Vessels of Lower Extremity
453.40 - Acute venous Embolism and Thrombosis of Deep Vessels of Lower Extremity; Of Vena Cava, Venous Embolism and Thrombosis of Unspecified Deep Vessels of Lower Extremity; Deep Vein Thrombosis NOS; DVT NOS
453.41 - Acute venous Embolism and Thrombosis of Deep Vessels of Lower Extremity; Of Vena Cava, Venous Embolism and Thrombosis of Deep Vessels of Proximal Lower Extremity; Femoral; Iliac; Popliteal; Thigh; Upper leg NOS
453.42 - Acute venous Embolism and Thrombosis of Deep Vessels of Lower Extremity; Of Vena Cava, Venous Embolism and Thrombosis of Deep Vessels of Distal lower Extremity; Calf; Lower leg NOS; Peroneal; Tibial

Overview

Deep vein thrombosis (DVT) is the formation of a blood clot (thrombus) in a vein, usually deep within the muscles of the lower leg (calf) or thigh. The thrombus obstructs blood flow through the vessel. Underlying all cases of DVT and development of thrombi are three conditions known as the Virchow triad; they include reduced blood flow (venostasis), hypercoagulability, and injury to the innermost lining of the blood vessel (vessel intimal injury).

DVT usually occurs at a site in the blood vessel that has been narrowed by hardening of the arteries (atherosclerosis), at valve pockets within the vein, in a place where the vein has been damaged, or in areas of venous stasis (Patel). The condition may cause pain and swelling of the affected limb, although in many cases it causes no symptoms. A detached thrombus from the vein is called an embolus, and the obstruction of a blood vessel by an embolus is called an embolism. Emboli pass through the bloodstream to the heart and then may lodge in a lung artery and cause obstruction of blood flow. This is called a pulmonary embolism and may result in organ damage or death. In individuals with an atrial septal defect (patent foramen ovale) or a ventricular septal defect, an embolus of venous origin can pass through the septal defect from the right to the left side of the heart, and cause a brain embolism called a paradoxical embolism.

Thrombi that form in a surface (superficial) vein, as opposed to a deep vein, cause a condition referred to as thrombophlebitis, phlebitis, or superficial venous thrombosis (SVT). These clots usually do not travel to other organs and are not considered as serious as deep vein thrombi; however, SVT may be associated with DVT in up to 65% of cases, thus caution is required in monitoring individuals with SVT.

Incidence and Prevalence: Incidence of DVT in the US is 117 per 100,000 individuals (Patel). However, up to three-quarters of cases of DVT are unrecognized (Ennis).

Source: Medical Disability Advisor



Causation and Known Risk Factors

The most common risk factors for DVT include prolonged bed rest or immobilization, previous DVT, recent surgery and/or orthopedic procedures, and previous or current cancer. Other risk factors include anatomical abnormalities, limb trauma, stroke, myocardial infarction, congestive heart failure, ulcerative colitis, Crohn's disease, obesity, a family history of DVT, varicose veins, coagulation abnormalities, childbirth within the past 6 months, and the use of estrogen or birth control pills (oral contraceptives).

Individuals who have been hospitalized and those living in nursing homes are more likely to develop the condition and account for 50% of all cases of DVT (Hoffer). Aging is also a risk factor, with individuals over the age of 40 most at risk (Patel, Schreiber). The male to female ratio is 1.2:1 (Schreiber). Whites and African-Americans are 2.5 to 4 times more likely to develop a DVT than Asian or Hispanic individuals (Schreiber).

If blood thinners (anticoagulant therapy) are not used before surgery, the general postoperative risk of DVT is 19% to 25% (Ennis). Following total knee replacement, the risk is 60% to 85%, and after a total hip replacement the risk is 50% to 60% (Ennis). Eight percent of all cases of DVT occur in an upper extremity, possibly in part due to the placement of central venous catheters (e.g., for hemodialysis), cardiac pacemakers implantation, and clavicle fractures (Greben).

Source: Medical Disability Advisor



Diagnosis

History: A history of prolonged sitting, immobilization, bed rest, or recent surgery may be reported. Symptoms may include pain, tenderness, warmth, or swelling (edema) in only one leg. Reddening (erythema) and/or fatigue of the leg may be reported. Certain individuals may have a low-grade fever. Up to 75% of individuals with DVT report no symptoms (Ennis).

Physical exam: The extremity may appear red and swollen. Surface veins may be prominent. If the lower leg is affected, there may be a Homan's sign, in which the calf muscles become increasingly painful upon ankle dorsiflexion with the knee fully extended; however, Homan's sign is present in only 50% of individuals with DVT (Hoffer). Rarely, the leg may appear pale if the vein is occluded (phlegmasia alba dolens) or dusky or cyanotic when the collateral outflow veins are thrombosed (phlegmasia cerulea dolens) (Hoffer).

Tests: Color-flow Doppler ultrasound may be used to diagnose blood clots in the leg veins. Plethysmography, which measures changes in blood volume in the extremities, also may be used to evaluate the presence of venous obstruction. Less often, an x-ray of the veins following dye injection (venogram) may be performed. As with color-flow Doppler ultrasound, this test can identify the location of venous obstruction in a limb. Rarely, magnetic resonance imaging (MRI) or computed tomography (CT) scan may be performed. D-dimer blood tests are performed to measure clot-related substances in the blood and serve as a rapid screening test for DVT.

Source: Medical Disability Advisor



Treatment

Individuals with DVT above the knee often are admitted to a hospital. Treatment includes administration of intravenous or subcutaneous anticoagulation therapy to prevent further blood clot formation. Anticoagulation therapy may continue for up to 3 to 12 months, depending on risk factors and DVT recurrence (Hoffer). Anticoagulants should not be given individuals susceptible to bleeding due to other medical conditions such as esophageal varices, ulcers, and liver or kidney disease. Catheter-directed thrombolysis, where the blood clot is accessed directly via a catheter and a clot-dissolving drug (thrombolytic) is infused and/or surgery to place a stent to keep the vessel open, may be recommended. Surgical insertion of an umbrella device into the vena cava (vena cava filter) to block blood clots from traveling to the lungs may be employed if the individual cannot take anticoagulant medications. An embolectomy, a procedure to surgically remove a clot, is generally a procedure done as a last resort.

If the thrombus is below the knee, the likelihood of an embolism is reduced, and the individual may be treated with anti-inflammatory medications and local compressive devices. Compression stockings (thrombo-embolism deterrent [TED] hose) with a compression gradient 30 to 40 mmHg may be used to decrease the risk of fluids pooling in the legs that may contribute to further blood clot formation. Serial ultrasound tests may be performed over 7 to 10 days to assess for any growth or extension of the thrombus above the knee; up to one-third of untreated DVT will extend into the femoral vein (Hoffer). If this occurs, anticoagulation therapy is generally given.

Preventative (prophylactic) anticoagulation therapy usually is given close to the time of orthopedic surgery to prevent DVT and may consist of low-molecular-weight-heparin or a vitamin K antagonist (warfarin) (Bugamelli, Hull). After surgery, treatment also may include the use TED hose, external mechanical compresses, and venous foot pumps to decrease the likelihood of clot formation.

Source: Medical Disability Advisor



Prognosis

Although the prospect for recovery from a DVT is good, there is a modest long-term risk of chronic venous insufficiency, called post-thrombotic syndrome. Should this occur, individuals may have chronic swelling and tenderness of the affected leg and an increased risk of recurrent DVT and leg ulceration. After an asymptomatic DVT, incidence of post-thrombotic syndrome is only 5%; two years after a symptomatic above-the-calf (proximal) DVT has been treated, the incidence of post-thrombotic syndrome is 25% to 50%; at 7 to 10 years after treatment, the incidence is as high as 70% to 90% (Hoffer). The recurrence rate of DVT in untreated individuals is 50% within 3 months (Hoffer).

Although 20% of untreated proximal DVT cases will spontaneously resolve, an estimated 29% to 50% of untreated proximal DVT will progress to pulmonary emboli, which, in 10% to 12% of hospitalized cases, is fatal (Hoffer). With prompt treatment, the mortality rate decreases significantly. When DVT is treated promptly, pulmonary emboli occur in 2% to 4% of individuals (Hoffer). Overall, 1% of individuals with DVT will die from pulmonary embolism (Society of Interventional Radiology).

Source: Medical Disability Advisor



Rehabilitation

The goal of rehabilitation is to improve circulation in the legs. A supervised exercise program with an emphasis on walking may be recommended.

Source: Medical Disability Advisor



Complications

Complications include pulmonary embolism, systemic embolism, chronic venous insufficiency, and hemorrhage due to anticoagulant therapy. Post-thrombotic syndrome also may occur.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Individuals with job responsibilities requiring prolonged walking, standing or sitting, or heavy labor, are most likely to require accommodations. Accommodations may be needed to allow individuals recovering from DVT to improve the circulation in their legs; this may involve taking frequent breaks or short walks. For individuals receiving anticoagulants, work with significant risk of physical trauma should be avoided because of potential bleeding problems.

Source: Medical Disability Advisor



Failure to Recover

If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case.

Regarding diagnosis:

  • Has individual provided the physician with an adequate medical history, including information about recent periods of immobilization or surgery; recent childbirth; limb injury; use of birth control pills or estrogen; and chronic medical conditions that increase the risk for DVT?
  • Does individual have anatomical blood vessel abnormalities, stroke, myocardial infarction, congestive heart failure, ulcerative colitis, Crohn's disease, obesity, or a family history of DVT?
  • Has individual had central venous catheter, cardiac pacemaker implantation, or clavicle fracture?
  • Has individual recently been immobilized for a long period due to illness or extended airplane or auto travel?
  • Does individual have clotting abnormalities?
  • Has individual given birth within the past six months?
  • Has individual had previous DVT?
  • Has individual recently had limb trauma or an orthopedic procedure?
  • Does individual exhibit Homan’s sign?
  • Has the diagnosis been confirmed by color-flow Doppler ultrasound, plethysmography, venography, or other tests to identify the existence and location of an obstructed blood vessel? Has D-dimer assay been performed?

Regarding treatment:

  • Was DVT located above the calf?
  • Has individual been treated with anticoagulants or catheter-directed thrombolysis?
  • Have other specialists been consulted to treat coexisting chronic diseases that might complicate or prolong recovery?
  • Has a vascular surgeon been consulted to evaluate the options for surgical treatment?
  • Was embolectomy performed? Was vena cava filter or stent necessary?
  • Is individual active with a walking program to promote leg circulation?

Regarding prognosis:

  • Does individual have risk factors associated with poor outcome?
  • Would individual benefit from a weight management program?
  • Has individual been compliant with anticoagulation therapy?
  • Is there evidence of recurrence?

Source: Medical Disability Advisor



References

Cited

Bugamelli, S., et al. "Clinical Use of Parnaparin in Major and Minor Orthopedic Surgery: A Review." Vascular Health Risk Management 4 5 (2008): 983-990. PubMed. <PMID: 19183746>.

Ennis, Robert. "Deep Venous Thrombosis Prophylaxis in Orthopedic Surgery." eMedicine. Eds. Miguel A. Schmitz, et al. 12 Jun. 2009. Medscape. 17 Sep. 2009 <http://emedicine.medscape.com/article/1268573-overview>.

Greben, Craig, and Charles W. Hearns. "Deep Venous Thrombosis, Upper Extremity." eMedicine. Eds. Anthony Watkinson, et al. 28 Jul. 2009. Medscape. 17 Sep. 2009 <http://emedicine.medscape.com/article/421151-overview>.

Hoffer, Eric K., and John J. Borsa. "Deep Venous Thrombosis, Lower Extremity." eMedicine. Eds. Anthony Watkinson, et al. 10 Apr. 2009. Medscape. 17 Sep. 2009 <http://emedicine.medscape.com/article/420457-overview>.

Hull, R. D., et al. "Timing of Initial Administration of Low-Molecular-Weight Heparin Prophylaxis Against Deep Vein Thrombosis in Patients Following Elective Hip Arthroplasty: A Systematic Review." Archives of Internal Medicine 161 16 (2001): 1952-1960. PubMed. <PMID: 11525697>.

Patel, Kaushl (Kevin), and Craig Feied. "Deep Vein Thrombosis." eMedicine. Eds. William H. Pearce, et al. 16 Jan. 2009. Medscape. 17 Sep. 2009 <http://emedicine.medscape.com/article/462390-overview>.

Schreiber, Donald. "Deep Venous Thrombosis and Thrombophlebitis." eMedicine. Eds. Francis Counselman, et al. 5 Aug. 2009. Medscape. 17 Sep. 2009 <http://emedicine.medscape.com/article/758140-overview>.

Society of Interventional Radiology. "Deep Vein Thrombosis Overview." Society of Interventional Radiology. 17 Sep. 2009 <http://www.sirweb.org/patients/deep-vein-thrombosis>.

Source: Medical Disability Advisor






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