Compression stockings to prevent vein thrombosis

Venous thrombosis is one of the most important diseases of the circulatory system, capable in certain conditions of leading to pulmonary embolism, a dreaded cause of death.

What is venous thrombosis?

Venous thrombosis is the formation of blood clots within our veins that may be due, among others, to the slowing down of the blood flow of these vessels in the legs in people with risk factors for this.

Superficial vein thrombosis is called by some thrombophlebitis. It should be noted that the use of this word is given even when the term phlebitis by itself only means inflammation of the vein (which could happen without thrombosis).

Pulmonary embolism or also called pulmonary thromboembolism is the arrival of clots in the pulmonary circulation, originating mostly from venous thrombi that could be located in the legs. The blood current can drag them, thus passing to the right side of the heart, which with its contraction sends them or pumps them to the pulmonary arteries and it is even possible that in exceptional cases fragments of these clots reach the brain via the arterial route if there is any form of abnormal communication between the left and right side of the heart.

Clots that travel through the blood are called emboli. Once they reach the lungs, they will obstruct blood flow at this site, thus compromising gas exchange in the lung and oxygenation of the blood, leading to the risk of death to the patient.

Risk factors for vein thrombosis

There are many possible risk factors for venous thrombosis, some are abnormal conditions, while others, such as pregnancy, are normal periods of our lives in which we are most vulnerable to this entity.

Among the risk factors for venous thrombosis and pulmonary embolism we have:

• Varicose veins
• Prolonged rest, for example in bedridden and dependent people.
• Prolonged travel: Having other risk factors along with little leg movement for a long time has been found to be associated with so-called traveler’s thrombosis or economy class thrombosis.
• Gait disturbances (for example, people with sequelae of stroke, post trauma, etc.)
• Alterations of the coagulation of the blood that increase it like the called thrombophilias.
• Cancer patients: Both by the endogenous production of procoagulant substances and by rest, growth in some tumors that can compress the veins, reducing their flow, and by the action of many of the chemotherapies.
• Pregnancy. A normal condition where clotting increases is said to be during preparation for childbirth.
• In people with immunological diseases (for example lupus, antophospholipid syndrome, etc.).
• The use of some drugs such as contraceptives, steroids, post-menopausal hormone therapy, etc.
• Personal history of previous venous thrombosis. There is an estimated recurrence rate of 5–7% per year after a first episode of venous thrombosis.
• Post operative in which damage to the vein wall is involved, stasis due to rest or other concurrent diseases such as those that increase coagulation.
• Others: Old age, overweight, smoking.

How often does venous thrombosis occur?

Before talking about the rate of venous thromboembolic disease in the population, I must clarify that the results of epidemiological studies that seek this answer can hardly be extrapolated to populations other than those that were studied in them, so what is read about them are approximations. A study done in the United States is not necessarily a reflection of thrombosis rates in China, to take one example.

In addition to this, an obstacle to knowing its true incidence is the fact – recognized by us doctors – that it is an entity that is difficult to diagnose and therefore its real presence may be underestimated.

Here are some statistics exposed by a Brazilian group:

Venous thromboembolic disease occurs in approximately 1-2 per 1000 people per year. About 30% of apparently isolated pulmonary embolism episodes are associated with silent deep vein thrombosis. In patients presenting symptoms of deep vein thrombosis, the frequency of silent pulmonary embolism ranges from 40 to 50%. The short-term mortality rate due to pulmonary embolism is 3-6%. A common complication of deep vein thrombosis is post-thrombotic syndrome, which occurs in up to 50% of patients. Ribeiro, D D et al. “Epidemiology of recurrent venous thrombosis.” Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas vol. 45,1 (2012): 1-7.

What symptoms do venous thrombosis and pulmonary embolism give?

Symptoms of venous thrombosis

As I said before, in many cases the symptoms are so nonspecific that thrombosis may go unnoticed, but in general we associate sudden limb swelling or worsening of pre-existing swelling as symptoms suggestive of venous thrombosis in the lower limbs, accompanied by pain, change of color and temperature of the affected area. One or more associated risk factors are usually present.

It should be noted that other diseases can give these same symptoms such as trauma, a broken cyst on the knee (Baker’s cyst or popliteal), an infection, etc. Therefore, the patient with venous thrombosis must be evaluated by a doctor who will prescribe laboratory tests and, most likely, a Doppler echo, among others.

Symptoms of pulmonary embolism

The symptoms of pulmonary embolism thrombus are also a challenge for the doctor who should suspect its existence and indicate the paraclinical evaluations that he considers necessary for its elimination. The most frequently observed symptoms are:

• Chest pain
• Dyspnea or Shortness of breath
• Tachycardia
• In the event of a pulmonary infarction (death of part of the lung tissue), coughing up blood (called hemoptysis) may be observed.
• Possibly swelling or pain in a leg suggestive of preceding thrombosis.

This table is most likely accompanied by risk factors for venous thromboembolic disease. Symptoms are more intense depending on the size of the embolism and the patient’s previous conditions. It is a very dangerous condition because it carries a risk of death.

How do stockings help prevent venous thrombosis?

Compression therapy with stockings is called elastocompression and helps to decrease venous pressure in the legs by preventing slow flow in the veins, which helps reduce thrombus formation, inflammation of the venous wall, and poor oxygenation of the vein.

The compression stockings reduce by external compression the diameter of the distended superficial veins, thus increasing the speed of venous blood flow and the effectiveness of its valves since it keeps its edges together, reducing space for reflux (which is the blood that is returned abnormally when the valve fails).

Stockings to prevent a first thrombosis and stockings for those who have already suffered it

I think it is essential to clarify this point, the stockings that seek to prevent venous thrombosis and with it pulmonary embolism in those who have not had this before and have apparently healthy veins are not the same as the stockings required by someone who has already had a thrombosis with Secondary damage to their valves by this entity.

Venous thrombosis is usually accompanied by localized sequelae in the wall of the vein that frequently leave significant damage to its valves and with it a fertile territory for new thrombosis, therefore I mentioned that it has an estimated recurrence of 5–7% / year after of the first episode (and increases if associated with cancer).

The damage that the vein suffers after being the seat of a thrombosis generates an entity called post-thrombotic syndrome that can lead to very important venous insufficiency and hypertension. In that particular case, which we will discuss in another post, the degree of compression necessary that is recommended is greater than that used to only prevent thrombosis in those who have not had it before.

For these reasons, compression stockings in a patient with post thrombotic syndrome should be indicated by a doctor who specializes in vascular diseases.

Recommended degrees of compression

Each case must be individualized, take this as a means of orientation:

For the prevention of venous thrombosis in patients with no history of this entity: Lower degrees of compression (<20 mmHg) are usually used. The patient must be individualized and other factors involved must be known to determine if the treatment would warrant greater compression.

For post thrombotic syndrome: The compression of these patients is usually higher, so much that it can reach 30-40 mmHg, however the degree of compression is not to be determined lightly, the extent of the initial process must be known, the current degree of compromise, the triggering cause (it is important to know if it still persists), the patient’s comorbidity, arterial function, among others, to choose the compression closest to the ideal.

We understand the importance of individualizing each patient, which is why our opinions are published only as informative material and should never be taken as a therapeutic indication for readers for whom we suggest they go to a vascular doctor to be exhaustively treated.