Pulmonary embolism

Pulmonary embolism is migration of blood clots from some other part of the body into the blood vessels of the lung, blocking them. Usual source of clot is from the deep veins of the lower limbs. When blood clots in the deep veins of the legs, it is known as deep vein thrombosis (DVT).

What conditions predispose to pulmonary embolism?

In general, conditions which predispose to DVT are the ones which predispose to pulmonary embolism as well. Prolonged bed rest as after a surgery, childbirth or a major accident increases the chance of blood getting clotted in the deep veins of the leg due to stasis. In many of these conditions, the clotting tendency of blood is also enhanced. Sitting for long period in long haul flights are also known to cause DVT. This has been called economy class syndrome because space for leg movements is limited in such seats. Taking oral contraceptive pills and similar hormone pills have a tendency for increasing clot formation. There a few heritable disorders of blood clotting factors and their control factors which can also predispose to DVT, though rare.

What are the symptoms of pulmonary embolism?

In severe cases one might collapse and even die of massive pulmonary embolism. Lesser degrees produce breathlessness, chest pain, and sometimes spitting of blood. They may have associated evidence of DVT in the legs with swelling and pain.

What can be done to prevent DVT and pulmonary embolism?

Though it is a potentially life threatening condition, preventive measures are fairly simple. If you need to sit quiet for a long time during travel, keep moving your legs as much as possible so that stasis of blood is avoided. Same applies while taking rest after delivery or childbirth. If the person is too sick to move the legs, this can be done passively by the caretakers. In hospitals, intermittent pneumatic compression devices are available, which have bellows tied over the legs which are inflated automatically and pressure released intermittently.

Medications to prevent blood clotting can be given when the risk is deemed to be very high. This is routine practice after certain surgeries which have a high risk of DVT. Medications which can be given orally as well as injections are available, depending on the situation. Using compression stockings is another option.

How can DVT and pulmonary embolism be treated?

DVT and milder cases of pulmonary embolism can be treated with medications which prevent blood clotting. Initially injections are used and later oral medications have to be continued for a few months. In persons with recurrent episodes without any predisposing cause like surgery or delivery may require life long preventive medications. Some of the medications used for this purpose require regular monitoring of clotting function to prevent overdose.

Severe cases require clot dissolving medications (thrombolytic therapy), which has a higher bleeding risk as well. Mechanical methods of fragmenting the clots (mechanical thrombolysis) may sometimes be resorted to occasionally. This procedure is done in the cardiac catheterization laboratory.