A blood clot in the lungs is known as a pulmonary embolism. It is often a result of a blood clot forming in the deep veins of the legs, known as a deep vein thrombosis, or DVT, which then travels to the lungs where it is caught in the blood vessels there. The blood traveling to the lungs does not reach the lung tissue downstream from the clot, so the tissue does not receive oxygen. Symptoms may include chest pain and shortness of breath.
Intubation and Mechanical Ventilation
If the clot is large enough to significantly impair the exchange of gases in the lungs, it may be necessary to place a breathing tube and initiate mechanical ventilation to keep the person alive while starting treatment for the clot. The air contains 21 percent oxygen. During mechanical ventilation, it is possible to give up to 100 percent oxygen to help raise oxygen levels in the blood. It is also possible to control the rate and depth of breathing to change the levels of carbon dioxide in the blood, according to The Merck Manuals.
Anticoagulants
Anticoagulants include such drugs as heparin and warfarin. These drugs do not directly break down the clot themselves, but rather prevent new clots from forming and the present clot from expanding. This allows the body to break down the clot. Heparin is an intravenous drug that is usually given first, followed by warfarin in pill form. The heparin can usually be discontinued after a few days, while the warfarin continues to be administered. The warfarin may be given for 2 to 6 months, or even indefinitely if there is a risk of recurring pulmonary emboli, according to The Merck Manuals.
Thrombolytics
"Thrombo" means clot, and "lytic" means "to break down," so thrombolytics break down clots. They are also known as clot busters. These include the drugs streptokinase and TPA. They are only used in emergency situations because they can cause life-threatening bleeding. Because of this risk, they are generally not given to people who have a tendency to bleed, are pregnant, have had surgery in the last two weeks or have had a recent stroke, according to The Merck Manuals.
Procedural Therapy
Procedural therapy includes the use of catheters and surgery to break up the blood clot. A catheter is a flexible tube that is placed into a vein in the thigh or arm, then threaded to the lung. Once there, it can be used to deliver thrombolytic drugs or mechanically remove the clot.
Surgery may be indicated in some patients. During the procedure, a heart-lung machine is used to deliver oxygen and pump blood through the body. The sternum is opened and the clots are physically removed.
