Pulmonary embolism is a life-threatening situation, in which a blockage of the pulmonary artery or its branches occurs. The embolus is most often a blood clot, but it can also be fat tissue, amniotic fluid during childbirth, air or foreign bodies. Pulmonary embolisms are difficult to diagnose, because the symptoms can appear in other medical conditions.
Pulmonary circulatory system
Deoxygenated blood from the whole body is transported to the right atrium of the heart and then the right ventricule, from which it is pumped through the pulmonary artery into the lungs. The pulmonary artery branches into smaller and smaller vessels and in the capillaries where the blood releases carbon dioxide and takes in oxygen. Therefore oxygenated blood returns to the left side of the heart via the pulmonary veins, first the left atrium and then ventricle. From the left ventricle the oxygenated blood is pumped through the aorta which delivers blood to the entire body.
Symptoms of pulmonary embolism
Symptoms of pulmonary embolism do not always have to be apparent due to the small size of the embolus. In these cases, it is a clinically silent pulmonary embolism. The severity of symptoms depends on the size of the embolus. A pulmonary embolism causes an increase in pulmonary blood pressure which spreads into the right side of the heart and can cause heart failure. The main symptoms of pulmonary embolism are shortness of breath, coughing up blood, tachypnoe (fast breathing), cyanosis (blue colouring) of the fingers and lips, chest pain, quick pulse, low blood pressure and even loss of consciousness.
Causes of pulmonary embolism
In 85% of cases, the cause of pulmonary embolism is deep vein thrombosis of the lower limbs. This is a blood clot that forms on the vein wall and then loosens and travels through the heart and to the lungs. Often times, the origin is undiscovered. There are many factors that contribute to the formation of a thrombus (blood clot) which include damage to the vessel wall, increased blood coagulation, and slower blood flow. Apart from congenital abnormalities in blood coagulation, there are also risk factors such as surgical procedures, especially in people under 40, injury to the legs and pelvis, immobile pacients, cancer, heart failure, obesity, varicose veins, birth control, pregnancy, stroke, a family history of thrombosis or pulmonary embolism and long travel times.
Diagnosis of pulmonary embolism
Making a diagnosis of pulmonary embolism is not straight-foward, as its clinical symptoms are seen in a variety of illnesses. Diagnosis, though, is made based on clinical symptoms and laboratory tests where defects in blood coagulation are investigated. Electrocardiography (ECG), X-ray and CT methods are also used for diagnosis. ECG is a method that records the electrical activity of the heart muscle and in the case of pulmonary embolism, it shows signs of congestion on the right-side of the heart due to the blockage in the lungs. An ultrasound can also be used to visualize the blood clot. A fundamental diagnostic tool is the CT (computed tomography) scan. It is a modern diagnostic tool that creates a detailed picture of the human body using X-ray technology.
The treatment and prevention of pulmonary embolism
The prevention of pulmonary embolism mostly encompasses the fight against deep vein thrombosis. This is a serious condition that manifests with pain and swelling of the affected limb, often with a change in skin colour. Development of these symptoms requires immediate medical attention. Treatment includes anticoagulants, which are medications that decrease blood coagulability. Inicially, these are given intravenously (eg. Heparin) and then in tablet form (eg. Warfarin). These medications can be prescribed for varying periods of time, depending on the health of the pacient, sometimes even for life. These pacients must regularily go for blood tests to ensure proper dosage. Prevention includes using compression stockings after operations and quick rehabilitation. At-risk women should not use birth control, for example those with congenital blood coagulation defects and those with a family history of thrombosis. Other at-risk pacients must take anticoagulation medications. In acute, life-threatening situations, thrombolytic treatment is used which helps to dissolve the blood clot. The disadvantage of this treatment is the risk of bleeding, very rarely into the brain. This is why this treatment is used only in serious cases. Occasionally, it is possible to surgically remove the blood clot from the vessel. This is performed on pacients who cannot receive thrombolytic treatment due to risk of bleeding or in critical pacients.