Pulmonary embolism is defined as a blockage of a pulmonary artery caused by a thrombus dislodged usually from the deep veins of the lower limbs.
The typical presentation of the pulmonary embolism includes sudden onset of pleuritic chest pain, shortness of breath and hypoxia . Most of the patients might have no clinical presentation at all. Symptoms may also vary from patient to patient. Hence, the diagnosis is made in the case of unexplained respiratory problems after excluding the other probable causes.
The history and clinical examination of a case of pulmonary embolism are usually not sufficient to establish the diagnosis of pulmonary embolism with certainty. Hence, in cases of unexplained respiratory problems, certain investigations must be carried out to reach the final diagnosis .
A hypercoaguable workup must be carried out to screen for antithrombin 3 deficiency, protein C or protein S deficiency, connective tissue disorders and homocystinurea.
White blood count, arterial blood gases, D dimer testing, brain natriuretic peptide, serum troponin levels and ischemia modified albumin level are potentially useful laboratory tests that can indicate the presence or absence of pulmonary embolism in the patient.
Imaging techniques that are helpful in confirming the diagnosis of pulmonary embolism include computed tomography angiography, pulmonary angiography, chest radiography, ECG, magnetic resonance imaging (MRI), venography and duplex ultrasonography.
Anticoagulant therapy with heparin administration decreases the mortality rate from 30% to less than 10%. Various anti-coagulation medications include unfractionated heparin, low weight heparin, warfarin, fondaparinux and factor Xa inhibitors.
Thrombolytic agents such as alteplase/reteplase and urokinase/streptokinase are also used in the treatment of pulmonary embolism.
Surgical options for management of pulmonary embolism include:
Along with these treatment options, supportive care to the patient is ensured.
Up to 10% of the patients who develop pulmonary embolism die within the first hour. Recurrence of pulmonary embolism subsequently causes death in 30% of the patients.
With appropriate anti-coagulant therapy, the mortality rate reduced to less than 5%.
More than 90% of the pulmonary emboli result from the dislodging of thrombi from the deep veins of the lower limb. Other less common sites of thrombus formation include prostatic and pelvic veins. Pulmonary emboli usually do not originate in the upper limb except in intravenous drug abusers.
The factors that predispose to venous thrombosis in the lower limbs include the following.
Inherited coagulation defects:
The per annum incidence of pulmonary embolism in the United States is 1 case per 1000 persons . Although most of these patients are asymptomatic, 60-80% of the patients with DVT develop pulmonary embolism.
In hospitalized patients, pulmonary embolism is the third most common cause of death (up to 650,000 deaths per year). Venous thromboembolism is a major health problem with an incidence of about 250,000 incident cases per year  .
The incidence of pulmonary embolism and the mortality occurring from it varies from country to country. A research indicates that male sex is more prone to the development of pulmonary embolism with a mortality rate 20-30% higher as compared to females. Pulmonary embolism is much more common in blacks as compared to whites .
Pulmonary emboli arise most commonly from the deep veins of the calves. Any factor or disease that cases stasis of blood in the veins can predispose to the formation of thrombi. Dislodged thrombi reach the lung after traveling through the right side of the heart.
Large emboli occlude the proximal arteries and the right ventricular outflow, causing a rapid decrease in the the cardiac output and leading to right ventricular failure. The prominent features are those of vascular collapse e.g. hypotension and syncope.
In contrast, multiple micro-emboli occlude the capillary beds of the lungs. Due to collateral vascular supply, there is no pulmonary infarction but there insidious loss of the microvascular bed supplying the gas exchange units of the lungs leading to pulmonary hypertension and right ventricular failure.
Avoid venous stasis:
Venous stasis during surgery can be avoided by stimulation of the calf muscles. Following surgery, early mobilization and leg exercises are helpful in reducing the likelihood of venous thromboembolism.
Use of anticoagulants in susceptible individuals:
Anticoagulants such as warfarin and heparin are used in the patients who are at high risk for developing thromboembolism.
Pulmonary emboli are thrombi that dislodge into the lungs usually from the deep veins of the lower limbs. Less common sites of thrombus formation include the veins of the pelvis, prostate and the upper limbs.
Pulmonary emboli may be small, medium or large. Each of these cause respiratory and hemodynamic compromise by different mechanisms. Hence, pulmonary embolism is not a disease; rather it is the complication of deep venous thrombosis (DVT).
It is a life threatening emergency and needs to be diagnosed and treated promptly.
Pulmonary embolism refers to the state in which masses of clotted blood that form in the lower limbs dislodge into the lungs. Males are more prone to the development of this complication.
Smoking, obesity, decreased physical activity and intake of unbalanced diet make the person more prone to the development of pulmonary embolism. It is a very dangerous condition and the patient needs to be hospitalized immediately. High risk patients must be identified and preventive measures must be carried out.