Introduction:
Pulmonary infarction results from the obstruction of distal pulmonary arteries leading to ischemia (insufficient blood supply to lungs), hemorrhage (bleeding from a damaged blood vessel), and eventually ending up in necrosis (death) of lung parenchyma. Pulmonary infarction is caused by various reasons, but one of the main causes of pulmonary infarction is pulmonary embolism.
What Is Pulmonary Embolism?
Pulmonary embolism is the obstruction or blockage of the pulmonary artery caused by a blood clot (thrombus). This blood clot is either formed in the pulmonary blood vessel or is carried in the bloodstream, which is formed somewhere else in the body (embolus). The significant symptom of pulmonary embolism is shortness of breath. Pulmonary arteries are blood vessels that transport blood from the heart to the lungs, and in the lungs, the exchange of gasses takes place, and the blood returns its oxygen to the heart. From the heart, the blood containing oxygen is pumped to different parts of the body, thus providing oxygen to all the tissues in the body.
When this pulmonary artery is blocked or obstructed because of a blood clot (thrombus) or embolus, tissues will not receive sufficient amounts of oxygen. A large embolus can cause so much blockage that the heart is unable to pump enough blood through pulmonary arteries, and this leads to a decrease in blood pressure. Also, big-sized embolisms can cause obstruction of the blood flow to the lungs leading to the death of lung tissues, and this condition is called pulmonary infarction. Pulmonary infarction is a fatal condition, but it can be reversed.
Usually, the body splits up the smaller clots quickly when compared to larger ones so that the damage can be minimal. Large clots take too much time to disintegrate, and this leads to the scar forming on the blood vessel leading to increased blood pressure in the blood vessels of the lungs. This condition is known as pulmonary hypertension, and this causes permanent damage to the lungs.
What Are The Risk Factors Of Pulmonary Infarction?
Anything which increases the chance of getting a disease is known as a risk factor. The presence of a risk factor indicates that the person is more susceptible to the disease. The risk factors of pulmonary infarction include:
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Smoking: This is considered a major risk factor for not only pulmonary infarction but also pulmonary embolism.
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Age and Height: The population who are young (below 40 years), increased height are more likely to develop pulmonary infarction.
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Sickle Cell Disease: Patients with sickle cell hemoglobin (HBS) are likely to develop vascular infarction due to the blockage. The sickle-shaped cells adhere directly to the pulmonary artery, leading to pulmonary blockage and infarction.
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Prolonged Hospitalization: People who are bedridden for longer periods are more likely to develop embolus, thus leading to the formation of pulmonary infarction.
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Leg Surgeries: People who have undergone hip and knee joint replacements are at risk of developing embolism. This is mainly due to immobilization after surgery. Hence patients are advised to go back to their routine daily work as soon as possible after surgery.
How To Diagnose Pulmonary Infarction?
The diagnosis of pulmonary infarction is mainly done by imaging tests and correlating them with the clinical signs and symptoms.
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Computed Tomography (CT): This is the most commonly used diagnostic tool to determine pulmonary infarction. Computed tomography associated with an infarction looks like a feeding vessel appearance of a lung nodule along with the blood vessel. It is also called a vessel sign, and it appears in a semicircular shape with central translucency.
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X-rays: X-rays of the chest region are the primary diagnostic tool to give the first indication of infarction. The findings in the X-ray appear as follows:
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Hampton's Hump: A dome-shaped opacification in the lung commonly caused due to pulmonary embolism and lung infarction
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Westermark's Sign: The chest X-ray shows diffused translucency due to decreased blood flow to the lungs. The foremost cause of insufficient blood flow is pulmonary embolism.
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Fleischner Sign: It is mostly seen in the central pulmonary artery that is blocked due to embolism.
How To Treat Pulmonary Infarction and Embolism?
Pulmonary infarction leads to respiratory failure and hemodynamic collapse (fluctuating and abnormal blood pressure). These two are life-threatening situations that need to be addressed immediately. If not treated in time, patients suffer from shock and cardiorespiratory arrest (improper heart and lung function), which are permanent and can lead to death. In order to prevent these fatal situations, patients should be placed on:
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Supportive Care Management: Relieving the symptoms and maintaining blood oxygen levels is the primary focus of supportive care. Oxygen support, administering analgesics (for pain relieving), and maintaining adequate blood pressure is done at this stage. In case of respiratory failure, a patient is placed on a mechanical ventilator to enhance oxygen supply to the tissues.
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Anticoagulation Therapy: Anticoagulants (blood thinners) are injected intravenously so that they can act quickly by dissolving the clot. Warfarin, Heparin, and Apixaban are the choice of anticoagulants.
How To Prevent Pulmonary Infarction Caused By Pulmonary Embolism?
Due to the hazards caused by pulmonary embolism and its limited treatment options, doctors suggest preventing blood clot formation in the veins of people who are at risk of developing embolism. People are advised to have good physical activity every day and walk around as much as possible. People traveling are suggested to walk for a few minutes every two hours during their journey. Along with this, the patient's health condition should also be checked thoroughly.
Anticoagulants As Preventive Measure:
People who are at risk of developing embolus are advised to have anticoagulants as a part of a preventive regimen. Among the anticoagulants, Heparin is the most commonly prescribed drug. Heparin can be administered in two forms, namely:
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Conventional Heparin.
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Low molecular weight Heparin.
Heparin is mostly suggested in patients who have undergone leg surgeries. It is injected beneath the skin every 6 to 12 hours or until the patient gets up and starts walking. People who are suffering from cardiac diseases, obesity, immobility, and prolonged hospitalization are advised with minor doses of Heparin. The advantage of low doses of Heparin is that it does not cause any bleeding disorders; instead, it causes the oozing of blood from small wounds.
Conclusion:
Pulmonary embolism is the primary cause of pulmonary infarction. Through investigation, procedures should be carried out as pulmonary infarction could mimic those of lung nodules. Patients are educated regarding the stoppage of smoking, as tobacco is considered the major risk factor. Since pulmonary infarction is a fatal condition, maintenance of adequate blood flow to the tissues, followed by anticoagulation therapy, is recommended. A multidisciplinary approach involves surgeons, cardiologists, hematologists, and internal medicine specialists working as a team to treat pulmonary infarction.
