OVERVIEW

What is Pulmonary Embolism?

The human heart and lungs work closely together to supply oxygen to the body.

Venous blood, low in oxygen, returns to the right atrium and flows into the right ventricle, then enters the pulmonary artery (carrying deoxygenated blood). It passes through the capillary network in the lungs, where oxygen exchange occurs in the alveoli, increasing the blood's oxygen content. The oxygenated blood then returns via the pulmonary veins (carrying oxygen-rich arterial blood) to the left atrium and left ventricle, which pumps it to organs throughout the body.

Pulmonary embolism occurs when an embolus—such as a blood clot, fat globule, amniotic fluid, or air bubble—blocks the pulmonary artery, disrupting this oxygen supply mechanism and causing hypoxia.

Pulmonary thromboembolism is the most common type of pulmonary embolism, often referred to simply as pulmonary embolism, and is the primary focus of this Q&A.

Is Pulmonary Embolism Common?

Pulmonary embolism is a prevalent cardiovascular disease. In the U.S., an estimated 600,000 to 700,000 new cases occur annually, making it the third most common cardiovascular condition after coronary artery disease and hypertension. Untreated pulmonary embolism has a mortality rate as high as 25%–30%.

SYMPTOMS

What are the common manifestations of pulmonary embolism patients?

Pulmonary embolism is a "versatile actor" with diverse and nonspecific clinical presentations. Mild cases may have no discomfort, while severe cases can lead to sudden death. Most patients seek medical attention due to dyspnea (shortness of breath), chest tightness, or chest pain. Approximately half of the patients experience restlessness. Other symptoms may include cough, hemoptysis, fever, loss of consciousness, and profuse sweating.

Since pulmonary embolism thrombi often originate from deep veins in the lower limbs, some patients may exhibit asymmetric swelling in the legs.

What diseases can pulmonary embolism cause?

Pulmonary infarction (necrosis of lung tissue supplied by the occluded pulmonary artery, leading to hemoptysis), pulmonary hypertension, right heart dysfunction (right heart enlargement, systemic edema, acute or chronic cor pulmonale). In the most severe cases, it can result in circulatory failure and death.

Is pulmonary embolism likely to cause death by suffocation?

Untreated pulmonary embolism patients have a mortality rate of nearly 30%. As mentioned earlier, the severity of pulmonary embolism varies, and the vast majority of patients do not die suddenly from "suffocation."

Patients who die from "suffocation" due to pulmonary embolism often show subtle warning signs beforehand, such as shortness of breath after activity (reduced physical endurance), chest tightness, or asymmetric leg swelling. Therefore, the key lies in raising awareness of "pulmonary embolism" and seeking timely treatment.

CAUSES

Which groups are prone to pulmonary embolism?

The emboli in pulmonary thrombosis primarily originate from deep vein thrombosis, most commonly in the deep veins of the lower limbs and pelvic veins.

If blood flow in the venous system is slow, the vascular endothelium is damaged, or the blood itself is prone to clotting, these three factors increase the risk of venous thrombosis. Some individuals naturally have blood that clots more easily, which is a primary high-risk factor for pulmonary embolism and can be screened through a series of tests.

Obese individuals, the elderly (especially those with hyperlipidemia), those who are bedridden for long periods, or those who remain sedentary for extended durations (such as overnight computer use, marathon mahjong sessions, or long-distance travel by plane, train, or ship with limited lower limb movement) experience slower blood flow in the lower limbs, which is a secondary risk factor for pulmonary embolism.

Women of childbearing age taking oral contraceptives may experience interference with their blood coagulation mechanisms. Pregnant women are prone to pelvic vein thrombosis due to compression of pelvic blood vessels by the enlarged uterus. Occupations requiring prolonged standing (such as surgeons or hairdressers) also increase the risk of varicose veins in the lower limbs, which can easily develop into thrombosis and are another high-risk factor for pulmonary embolism.

In which diseases does pulmonary embolism commonly occur?

Pulmonary embolism often occurs in patients with poor lower limb circulation, hypercoagulable blood, or vascular damage, as well as those with abnormal coagulation function, trauma, fractures, abdominal surgery, stroke, Crohn's disease, heart failure, myocardial infarction, or malignant tumors.

Can frequent foot massages cause pulmonary embolism?

Foot massages promote blood circulation and are generally unfavorable for thrombus formation in the lower limbs. However, for individuals with existing lower limb swelling, unstable thrombi may have already formed, and foot massages could potentially dislodge them, leading to pulmonary embolism.

Particularly in cases of asymmetrical lower limb swelling, massaging the affected limb must be avoided, and medical attention should be sought promptly.

DIAGNOSIS

How is pulmonary embolism diagnosed?

If a high-risk patient presents with symptoms such as dyspnea, chest pain, or asymmetrical swelling of the lower limbs, pulmonary embolism should be investigated. Common diagnostic tests include D-dimer, electrocardiogram (ECG), chest X-ray, arterial blood gas analysis, echocardiography, lower extremity venous ultrasound, ventilation/perfusion (V/Q) scan, CT pulmonary angiography (CTPA), and pulmonary angiography.

For patients diagnosed with pulmonary embolism, further examinations are required to identify evidence of deep vein thrombosis and other high-risk factors.

Which diseases resemble pulmonary embolism and are difficult to distinguish?

The following conditions share similar symptoms with pulmonary embolism: coronary artery disease (chest tightness), acute myocardial infarction (chest pain, profuse sweating), acute left heart failure (shortness of breath, hemoptysis, profuse sweating), aortic dissection (chest pain, loss of consciousness), pneumothorax (chest pain, dyspnea, cough), asthma (chest tightness, dyspnea, cough, restlessness, sweating), pneumonia (fever, cough, dyspnea), and pleurisy (chest pain, fever).

Due to overlapping symptoms, self-diagnosis and medication are strongly discouraged. Patients experiencing "alarm symptoms" such as chest pain, dyspnea, or profuse sweating should seek medical attention immediately. Physicians should conduct targeted questioning, physical examinations, and specific diagnostic tests to identify the underlying cause.

TREATMENT

How is pulmonary embolism treated?

The pulmonary artery lesions in pulmonary embolism are like blocked river channels, where silt (deep vein thrombosis) may further obstruct the channel (pulmonary artery). However, the body also has the ability to clear the channel (dissolve the thrombus) on its own. Therefore, some patients with pulmonary embolism may experience symptom relief without treatment, while others may see their condition worsen.

Different treatment plans are available depending on the severity of the condition and individual factors, such as medication, surgery, or interventional therapy (minimally invasive treatment). Severe cases may require ventilator-assisted breathing or vasopressors to raise blood pressure.

What is the initial hospital management for pulmonary embolism?

Hospitalized patients require bed rest, oxygen therapy, and pain relief. Monitoring of respiration, heart rate, blood pressure, electrocardiogram, and pulse oximetry is also necessary.

What are the medication treatments for pulmonary embolism?

Medication treatments for pulmonary embolism vary depending on the severity of the disease.

• Anticoagulation therapy:
  For mild cases where the main pulmonary artery is not completely blocked, the focus is on preventing further deep vein thrombosis and worsening pulmonary embolism. Anticoagulation therapy is the cornerstone of treatment, aiming to reduce the recurrence rate of thrombosis.
  During hospitalization, heparin or low-molecular-weight heparin may be used, gradually transitioning to oral warfarin. Since warfarin affects coagulation, regular blood tests are required to monitor clotting function and prevent major bleeding. Anticoagulation typically lasts six months, but if risk factors persist or cannot be eliminated, long-term or even lifelong anticoagulation may be necessary.

• Thrombolytic therapy:
  For severe cases where the main pulmonary artery is completely blocked, leading to hypotension or shock, thrombolytic therapy (clearing the "silt" blocking the artery) may be considered. However, thrombolysis carries risks, with bleeding being the most common complication (occurring in about 5% of cases, including a 1% rate of fatal bleeding such as cerebral hemorrhage).
  Patients and family members should watch for signs of bleeding, such as red urine or sputum, black or bloody stools, or uncontrolled bleeding. Any significant changes in consciousness or limb strength should be reported immediately to medical staff.

When is surgery needed for pulmonary embolism?

Surgical removal of pulmonary artery thrombi may be considered if medication fails or cannot be used due to high complication risks.

These patients are usually in worse condition, and anesthesia risks pose another major challenge. Therefore, thorough doctor-patient communication is essential to discuss the pros and cons of surgery based on the patient's specific situation.

What is interventional therapy for pulmonary embolism?

Given the extensive network of human blood vessels, minimally invasive methods can be used to reach the blocked pulmonary artery. Catheter-based techniques can fragment or aspirate thrombi, partially replacing surgery.

If a patient cannot tolerate anticoagulation or has bleeding complications, an inferior vena cava filter may be placed to prevent large deep vein thrombi from dislodging and blocking the pulmonary artery again.

How long can a pulmonary embolism patient live?

Thrombosis is generally a chronic process. Patients with undiagnosed pulmonary embolism may have shorter lifespans due to delayed treatment. Early diagnosis and treatment can improve prognosis.

Can pulmonary embolism be cured?

Treatment outcomes vary depending on the cause. For example, patients with pulmonary embolism caused by prolonged immobility may fully recover with timely treatment.

However, patients with underlying clotting disorders may require long-term medication under medical supervision.

Can pulmonary embolism recur?

If the underlying cause or high-risk factors persist, recurrence is possible.

DIET & LIFESTYLE

What are the daily life precautions for patients with pulmonary embolism?

The severity of pulmonary embolism varies, so there’s no need for excessive worry. Cooperating with your doctor is the wisest approach. Most patients need to take warfarin orally under medical supervision, as this medication affects blood clotting.

Different foods and other drugs can also influence its effects, so patients must regularly monitor their blood coagulation indicators.

Are there any lifestyle restrictions for patients with pulmonary embolism?

Pulmonary embolism is essentially a thrombotic disease.

Obese patients tend to exercise less, which promotes blood clot formation. Therefore, it’s important to control weight, engage in moderate exercise, and avoid overly greasy diets.

PREVENTION

How to Prevent Pulmonary Embolism?

Since the human body naturally has a dual function of "forming blood clots/dissolving blood clots," pulmonary embolism generally does not occur, so excessive panic is unnecessary. We should improve our ability to recognize high-risk factors for pulmonary embolism.

Since most emboli originate from the lower limbs, we should avoid prolonged sitting or inactivity. After surgery, if bedridden, it is necessary to move the lower limbs as much as possible. Elderly patients who cannot move their lower limbs independently after surgery should be assisted with passive limb exercises. If asymmetrical swelling of both lower limbs is observed, seek medical attention promptly.

For recurrent pulmonary embolism, it is essential to actively identify risk factors to prevent recurrence.