Pulmonary Embolism – Diagnosis, Symptoms, and Treatment

What is a Pulmonary Embolism?

Pulmonary embolism is the medical term for a blood clot that develops elsewhere in the body and then travels to the lungs and becomes stuck, obstructing blood flow to that area of the lung. 

The blockage of blood flow to a section of the lung will result in death of that segment of lung. This causes chest pain, shortness of breath, and in some patients may even cause sudden death. 

What Causes a Pulmonary Embolism?

Pulmonary embolism is typically caused by a blood clot originating the lower limbs called a deep vein thrombosis.  These blood clots can dislodge and travel to the lung – producing symptoms such as sudden chest pain and shortness of breath.  People also frequently develop low oxygen levels (hypoxia) because the areas of the lung that are without blood flow are useless for absorbing oxygen. 

The risk of pulmonary embolism is primarily based on the factors that increase the risk of deep vein thrombosis. The most common risk factors for the development of deep vein thrombosis and pulmonary embolism include:

• Prior history of deep vein thrombosis or pulmonary embolism
• Prolonged immobility
• Recent hip surgery
• Cancer
• Genetic defects – prothrombin mutation, anti-thrombin deficiency, factor V–Leiden, protein C & S deficiency
• Certain medications – oral contraceptives, estrogen/progesterone therapy

Prolonged immobility can happen in situations such as recent hip surgery, airplane travel, or car rides.  It is usually recommended that individuals on flights take frequent breaks from sitting to prevent pooling of blood in the lower limbs and clot formation.  Massaging and stretching the legs can also be beneficial in preventing blood clots from forming.

Prolonged immobility may also occur in the elderly, patients with severe joint pain and arthritis, individuals with recent para- or quadriplegia from spinal cord injuries.  

Common Complications of pulmonary embolism include:

• Life-threatening arrhythmias – abnormal heart rhythms
• Heart failure
• Hypoxia (low oxygen levels)
• Death

How Common is a Pulmonary Embolism?

Pulmonary embolism is thought to be relatively common especially among those with risk factors for deep vein thrombosis. The exact number of those who suffer from these conditions is unknown as some patients never present to the hospital or have any major symptoms. The United States Centers for Disease Control estimate that 900,000 individuals in the United States are affected by either deep vein thrombosis and/or pulmonary embolism in a given year. Among those that do seek medical care it is estimated that over 100,000 individuals in the United States die from pulmonary embolism every year. 

Signs and Symptoms

Pulmonary embolism has a varied presentation, it is estimated that around 25% of pulmonary embolisms lead to sudden death. Another 10% to 30% of patients will die within a month of experiencing a pulmonary embolism. Among those that survive the most common symptoms of a pulmonary embolism include:

• Sudden chest pain
• Difficulty breathing
• Coughing up blood (hemoptysis)
• Wheezing

The pain can worsen on deep breathing or inspiration – a phenomenon called pleuritic chest pain.  Patients with pulmonary emboli typically have elevated heart rates (tachycardia) and low oxygen levels (hypoxia).  

Patients with pulmonary embolism frequently have the signs and symptoms of a deep vein thrombosis such as swelling, pain, warmth, and redness in one leg.

Diagnosis

If your doctor suspects pulmonary embolism based on symptoms and signs, they may call 911 and direct you to the nearest emergency department for further evaluation.  This is a medical emergency that typically requires hospitalization.

In the hospital, they will order an EKG (electrocardiogram) and ultrasound of the heart (echocardiogram) to evaluate the heart’s function and structure.  One of the most commonly used studies to confirm a pulmonary embolism is called a CT angiography – a CT scan evaluating for interruptions of blood flow to the lungs.  Occasionally, your doctor will order a study called a V/Q scan, which looks for an imbalance between the flow or air and blood within the lungs.

Your doctor will also likely order blood tests such as an arterial blood gas, CMP (comprehensive metabolic panel), CBC (complete blood cell count), and coagulation studies (PT/INR, PTT).  If they think you could have systemic lupus erythematosus, an uncommon cause of deep vein thrombosis, they will typically order an antinuclear antibody (ANA) and anti-double-stranded DNA antibody (anti-DS DNA).

Your doctor will also usually evaluate for genetic disorders that lead to blood clot formation.  These include:

• Factor V Leiden
• Anti-thrombin deficiency
• Protein C and S deficiency
• APC resistance
• Prothrombin mutation

They may also perform age-appropriate cancer screening as cancer anywhere in the body increases the risk of blood clots.  This may include a prostate- specific antigen (PSA) for prostate cancer in men and a Papaniculaou (PAP) smear for cervical cancer in women.  Additional recommendations may include a colonoscopy if you have risk factors such as family history or age over 50 years.  Breast cancer screening in women is also an important consideration.

Pulmonary Embolism Medication and Treatment

Pulmonary embolism is treated as a medical emergency.  If you have signs of heart strain or failure, you doctor will likely prescribe a medication called a thrombolytic.  Thrombolytics (e.g., tissue plasminogen activator) are a class of drugs that work by rapidly breaking down blood clots and opening-up blood vessels.  In the case of pulmonary embolism, these drugs are injected into the vein to break up venous clots. 

Alternatively, some patients may benefit from advanced surgical techniques that can physically remove the clots from the lungs.

If you have no signs of heart strain or failure, you doctor will most likely start you on either one of these blood thinner medications: heparin or Lovenox (Enoxaparin).

If you and your doctor determine the benefits of oral anticoagulation outweigh its risks, they may prescribe a long-term oral blood thinner called Coumadin (Warfarin).

Warfarin interacts with a host of medications and foods (e.g., spinach).  This medication also needs to be monitored very closely with regular blood tests – therefore, a lot of patients are started on newer oral anticoagulants such as:

• Xarelto (Rivaroxaban)
• Eliquis (Apixaban)
• Pradaxa (Dabigatran)

These anticoagulants are critical in preventing repeated pulmonary embolisms. For patients with few or no risk factors six months of anticoagulation is generally prescribed. If you have multiple risk factors, a severe pulmonary embolism, or if you have had more than one pulmonary embolism anticoagulation is generally prescribed indefinitely.