What Are The Symptoms Of A Blood Clot In Your Lungs?

Overview

A blood clot in the lungs is medically termed a pulmonary embolism. It occurs in the lungs when there is a blockage in a blood vessel that restricts blood flow. Signs include chest pain and difficulty breathing, which may cause pulmonary embolism to be neglected or undiagnosed given that other diseases share the same symptoms.

Pulmonary embolism

Pulmonary embolism is an aftermath of deep vein thrombosis, a blood clot that forms in deep veins, such as those in the legs, arms and intestines. This blood clot can escape the site of clotting and potentially make its way into the lungs through the bloodstream, causing a blockage in a blood vessel supplying the lungs. Pulmonary embolism and deep vein thrombosis are both indicators of venous thromboembolism (VTE).^1,2,3

There are two types of pulmonary embolism:⁴

Deep vein thrombosis (DVT)

as mentioned earlier, deep vein thrombosis occurs when a blood clot forms in veins.

De novo pulmonary embolism (DNPE)

This type of pulmonary embolism typically occurs in the absence of deep vein thrombosis. De novo pulmonary embolism is associated with people who have a history of accidents or trauma, especially to the chest.

How serious is a pulmonary embolism?

Venous thromboembolism is the third most frequent acute cardiovascular syndrome globally, with heart attack and stroke being the two leading causes of cardiovascular events. The annual incidence rate of pulmonary embolism range from 39 to 115  for every 100,000 people.³ Pulmonary embolism has a high mortality rate (the rate at which it causes death) of about 10%and a high morbidity rate (the frequency of its occurrence), according to the Centers for Disease Control. Pulmonary embolism accounts for approximately 60,000 to 100,000 deaths in the United States annually. In 6 European countries, VTE mortality was observed in more than 370,000 people annually, more than the reported combined mortality from breast cancer, AIDS, prostate cancer, and traffic accidents.⁷

In the past, pulmonary embolism was thought to only affect the elderly. However, there have been incidents where children have been diagnosed with pulmonary embolism. Although uncommon, pulmonary embolism affects children with conditions that put them at risk of venous thromboembolism.⁵ The incidence of pulmonary embolism is still rare in the paediatric population, affecting1 child in every 100,000 children, and very common after 75 years of age, affecting 1 in every 100 people.¹

Symptoms of a pulmonary embolism

The symptoms of a pulmonary embolism may go unnoticed and prevent diagnosis because the symptoms are also indicators of other diseases that may or may not be life-threatening. The severity of symptoms when a pulmonary embolism is present depends on how large the blood clot is and how soon it is noticed. Pulmonary embolism can be asymptomatic, meaning it does not show any symptoms, or show mild symptoms, as seen in cases of acute pulmonary embolism.⁸

Some indicators for a potential diagnosis include:

Dyspnea

Dyspnea, also known as shortness of breath, is characterised by difficult or laboured breathing, due to low levels of oxygen. Dyspnea can cause an intense tightening in the chest, a feeling of suffocation and the need to inhale air. Shortness of breath is usual after intense exercise. It can also occur in individuals with obesity or due to factors such as extreme temperatures or high altitude. Dyspneanot associated with any of these typical factors could indicate a medical condition.¹⁰

Pleuritic chest pain

Pleuritic chest pain is characterised by sudden and intensely sharp, stabbing, or burning pain in the chest when inhaling and exhaling. Pulmonary embolism is the most common and serious cause in 5% to 21% of patients who present to an emergency department with pleuritic chest pain.¹¹

Cough

The presence of a cough in patients with pulmonary embolism is not well understood. It is assumed that when pressure receptors in pulmonary vessels, in the right atrium or in C-fibres (nerve fibres that control our response to pain, temperature, and itch) are stimulated, a cough response is produced In cases of an irritating cough that does not respond to inhaler treatment, a d-dimer positive blood test (to test for blood clot) and a normal chest X-ray can be done to diagnose pulmonary embolism if other symptoms are also present.¹³

Hemoptysis

Hemoptysis is the coughing up of blood-stained phlegm (mucus) from the respiratory system. This mucus could come from the larynx, lungs, bronchi or trachea and could be caused by the presence of blood in the pulmonary system.¹⁵

Presyncope

The feeling that you are about to pass out without necessarily losing consciousness. This feeling may be accompanied by general weakness, lightheadedness, warmth, nausea, sweating to an unusual degree, palpitations and blurry vision.¹⁶

Syncope

According to the American Heart Association, syncope is a temporary loss of consciousness caused by insufficient blood flow to the brain. Syncope may also be caused by heart conditions and non-life threatening factors such as overheating, dehydration, exhaustion, heavy sweating, or pooling of blood in the legs from sudden changes in body position.¹⁷

Sometimes, pulmonary embolism has sudden death as its only symptom; it happens in about 25% of people with a pulmonary embolism.⁶ 

Risk factors of blood clots

The incidence of pulmonary embolism is not limited to children or the elderly; anyone can have a pulmonary embolism. Risk factors of a blood clot may be acquired or inherited (genetic). Moreover, you are more susceptible to pulmonary embolism when you have other diseases that increase your risk of developing a blood clot.^1,8,17

Some risk factors for blood clots, as determined by research, include:^1,8,18,19,20

Genetic risk factors

• Thrombophilia - a condition when the blood produces an abnormally large number of blood clots that are ineffectively cleared out of the body
• Prothrombin gene mutation - increased production of a blood clotting protein known as prothrombincauses blood to clot more easily
• Hyperhomocysteinemia - homocysteine is an amino acid that helps your body make proteins. High amounts of it in the blood can damage the walls of arteries and put you at risk of deep vein thrombosis
• Protein C or Protein S deficiency - proteins help to repair cells and make new ones. Proteins C and S help the body regulate blood coagulation. Thus, when these proteins are low, there is a risk of blood clotting. The deficiency can be genetic or acquired

Acquired risk factors 

• Reduced blood flow caused by not moving for prolonged periods, such as bed rest greater than three daysor long periods of travel (greater than 4 hours) by car, bus, train, or air. Surgery. For example, a recent orthopaedic surgery
• Age
• Indwelling venous catheter
• Obesity
• Inflammatory bowel disease
• Burns
• Diabetes
• Pregnancy and childbirth
• Cigarette smoking
• Oral contraceptive pill or use of hormonal therapy
• Certain medical conditions, such as lung disease, heart disease -which may cause pulmonary hypertension- and certain cancers. As suggested by Thrombosis UK²¹, up to 20% of cancer patients develop blood clots.

Diagnosis

Pulmonary embolism can be difficult to diagnose due to its varying symptoms, determined by the extent of the blood clot and the location of the deep vein thrombosis, if not asymptomatic.¹⁸ Acute pulmonary embolism may be misdiagnosed, underdiagnosed, or overdiagnosed. This can delay a correct diagnosis from being made and result in a patient’s death.Hence, there is a significantneed for early diagnosis of pulmonary embolism.^1,4,7.22

For a proper diagnosis to be made, your healthcare provider will ask for your health history; this can include your risk factors and symptoms. You will also undergo a physical examination during which diagnostic scoring systems, such as the Well’s criteria, Geneva score, the Pulmonary Embolism Rule-Out Criteria (PERC) and the simplified pulmonary embolism severity index (sPESI), will be used to help predict the presence of a thrombus. The outcome of the diagnostic scores, especially in low-risk patients, will decide if you are sent for further testing., These may be blood testsor imaging tests like a CT scan, X-ray, MRI scan or a pulmonary angiogram.^7,8,2

It is worth noting that the actual incidence of pulmonary embolism is likely notably higher because autopsy studies show that only 30% to 40% of patients whose cause of death was a pulmonary embolism had been diagnosed with it while alive.¹ 

Treatment

Your healthcare provider will choose the treatment path according to the risk of pulmonary embolism. There are three risk levels of risk factors:³

• Low risk includes immobility, diabetes, arterial hypertension, age, pregnancy and varicose veins
• Intermediate risk includes autoimmune diseases, blood transfusion, intravenous catheters and leads, chemotherapy, congestive heart failure, thrombophilia and arthroscopic knee surgery
• High risk may arise from hospitalisation for heart failure, hip or knee replacement surgery, major trauma, spinal cordinjury, previous venous thromboembolism or lower limb fracture 

Typically, your healthcare provider will prescribe blood thinners, a class of drugs known as anticoagulants, to help mitigate or prevent the chances of a blood clot. Thrombolytics may alternatively be administered to help dissolve blood clots.

Non-medicinal treatment lines include:

• A vena cava filter - a procedure where a filter is inserted into deep veins of the vena cava to filter out blood clots before they get to the lungs. This method is chosen for people who, for any reason, are not able to take anticoagulants. It does not stop the formation of new clots
• Catheter-assisted thrombus removal - your healthcare provider inserts a flexible tube into the lungs and proceeds to break apart the thrombus into tinier bits. Medicine may also be administered through this tube by your healthcare provider

Prevention

Globally up to 60% of blood clots occur within 90 days of hospital discharge, about 33% of people with deep vein thrombosis or pulmonary embolism will have a recurrence within 10 years and 10% to 30% of people will die within one month of receiving their diagnosis.^21,6

You first need to prevent blood clots to prevent the recurrence of deep vein thrombosis or pulmonary embolism. You can do any or all of the following:

• Move around often, and avoid immobility. If you are going to sit for an extended time, use compression socks, move your legs around or move around as soon as possible if you recently had surgery
• If your healthcare provider prescribed blood thinners, continue to take them and go for a regular check-up
• Lifestyle changes ranging from a heart-healthy diet, quitting smoking and exercising regularly

Summary

Symptoms of blood clots in the lungs may vary due to many factors. Keeping an eye out for any changes in how your respiratory system works can help with early diagnosis, treatment and management of pulmonary embolism. You should take special care if you are at risk of pulmonary embolism and after treatment, you should take preventative measures to avoid a recurrence.