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Date issued: March 2022

Review date: March 2024

Ref: A-493

PDF: Pulmonary Embolism final March 2022.pdf [pdf] 114KB

What is a Pulmonary Embolism?

A pulmonary embolism (or "PE") is a blockage in 1 or more of the blood vessels that supply blood to the lungs. These blockages are usually caused by blood clots that form elsewhere and then travel to the lungs.

A PE can be in an artery in the centre of the lung or one near the edge of the lung. The clot can be large or small and there can be more than one clot.

What are the symptoms of PE?                                      

Common symptoms include:

• Panting, shortness of breath, or trouble breathing
• Sharp, knife-like chest pain when you breathe in or strain
• Coughing or coughing up blood
• A rapid heartbeat or feeling faint

If you get these symptoms, especially if they happen over a short period of time and progress quickly, or if you feel faint or collapse, call 999 for an ambulance.

Why is a PE dangerous?

If a blood clot forms or gets stuck inside a blood vessel, it can block the vessel and prevent blood from getting where it needs to go. When that happens in the lungs, the lungs can be damaged. Having blocked arteries in the lung can make it hard to breath and can be life-threatening if left untreated.

What causes a PE?

A PE usually happens when a blood clot forms in the leg or pelvis (a deep vein thrombosis), and travels to the lung. Sometimes a reason cannot be found as to why the blood clot has formed, but risk factors for blood clots include:

• Previous blood clots or a family history of blood clots
• Pregnancy
• Oral contraceptive pill
• Surgery or immobility
• Long haul flights (and other travel if more than four hours in duration)
• Smoking
• Being overweight
• Increasing age
• Cancer
• An underlying condition of ‘sticky blood’

Doctors call a PE with no associated risk factors ‘unprovoked’.

How is a PE treated?

Blood clots in the lungs are treated with medicines that keep clots from getting bigger and help your body to dissolve them. These medicines are called "anticoagulants" or "blood thinners," (although they do not actually thin the blood). Anticoagulants are available as injections or tablets. Patients usually PE begin their PE treatment in hospital.

Duration of use:

Most people start treatment with injections and then move onto tablets after a few days. If for some reason you can't take tablets you may remain on an injectable anticoagulant. You will need to take the medicine for at least 3 months. Many patients will be advised to take anticoagulant treatment for the rest of their lives to prevent a recurrence. This is usually because the risks from another episode of PE are considered greater than the risks of bleeding from prolonged use of anticoagulants. For example, with an ‘unprovoked’ PE, there is a 20-30% risk of recurrence after 5 years if anticoagulation is stopped. A small proportion of these recurrences (2-3%) will be fatal. There is a 10-15% chance of a major bleeding episode (i.e., bad enough to require hospital admission) with anticoagulation over this period of time. It is widely recommended that patients who have suffered an unprovoked PE, or have previously had a PE, should remain on treatment indefinitely. The risks and benefits should be reviewed by you and your doctors every year and if your health changes for any reason.  We aim to offer all patients who have had an unprovoked PE an appointment with a blood-clotting specialist about 3 months after discharge from hospital. For patients experiencing their first PE where there has been an obvious temporary ‘provoking’ factor (e.g., a long journey or an operation), 3 months treatment is sufficient.

How they work:

The medicines do not dissolve existing blood clots, but they do keep them from getting bigger. They also help keep new blood clots from forming. Taking the medicine for at least 3 months is important because it gives your body time to dissolve the old clot.

You will need to mention that you take anticoagulants ‘blood thinners’ to any other doctors or surgeons you might see to your dentist and to your pharmacist. If you become pregnant or are planning to start a family, you should mention this to your GP as soon as possible.

There are several different drugs (tablets) used to prevent and treat blood clots. They include apixaban, dabigatran, edoxaban, rivaroxaban, and warfarin. Each medicine is different in terms of the dose, monitoring required and how often you take it. Some choices interact with alcohol and other prescribed medicines or natural therapies. Your doctor will talk to you about your options and preferences. You should avoid taking aspirin or ibuprofen while you receive anticoagulant therapy, unless a doctor has confirmed this is appropriate for you. Paracetamol is safe to use as a painkiller.

Be aware that some injectable anticoagulants are of animal origin and that some tablet anticoagulants contain lactose from cow’s milk. Your doctor can discuss this with you if required.

Watch for signs of bleeding: Abnormal bleeding is a risk with all the medicines used to prevent and treat blood clots. That's because while these medicines help prevent dangerous blood clots, they also make it harder for your body to control bleeding after an injury. So it's important to try to avoid getting injured, and to tell your doctor right away if you do have signs of bleeding. This might mean that certain activities, such as contact sports, need to be stopped while you take this treatment.

Other treatments:

In some cases, a person has a clot that is severe enough to cause dangerously low blood pressure. If this happens, doctors can give medicine to dissolve the clot. This is sometimes called "clot-busting" medicine, and is given through a vein. There is a greater risk of bleeding with this treatment.

In exceptional cases, doctors operate to remove the PE. This is reserved for very unwell patients.

People who cannot take medicines to prevent and treat clots, or who do not get enough benefit from the medicines, may receive an "inferior vena cava filter".

Supportive treatment: is often given in the early stages to help the body cope with the effects of the PE. This may include oxygen, intravenous fluid and painkillers.

For outpatients: Why are we not admitting you to the hospital?

The risks from a PE depend on a number of factors and can be estimated using a scoring system. Low risk patients can be safely managed as an outpatient.

How long will I feel breathless?

It’s common to feel breathless for a few weeks or months after a pulmonary embolism. It is safe to start resuming exercise after 1-2 weeks of starting treatment. Initially you should avoid any heavy lifting or exercise that leaves you gasping for breath. Gradually build up the time and intensity of your exercise, aiming to return to your normal level by approximately 8 weeks from starting treatment.

There are lots of conditions that can make you feel short of breath after a pulmonary embolism. If you still feel breathless on exertion after 8 weeks, talk to your GP. Your health care professional will want to check that it is not caused by other problems with your heart or lungs, or that the anticoagulant medication has been ineffective.

What happens when my treatment ends?

We aim to offer all patients with an unprovoked or recurrent PE an appointment with a blood specialist 3 months after discharge. This will be an opportunity to consider further investigations to see if there was a reason for the clot. We will also discuss the potential harms and benefits of continuing long term anticoagulant therapy.

What is the outlook for a PE?

If a PE is treated promptly, the outlook (prognosis) is excellent, and most people will make a full recovery. The outlook is less good if there is a pre- existing serious illness that helped to cause the embolism, for example, advanced cancer.

A PE is a serious condition, but the risks are greatly reduced by early treatment.

There is a high risk of another PE occurring within six weeks of the first one. This is why treatment is needed immediately and is continued for at least three months.

What can I do to avoid pulmonary embolism?

Keep active:

After surgery, move around or do leg exercises as soon as you can.

On long-haul flights and other long journeys, do leg stretching exercises: bend and straighten your legs, feet and toes every 30 minutes when you’re sitting. Stand up and walk around when you can. Do some deep breathing. It also helps if you drink water regularly. Wear flight socks.

If you’re at risk of developing blood clots, consult your health care professional before travelling long distances.

Change habits:

We can all reduce our risk of having a pulmonary embolism by changing our habits. For example:

• Stop smoking, your GP can support you with this

• Take regular exercise, at least 150 minutes a week

• Avoid sitting still for a long time, such as when watching TV or using a computer. Take an active break every 30 minutes or so

• Eat a healthy balanced diet, with plenty of fruit and vegetables and  maintain a healthy weight

Important contact numbers:

You may wish to discuss further details with one of the following:

• Your General Practitioner for advice regarding your recovery and any further tests

• Your local pharmacist regarding your new treatment and any other medicines you take, including herbal or natural medicines

• Your consultant regarding details of your admission, the tests you received and any plans for follow up. Your consultant’s contact details should be available on the discharge letter. Please contact the Patient Advice and Liaison Service if you need help with this (tel: 01752 439884 or email: plh-tr.PALS@nhs.net)