In this Medical Monday series, we’re talking about how your doctor reaches a diagnosis of common conditions associated with coagulation. It may help if you first read the introduction, before reading about today’s topic of pulmonary embolism. Altogether we’re covering
- DVT, Deep Vein Thrombosis
- Post-thrombotic syndrome
- PE, Pulmonary Embolism
- Pulmonary hypertension
- AF, Atrial Fibrillation
- Heart Valve conditions – aortic and mitral
The symptoms of a pulmonary embolus range from virtually nothing to a life-threatening collapse. A major pulmonary embolus can present with sudden onset of chest pain and acute breathlessness with a rapid loss of consciousness. The symptoms occur because the blood supply to the lungs is severely compromised and the amount of blood returning to the heart from the lungs drops very quickly. This is a life-threatening situation and accounts for approximately 10% of pulmonary emboli.
A moderate size clot is likely to cause sudden onset of chest pain and shortness of breath. The pain can be an aching in the chest but is often what is called pleuritic pain. This is a sharp pain at a local site in the chest that gets worse on taking a deep breath. It is due to inflammation of the pleura or the covering of the lung. This type of clot can also cause a cough and occasionally people cough up a small amount of blood. People with a moderate clot may feel light-headed and generally unwell. You can even get a slight fever. This type of clot is not always diagnosed with the first event. You may have several similar episodes before your doctor considers a pulmonary embolus. I visited the emergency department with chest pain on 3 occasions over 2 years before my clot was diagnosed.
Smaller blood clots can be very difficult to diagnose as they may not cause symptoms at the time they occur. Small clots can gradually affect blood flow. I had a colleague who found it was getting increasingly difficult to get to the top floor of the hospital. It was only when he collapsed while at work in the operating theatre that a pulmonary embolus was considered. Recurrent small clots can lead to long-term damage in the lungs causing a condition called pulmonary hypertension which is a very serious complication, which we’ll be covering next Monday.
Questions your doctor may ask
If you have chest pain your doctor will take this very seriously and will want to know when the pain started, where it is in your chest, the type of pain, and if you have any other symptoms with it. Your doctor will be trying to decide if the pain is from heart disease or something else. A large pulmonary embolus can cause central chest pain with sweating a bit like a heart attack. This needs urgent attention. Most people with severe pain tend to go to the emergency department and will get investigated quickly.
Diagnosing a PE is much harder if the clot is smaller. People with smaller clots may present to their family doctor with far vaguer symptoms such as occasional twinges of pain in the chest and breathlessness on exercise. There are many causes of mild chest pain and breathlessness, so your doctor may be thinking about muscle pain, indigestion and heart conditions. The pain from a PE can be in the upper abdomen or back making it even harder for your doctor.
One time I had a pulmonary embolus, I had pain in my right lower chest towards the back. This was diagnosed as renal colic, even though the man in the next cubicle who had renal colic was writhing around in pain, groaning and vomiting, whereas I was able to lie still quietly.
Another time I had a sharp pain in the centre of my chest, which was diagnosed as pericarditis (an inflammation of the sac containing the heart). It was only when a Pulmonary embolus was diagnosed with my fourth presentation with pain, that the doctors realised a PE was probably the cause of my previous symptoms.
Your doctor will want to know if you have previously had a DVT or PE and will want to know about your medication. If you are taking an oral contraceptive or hormone replacement therapy you should tell your doctor as these increase your risk of having a blood clot.
What your doctor may find
With a large clot the heart is under strain and the heart rate increases and the blood pressure drops as the amount of blood circulating drops. The respiratory rate also goes up and the oxygen level in the blood drops.
With a smaller clot your doctor may not find much wrong. If you have sharp chest pain your doctor may hear a rough sound in your chest called a pleuritic rub or may find a small amount of fluid around your lungs. I find measuring the oxygen saturation in the blood helpful. In a young fit person this should be around 98% if it is below 95% this is a sign that something could be wrong with oxygen transport. If there are no other chest signs a PE should be considered.
Your doctor will also examine your legs to see if there are any signs of a DVT.
Your doctor may use details of your symptoms and examination to calculate your probability of a PE using the PE Wells score, but this is not widely used compared with the Wells score used for DVT.
Tests you may have
If you are acutely ill the doctors will do blood tests to check your blood count, kidney function and liver function. They may also want to take an arterial sample of blood to measure your oxygen level, this is more accurate than the oximeter on your finger.
The doctor will do an ECG to look at your heart rhythm and to see if there are changes on the heart trace that suggest a PE or heart attack. To try to exclude a PE they will measure the d-dimer. This is useful if it is negative but that is rarely the case if you have presented with significant symptoms as the d-dimer is positive with many acute illnesses and after recent surgery.
If the doctors suspect a PE they will do one of two tests; either a CTPA or a ventilation/perfusion scan (V/Q scan). Most places will do a CTPA (see tomorrow’s post on CTPA) as it is quick to organise and can give additional information if the symptoms are not due to a PE, however a CTPA can be difficult to interpret and detects very small clots that might not be significant.
What it could be
Some causes of chest pain
- Heart attack
- Chest infection
- Collapse lung (pneumothorax)
- renal stones
Some causes of breathlessness
- Chest infection
- Heart failure
- Panic attack
- Collapsed lung
- Irregular heart rhythm