Breathlessness - Consult Cardiologist

Breathlessness (also known as dyspnoea) refers to the sensation of shortness of breath or difficulty breathing. It is an extremely common symptom but can be both distressing and frightening for patients and carers. Breathlessness may occur in conjunction with other symptoms such as cough, chest pain and fever. It can be caused by a variety of conditions affecting the lungs, heart and/or general circulation. In these cases, breathlessness occurs due to a fall in the levels of oxygen in the blood, increased levels of carbon dioxide or just difficulty expanding the lungs. The possible causes of breathlessness are extensive. It is is frequently seen in emphysema, chronic airflow limitation, pneumonia (infection of the lungs), asthma, heart failure, dementia, multiple sclerosis and AIDS. The majority cancerpatients also experience some degree of shortness of breath, even if the primary cancer did not arise in the lung. You should consult your doctor if you experience shortness of breath or related symptoms as it may be the sign of a serious underlying disease.

What is breathlessness?

Breathlessness (or dyspnoea) is described as the feeling of shortness of breath. It is a very common complaint associated with various medical conditions affecting the heart, lungs and other systems. Breathlessness can be distressing and frightening for both patients and carers. If you experience breathlessness it is worth seeing a doctor so they can exclude any serious underlying pathology and help you to manage your disorder. Breathlessness is normally worse on exertion or exercise. Doctors grade the severity of your breathlessness according to the degree of activity that causes the symptom. Grade four is the worst and this is associated with shortness of breath at rest. Breathlessness caused by diseases of the heart may become worse when you lie down. This is caused orthopnoea. Sometimes breathlessness is caused by no disease at all and may be associated with poor fitness and reduced exercise tolerance. It may however still be worth be checked by your doctor.

How does it develop?

In general, there are four main mechanisms which can make someone feel short of breath:

  • Decreased oxygen levels in the blood stream.
  • Increased levels of carbon dioxide in the blood stream.
  • Decreased ability of the lung to expand.
  • Increased workload associated with normal breathing.

Common causes of breathlessness

There is a very long list of possible causes for breathlessness. As fore mentioned, several different systems may be involved (not necessarily only the lungs) making diagnosis somewhat difficult. However, the pattern of breathlessness and other symptoms can give clues to the likely cause. Some possible causes of breathlessness are described below:

Respiratory Causes

  • Airway obstruction- Obstruction of the air passages in the nose, mouth or throat can cause breathing difficulties. A characteristic example of obstructive lung disease is asthma. In this condition the bronchi (large airways) are narrowed and clogged with lots of mucous. Other obstructive airway disease include chronic obstructive pulmonary disease (COPD), emphysema, bronchiectasis and acute or chronic infection (bronchitis.
  • Damaged or reduced amount of functioning lung tissue- Lung tumours, infection (pneumonia) or fluid in the lungs (pulmonary oedema) can affect the ability of the airways to fill and transfer oxygen into the blood stream. Restrictive lung diseases caused by fibrosis (e.g. radiation damage) also limit the ability of the lungs to expand and exchange gases with the blood.
  • Impaired ventilatory movement- Pain in the chest, abnormalities in the abdomen (that compress on the lungs), deformities of the chest wall (such as kyphosis) and weakness of respiratory muscles (caused by diseases such as multiple sclerosis) may all reduce the amount the lungs expand.
  • Pulmonary circulation- Clots in the lungs called pulmonary emboli (PE) cause a sudden onset of shortness of breath because blood is unable to reach the airspaces to pick up the oxygen needed by the body.


Cardiac Causes

Heart failure, mitral valve disease, cardiomyopathy, pericarditis and many other cardiac problems frequently cause shortness of breath. This occurs because the heart is unable to pump enough blood to supply enough oxygen to the rest of the body. In addition, heart problems can cause pooling of blood and fluid in the lungs (pulmonary oedema) which further limits gas exchange in the lungs. Heart diseases usually first cause shortness of breath during exertion but later they develop the characteristic types of breathlessness called orthopnoea (breathlessness whilst lying flat so you may find it more comfortable sleeping on several pillows) and paroxysmal nocturnal dyspnoea (PND; breathlessness that wakes you up from sleep).

Neoplasia or cancer

Lung cancers often lead to breathlessness in the later stages of disease. This often occurs because the cancer invades or obstructs airways, causes lobar collapse or produces malignant pleural effusion (fluid around the lung that prevents it from expanding). Lung cancer can also cause a condition called lymphangitis which is thickening of the lymphatics in the lung. Lung cancer may cause other symptoms such as chest pain or haemoptysis (coughing up blood) and is frequently associated with smoking. Cancers in other parts of the body can also cause shortness of breath from cachexia, anaemia or metastasis (spread) to the lung.


Anaemia is associated with a reduced amount of red blood cells in the bloodstream. These are the primary cells involved in transporting oxygen from the lungs to the body. They do this by binding oxygen to a special protein called haemoglobin. Without enough blood cells, tissues do not receive adequate oxygen and the heart compensates by trying to pump more blood. This eventually can cause permanent cardiac damage and worsening of angina and congestive heart failure both of which may lead to dyspnoea.

Other causes

Sometimes emotional distress or anxiety (nervousness) can cause you to breathe faster (hyperventilation) and make you feel short of breath. This can create a vicious cycle as you can become more worried because you feel breathless which leads to more difficulty breathing. Obesity, hyperthyroidismand other metabolic problems can also cause you to become breathless. >Fatigue is another possible cause because the level of effort required to breathe cannot be sustained. Therefore there are a large number of conditions causing breathlessness that do not arise in the lungs. In the case of breathlessness, it is first important to rule out all the serious causes such as acute asthma, pulmonary embolus, pneumothorax, haemothorax, acute pulmonary oedema and pneumonia, before considering some of the other causes.

Signs and symptoms

Shortness of breath can manifest as a variety of signs and symptoms, due to the large number of possible causes. However, the most common frequent presentation is breathlessness and cough. Other common symptoms include cyanosis (blue discolouration often of fingers, toes or mouth due to an increase in the concentration of deoxygenated haemoglobin), chest pain, haemoptysis (coughing up blood), abnormal sputum and altered breathing patterns. If you have a fever associated with your breathlessness you may have an infection of the lungs (pneumonia). All problems with breathing whether of sudden onset or long-term and regardless of other symptoms should be considered seriously. Although many of the possible causes are harmless and easily treated, you should still see your doctor for a thorough medical evaluation.

What to expect at the doctor

When you attend a doctor’s surgery with shortness of breath, the doctor will need to ask several detailed questions to determine the likely cause of your breathing difficulties. The following information is very important:

  • The onset and duration of the breathlessness.
  • When the breathlessness occurs and any triggers.
  • Description of the episodes of breathlessness.
  • Effect of position on the degree of breathlessness.
  • Other symptoms such as wheezing, grunting, chest pain etc.
  • Past medical history- Paying particular attention to previous respiratory disease/surgery. Recent illnesses such as the cold, flu or other infections are also important.
  • Your current medications (including Oxygen) and any allergies.
  • The effect of the breathlessness on your life and daily activities. Your doctor will ask specific questions such as how far you can walk, how many flights or stairs you can climb and whether you can dress yourself without becoming breathless.
  • Smoking history as smoking is the major cause of respiratory disease.
  • Your occupational history as some jobs are associated with exposure to lung irritants (e.g. asbestos exposure).


Next your doctor will examine you in particular looking at your general colour, demeanour and breathing pattern. They will also thoroughly examine your chest (lungs), heart and upper airways. In most cases the examination findings, description of your breathlessness and knowledge of past respiratory problems is sufficient for your doctor to make a reasonably accurate diagnosis.

Tests and investigations

Sometimes your doctor will order some tests to find more information. The two most important initial investigations for breathlessness are chest x-ray and pulmonary function tests. These are ordered in all cases where the cause of breathlessness is doubtful. Other useful tests that may be used include:

  • Full blood picture mainly looking at the number of blood cells (to exclude anaemia) and any evidence of infection. Arterial blood gases are particularly useful to monitor the severity of disease and type of respiratory failure. For this a sample of blood is taken from the wrist (near pulse) via a syringe.
  • Pulse oximetry- This is a clip device placed on the toe or finger that measures oxygen saturation.
  • Cardiac investigations- ECG, echocardiography (ultrasound or picture of the heart) and cardiac enzymes may be ordered if the breathlessness is thought to be due to a heart problem.
  • Further imaging of the respiratory tract such as CT scan, MRI or ventilation/perfusion scanning (useful to exclude PE).
  • Lung/pleural biopsy- Taking a sample of lung tissue for examination under the microscope.

Treatment of breathlessness

Severe cases of breathlessness may require hospitalisation. Here it is likely you will receive oxygen and a several different medications aimed at treating your breathing difficulty. Treatment will vary between patients due to the numerous different causes for breathlessness. For example if you suffer from a heart problem, you will be treated with cardiovascular drugs that reduce blood pressure and the workload of the heart, and diuretics to drain the excess fluid off the lungs. If you are anaemic, treatment will focus on increasing your blood counts by an iron rich diet and iron supplements. Symptoms of dyspnoea will then tend to resolve with treatment.

General treatments Regardless of the cause of breathlessness, some general methods help to relieve symptoms in most patients. These include:

  • Morphine- Opioid medications given intravenously can help to slow down your breathing.
  • Benzodiazepines- Anti-anxiety drugs (given under the tongue) can help breathlessness by reducing your worry and calming you down. The above two drugs have been proven to be beneficial in clinical trials but should NOT be used in acute asthma attacks.
  • Oxygen- Most patients will benefit from oxygen by a mask or nasal prongs to help restore the low levels of oxygen in the blood. However high levels of oxygen can be hazardous in some patients with chronic breathlessness as it can reduce their drive to breathe.
  • Bronchodilators- Drugs such as ventolin and steroids are helpful in some patients who are breathless as they open up the airways.


Treatment at home There are several things you can do yourself to reduce your breathlessness. Your doctor will teach you breathing exercises such as slow, deep breathing, all the way to your abdomen. Relaxation methods are also useful. If your experience an episode of breathlessness at home make sure you sit upright in a supportive chair, try to breathe slowly and deeply and administer oxygen and opioids as prescribed by your doctor. If the shortness of breath does not resolve make sure you seek medical attention.


Breathlessness was last modified: March 2nd, 2021 by Team