The most all-inclusive meaning is “breathing discomfort, due to various sensations”. To most people, it implies struggling to breathe comfortably during normal activities.
Normal breathing is a complex action, requiring the interplay between:
- Brain centres controlling respiratory muscles,
- Sensors monitoring oxygen and carbon dioxide levels,
- Chest wall muscles,
- The diaphragm and the nerve controlling it,
- The airways, including the mouth and nose,
- The heart and circulatory system,
- Psychological factors like anxiety, and
- Kidney function influencing fluid load of the body.
Problems arising in any of these areas can lead to breathlessness, though the most common causes are:
- Heart problems
The failing heart (due to causes such as hypertension, coronary artery disease or cardiomyopathy), cannot pump enough blood into and out of the lungs to meet the body’s needs. Patients thus feel very short of breath, even with minimal exertion, sometimes even at rest. The lungs may have normal function, but they cannot do their work unless the heart is able to pump the blood through them. Patients with heart valve problems may also feel breathless: narrowed or leaking valves prevent blood being circulated effectively.
- Lung disease
Examples are chronic obstructive airways disease, emphysema and pulmonary fibrosis. Here, even if the heart is still working well, the lungs cannot function properly. This means that poorly oxygenated blood is being circulated.
- In asthma, both the heart and lungs may be working well, but the obstruction of the airways causes air to be trapped in the lungs, so the patient has difficulty breathing out, and feels almost suffocated.
- Cigarette smoking causes damage to lungs, but also causes some airways obstruction, and interferes with oxygen exchange. Smoking can thus cause breathlessness in three ways and lead to heart disease as well.
- Tumours can obstruct major airways, causing lung collapse and infection as well.
- Aspiration of fluids from the mouth (including vomit) can cause serious problems due to contamination of the lungs, and cause difficulty breathing.
- Pulmonary embolism is caused by a large clot from elsewhere in the body lodging in a major lung artery. This causes sudden breathlessness and is a medical emergency. Many small clots may lodge in smaller vessels over a long period, without causing dramatic symptoms, but leading eventually to constant breathlessness.
- Haemoglobinin red blood cells is required to carry oxygen in the blood. If there is a shortage of red cells (anaemia or excess blood loss) or an abnormality of haemoglobin, the patient may feel oxygen-deprived.
- Kidney disease can result in fluid overload to the heart, with corresponding breathlessness.
- Neurological disorders affecting respiratory muscles, like spinal cord problems or strokes, can also cause breathlessness.
- Anxiety and other psychological problems can cause a sensation of breathlessness.
- Nasal problems such as constant congestion (usually due to allergy), polyps, or a deviated septum may cause difficulty breathing normally.
Diagnosis and treatment
The patient often cannot describe the sensation, and may need to be questioned in depth about their medical history, and what now triggers, aggravates or improves symptoms. Important treatable organic causes must be identified and excluded.
Examination may reveal, for instance, a source of blood clot, obvious asthma or anaemia, and will help determine the best investigations.
Helpful tests are:
- Blood tests (such as for anaemia and kidney function),
- Chest X-rays or other scans (for lung disease and pulmonary embolism),
- Lung function tests to distinguish obstructive disease (like asthma) from restrictive disease (lung fibrosis), and
- Cardiology screening for heart function.
If specific disorders are identified, the patient may need referral to the appropriate specialist for long-term management.
Interim measures may include diuretics to decrease fluid overload, supplemental oxygen, drugs to open up airways for asthmatics, and anxiolytics for anxious patients.
(Dr AG Hall, Health24)