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When man grows old … there is much gas within his thorax, resulting in panting and troubled breathing.
HUANG TI (2697–2597 BCE), THE YELLOW EMPEROR’S CLASSIC OF INTERNAL MEDICINE
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Dyspnoea is the subjective sensation of breathlessness that is excessive for any given level of physical activity. It is a cardinal symptom affecting the cardiopulmonary system and can be very difficult to evaluate. Appropriate breathlessness following activities such as running to catch a bus or climbing several flights of stairs is not abnormal but may be excessive due to obesity or lack of fitness.
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Key facts and checkpoints
Determination of the underlying cause of dyspnoea in a given patient is absolutely essential for effective management.
The main causes of dyspnoea are lung disease, heart disease, obesity and functional hyperventilation.1
The most common cause of dyspnoea encountered in family practice is airflow obstruction, which is the basic abnormality seen in chronic asthma and chronic obstructive pulmonary disease (COPD).2
Wheezing, which is a continuous musical or whistling noise, is an indication of airflow obstruction.
Some patients with asthma do not wheeze and some patients who wheeze do not have asthma.
Other important pulmonary causes include restrictive disease, such as fibrosis, collapse and pleural effusion.
Dyspnoea is not inevitable in lung cancer but occurs in about 60% of cases.3
Normal respiratory rate is 12–16 breaths/minute.
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It is important to emphasise that dyspnoea or breathlessness is a subjective sensation of the desire for increased respiratory effort and must be considered in relation to the patient’s lifestyle and individual tolerance of discomfort. It also depends on the age, physical fitness and physical expectations of the person. Patients may complain of tightness in the chest and this must be differentiated from angina.
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The American Thoracic Society guide for grades of dyspnoea is:
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Glossary of terms
Hyperpnoea An increased level of ventilation (e.g. during exertion).
Hyperventilation Overbreathing.
Orthopnoea Breathlessness lying down flat.
Paroxysmal nocturnal dyspnoea Inappropriate breathlessness causing waking from sleep.
Tachypnoea An increased rate of breathing.
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DIFFERENCE BETWEEN HEART AND LUNG CAUSES
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The distinguishing features between dyspnoea due to heart disease and to lung disease are presented in TABLE 49.1.
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