Shortness of breath or dyspnoea is a subjective phenomenon where a person feels like running out of air and of not being able to breathe fast or deeply enough (1).
The American Thoracic Society (ATS) defines dyspnoea as:
“A subjective experience of breathing discomfort that consists of qualitatively distinct sensations that varies in intensity.” (2)
Physiological breathlessness is the sensation of increased work of breathing which the patient usually recognises as being normal for the current level of physical exertion.
Pathological breathlessness is experienced in situations which would not normally cause laboured breathing, e.g. climbing a few stairs or lying down.
Dyspnoea can be classified as
- acute - breathlessness which develops over minutes, hours, or days
- chronic - breathlessness which develops over weeks or months