dyspnea
Meaning of dyspnea: When it comes on and in what position narrows the cause far faster than the sensation itself ever does.
Definition of dyspnea
Dyspnea is the experience of breathing that feels difficult, laborious or not enough, usually described as shortness of breath, chest tightness or a hunger for air. It is something a person reports rather than something an instrument measures, and it can arise from the lungs, the heart, the blood, the muscles, body chemistry or emotional state.
How dyspnea is built
- dys- Prefix · Greek difficult, painful, disordered
- -pnea Suffix · Greek breathing
A medical term is read from its ending backwards: the suffix first, then the prefix, then the root. See all 223 word parts.
What produces the sensation?
Breathing is normally automatic and unnoticed. Dyspnea appears when the brain's demand for breathing and the body's ability to deliver it stop matching. Three streams of information feed that comparison: sensors in blood vessels reporting carbon dioxide and oxygen, stretch sensors in the lungs and chest wall reporting how much movement actually occurred, and a copy of the command the brain sent to the breathing muscles. When the command is large and the resulting movement is small, the mismatch is registered as effort or air hunger. This is why the feeling can be intense while an oxygen reading looks normal, and why someone with very low oxygen may feel little at all.
What causes it?
| System | Examples |
|---|---|
| Airways and lungs | Asthma, chronic obstructive pulmonary disease, pneumonia, a clot in the lung, collapsed lung, scarring of lung tissue, fluid around the lung |
| Heart | Heart failure, a heart attack, an abnormal rhythm, valve disease, fluid around the heart |
| Blood and body chemistry | Anemia, and states of metabolic acidosis in which breathing speeds up to blow off acid |
| Muscles and nerves | Weakness of the diaphragm or chest wall muscles from neuromuscular disease |
| Other | Panic and anxiety, deconditioning, obesity, advanced pregnancy, high altitude |
What does the pattern tell?
Timing and posture carry most of the information. Breathlessness that appears over seconds suggests a sudden mechanical or vascular event, over hours an infection or a flare of airway disease, and over months an accumulating problem in the respiratory system or the heart. Difficulty that arrives on lying flat and eases on sitting up is called orthopnea; waking from sleep gasping, an hour or two after going to bed, is a related pattern. Both point toward fluid redistributing when the body is horizontal. Breathlessness only on exertion, and the amount of exertion needed to bring it on, is the usual way severity is tracked, and its measurement over time is a standard part of respiratory therapy assessment.
Also known as
Used in a sentence
The patient experienced dyspnea while climbing stairs.
Good to know
Dyspnea is a reported sensation rather than a measurement, and its intensity does not track reliably with oxygen levels, so it can be severe when readings are normal and slight when they are not.
Word origin
Where “dyspnea” comes from
From Greek dys-, meaning difficult, and pnoe, meaning breathing.