Definition of "Shortness of breath"

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SOB (shortness of breath, aka dyspnea, respiratory distress) is feelings of distress associated with impaired breathing. It can cause the tripod position (i.e. sits or stands, leaning forward, supporting the upper body w/ hands on the knees or another surface).

WOB (work of breathing) is the effort required to inspire air into lungs, and accounts for 5% of total body oxygen consumption in normal resting state, but can increase dramatically during acute illness.

Air hunger is the feeling of having not enough oxygen.

Patient information

Puff-puff-puff-puff. What's happening to me ?!
It seems like you're short of breath !

Short of breath. And work of breathing. What's the difference?
Short of breath is that awful feeling you feel when you need to breathe, but can't. Work of breathing is the effort required to satisfy the need to breathe.

  • SOB is caused by a mismatch in the afferent signal (need for ventilation) and the efferent signal (not being matched by physical breathing)
  • Afferent neurons originate from the carotid bodies (chemoreceptors near fork of carotid artery, detecting partial pressure of oxygen in blood), medulla oblongata (inter alia, respiratory center), lungs, and chest wall
  • Efferent neurons innervate the respiratory muscles (diaphragm, intercostal muscles, abdominal muscles, etc)

Patient information

What exactly makes you short of breath?
Because there's a difference between 2 signals. The need to breathe. And the physical breath being taken.

How are these 2 things exactly signals?
The need to breathe is detected by receptors which detect oxygen, at the fork of the carotid artery, and elsewhere around the brain and lungs. The physical breath being taken is initiated by muscles of breathing.

  • Intensity of distinct sensations
  • Degree of distress involved
  • Burden/impact on ADL's

Patient information

Is being short of breath it? Anything more to it?
Yeah. You can be at different levels of shortness, of the breath, depending on your shortage of oxygen. It can also feel different, depending on what's causing it. And it can affect people's lives in different ways, because everybody's different.


Causes include:

  • Physiological, due to heavy exertion
  • Respiratory:
    • Asthma
    • Pneumonia → fever
    • Interstitial lung disease
    • COPD, emphysema
    • Bronchiolitis
    • Bronchitis
    • URTI, like diptheria, croup
    • Choking
    • Pulmonary embolism → can have fever
    • Lung cancer
    • Pulmonary fibrosis
    • Pneumothorax
    • Anaphylaxis, allergic reaction
  • Cardiac:
    • Cardiac ischemia
    • Congestive heart failure
  • Rib fracture, obesity, causing ineffective respiratory muscle action
  • Psychogenic causes, including:
    • Panic attacks
    • Anxiety
  • Poor ventilation, High altitudes with low oxygen levels

Patient information

What makes you short of breath?
Well first and foremost, it can be normal ! But if there is a true problem, the big ones we're concerned is something related to your breathing, or even heart! It could also be musculoskeletal, as in a fracture of your ribs. Or it could be psychological, or even something to do with the air itself...!

Let's start with your breathing. What about it?
Well just about anything that can affect your airways can cause problems. It could be asthma, pneumonia, COPD, bronchiolitis, choking, anaphylaxis. Really, just anything that can go wrong with your breathing, can be an issue.

How about your heart, what can cause shortness of breath there?
Heart failure, cardiac ischemia. Blood is required to deliver oxygen, so without blood... you're going to feel short of breath!

  • Hx, including:
    • Onset and progression
    • Relieving and exacerbating factors, including:
      • Rest or exertion. Quantify exercise tolerance, before getting SOB, including previous and current performance
      • Orthopnea or paroxysmal nocturnal dyspnea
    • Duration
    • Attempts to Tx SOB
    • Associated Sx, including:
      • Angina
      • Cough
      • Fever
      • Pleuritic chest pain

Patient information

How do you look further into, being short of breath?
You can ask questions. Like when it started, what's happened throughout time, how long it's gone on for. What makes it better or worse. For example, whether moving makes it worse, resting helps. Whether it's worse when the patient is lying down. Whether it wakes the person up from sleep. Any treatment they've tried.

What do you mean by associated symptoms?
It's like when someone buys a burger, asking whether they had fries with it. It's just stuff that commonly goes together. So for example chest pain, might suggest a heart attack. Cough, or pain when breathing harder, might suggest a breathing problem. Fever might suggest an infection.

  • Depends on underlying cause
See also

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Definition of Shortness of breath | Autoprac

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