The term dyspnoea refers to sudden and severe shortness of breath, or difficulty in breathing. It is one of the most common reasons for visits to the accident and emergency department of the hospital.

Breathlessness may be normal after exercise or exertion. However, this usually resolves on rest and is not severe.

Breathlessness that comes on suddenly and unexpectedly may be a warning sign of an underlying medical condition. The problem may lie in the heart or in the lungs.

There are other problems that may also cause severe dyspnoea including panic attacks, anxiety, obesity etc.

Definitions of dyspnoea

Some of the definitions of dyspnoea include:-

• awareness of respiratory distress
• an uncomfortable sensation of breathing
• difficult, laboured, uncomfortable breathing
• the sensation of feeling breathlessness or experiencing air hunger

Causes of dyspnoea

• Lung disorders:-
  • Acute or sudden flare up of bronchial asthma. In this condition the airways are severely narrowed leading to obstruction and difficulty in adequate oxygenation of the lungs. There is additional presence of wheezing or noisy breathing and cough.
  • Lung infections like pneumonia
  • Emphysema
  • Chronic or acute bronchitis
  • Chronic obstructive lung disease
  • Obstruction of the upper airways – if something is stuck in the upper airways or wind pipes especially when choking; there may be sudden and severe dyspnoea and difficulty in breathing.
  • Lung collapse due to lung tear or injury
  • Bronchiectesis or damage to the lung tissues caused by infection.
  • Pneumothorax or air or pleural effusion or fluid being trapped in the spaces around the lungs making their expansion difficult.
  • Blockage of the blood vessels of the lungs with a ball of blood clot called pulmonary embolism. This is a life threatening condition.
  • Lung cancer and tumours of the lungs
• Heart disorders:-
  • Heart attacks may manifest as a sudden bout of dyspnoea along with chest pain.
  • Heart failure is the failure of the heart to pump out blood into the organs as well as into the lungs for purification. This leads to build-up of water inside the lungs, which makes breathing more difficult and leads to dyspnoea.
  • Arrythmias like atrial fibrillation or supraventricular tachycardia  may also lead to breathlessness.
• Other causes:-
  • Panic attacks – these result in rapid deep breaths called hyperventilation. After a few breaths this may result in severe breathlessness.
  • Diabetic ketoacidosis – here ketones get accumulated in blood leading to changes in the blood acid and base balance and this may lead to respiratory acidosis and dyspnoea.
  • Obesity may cause long term breathlessness due to inability of the lungs to expand to their full capacity.
  • Anemia of severe degrees may also lead to rapid and shallow breathing and dyspnoea.