Tachypnoea is the medical term for an abnormally fast breathing rate. In adults, a normal resting respiratory rate is 12 to 20 breaths per minute; tachypnoea is generally defined as a rate above 20 breaths per minute at rest. It is one of the earliest and most sensitive indicators of physiological deterioration and is a key parameter in the National Early Warning Score (NEWS2).
Tachypnoea occurs as a compensatory response to conditions that disrupt normal gas exchange or increase metabolic demand. Common causes include respiratory conditions (pneumonia, pulmonary embolism, asthma, COPD, pleural effusion), cardiac causes (heart failure with pulmonary oedema, cardiac tamponade), metabolic causes (diabetic ketoacidosis, sepsis, severe anaemia), and pain or anxiety. After cardiac arrest, tachypnoea may indicate inadequate ventilation, pulmonary complications, or physiological stress.
Tachypnoea is distinct from dyspnoea (subjective difficulty breathing) and from hyperpnoea (deep breathing where rate may be normal). All three can occur together. Rapid breathing increases the rate at which carbon dioxide is exhaled; when very fast and deep, it can lead to hypocapnia (low CO2) and respiratory alkalosis, causing light-headedness and tingling in the hands and feet.
A resting adult respiratory rate above 25 breaths per minute is a significant clinical warning sign requiring urgent assessment. In the intensive care setting, mechanical ventilation is used to correct inadequate breathing in patients who cannot maintain adequate gas exchange independently.
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