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Breathlessness is the feeling of being out of breath. This is normal in healthy people who exert themselves physically, but can be a sign of illness if it occurs at a much lower level of exertion than expected.

The basis behind breathlessness is a balance. On the one hand, there is the body’s need for oxygen and its supply from the lungs. On the other hand, there is the level of waste gas (carbon dioxide, or CO2) that builds up in the body during exercise. Muscles working hard in exercise need more oxygen, and produce more CO2. Special cells in the main arteries detect the levels of oxygen and CO2, and these send signals to the brain and heart to increase breathing and pulse rates. This means that more blood is pumped around the body, picking up more CO2 from the muscles, to be released in the lungs to be breathed out, and picking up more oxygen there to deliver to the muscles.

In a healthy person, physical fitness will set the level when breathlessness is experienced. The more regular physical exercise a body is used to, the more efficient the muscles are. They use oxygen better and create less CO2, and the lungs and heart are more efficient, too. This is why a fit person can do more exercise without getting breathless than an unfit person can.

Certain illnesses can mimic the effects of unfitness, but at much lower levels of exertion than simple exercise, so that even crossing a room slowly can be a major effort. Breathlessness is said to be acute if it happens suddenly and severely, and chronic when it has built up gradually over a long time. The causes of these two types are generally different.

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Most cases of breathlessness occur because of a lack of fitness, often made worse by obesity. This kind of breathlessness can always be corrected by sustained, graded exercise and by losing excess weight.

Other common causes of sudden breathlessness include:

  • Asthma Pneumonia (chest infection)
  • Heart failure (inefficient pumping because of heart disease)
  • Sudden worsening of long-term Lung disease (e.g. Emphysema)
  • Hyperventilation (over breathing due to anxiety).

Common causes of chronic breathlessness include:

  • Obesity (overweight)
  • Chronic obstructive lung disease
  • Anaemia
  • Heart failure (inefficient pumping)
  • Asthma.

Breathlessness can sometimes be caused for other reasons. Smoking is a particularly important cause of breathlessness for several reasons. For instance, cigarette smoke contains carbon monoxide, a poisonous gas that combines so tightly with haemoglobin in the blood that the affected haemoglobin can’t perform its normal function.

One of the most important causes of severe breathlessness is left heart failure. When the left side of the heart is unable to clear the blood from the lungs quickly enough, fluid accumulation in the lungs causing breathlessness. This is the main symptom of left heart failure and it may occur on mild exertion or even when the affected person is at rest. There may be attacks of sudden breathlessness during the night.

Breathlessness can sometimes have a psychological cause as part of a panic reaction. The most common form of this is over-breathing known as hyperventilation. If this persists, so much carbon dioxide is breathed out that the blood becomes alkaline and its calcium level drops.

Anaemia, in which the oxygen-carrying capacity of the blood is reduced, will cause increased breathlessness on effort. And any loss of heart efficiency, from any cause, will interfere with the efficient circulation of the blood and cause breathlessness.

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Abnormal breathlessness may be a sign of some other medical problem and should be investigated by a doctor.

Breathlessness can be linked to so many different diseases that a diagnosis can really only be made after careful questioning and examination by a doctor. If the doctor needs more information to tell what is wrong, blood tests, a chest X-ray or maybe breathing tests will be advised.

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Treatment varies according to the cause of breathlessness.

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Breathlessness from lack of fitness can be reduced by regular exercise.

You can find out if your weight may be causing breathlessness by referring to a Body Mass Index (BMI). This works by taking into account your weight and height to find out if your body mass may be contributing to poor health. You can calculate your BMI by following these steps:

  • Work out your height in metres (for example, 1.6 metres), and multiply the figure by itself (for example 1.6 x 1.6 = 2.56)
  • Measure your weight in kilograms (for example, 65kg)
  • Divide your weight in kilograms by the answer to step 1 (for example, 65 divided by 2.56 = 25.39).

A healthy BMI is between 20 and 25. A BMI over 25 may mean that your health could suffer in the future.

Stopping smoking is the best things you can do to reduce common breathlessness and increase blood oxygen levels and lung efficiency.

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