Breathlessness

Question 1

What is meant by breathlessness?

Answer 1

Undue awareness of breathing or awareness of difficulty breathing

Question 2

Outline the physiology behind breathlessness

Answer 2

There are three main components: afferent signals, efferent signals and central information processing. If the central processing in the brain compares the afferent and efferent signals and there is a mismatch between the two, this leads to dyspnoea

Question 3

How does hypoxia lead to breathlessness?

Answer 3

low pO2 in the peripheral chemoreceptors

Question 4

How does metabolic acidosis lead to breathlessness?

Answer 4

Compensatory respiratory acidosis is achieved by stimulating hyperventilation

Question 5

How does exercise cause breathlessness?

Answer 5

Increases pCO2 levels to increase ventilation rate, but also acts via skeletal muscle afferents to the respiratory centres directly

Question 6

How does pregnancy cause breathlessness?

Answer 6

Progesterone directly affects the respiratory centre

Question 7

How does anxiety and pain cause breathlessness?

Answer 7

Impulses are sent from the hypothalamus to the respiratory centre

Question 8

How does pulmonary oedema cause breathlessness?

Answer 8

Stimulates J receptors in the lungs

Question 9

How does anaemia cause breathlessness?

Answer 9

pO2 is reduced, stimulating the respiratory centre to increase ventilation rate