What is oxygen delivery?

When you're resting blood typically takes 3/4 second to pass through the capillaries in the lungs. During this time it picks up as much oxygen as it can. This oxygenated blood then flows back to the left side of the heart which pumps it round the body.

Oxygen delivery is the amount of oxygen 'delivered' to your body by your lungs and cardiovascular system. For sufficient oxygen to be delivered to your body a number of things all have to work well:

• Ventilation moving air into your lungs
• External respiration, moving the oxygen from alveoli into your blood
• Enough normal haemoglobin to carry the oxygen
• An efficiently working cardiovascular system to transport the blood round your body

However the oxygen is still not at your body's cells where it is needed.