What Determines Oxygen Delivery?

The pathophysiology underlying shock varies enormously from cause to cause.

Take a moment to think about the key factors that determine global oxygen delivery i.e. the amount of oxygen leaving the left ventricle every minute [7,9].

Global oxygen delivery is determined by cardiac output (CO) and arterial oxygen content (CaO2).

CO is heart rate (HR) x stroke volume (SV).

The vast majority of oxygen carried in the blood is bound to haemoglobin. Only a tiny proportion is in solution (measured by PaO2). So the main determinants of arterial oxygen content are oxygen saturation and haemoglobin concentration.

For practical purposes global oxygen delivery can be calculated as:

(HR x SV) x [Hb]g/dl x 10 x 1.34 x sO2 ml/l


  • The 10 is to convert g/dl of Hb to g/l
  • The 1.34 represents the amount of oxygen (in ml) carried by one gram of 100% saturated haemoglobin