Figure 1

Carboxyhemoglobin (COHb) versus oxygen delivery capacity of the blood and increased cardiac output required to deliver the same amount of oxygen. (a) This is shown with a linear progression in COHb. (b) In the more likely scenario, there is continuous exposure to COHb and the rate of uptake of COHb is roughly proportional to cardiac output, resulting in a very rapid deterioration to life-threatening poisoning, after a relatively long mild poisoning stage. CO, carbon monoxide; O₂, oxygen.