Normal human blood has a significant excess oxygen transport capability, only used in cases of great physical exertion.
The body detects the lower hemoglobin level, and compensatory mechanisms start up.
These adaptations are so effective that if only half of the red blood cells remain, oxygen delivery may still be about 75 percent of normal.
With enough blood loss, ultimately red blood cell levels drop too low for adequate tissue oxygenation, even if volume expanders maintain circulatory volume.
[citation needed] Normal saline (NS) is the commonly used term for a solution of 0.9% w/v of NaCl, about 300 mOsm/L.
It is very similar – though not identical – to Hartmann's solution, the ionic concentrations of which differ slightly.
[11] Common colloids used in the medical context include albumin and fresh frozen plasma.
[citation needed] Hydroxyethyl starch (HES/HAES, common trade names: Hespan, Voluven) is controversial.
[2][12] Gelofusine is a colloid volume expander which may be used as a blood plasma replacement when a significant amount of blood is lost due to extreme hemorrhagia, trauma, dehydration, or a similar event.