Blood substitution

Blood substitution refers to the use of a blood substitute or blood surrogate to fulfill the function of blood in the body. This is often used in situations where a blood transfusion is not possible or not desirable. Blood substitutes can be divided into two main categories: oxygen carriers and volume expanders.

Oxygen Carriers

Oxygen carriers are designed to carry oxygen to the tissues in the same way that red blood cells do in natural blood. There are two main types of oxygen carriers: hemoglobin-based oxygen carriers (HBOCs) and perfluorocarbons (PFCs).

Hemoglobin-Based Oxygen Carriers

Hemoglobin-based oxygen carriers (HBOCs) are made from human or animal hemoglobin, the protein in red blood cells that carries oxygen. The hemoglobin is modified to prevent it from breaking down and to allow it to carry oxygen effectively.

Perfluorocarbons

Perfluorocarbons (PFCs) are synthetic compounds that can carry and release oxygen. They are not based on hemoglobin and do not have the same limitations as HBOCs.

Volume Expanders

Volume expanders are used to increase the volume of blood in the body. They do not carry oxygen but can help to maintain blood pressure and circulation. There are two main types of volume expanders: crystalloids and colloids.

Crystalloids

Crystalloids are solutions of minerals and other water-soluble molecules. They are cheap and easy to produce, but they do not stay in the bloodstream for long.

Colloids

Colloids contain larger, insoluble molecules that stay in the bloodstream for longer. They are more expensive to produce than crystalloids.

See Also

• Artificial blood
• Blood transfusion
• Hemoglobin
• Perfluorocarbon