Plasma expanders are substances or solutions that increase the volume of blood plasma in the circulatory system. These are high molecular weight substances; when we infuse them, they exert an osmotic pressure on the vascular compartment. They are widely used in conditions such as severe dehydration, shock, or certain medical procedures.
There are several types of plasma expanders, including:
1. Crystalloids:
These solutions contain electrolytes and water. Examples include Ringer’s lactate solution and saline solution (0.9% sodium chloride). They are readily available, cost-effective, and used in a wide range of other clinical conditions such as dehydration and shock.
2. Colloids:
These solutions have larger molecular sizes, such as starch and albumin. Compared to crystalloids, colloids stay in the bloodstream for a longer duration. In cases of hypovolemia, colloids are preferred over crystalloids. However, the use of colloids in patients is restricted due to potential side effects.
3. Blood Products:
Whole blood or blood components like packed red blood cells (PRBCs) or fresh frozen plasma (FFP) are also used as plasma expanders. These are mostly used when there is a need to replace both volume and specific blood components.
Properties of plasma expanders:
Plasma expanders should exert an oncotic pressure, remain in the circulatory system, be inert pharmacodynamically, not cause allergies, pyrogenic reactions, or antigenic responses. They should not interfere with blood compatibility, be stable, and be cost-effective.
Substances commonly employed are:
- Human albumin
- Dextran
- Polygeline
- Hetastarch
Uses
- used in severe burns
- Hypovolemic shock
- endotoxin shock
- severe trauma
- extensive tissue damage
- maintanance of blood volume
