Plasma expanders are medical solutions administered intravenously to increase circulating plasma volume — the fluid portion of blood. They work by drawing fluid from tissues into the bloodstream and increasing intravascular volume. Different types of plasma expanders are used for various medical conditions where fluid loss or volume depletion is a concern.

Types of Plasma Expanders

Colloids:
Albumin: Human albumin is extracted from human blood plasma donations. It is highly effective at expanding intravascular volume. Albumin binds to water molecules and draws fluid from tissues into the circulation. It has a long intravascular retention time of around 18–20 days.

Hydroxyethyl Starches (HES): HES are semisynthetic colloid plasma volume substitutes. They are not derived from blood but instead are manufactured chemicals. Earlier generation HES products have been associated with potential kidney toxicity issues. Newer lower molecular weight balanced HES solutions are generally safer.

Gelatins: Gelatins are another semisynthetic colloid derived from collagen found in bovine or porcine skin or bone. They are increasingly being replaced by albumin or HES due to potential allergic reactions and shorter intravascular retention time.

Crystalloids:
Saline (0.9% NaCl): Normal saline or 0.9% sodium chloride solution is the most commonly used crystalloid fluid. It expands plasma volume by distributing throughout the extracellular fluid compartment. However, its effect is relatively short-lived as it easily leaks out of blood vessels.

Lactated Ringer’s Solution: Ringer’s lactate solution contains sodium, potassium, calcium and lactate ions. It is isotonic and considered a buffered version of saline. Its composition more closely matches that of plasma.

Uses of Plasma Expanders

Hypovolemia: Plasma Expander are used to restore intravascular volume and venous return in various causes of hypovolemia such as hemorrhage, dehydration, burns etc. Albumin and crystalloids are commonly used.

Preoperative Optimization: Plasma volume optimization prior to elective surgery reduces risks of hypotension during anesthesia and surgery by improving hemodynamics and organ perfusion. Colloids such as HES or albumin are preferred.

Dengue Shock Syndrome: Fluid resuscitation with crystalloids such as Ringer’s lactate solution forms the mainstay of early Dengue management. Later colloid use with albumin reduces complications from vascular leakage.

Severe Sepsis: Early goal-directed therapy with fluid resuscitation using crystalloids improves outcomes in severe sepsis and septic shock. Crystalloids are usually sufficient but colloids may be added if inadequate response.

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