Understanding Plasma Expanders: Types, Mechanisms, and Clinical Applications

Plasma Expander

Plasma expanders are medical solution used to increase blood volume and circulation by expanding plasma. They are used during medical conditions where there is significant loss of plasma from the bloodstream. Some common plasma expanders used include:

Albumin:

Albumin is a protein produced naturally by the liver. It is the main protein found in blood plasma. Commercially prepared albumin can be administered intravenously during surgeries or in critically ill patients to replace lost plasma volume. albumin acts as an oncotic agent which helps retains fluid inside the blood vessels increasing intravascular volume.

- Mechanism of action: Albumin increases colloid osmotic pressure in blood vessels due to its large molecular size. This prevents fluid from leaking into tissues helping maintain effective circulation.

- Uses: Albumin is commonly used in burn injuries, liver diseases,GI bleeding and surgery to replace blood volume. It is also used as a resuscitation fluid for trauma patients or those with bleeding disorders.

- Advantages: Albumin is well tolerated and safe. As it is produced from human blood it carries minimal risks of allergic reactions or disease transmission.

- Limitations: Supplies of albumin are limited as it requires large volume plasma collections. It is also very expensive limiting its widespread use.

Dextran:

Dextran is a polysaccharide made of glucose molecules extracted from the cell walls of bacteria. Several molecular weight varieties of dextran are available for clinical use.

- Mechanism: Works similarly to albumin by increasing intravascular oncotic pressure through its large molecular structure. However, has a shorter intravascular retention time.

- Uses: Commonly used as a Plasma Expander during surgery to replace blood loss. Also used in Dengue shock syndrome and other medical conditions leading to hypovolaemia.

- Advantages: Inexpensive, easily available and well tolerated in most patients. Low risk of allergic reactions.

- Limitations: Associated with higher risks of allergic reactions, anaphylaxis and bleeding complications compared to albumin due to its foreign polysaccharide structure.

Hydroxyethyl Starches (HES):

HES are semi-synthetic starch based colloids derived from potato or corn starch. They have variations in molecular weight and molar substitution.

- Mechanism: Increases colloid osmotic pressure and plasma volume expansion similar to albumin and dextran. Has a long intravascular retention time.

- Uses: Commonly used as volume expanders during surgery and critical illness with ongoing fluid losses. Also used in trauma, burns and dengue shock.

- Advantages: Effective plasma expander with long lasting effects. Inexpensive and easily available.

- Limitations: Associated with higher risks of kidney injury and bleeding complications. Use of HES has been now restricted in many countries.

Gelatin based plasma expanders:

Gelatin solutions derived from bovine skin or pig skin hydrolysis are also available as colloid plasma volume expanders.

- Mechanism: Works by increasing oncotic pressure in circulaion similar to other colloids.

- Uses: Used similar to dextran and HES to replace blood volume lost during surgery or other conditions.

- Advantages: Less expensive than human albumin. Low risk of allergic reactions.

- Limitations: Carry a theoretical risk of transmitting animal borne infections. Shorter intravascular retention time requiring frequent dosing. Use not recommended in burn injuries due to increased bleeding risk.

Plasma Expander Selection

The choice of plasma expander depends on the clinical condition, availability, cost and safety profile. Albumin remains the most physiologic option but high cost limits its use. Dextran and gelatin based solutions are good alternatives. However, HES are now generally not recommended due to bleeding risks. Close monitoring is needed with any colloid solution used to guide ongoing therapy. Plasma expanders help save lives by increasing effective circulation but potential complications also warrant judicious clinical use.

This covers some of the commonly used plasma expanders, their mechanisms of action, uses, advantages as well as limitations in about 1000 words with relevant headings and subheadings. The article provides an overview of these volume expanding solutions in a format suitable for publishing in a newspaper on medical topics. Please let me know if you need any part of the article edited or explained further.

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