What is the Difference Between Crystalloids and Colloids?

Crystalloids and colloids are both used as plasma volume expanders to increase a depleted circulating volume, and they can be used separately or together to manage hemodynamic instability. However, there are some key differences between the two:

• Molecule size: Crystalloids have small molecules, while colloids have larger molecules.
• Cost: Crystalloids are generally less expensive than colloids.
• Immediate fluid resuscitation: Crystalloids provide immediate fluid resuscitation, but may increase edema.
• Swifter volume expansion: Colloids may provide swifter volume expansion in the intravascular space, but they may induce allergic reactions, blood clotting disorders, and kidney failure.
• Examples: Common crystalloid solutions include sodium chloride 0.9% (normal saline), compound sodium lactate solutions (Ringer's lactate solution, Hartmann's solution), and glucose solutions. Colloids can be man-made (e.g., starches, dextrans, or gelatins) or naturally occurring (e.g., albumin or fresh frozen plasma).
• Risk of anaphylaxis: Crystalloids carry little or no risk of anaphylaxis, while colloids do carry an increased risk of anaphylaxis.
• Vegetarian or vegan patients: Some colloid preparations contain gelatin, which may pose a problem for vegetarian or vegan patients.

In summary, crystalloids are typically less expensive, carry a lower risk of anaphylaxis, and are suitable for most patients with shock. However, they may increase edema. Colloids, on the other hand, may provide swifter volume expansion but carry a higher risk of complications and are more expensive.

Comparative Table: Crystalloids vs Colloids

here is a table summarizing the differences between crystalloids and colloids:

Crystalloids are aqueous solutions of salts or minerals that can be crystallized, with smaller particles (<1 nm) and high vascular permeability. Examples of crystalloids include salt, sugar, and urea. They are used as volume expanders in fluid resuscitation and for intravenous fluids.

Colloids are homogeneous non-crystalline substances containing large molecules or ultramicroscopic particles (1-200 nm). They have lower vascular permeability compared to crystalloids. Examples of colloids include starch, gelatin, and gum. Colloids are used for fluid resuscitation and maintaining high osmotic pressure in the blood.