What best describes colloids in IV fluid therapy?

Colloids in IV fluid therapy are characterized by their larger particle size, which causes them to remain suspended in the solution and prevents them from easily traversing semi-permeable membranes. This property allows colloids to exert oncotic pressure, drawing fluid into the intravascular space and thereby helping to maintain blood volume and circulation.

The effectiveness of colloids is primarily due to their composition, which includes substances like gelatin, hydroxyethyl starch, or dextrans. These large molecules increase the osmotic pressure within the blood vessels, making colloids effective in treating conditions such as hypovolemia or when there is a need to quickly restore blood volume.

Other characteristics mentioned in the response options do not accurately reflect the nature of colloids. While colloids can influence osmotic balance, they do not directly maintain osmotic balance within cells, as that is primarily the function of electrolytes and small solutes. Their primary use is not for hydration alone, as they focus more on volume expansion. Furthermore, while some colloid solutions can be isotonic, not all colloids are isotonic; their classification is based more on particle size than on their tonicity.