Colloids are an option to address hypoproteinemia. They are large molecules that remain in the vascular space far longer than crystalloid fluids. Colloids can also mitigate hypotension.
Because of their large size, colloids exert drag on fluid molecules that either keep water and electrolytes within the vasculature, or draw water and electrolytes from the interstitium into the vasculature. Remember, a hypoVolemic patient needs more fluid in the Vasculature, whereas a dehydrated patient needs more fluid in the interstitium.
Natural colloids (e.g., albumin, plasma, blood) are best for this purpose. However, synthetic colloids are also useful to help maintain osmotic pressure and prevent fluid loss from circulation.
Synthetic colloids are solutions with high osmotic pressure due to the presence of high molecular weight compounds, usually starches or dextrans (e.g., Hetastarch®, Hextend®, Vet Starch®). Synthetic colloids are cheaper and more readily available than most natural colloids; however, they can exacerbate bleeding and potentiate kidney injury.
