Colloids

Iso-oncotic human serum albumin colloid

Heat-treated, pasteurized human serum albumin in 0.9% NaCl at 5% concentration. Iso-oncotic with normal plasma — expands intravascular volume approximately 1:1 with infused volume by maintaining colloid oncotic pressure.

Hyper-oncotic human serum albumin colloid

5× more concentrated than 5% albumin. Hyper-oncotic — pulls interstitial fluid into the intravascular space. 100 mL of 25% albumin can expand plasma volume by 400–500 mL by drawing fluid across the capillary membrane.

Synthetic colloid — modified amylopectin

Polymer of hydroxyethylated glucose units derived from waxy maize. Provides oncotic volume expansion similar to albumin. Higher-molecular-weight / higher-substitution products (Hespan) cause more renal dysfunction than lower-substitution products (Voluven), but both have been shown harmful in critical illness.