Albumin in severe sepsis and septic shock

Albumin is the primary component of plasma proteins and accounts for 80% of colloid osmotic pressure. Its three domains determine the binding properties for several endogenous molecules and drugs. The cystein –SH residue accounts for its antioxidant properties and binding of nitric oxide, modulating its effect. The imidazole residues of 16 istidine molecules make albumin the most powerful buffer in the extravascular space. Plasma albumin concentration is a powerful dose-dependent predictor of mortality. Three relevant subsequent metanalysis, in sequence, found albumin administration harmful, neutral and advantageous. The blind, controlled and randomized SAFE study, performed in a large Intensive Care population, found similar outcomes in patient treated with 4% albumin or crystalloids for fluid resuscitation. The subgroup analysis showed a beneficial trend in septic patients treated with albumin and unfavourable trend in trauma patients with brain injury. Unfortunately albumin has been mainly tested only for its volume effects. For a given reached intravascular volume this effect must be similar for crystalloids, artificial colloids and albumin. Consequently, possible advantages of albumin should be due to a lower complication occurrence and/or to non-oncotic functions. Crystalloids may increase edema, weight and may cause metabolic acidosis. Artificial colloids lead to coagulation impairment. In contrast, albumin did not show these complications and showed antioxidant properties and buffer-effect on nitric oxide metabolism. The results obtained in the hepatorenal syndrome and the favourable trend in sepsis indirectly suggest that the albumin non-oncotic functions are relevant; however, ad hoc studies must specifically address this issue.