Albumin and artificial colloids in fluid management: where does the clinical evidence of their utility stand?

Key questions remain unresolved regarding the advantages and limitations of colloids for fluid resuscitation despite extensive investigation. Elucidat ion of these questions has been slowed, in part, by uncertainty as to the o ptimal endpoints that should be monitored in assessing patient response to administered fluid. Colloids and crystalloids db not appear to differ notab ly in their effects on preload recruitable stroke volume or oxygen delivery . Limited evidence nevertheless suggests that colloids might promote greate r oxygen consumption than crystalloids. it remains unclear, in any case, to what extent such physiological parameters might be related to clinically r elevant outcomes such as morbidity and mortality. Recent randomized control led trial results indicate that, at least in certain forms of fluid imbalan ce, albumin is effective in significantly reducing morbidity and mortality. Much further investigation is needed, however, to determine the effects of colloid administration on clinically relevant outcomes in a broad range of critically ill patients. The ability of administered colloids to increase colloid osmotic pressure (COP) constitutes one mechanism by which colloids might reduce interstitial oedema and promote favourable patient outcomes. H owever, the applicability of this mechanism may be limited. due to the oper ation of compensatory mechanisms such as increased lymphatic drainage. Atte mpts to increase COP might also be less useful in states of increased vascu lar permeability such as acute respiratory distress syndrome, although this issue has by no means been settled by empirical data. Colloids are clearly more efficient than crystalloids in attaining resuscitation endpoints as j udged by the need for administration of far smaller fluid volumes. Among th e colloids, albumin offers several advantages compared with artificial coll oids, including less restrictive dose limitations, lower risk of impaired h aemostasis, absence of tissue deposition leading to severe prolonged prurit us, reduced incidence of anaphylactoid reactions, and ease of monitoring to prevent fluid overload. The cost of albumin, nevertheless, limits its usag e. Crystalloids currently serve as the first-line fluids in hypovolaemic pa tients. Colloids can be considered in patients with severe or acute shock o r hypovolaemia resulting from sudden plasma loss. Colloids may be combined with crystalloids to obviate administration of large crystalloid volumes. F urther clinical trials are needed to define the optimal role for colloids i n critically ill patients.