Several albumin solutions are available for volume expansion. Hyper-oncotic solutions (≥ 20%) are more effective than hypo-oncotic (≤ 5%) as they recruit endogenous extracellular fluid into blood vessels rather than adding volume. The latter may cause volume overload, with several associated complications. This systematic review aimed to evaluate evidence on the efficacy and safety of hyper-oncotic vs. hypo-oncotic albumin solutions across different clinical settings. The review was conducted according to PRISMA guidelines. Ninety articles were retained (58 randomized controlled trials). Four studies directly compared albumin solutions. SWIPE showed that cumulative fluid balance at 48 h was significantly lower with 20% vs. 5% albumin (mean − 576 mL; P = 0.01). Twenty percent albumin was also associated with decreased chloride load vs. 4% albumin in critically ill patients. All 10 pre-/intraoperative studies evaluated 4–5% solutions; 14 studies evaluated 4–5% albumin in postoperative patients. Renal injury was reported in some studies; however, hydroxyethyl starch was associated with higher incidence vs. albumin. Importantly, 20% albumin preserved cumulative organ function in liver transplantation, and 25% albumin was more beneficial than saline in cardiac surgery patients. Thirty-two studies were performed in critically ill patients. Several studies reported increased risk of positive fluid balance and chloride load with hypo-oncotic albumin, whereas multiple benefits were associated with 20% albumin, including improved endothelial function and perfusion. Of 18 pediatric studies that evaluated ≤ 10% albumin, benefits such as correction of hypotension and improved cardiac output were noted. In conclusion, hyper-oncotic albumin solutions should be more routinely used to avoid potential risks associated with hypo-oncotic solutions.
