Two prospective non-randomised interventional case series were conducted consecutively at a single university hospital mixed intensive care unit, in patients with severe sepsis and acute respiratory distress syndrome. The first series describes the administration of 200 ml of 20% human albumin solution over 120 s in 13 patients, examining the hypothesis that raising plasma albumin should improve oxygenation. The second series describes the effect of administering 30 mg of furosemide intravenously along with the albumin in 15 patients, exploring whether this would produce more sustained improvement in oxygenation than albumin only. Oxygenation and haemodynamic parameters were measured for 4 h, during the period of peak oncotic effect. Hyperoncotic albumin given alone or with furosemide produced only transient improvement in oxygenation and haemodynamics, which was statistically significant only in the patients given albumin alone. Although the plasma albumin remained significantly elevated at 4 h in both series, no sustained improvement in oxygenation was seen.