Plasma volume expansion of 5% albumin, 4% gelatin, 6% HES 130/0.4, and normal saline under increased microvascular permeability in the rat

Objective: To compare the colloids 5% albumin, 4% gelatin, and 6% HES 130/0.4 with one another and with normal saline regarding their plasma expanding effects at increased permeability and to compare the results with those from a previous study at normal permeability. Design and setting: Prospective controlled randomized laboratory study in a university research laboratory. Subjects: 48 adult male Sprague-Dawley rats. Interventions: Permeability was increased by an injection of 0.5 ml dextran 70 using the fact that dextran causes anaphylactic reaction in the rat. Plasma volume was determined (I-125 albumin tracer technique) after anesthesia, 1 h after dextran injection (before infusion for 10-15 min of 20 ml/kg bw of each of the colloids or 80 ml/kg saline), and 3 h later. Blood pressure, hematocrit, blood gases, and electrolytes were measured. CVP was measured in four rats. Measurements and results: Plasma volume was 41.1 +/- 1.9 ml/kg at baseline (n = 9), and 29.1 +/- 4.1 ml/kg (n = 35) 1 h after the dextran injection. Three hours after infusion of the plasma expander plasma volume had increased by 17.1 +/- 3.4 ml/kg in the albumin group, 7.9 +/- 3.6 ml/kg in the gelatin group, 7.4 +/- 4.4 ml/kg in the HES group, and 12.2 +/- 3.1 ml/kg in the saline group. It was unchanged in a control group given no solution (n = 7 for all groups). Conclusion: Albumin was a more effective plasma volume expander than gelatin or HES or saline (saline in 4 times larger volume). Gelatin and HES were equally effective. All solutions showed a smaller plasma expanding effect than observed in a previous study with normal permeability.