Advantages of a narrow-range, medium molecular weight hydroxyethyl starch for volume maintenance in a porcine model of fecal peritonitis 
 OBJECTIVE: To compare the effectiveness of two hydroxyethyl starch solutions of different molecular weight ranges for volume maintenance in a porcine model of fecal peritonitis.
 DESIGN: Randomized prospective trial.
 SETTING: Laboratory investigation.
 SUBJECTS: Adolescent female pigs weighing approximately 30 kg.
 INTERVENTIONS: We compared diafiltered 6% pentastarch with 6% high molecular weight hetastarch for volume maintenance in a porcine model of fecal peritonitis.
 The number average molecular weight of pentastarch is higher than hetastarch, although the weight average molecular weight is lower, i.e., a narrow range of medium weight molecules.
 The infusion rate of each agent was adjusted to maintain baseline arterial Hct for less than or equal to 7 hr after instrumentation and induction of fecal peritonitis.
 MAIN OUTCOME MEASUREMENTS: The volume of fluid required to maintain arterial Hct was compared along with comparisons of hemodynamic and histologic responses associated with the two agents.
 RESULTS: Significantly less pentastarch was required to prevent hemoconcentration than hetastarch (109 +/- 22.8 vs.
 150 +/- 10.3 mL/kg; p less than .05) while hemodynamics, colloid osmotic pressure, and oxygen transport responses were similar.
 Capillary patency was greater (21.99 +/- 3.68 vs.
 10.09 +/- 1.17%; p less than .05) and mean alveolar capillary barrier thickness was less (2.36 +/- 0.13 vs.
 3.06 +/- 0.17 microns; p less than .05) with pentastarch than with hetastarch, as judged by electron microscopy.
 CONCLUSIONS: These data suggest that pentastarch is better retained in the circulation in capillary leak syndromes compared with hetastarch.
