The effect of iso-oncotic plasma substitutes: gelatine, dextran 40 (50 g/l) and the effect of Ringer's lactate on the plasma volume in healthy subjects.

82 healthy subjects undergoing Extra-corporeal Shock Wave Lithotripsy (ESWL) under epidural anesthesia were given 1000 ml of either gelatine (Geloplasme), dextran 40, 50 g/l (Isodex) or Ringer's lactate. The purpose of the study was to determine the efficacy of the three described solutions in respect to blood volume changes. A clear differentiation is only possible under absolutely defined physiological conditions and therefore in contrast to other studies, none of these patients was suffering from any shock syndrome or had any blood loss, so no capillary leakage or transcapillary refill problem was present. Plasma volume (PV), colloid oncotic pressure (COP) and hematocrit (Hct) were measured before and 15, 120 and 240 min. after infusion. PV increased both in the gelatine and dextran groups with a higher initial increase in the dextran group. COP increased after 15 min. and Hct decreased after 15 min. in the gelatine and dextran groups. With regard to absolute contraindications this study suggests that dextran 40 can be recommended as plasma substitute due to its higher initial increase in PV, its moderate duration of effect and its low incidence of anaphylactic reaction after a preceding infusion of 20 ml dextran Mw 1000 (Promiten).