Effects of hetastarch and mannitol on prolonging survival in stable hypothermia in rats.
In rats, prolonged stable hypothermia ( approximately 24 h at body temperature of 19 degrees C) is characterized by a time-dependent increase in hematocrit, plasma osmolality, and red blood cell fragility and a decrease in plasma volume. These changes impede tissue microcirculation and could limit survival. As a countermeasure, we used plasma volume expanders of both long (hetastarch)- and short-lasting (mannitol) characteristics to improve microcirculation and hopefully hypothermia survival. Infusion of 6% hetastarch at hour 3 in hypothermia significantly (P < 0.05) enhanced survival over saline control (33.5 vs. 23.8 h); a significant delay in the increases of hematocrit and cell fragility was also observed compared with those in saline controls. Treating the animal with 6% hetastarch at hour 20 during hypothermia caused a similar but less-effective improvement in survival. In contrast, treating the rats with 6% mannitol at hour 3 or 20 during hypothermia failed to enhance survival over saline control, although transient improvement in plasma volume was observed. Our results indicate that by using a long-lasting volume expander, which tends to better maintain plasma volume and rheological parameters governing microcirculation than does saline or a short-lasting volume expander, hypothermia survival can be significantly improved.
Lee
T F
TF
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9.
Westly
J
J
Wang
L C
LC
D000818:Animals; D001810:Blood Volume; D004234:Diuretics, Osmotic / Q000494:pharmacology*; D004907:Erythrocyte Deformability; D006400:Hematocrit; D006895:Hydroxyethyl Starch Derivatives / Q000494:pharmacology*; D007035:Hypothermia / Q000188:drug therapy* / Q000401:mortality; D008297:Male; D008353:Mannitol / Q000494:pharmacology*; D008833:Microcirculation / Q000502:physiology; D009994:Osmolar Concentration; D010952:Plasma Substitutes / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012965:Sodium Chloride / Q000494:pharmacology; D016019:Survival Analysis
D004234:Diuretics, Osmotic; D006895:Hydroxyethyl Starch Derivatives; D010952:Plasma Substitutes; D008353:Mannitol; D012965:Sodium Chloride