| Autor: |
Danoff, S J, Reinhart, W H, Usami, S, Chien, S, James, L S |
| Zdroj: |
Pediatric Research; April 1984, Vol. 18 Issue: 1, Number 1 Supplement 4 p318A-318A, 1p |
| Abstrakt: |
Whole blood viscosity is determined by hematocrit, plasma viscosity, red cell deformation, and red cell aggregation. Hyperviscosity is thought to be prevalent in neonates due to polycythemia and diminished red cell deformation. Recent studies in animals and full term infants have demonstrated decreased blood viscosity related to lower plasma viscosity. Extending these observations, we examined hemorheologic paramters in a group of low birth weight neonates (500-1500gms) compared to pregnant and nonpregnant females and full term neonates measuring whole blood viscosity, plasma viscosity, red cell deformation, and red cell aggregation. A new capillary microviscometer based on Poiseuille's law was developed, providing viscosity measurements on 0.2ml samples. Blood from low birth weight and full term neonates is significantly hypoviscous when compared to that of adults. This hypoviscosity is related to low plasma viscosity due to lower plasma proteins and fibrinogen in neonates. Assessment of red cell deformation by filtration through 2.6um and 6.9um pores revealed that red cell deformation is comparable in neonates and adults in the 6.9um pore, but significantly lower when the larger neonatel red cell filtered through the 2.6um pore. The full term neonate, in spite of polycythemia and larger red cells, is hypoviscous compared to adults with the same Hct. The low birth weight infant is even more hypoviscous than adults and full term infants due to lower plasma viscosity, proteins and Hct. This could be considered another adaptive mechanism protecting the neonate during its transition from the intrauterine to extrauterine environment. |
| Databáze: |
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