Linderkamp O, Stadler A A, Zilow E P
Department of Pediatrics, University of Heidelberg, Germany.
Pediatr Res. 1992 Jul;32(1):97-102. doi: 10.1203/00006450-199207000-00019.
Blood viscosity is an important determinant of blood flow resistance. Because a substantial part of flow resistance arises in small arteries and arterioles with diameters of 100 microns and less, rheologic properties of blood from preterm infants (24 to 36 wk of gestation), full-term neonates, and adults were measured in glass tubes with diameters of 50, 100, and 500 microns for a wide range of adjusted feed hematocrits (0.15-0.70). At each of the feed hematocrits, blood viscosity decreased when going from a 500-microns tube to a 50-microns tube. The viscosity reduction increased with increasing hematocrit. Moreover, the viscosity reduction was more pronounced in the neonates than in the adults. At a hematocrit of 0.70, the viscosity reduction averaged 56% in preterm infants, 50% in full-term neonates, and 39% in adults (p less than 0.005). However, the viscosity reductions at a hematocrit of 0.30 were only 35, 29, and 19%, respectively (p less than 0.05). In all four groups, blood viscosity increased exponentially with increasing hematocrit. The steepness of the hematocrit-viscosity curves decreased with decreasing tube diameter and with decreasing maturity of the infants. Erythrocyte transport efficiency (hematocrit/blood viscosity) was calculated to estimate the optimal hematocrit (i.e. hematocrit with maximum erythrocyte transport). In 500-microns tubes, the optimal hematocrit was about 0.40 in all of the groups. In 100-microns tubes, the optimal hematocrit was 0.44 +/- 0.05 in the adults and 0.52 +/- 0.04 in the neonates (p less than 0.05). In 50-microns tubes, the optimal hematocrit was 0.51 +/- 0.04 in adults and 0.60 +/- 0.05 in the neonates.(ABSTRACT TRUNCATED AT 250 WORDS)
血液粘度是血流阻力的一个重要决定因素。由于相当一部分血流阻力产生于直径为100微米及以下的小动脉和微动脉，因此在直径为50、100和500微米的玻璃管中，针对不同调整后的喂食血细胞比容（0.15 - 0.70），测量了早产儿（妊娠24至36周）、足月儿和成年人的血液流变学特性。在每个喂食血细胞比容下，当从500微米的管子转到50微米的管子时，血液粘度都会降低。粘度降低幅度随血细胞比容增加而增大。此外，新生儿的粘度降低比成年人更明显。在血细胞比容为0.70时，早产儿的粘度降低平均为56%，足月儿为50%，成年人则为39%（p < 0.005）。然而，在血细胞比容为0.30时，粘度降低分别仅为35%、29%和19%（p < 0.05）。在所有四组中，血液粘度均随血细胞比容增加呈指数上升。血细胞比容 - 粘度曲线的斜率随管径减小和婴儿成熟度降低而减小。计算红细胞运输效率（血细胞比容/血液粘度）以估计最佳血细胞比容（即红细胞运输量最大时的血细胞比容）。在500微米的管子中，所有组的最佳血细胞比容约为0.40。在100微米的管子中，成年人的最佳血细胞比容为0.44±0.05，新生儿为0.52±0.04（p < 0.05）。在50微米的管子中，成年人的最佳血细胞比容为0.51±0.04，新生儿为0.60±0.05。（摘要截选至250字）
