Brun Jean-Frédéric, Boulot Pierre, Varlet-Marie Emmanuelle
UMRCNRS 9214-InsermU1046, «Physiopathologie & Médecine Expérimentale du Cœur et desMuscles - PHYMEDEXP», Unité d'Explorations Métaboliques (CERAMM), Université de Montpellier, Département de Physiologie Clinique, Hópital Lapeyronie CHU Montpellier, France.
Service de Gynécologie Obstétrique, Hópital Arnaud de Villeneuve, CHU Montpellier, France.
Clin Hemorheol Microcirc. 2016;64(4):789-797. doi: 10.3233/CH-168016.
Physiological studies on fetal blood in narrow glass tubes have suggested that fetal optimal hematocrit (hct) might be as high as 60%. A theoretical 'ideal' hct can also be predicted with a theoretical curve of hematocrit/viscosity (h/η) ratio vs hct constructed with Quemada's model. We used the database of one of our previous papers on fetal hemorheology to reinterpret its results with this concept. A series of 28 intrauterine cord punctures (between 19 and 33 weeks gestation) with doppler measurements of resistance in umbilical arteries was studied. The theoretical 'optimal hematocrit' was well correlated to actual (r = 0.857, p < 0.01) but systematically lower (Bland-Altman plot +12.1[8.52-15.7]) than the actual one. Umbilical artery resistance index is correlated with actual hematocrit (r = 0.407, p < 0.05), the discrepancy between ideal and actual (r = - 0.542, p < 0.05) but not predicted ideal hematocrit, suggesting that the discrepancy between ideal and actual may reflect an adaptative decrease aiming at reducing vascular resistance. These findings indicate that prediction of ideal hematocrit with Quemada's equation makes sense in fetal blood, and suggest that a 'viscoregulatory mechanism' maintains hematocrit below this theoretical value in order to avoid excess vascular resistance.
在细玻璃管中对胎儿血液进行的生理学研究表明，胎儿的最佳血细胞比容（hct）可能高达60%。也可以用基于凯马达模型构建的血细胞比容/粘度（h/η）比值与血细胞比容的理论曲线来预测理论上的“理想”血细胞比容。我们利用之前一篇关于胎儿血液流变学论文的数据库，用这一概念重新解释其结果。研究了一系列28例子宫内脐带穿刺（妊娠19至33周之间），同时用多普勒测量脐动脉阻力。理论上的“最佳血细胞比容”与实际值具有良好的相关性（r = 0.857，p < 0.01），但系统地低于实际值（布兰德-奥特曼图显示为+12.1[8.52 - 15.7]）。脐动脉阻力指数与实际血细胞比容相关（r = 0.407，p < 0.05），与理想值和实际值之间的差异相关（r = - 0.542，p < 0.05），但与预测的理想血细胞比容无关，这表明理想值与实际值之间的差异可能反映了一种旨在降低血管阻力的适应性降低。这些发现表明，用凯马达方程预测理想血细胞比容在胎儿血液中是有意义的，并表明一种“粘度调节机制”将血细胞比容维持在该理论值以下，以避免血管阻力过大。
