Rheology of Fetal and Maternal Blood

Reinhart, Walter H.; Danoff, Stuart; King, Robert G.; Chien, Shu

doi:10.1203/00006450-198501000-00038

Cited by 33 publications

(21 citation statements)

References 13 publications

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“…These results are not contradictory to the reports of decreased filterability of neonatal RBC (13)(14)(15)(16) because the impaired filterability may be due to small subpopulations of poorly deformable (Fig. 3) and of very large RBC (10,21) in neonatal blood.…”

Section: Discussioncontrasting

confidence: 56%

“…(Pediatr Res 20:93-96, 1986) Abbreviation RBC, red blood cell Studies on the deformability of RBC from full-term neonates gave conflicting results: neonatal and adult RBC show no difference in deformability when studied under defined shear forces by a rheoscope (10) or an ektacytometer (1 1). However, RBC from term neonates require higher suction pressures for complete aspiration into narrow micropipettes (12) and are less filterable (1 [3][4][5][6][7][8][9][10][11][12][13][14][15][16] than adult RBC.…”

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Erythrocyte Deformability in the Fetus, Preterm, and Term Neonate

et al. 1986

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ABSTRACT. Deformability of red blood cells (RBC) is an important determinant of microcirculation, of oxygen transport and release to the tissues, and of RBC life span. Deformability of RBC from five fetuses, 20 preterm infants, 20 term neonates, and 20 adults was determined by direct microscopic observation of RBC subjected to shear stresses of 6 to 85 dyn/cm2 using a counter-rotating rheoscope. There was no significant difference in deformability among RBC from the fetuses, the preterm and term neonates, and the adults at any shear stress. More than 95% of fetal, neonatal, and adult RBC were capable of tanktread motion. Compared to adults, the frequency distribution of RBC deformability was slightly broader in the fetuses and neonates because of the presence of more highly and poorly deformable RBC. The increased number of rigid RBC may contribute to the shortened life span of fetal RBC. (Pediatr Res 20:93-96, 1986) Abbreviation RBC, red blood cell Studies on the deformability of RBC from full-term neonates gave conflicting results: neonatal and adult RBC show no difference in deformability when studied under defined shear forces by a rheoscope (10) or an ektacytometer (1 1). However, RBC from term neonates require higher suction pressures for complete aspiration into narrow micropipettes (12) and are less filterable (1 3-16) than adult RBC.Little is known about the deformability of RBC from preterm infants. Buchan (15) studied filterability of RBC from preterm infants with gestational age of 34 to 37 wk and measured lower filtration rates in preterm infants compared to term neonates. Coulombel et al.(1 1) used an ektacytometer to determine deformability of RBC from 1 I neonates with 35 to 40 wk of gestational age. They did not find a correlation between RBC deformability and gestational age. Studies on the deformability of RBC from fetuses and small preterm infants do not appear to exist in the literature.In the present study, deformability of RBC from fetuses with 18 to 20 wk and from preterm and term neonates with 24 to 4 1 wk of gestational age were measured by means of a rheoscope. Our results indicate no significant difference in deformability between RBC from fetuses, preterm infants, term neonates, and adults.For the premature infant, maintenance of an adequate tissue MATERIALS AND METHODS oxygen supply is a major problem. Oxygen transport to the tissues is dependent on effective blood flow and on rapid oxygenThe deformability measurements were performed on blood release from the RBC. Both effective blood flow and the rate of samples from five fetuses (18-20 wk of gestation), 20 preterm oxygen uptake are influenced by the ability of RBC to deform infants, 20 term neonates, and 20 adults. The study was approved (i.e. to assume new shapes) (1-3). RBC deformability is essential by the Department of Pediatrics Human Subjects Research Comat four levels: 1) adaptation to higher shear forces in large vessels mittee. Informed consent was obtained from the mothers of the with rapid flow, thereby lowering bloo...

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Section: Discussioncontrasting

confidence: 56%

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Erythrocyte Deformability in the Fetus, Preterm, and Term Neonate

et al. 1986

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“…Hence, our results suggest that the hematocrit plays a major role as a flow resistance factor in neonatal skin capillaries. Despite the counteracting effects of a low plasma viscosity (4) and a low red cell aggregation tendency (21), the hematocrit is the principal factor producing the hyperviscosity commonly found in neonatal blood (3,4). The increase in capillary flow resistance may be due not only to the increase in the number of red cells but also to that in the larger size of the erythrocytes in the newborn, because the neonatal erythrocytes, although they have been reported to be equally deformable (22), have less in vitro capillary filterability than adult red cells (3,23).…”

Section: Discussionmentioning

confidence: 99%

“…Despite the counteracting effects of a low plasma viscosity (4) and a low red cell aggregation tendency (21), the hematocrit is the principal factor producing the hyperviscosity commonly found in neonatal blood (3,4). The increase in capillary flow resistance may be due not only to the increase in the number of red cells but also to that in the larger size of the erythrocytes in the newborn, because the neonatal erythrocytes, although they have been reported to be equally deformable (22), have less in vitro capillary filterability than adult red cells (3,23). Furthermore, the absence of rhythmic CBV changes in neonates indicates a less effective precapillary hematocrit control in neonatal skin microcirculation; periodic arteriolar contractions have been shown to substantially reduce the downstream skin capillary hematocrit in adults (17).…”

Section: Discussionmentioning

confidence: 99%

Capillary Blood Cell Velocity in Full-Term Infants as Determined in Skin by Videophotometric Microscopy

et al. 1988

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ABSTRACT. In order to study the neonatal microcirculation, the capillary hemodynamics in skin was investigated in 43 full-term infants 2-7 days after birth. The nailfold capillaries of the thumb were visualized by means of television microscopy and the capillary blood cell velocity (CBV) was videophotometrically quantified in 107 microvessels. The skin temperature, mean arterial blood pressure, and heel puncture hematocrit were measured simultaneously to evaluate any relation with the CBV. The mean CBV in all infants was 0.38 f 0.21 mm/s, with a range of 0.04 to 1.2 mm/s in individual capillaries. There was no correlation between CBV and skin temperature (27-33' C), mean arterial blood pressure (44-68 mm Hg), or postnatal age. However, a significant correlation was found between the log CBV and the skin prick hematocrit (r = -0.64, p < 0.001). It is concluded that the mean CBV during the 1st wk of life is not significantly different from the capillary velocity reported in adults. Normal variations in skin temperature and mean arterial blood pressure, as well as age differences 2-7 days after birth, do not significantly influence the neonatal skin capillary blood flow. However, the hematocrit is of major importance for skin capillary perfusion in the newborn infant. (Pediatr Res 23: 585-588,1988)

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“…(1 6) found no difference in filterability between RBC from term neonates and adults possibly because they used a very high filtration pressure of 34 cm H20. Two papers reported inverse relationships between filtration rate and MCV of RBC from term neonates and adults (9,15). Buchan (14) measured lower filtration rates in preterm infants with gestational age of 34-37 wk.…”

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Filterability of Erythrocytes and Whole Blood in Preterm and Full-Term Neonates and Adults

1986

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ABSTRACT. Filtration techniques are widely used to assess red blood cell (RBC) deformability and flow behavior of RBC in microcirculation. In this study filtration rates of RBC from 10 very low birth weight infants (24-30 wk gestation), 10 more mature preterm infants (31-36 wk gestation), 10 full-term neonates, and 10 adults were measured by using Nucleopore filters with pore diameters of 5 pm and filtration pressures of 1, 2,5, and 10 cm H20. The major results follow: 1) At each of four filtration pressures, filtration rates of washed RBC were significantly ( p < 0.05) lower in the preterm infants than in the term neonates who in turn showed lower values than adults. The differences among the four groups became less as the pressure was increased from 1 to 10 cm H20.2) The filtration rates increased with decreasing MCV (r = -0.86).3) The filter flow resistance (computed as ratio of filtration pressure and filter flow rate) decreased as the filtration pressure was raised from 1 to 10 cm H20. The largest drop, 31% ( p < 0.05), was observed in the most immature infants, the smallest, 10% (p > 0.05), was seen in adults. 4) At a pressure of 1 cm H 2 0 the calculated mean transit time for RBC through the 5-pm pores was on an average 3.7 times longer in the smallest preterm infants than in the adults (19.7 f 7.8 and 5.3 f 1.4 ms, respectively), whereas the factor was only 2.7 at a pressure of 10 cm H20 (13 t 0.4 and 0.5 f 0.1 ms, respectively). 5) Filtration rates of whole blood were determined at a pressure of 10 cm H20. These filtration rates were significantly (p < 0.05) less compared with filtration rates of washed RBC. The largest difference was observed in the smallest preterm infants (-77%), the smallest difference in adults (-41%). In conclusion, the filtration rate of RBC from preterm and term neonates may be lower than that of adults because of the larger size of neonatal RBC. At high pressure, filterability of neonatal RBC improves, possibly because of decreased resistance of neonatal RBC to elastic deformation. Filtration of whole blood from neonates may, in addition, be impaired because of the higher number of poorly deformable leukocytes and erythroblasts. (Pediatr Res 20:1269Res 20: -1273Res 20: , 1986 Abbreviations RBC, red blood cells PBS, phosphate buffered saline MCV, mean corpuscular volume Hyperviscosity in neonates is a frequent and potentially serious condition, which may cause circulatory failure and impaired microcirculation in various vital organs (1). Blood viscosity is mainly determined by hematocrit. However, decreased RBC deformability can also contribute to an increase in blood viscosity. At high hematocrit, the deformability of RBC is particularly crucial because blood viscosity exhibits a larger increase with increasing hematocrit when RBC deformability is impaired (2). Moreover, decreased RBC deformability may hinder the entry of 8-pm diameter RBC into capillaries with diameters of 3-4 pm (3), slow down oxygen uptake and release in capillaries (4), and block the passage through narrow ...

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Rheology of Fetal and Maternal Blood

Cited by 33 publications

References 13 publications

Erythrocyte Deformability in the Fetus, Preterm, and Term Neonate

Erythrocyte Deformability in the Fetus, Preterm, and Term Neonate

Capillary Blood Cell Velocity in Full-Term Infants as Determined in Skin by Videophotometric Microscopy

Filterability of Erythrocytes and Whole Blood in Preterm and Full-Term Neonates and Adults

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