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

Abstract

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 ...

Expression and Activity of the Ca²⁺-ATPase Enzyme in Human Neonatal Erythrocytes

“…Therefore, it is tempting to hypothesize that a portion of the PMCA molecules is inactive in immature infants. The cause of this relative inactivity is still to be elucidated, but perhaps some difference in the membrane properties could be at least partly responsible for the lower functionality of PMCA in preterm infants [23].…”

Blood Viscosity of the Neonate

“…The widely used filtration methods showed markedly reduced filterability of neonatal RBCs compared with those of adult cells due to the larger RBC volume in neonates. (13) (14) The pressure required to aspirate a single RBC completely into 3.3-mcm diameter pipettes also was higher for neonatal than for adult RBCs, but the aspiration pressure tended to be lower for neonatal RBCs when cells that had the same volume were compared. (12) Counterrotating devices based on the method of cone-plate viscometry apply well-defined shear forces and are influenced little by the cell volume.…”

Flow behavior of fetal, neonatal and adult RBCs in narrow (3–6 μm) capillaries – Calculation and experimental application

“…Immature fetuses and preterm infants have extremely large RBCs with volumes of up to 144 m 3 [10,27]. Due to the large RBC volume, neonatal RBCs are less filterable [21] than adult cells. This suggests impaired microcirculatory dynamics of neonatal RBCs in narrow capillaries.…”