Filterability of erythrocytes and whole blood in preterm and full-term neonates and adults.

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 micron and filtration pressures of 1, 2, 5, and 10 cm H2O. The major results follow: At each of four filtration pressures, filtration rates of washed RBC were significantly (p less than 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 H2O. The filtration rates increased with decreasing MCV (r = -0.86). 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 H2O. The largest drop, 31% (p less than 0.05), was observed in the most immature infants, the smallest, 10% (p greater than 0.05), was seen in adults. At a pressure of 1 cm H2O the calculated mean transit time for RBC through the 5-micron pores was on an average 3.7 times longer in the smallest preterm infants than in the adults (19.7 +/- 7.8 and 5.3 +/- 1.4 ms, respectively), whereas the factor was only 2.7 at a pressure of 10 cm H2O (13 +/- 0.4 and 0.5 +/- 0.1 ms, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)