Cellular and membrane deformability of red blood cells in preterm infants with and without growth retardation

Membrane and whole red cell deformability are essential for effective blood flow, oxygen uptake and release. Whole cell deformability (rheoscope with shear stresses of 0.6–30 Pa) and membrane shear elastic modulus (flow channel) of red blood cells (RBC) were studied in appropriate and small for gestational age preterm infants (28–32 wk of gestation), in healthy full‐term neonates and in adults. No significant differences were found between the two groups of preterm infants. The preterm infants showed significantly increased RBC deformation in the rheoscope when compared to the full‐term neonates who, in turn, showed more RBC deformation than adults. Correspondingly, the membrane shear elastic modulus (i.e., the resistance to elastic membrane deformation) was lower in the preterm infants than in the full‐term neonates and lower in full‐term infants than in adults. Thus, both whole cell and membrane deformability appear to be increased in preterm infants. Improved RBC deformability may aid in the maintenance of adequate blood circulation in preterm infants in spite of low vascular pressures.