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...
TIVITY (A) JlND tcPo z OF VERY PREl-'ATURE INFIlNTS NOcker M, GOntner M, KP unIversIty ChIldren's Hospital Munlch/FRG Nine Infants of 26-29 w pt.'GA (BW 780-1270 g)were exposed to the rrother's voice fran a tape recorder via loudspeaker (at"'70 dB) 5x30' a 'day between 29 and 38 w PI'GA(for)(8.2 w) after conditions were .st.abt l lzed, At 2 days each week the babies' behaviour (applying an A rating frnm 1 =qulet sleep to 6 = crying) and tcPo 2 was recorded every 10"for 1 hour, once wlthcut and once with m's voice (30' after 30'''base line"). Results: A ano tcPo z varied significantly during tests In percent of "blanc" observations and wIth m's voice (table), but In the latter case significantly rrore often A Tevel fell (.6)(':'.5 po lrrt.s) P<.00l) and tcPo z level rose kPaj P<.005) during stlrrulatlon. Means of 15'perlods of A and tcPo 2 correlated Inversely (r =-.55). Conclusions: 1) Premature Infants react to acoustic stlrrull after 28 w pt.'GA, If hearing Is unlrrpalred and/or stronger stlrrull do not Interfere. 2) M's voice can tranquilize the baby Increasingly reproducible causing a transient Increase of tcPo 2 • 3) Recorded m's Changes (within 1.hl of 1Ict:iYity td'o voIce may serve as a (vanance analYS1S)
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