Changes in circulating red cell volume during the first 6 weeks of life in very-low-birth-weight infants

Abstract

ArticlesClinical Investigation nature publishing group background: Little is known about the change in circulating red cell volume (RCV) of very-low-birth-weight (VLBW) infants during the first weeks of life. Methods: RCV was measured during the first 5 d in 35 VLBW infants using chromium-51 labeling of the infants' red blood cells (RBCs). RCV was measured again at 6 wk of age in 12 infants, and the volumes of RBCs lost by phlebotomy and those gained by transfusion were recorded between the RCV measurements. In six infants, the volume of waste blood on materials contaminated with blood during phlebotomy, which would usually be discarded, was measured by radioactive counting. results: The mean RCV in the first several days of life was 39.6 ml (35.7 ml/kg; range: 20.1-58.7 ml/kg). Of the 12 infants whose RCV was measured twice, all but one had a decrease in absolute RCV. The mean RCV initially and at 6 wk were 37.3 and 26.6 ml, respectively. The mean volume of RBCs lost through phlebotomy was 29.2 ml, and the mean volume of RBCs given by transfusion was 34.5 ml. conclusion: During the first 6 wk of life, when the anemia of prematurity is evolving, the RCV falls despite complete replacement of RBCs lost by diagnostic phlebotomy with transfused RBCs.

Measurement of Posttransfusion Red Cell Survival With the Biotin Label

“…Because flow cytometric enumeration requires very small blood volumes (~200,000 RBC/0.05 μL of blood), quantification of BioRBC enrichment of single blood samples used in RCV and RCS studies can be performed on 15 μL of blood. In contrast, the 51 Cr method requires 5–10 mL of blood unless special microsampling and counting techniques are applied [48]. The biotinylation reagents are readily available from commercial sources at modest cost, and flow cytometers with adequate technical characteristics are readily available in most medical centers and hospital laboratories.…”

Ecofisiologia da migração e reprodução de Elaenia chiriquensis (Aves, Tyrannidae) no Cerrado

“…A relação entre massa corporal e o volume sanguíneo é bem conhecida para seres humanos saudáveis e largamente utilizada em cálculos hematológicos no tratamento de doenças (Bell et al 2014). Cerca de 7 a 8,5% do massa corporal dos animais corresponde ao seu volume sanguíneo (Prosser & Weinstein 1950), sendo que para animais de pequeno porte o hematócrito é correlacionado com tamanho corporal e geralmente apresenta valores altos, devido ao maior trabalho cardiorrespiratório e menor superfície corpórea (Sealander 1964).…”