title: Whole blood viscosity of preterm infants - differences to term neonates.
abstract: Determination of shear stresses at given shear rates with the LS 300 allows approximation of flow curves by mathematical models and to calculate viscosities of non-Newtonian fluids across the entire physiological shear range. Particular in preterm neonates, which in comparison to term neonates and adults have a substantially lower mean arterial blood pressure (MAP), rheological blood properties play a decisive role to maintain the perfusion. Whole blood viscosity was measured in umbilical cord blood taken from 34 preterm neonates using the LS 300 viscometer. In addition aggregation index, plasma viscosity, hematocrit and red blood cell (RBC) deformability was determined. The highest quality of approximation of the flow curve of whole blood was achieved by the method of Ostwald. Shear stresses of whole blood of preterm neonates were significantly lower compared to term neonates at similar shear rates (velocity range 6.16 s-1-50 s-1). With hematocrit calculated to 0.40 the related exponent (n) of the viscosity of preterm neonates (by Ostwald) showed a significant lower exponent (n) (0.71 ± 0.07) than term neonates (0.76 ± 0.06). The highest quality of approximation of the flow curve of plasma was achieved with the model of Ostwald in preterm neonates as well as in term neonates. The viscosity of plasma determined by Newton was lower for preterm neonates (0.89 ± 0.19) than for term neonates (1.04 ± 0.16). Concurrent to term neonates the whole blood of preterm neonates showed a very low aggregation index (term neonates 2.97 ± 2.10; preterm neonates 2.37 ± 1.32) and preterm neonates showed higher RBC deformability than term neonates. Because of the physiologically lower MAP and the particular viscous properties of neonatal blood special attention should be given when treating neonates with conventional blood products derived from adult donors.
authors.affiliation: Clinic of Neonatology, Department of Pediatrics, University of Heidelberg, Im Neuenheimer Feld, Heidelberg, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Kuss
authors.affiliation: Clinic of Neonatology, Department of Pediatrics, University of Heidelberg, Im Neuenheimer Feld, Heidelberg, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Bauknecht
authors.affiliation: Clinic of Neonatology, Department of Pediatrics, University of Heidelberg, Im Neuenheimer Feld, Heidelberg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Felbinger
authors.affiliation: Technical Expert's Bureau for Rheology, Am Seeberg 14a, Bad Homburg vor der Höhe, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Gehm
authors.affiliation: Technical Expert's Bureau for Rheology, Am Seeberg 14a, Bad Homburg vor der Höhe, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Gehm
authors.affiliation: Clinic of Neonatology, Department of Pediatrics, University of Heidelberg, Im Neuenheimer Feld, Heidelberg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Pöschl
authors.affiliation: Clinic of Neonatology, Department of Pediatrics, University of Heidelberg, Im Neuenheimer Feld, Heidelberg, Germany.|Clinic of Pediatrics, SLK-Kliniken Heilbronn GmbH, Heilbronn, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Ruef
mesh_terms: D001809:Blood Viscosity / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D008833:Microcirculation / Q000502:physiology; D033081:Shear Strength
keywords: Casson; Ostwald; flow curve; preterm; viscosity; yield shear stress