title: The effect of moderate hypovolaemia on microcirculation in healthy older blood donors.
abstract: Compensation for acute blood loss requires cardiovascular integrity. In older people, asymptomatic cardiovascular impairment is common. In these subjects, even moderate blood loss is often treated by external volume replacement although its benefits are not clear. We investigated the effect of 450 ml of blood loss on the microcirculation and compensatory mechanisms in healthy older blood donors. Red blood cell count, plasma viscosity and protein concentration were measured. Plasma volume replacement was calculated using haematocrit. We measured microcirculation tissue perfusion by laser Doppler fluxmetry prior to, during and after blood donation. Blood loss was immediately accompanied by a median rapid water shift of 208 ml (interquartile range 134-298 ml). Haemodilution led to a decrease in haematocrit, protein and plasma viscosity. We observed no changes in cutaneous microcirculation. Moderate blood loss is tolerated in older cardiovascularly asymptomatic patients without having an impact on microcirculation. This may reduce the need for external volume replacement.
authors.affiliation: Institute of Transfusion Medicine and Clinical Immunology, Red Cross Blood Service of Baden-Württemberg, Faculty of Clinical Medicine Mannheim, University of Heidelberg, Germany. k.jantzko@blutspende.de
authors.forename: K
authors.initials: K
authors.lastname: Janetzko
authors.forename: H
authors.initials: H
authors.lastname: Klüter
authors.forename: H
authors.initials: H
authors.lastname: Kirchner
authors.forename: K F
authors.initials: KF
authors.lastname: Klotz
mesh_terms: D000368:Aged; D001782:Blood Donors; D001798:Blood Proteins / Q000032:analysis; D001809:Blood Viscosity; D004906:Erythrocyte Count; D005260:Female; D018495:Fluid Shifts / Q000502:physiology; D006400:Hematocrit; D006801:Humans; D020896:Hypovolemia / Q000503:physiopathology*; D017078:Laser-Doppler Flowmetry; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D018709:Statistics, Nonparametric
chemical_list: D001798:Blood Proteins