title: The choice of the intravenous fluid influences the tolerance of acute normovolemic anemia in anesthetized domestic pigs.
abstract: BACKGROUND
  The correction of hypovolemia with acellular fluids results in acute normovolemic anemia. Whether the choice of the infusion fluid has an impact on the maintenance of oxygen (O₂) supply during acute normovolemic anemia has not been investigated so far.
  
  
  METHODS
  Thirty-six anesthetized and mechanically ventilated pigs were hemodiluted to their physiological limit of anemia tolerance, reflected by the individual critical hemoglobin concentration (Hbcrit). Hbcrit was defined as the Hb-concentration corresponding with the onset of supply-dependency of total body O₂-consumption (VO₂). The hemodilution protocol was randomly performed with either tetrastarch (6% HES 130/0.4, TS-group, n = 9), gelatin (3.5% urea-crosslinked polygeline, GEL-group, n = 9), hetastarch (6% HES 450/0.7, HS-group, n = 9) or Ringer's solution (RS-group, n = 9). The primary endpoint was the dimension of Hbcrit, secondary endpoints were parameters of central hemodynamics, O₂ transport and tissue oxygenation.
  
  
  RESULTS
  In each animal, normovolemia was maintained throughout the protocol. Hbcrit was met at 3.7 ± 0.6 g/dl (RS), 3.0 ± 0.6 g/dl (HS P < 0.05 vs. RS), 2.7 ± 0.6 g/dl (GEL, P < 0.05 vs. RS) and 2.1 ± 0.4 g/dl (TS, P < 0.05 vs. GEL, HS and RS). Hemodilution with RS resulted in a significant increase of extravascular lung water index (EVLWI) and a decrease of arterial oxygen partial pressure (paO₂), and O₂ extraction ratio was increased, when animals of the TS-, GEL- and HS-groups met their individual Hbcrit.
  
  
  CONCLUSIONS
  The choice of the intravenous fluid has an impact on the tolerance of acute normovolemic anemia induced by acellular volume replacement. Third-generation tetrastarch preparations (e.g., HES 130/0.4) appear most advantageous regarding maintenance of tissue oxygenation during progressive anemia. The underlying mechanism includes a lower degree of extravasation and favourable effects on microcirculatory function.
authors.affiliation: Clinic of Anesthesiology, Intensive Care Medicine and Pain Management, JW Goethe-University Hospital Frankfurt, Theodor-Stern-Kai 7, Frankfurt/Main, 60590, Germany. a.pape@em.uni-frankfurt.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Pape
authors.forename: Saskia
authors.initials: S
authors.lastname: Kutschker
authors.forename: Harry
authors.initials: H
authors.lastname: Kertscho
authors.forename: Peter
authors.initials: P
authors.lastname: Stein
authors.forename: Oliver
authors.initials: O
authors.lastname: Horn
authors.forename: Mischa
authors.initials: M
authors.lastname: Lossen
authors.forename: Bernhard
authors.initials: B
authors.lastname: Zwissler
authors.forename: Oliver
authors.initials: O
authors.lastname: Habler
mesh_terms: D000704:Analysis of Variance; D000740:Anemia / Q000209:etiology* / Q000503:physiopathology*; D000818:Animals; D001810:Blood Volume; D004562:Electrocardiography; D023381:Endpoint Determination; D005440:Fluid Therapy / Q000379:methods*; D005780:Gelatin / Q000494:pharmacology; D006438:Hemodilution / Q000379:methods*; D006439:Hemodynamics / Q000502:physiology; D006454:Hemoglobins / Q000032:analysis; D006895:Hydroxyethyl Starch Derivatives / Q000494:pharmacology; D020896:Hypovolemia / Q000628:therapy*; D007552:Isotonic Solutions / Q000494:pharmacology; D010101:Oxygen Consumption / Q000502:physiology; D011097:Polygeline / Q000494:pharmacology; D011897:Random Allocation; D012044:Regression Analysis; D012121:Respiration, Artificial; D000077331:Ringer's Solution; D013552:Swine
chemical_list: D006454:Hemoglobins; D006895:Hydroxyethyl Starch Derivatives; D007552:Isotonic Solutions; D000077331:Ringer's Solution; D005780:Gelatin; D011097:Polygeline