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Open Access Research

The choice of the intravenous fluid influences the tolerance of acute normovolemic anemia in anesthetized domestic pigs

Andreas Pape1*, Saskia Kutschker1, Harry Kertscho1, Peter Stein1, Oliver Horn1, Mischa Lossen1, Bernhard Zwissler2 and Oliver Habler3

Author Affiliations

1 Clinic of Anesthesiology, Intensive Care Medicine and Pain Management, J.W. Goethe-University Hospital Frankfurt, Theodor-Stern-Kai 7, Frankfurt/Main, 60590, Germany

2 Clinic of Anesthesiology, Ludwig Maximilians University Hospital, Marchioninistraße 15, Munich, 81377, Germany

3 Clinic of Anesthesiology, Surgical Intensive Care Medicine and Pain Management, Krankenhaus Nordwest, Steinbacher Hohl 2-26, Frankfurt/Main, 60488 Germany

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Critical Care 2012, 16:R69  doi:10.1186/cc11324

Published: 30 April 2012

Abstract

Introduction

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.