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The impact of an hematocrit of 20% during normothermic cardiopulmonary bypass for elective low risk coronary artery bypass graft surgery on oxygen delivery and clinical outcome – a randomized controlled study [ISRCTN35655335]

Christian von Heymann1*, Michael Sander1, Achim Foer1, Anja Heinemann1, Bruce Spiess2, Jan Braun1, Michael Krämer1, Joachim Grosse1, Pascal Dohmen3, Simon Dushe3, Jürgen Halle3, Wolfgang F Konertz3, Klaus-Dieter Wernecke3 and Claudia Spies1

Author Affiliations

1 Department of Anesthesiology and Intensive Care Medicine, Charité – University Hospital Berlin, Charité Campus Mitte, Berlin, Germany

2 Department of Anesthesiology and the Virginia Commonwealth University Reanimation Engineering Shock Center (VCURES), Virginia Commonwealth University Medical Center, Richmond, Virginia, USA

3 Department of Cardiovascular Surgery, Charité – University Hospital Berlin, Charité Campus Mitte, Berlin, Germany

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Critical Care 2006, 10:R58  doi:10.1186/cc4891

Published: 10 April 2006

Abstract

Introduction

Cardiopulmonary bypass (CPB) induces hemodilutional anemia, which frequently requires the transfusion of blood products. The objective of this study was to evaluate oxygen delivery and consumption and clinical outcome in low risk patients who were allocated to an hematocrit (Hct) of 20% versus 25% during normothermic CPB for elective coronary artery bypass graft (CABG) surgery.

Methods

This study was a prospective, randomized and controlled trial. Patients were subjected to normothermic CPB (35 to 36°C) and were observed until discharge from the intensive care unit (ICU). Outcome measures were calculated whole body oxygen delivery, oxygen consumption and clinical outcome. A nonparametric multivariate analysis of variance for repeated measurements and small sample sizes was performed.

Results

In a total of 54 patients (25% Hct, n = 28; 20% Hct, n = 26), calculated oxygen delivery (p = 0.11), oxygen consumption (p = 0.06) and blood lactate (p = 0.60) were not significantly different between groups. Clinical outcomes were not different between groups.

Conclusion

These data indicate that an Hct of 20% during normothermic CPB maintained calculated whole body oxygen delivery above a critical level after elective CABG surgery in low risk patients. The question of whether a transfusion trigger in excess of 20% Hct during normothermic CPB is still supported requires a larger prospective and randomized trial.