Impact of Acute Normovolemic Hemodilution on Blood Viscosity

Impact of Intravascular Fluid Resuscitation for Acute Normovolemic Hemodilution on Blood Viscosity and Oxygen Delivery in Coronary Artery Bypass Graft Surgery

Acute normovolemic hemodilution (ANH) has long been employed for reducing allogenic blood transfusion for cardiac surgery, and hydroxyethyl starch has been used as an intravenous replacement fluid during ANH procedure. However, possible impact of ANH employing HES on blood viscosity and oxygen delivery have not been well investigated in patients undergoing off-pump coronary artery bypass (OPCAB) surgery . Anesthesia is induced and maintained by using propofol-remifentanil-rocuronium in OPCAB surgery (n=21). ANH is performed by using 5 ml/kg of blood salvage and administering 5 ml/kg of balanced HES 130/0.42 (Tetraspan™) for 15 min during vascular graft harvesting. For the present study, three arterial blood samples (3 ml each) are taken before (Sample 1) and after ANH (sample 2 and 3) and they are stored in 3 tubes. Sample 3 (in tube) undergoes further 30% in-vitro dilution by adding 1-1.5 ml HES. By using a scanning capillary tube viscometer (Hemovister™), Blood viscosity at low shear rate (5/sec) of the three samples are determined. By using a formula with blood viscosity and hematocrit, tissue O2 delivery index (TODI, = hematocrit/viscosity at 5/sec) is calculated.

acute normovolemic hemodilution, coronary artery bypass graft surgery, hydroxyethyl starch, blood viscosity

Acute normovolemic hemodilution consists of phlebotomy and intravascular volume resuscitation by using crystalloid/colloid in a same amount of phlebotomy

adding additional hydroxyethyl starch for achieving further 30% dilution of whole blood sample which already underwent ANH of 4-6 ml/kg.

acute normovolemic hemodilution (ANH) is performed by using 5 ml/kg of blood salvage and intravenously administering 5 ml/kg of balanced hydroxyethystarch 130/0.42 (Tetraspan™) for 15 min

Blood sample after ANH 5 ml/kg undergoes further 30% in-vitro dilution by adding 1-1.5 ml hydroxyethystarch 130/0.42

By using a scanning capillary tube viscometer (Hemovister™), Blood viscosity at shear rate 5/sec of the three samples are determined

By using a scanning capillary tube viscometer (Hemovister™), Blood viscosity at shear rate 300/sec of the three samples are determined

Inclusion Criteria: patients undergoing off-pump coronary artery bypass graft surgery Exclusion Criteria: Preoperative anemia LV ejection fraction < 50%