Impact of Acute Normovolemic Hemodilution on Blood Viscosity

Study Overview
=================
Brief Summary
-----------------
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.

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

Conditions
-----------------
Ischemic Heart Disease, Coronary Artery Disease

Intervention / Treatment
-----------------
* Procedure: acute normovolemic hemodilution
* Procedure: In-vitro hemodilution


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: patients undergoing off-pump coronary artery bypass graft surgery Exclusion Criteria: Preoperative anemia LV ejection fraction < 50%
Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Supportive Care
Allocation: Non-Randomized
Intervention Model: Factorial Assignment
Interventional Model Description: Acute normovolemic hemodilution consists of phlebotomy and intravascular volume resuscitation by using crystalloid/colloid in a same amount of phlebotomy
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Acute normovolemic hemodilution<br>acute normovolemic hemodilution by using hydroxyethyl starch | Procedure: acute normovolemic hemodilution<br>* 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<br>Procedure: In-vitro hemodilution<br>* Blood sample after ANH 5 ml/kg undergoes further 30% in-vitro dilution by adding 1-1.5 ml hydroxyethystarch 130/0.42<br>|
| Experimental: In-vitro hemodilution<br>adding additional hydroxyethyl starch for achieving further 30% dilution of whole blood sample which already underwent ANH of 4-6 ml/kg. | Procedure: In-vitro hemodilution<br>* Blood sample after ANH 5 ml/kg undergoes further 30% in-vitro dilution by adding 1-1.5 ml hydroxyethystarch 130/0.42<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| blood viscosity at shear rate 5/sec | By using a scanning capillary tube viscometer (Hemovister™), Blood viscosity at shear rate 5/sec of the three samples are determined | 5 min after acute normovoelmic hemodilution, 5 min after in-vitro dilution | 
| hematocrit/blood viscosity at 5/sec | oxygen delivery index calculated with a formula (= hematocrit/blood viscosity) | 5 min after acute normovoelmic hemodilution, 5 min after in-vitro dilution | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| blood viscosity at shear rate 300/sec | By using a scanning capillary tube viscometer (Hemovister™), Blood viscosity at shear rate 300/sec of the three samples are determined | 5 min after acute normovoelmic hemodilution, 5 min after in-vitro dilution | 
| Hematocrit/viscosity at shear rate 300/sec | oxygen delivery index calculated with a formula (= hematocrit/blood viscosity) | 5 min after acute normovoelmic hemodilution, 5 min after in-vitro dilution | 
| Coagulation profiles in ROTEM | clot formation time in extem, MCF in extemA5 in fibtem, | 5 min after acute normovoelmic hemodilution, 5 min after in-vitro dilution | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
acute normovolemic hemodilution, coronary artery bypass graft surgery, hydroxyethyl starch, blood viscosity