Impact of Intravascular Fluid Resuscitation on Whole Blood Viscosity During Cardiac Surgery

After obtaining approval from the Institutional Review Board of our institution, written informed consent is obtained from patients undergoing cardiac surgery are enrolled in this prospective study and randomly allocated into one of two groups: Group-C (n=15) and Group-HES (n=15). All recruited patients will be given patient identification number (PIN) for the present study of 01-30 according to their order of interview and recruitment. Investigators will prepare 15 yellow and 15 green cards, which will be inserted in 30 thick-paper envelopes. Then, all envelopes will be sealed, mixed and randomly allocated to get numbers of 01 to 30 (Envelop number). After printing the envelope number outside envelope, all sealed envelopes with cards will be conveyed to and kept in pharmacy department. According to the color of the card, attending anesthesiologists will give crystalloid for yellow card or HES for green cards, respectively, to maintain stroke volume variation < 15 during volume controlled ventilation (8 ml/kg tidal volume) of O2/air mixture. Patient data and statistical analyses: Patient's data whole blood viscosity, PaO2, FiO2, Hemoglobin, urine amount, s-glucose will be determined from the patients' medical record after patient's discharge. All statistical analyses will be performed after the 30th patient's discharge and data acquisition