The influence of priming solutions used in cardiopulmonary bypass on blood viscosity in hypothermic conditions

Vessel diameter, flow velocity, temperature, and viscosity are among the factors determining blood flow in vessels. To assess the influence of arterial blood flow on veins in a cardiac operation, the viscosity of blood diluted with priming solutions must be known. This study aimed to demonstrate the alteration of blood viscosity following dilution with priming solutions: hydroxyethyl starch (HES), gelatin, albumin, and Ringer's lactated solution (RL). Sixty volunteers were (15 female, 45 male) included in the study. Using a 50-ml syringe containing heparin, 40-ml fasting blood was drawn from antecubital veins. Six milliliters of blood was added to glass tubes previously filled with 2 ml of HES 6%, gelatin 4%, albumin, and RL solutions. Relative viscosity values of these mixtures were measured with an Ostwald viscometer device while the temperature was kept constant at 15 degrees C and 30 degrees C by means of a water bath. Measured viscosity values were compared with the calculated viscosity values and corrected values were obtained. All mixtures demonstrated decreased viscosity; however, it was evident that the mixtures containing HES and gelatin presented a lesser degree of decrease in viscosity when compared with the mixtures containing albumin and RL solution. Viscosity of all mixtures except RL decreased significantly at deep hypothermia (15 degrees C).