Intraoperative fluid management: administration of 6-10 ml/kg/hr of crystalloid solution.

Intervention: administration of vasopressin 0.01 - 0.04 U/min after induction of anesthesia.

Intraoperative fluid management: administration of 2-4 ml/kg/hr of crystalloid solution.

Vasopressin, is a hormone synthesized as a peptide prohormone in neurons in the hypothalamus, and is converted to arginine vasopressin. It then travels down the axon of that cell, which terminates in the posterior pituitary, and is released from vesicles into the circulation in response to extracellular fluid hypertonicity (hyperosmolality). Arginine vasopressin has two primary functions. First, it increases the amount of solute-free water reabsorbed back into the circulation from the filtrate in the kidney tubules of the nephrons. Second, arginine vasopressin constricts arterioles, which increases peripheral vascular resistance and raises arterial blood pressure.

Comparison of the amounts of estimated blood loss in the two groups.

Comparison of total units of red blood cell transfusion in the two groups.