The Norwood procedure still has a high mortality rate of about 15%, and the surgery and its postoperative management require the meticulous care. Of particular importance is maintaining an appropriate balance between systemic and pulmonary blood flow in the face of ever-changing circulatory conditions, for which various parameters must be understood. These parameters include systolic blood pressure, diastolic blood pressure, mean blood pressure, central venous pressure, oxygen saturation, venous oxygen saturation, lactate, and urine output. I believe that one of the keys to improving outcomes is to make full use of these parameters and to administer appropriate drugs and procedures at the right time. In particular, the pulmonary to body blood flow ratio in the immediate postoperative state and in the stable postoperative state are different, and it is important to predict these while ultimately creating the best circulation for the patient.