Abstract
The mixed venous oxygen saturation (SVO_2) is considered to be manifested the situations of demand and supply of tissue oxygen. Accordingly, we have been applied SVO_2 to an index of tissue oxygen behavior on pulmonary surgery of elderly patients. In the stable SVO_2 of our 32 cases the safety-zone was determined to be 71.2±4.1%. Similarly, the standard values of cardiac output and oxygen consumption were determined to be 3.54±0.97 liters/min/m2 and 130cc/min/m^2, respectively. The SVO_2 correlated well with the cardiac output and oxygen consumption. That is, when the cardiac output was lowered and the oxygen consumption was increased, the SVO_2 dropped apparently. Despite the increase of oxygen consumption, if the cardiac output increases, the oxygen supply in tissues is maintained, and the SVO_2 maintains the safety-zone. If both cardiac output and oxygen consumption are lowered, as far as the balance of oxygen demand and supply in tissues is maintained, the SVO_2 remains within the safety-zone. Thus, since the SVO_2 is apparentey related with the states of demand and supply of oxygen in tissue respiration, it seems to be effective as an index for operative and postoperative management of elderly patients.
