There were 36 risk factors in the control group and 34 in the protocol group. Based on a ten-yr study of the high-risk preoperative criteria, the mortality in the control group would be expected to be 33 percent and in the protocol group 28 percent.
The therapeutic goals in the control group were normal values, while those in the protocol group were empirically determined from survivors. The therapy for both groups was the same: crystalloid, colloids, packed red blood cells, inotropic agents, and vasodilators; the difference between the two groups was the goals of therapy.
Triple-lumen thermodilution pulmonary artery (PA) and radial artery catheters were placed before surgery.12 N Cardiac output was measured by thermodilution using a cardiac output computer (American Edwards Laboratories model 9520). Immediately after three or more cardiac output measurements were made, samples of arterial and mixed venous blood were taken simultaneously; pH, blood gas tensions, hemoglobin (Hgb) level, Hgb saturation, and the hematocrit were measured. Oxygen delivery was calculated as the product of Cl and the arterial oxygen content (CaO). Oxygen consumption was calculated as the product of Cl and its simultaneously measured arteriovenous oxygen content difference (C[a-v]Oa). Measurements were made during the preoperative control period, at frequent intervals during surgery, and in the immediate postoperative period.