Second, we studied 20 patients in a prospective randomized clinical trial. Patients were selected for study if after adequate volume therapy indicated by PaOP greater than 15 mm Hg in the immediate postoperative period they did not achieve the median cardiorespiratory values previously observed in survivors of high-risk postoperative patients; ie, CI>4.5 L/mi*m2, Do2 >600 ml/ minm and Vo, >170 ml/minm. buy birth control online
The radial artery was catheterized with an 18-gauge plastic catheter and the pulmonary artery was catheterized with a balloon-tipped, flow-directed thermodilution catheter (American Edwards Laboratories, Santa Ana, CA) by previously described methods. Cardiac output was measured in triplicate by thermodilution (model 9520A, Cardiac Output Computer, American Edwards Laboratories, Santa Ana, CA). Arterial and mixed venous (pulmonary arterial) blood samples were drawn simultaneously at the time of the last CO measurement and promptly analyzed for pH, blood gas values, hemoglobin saturation and hematocrit level. Hemodynamic and oxygen transport variables were calculated by standard formulas. Oxygen delivery was calculated as Cl multiplied by arterial Oa contents and Vo2 as Cl multiplied by arteriovenous 02 content difference. Flow-derived variables were indexed according to the patients body surface area obtained from standard nomograms.