Flow-directed, balloon-tipped PA catheters were placed percutaneously in study patients via an internal jugular or subclavian vein, and radial arterial catheters were put in place in the ICU before preoperative medication. Pulmonary arterial pressures, HE, MAE CV£ and pulmonary capillary WP were measured. Cardiac output then was measured by thermodilution using a cardiac output computer (Model 9520, American Edwards Laboratories, Santa Ana, CA). Immediately after cardiac output was measured, arterial and mixed venous blood were sampled; pH, blood gas tensions, hemoglobin, hemoglobin saturation, and hematocrit were promptly measured. The LVSWI, SVRI, and PVRI, Qsp/Qt, Do2 defined as the product of Cl and arterial oxygen content, (Vo2), and oxygen extraction were calculated using standard formulas. All flow and volume measurements were indexed to body surface area.
The measurements of each data set were taken within a 1- to 2-min period in order to calculate a complete set of oxygen transport and other derived variables for each of the various time intervals; 2,186 sets of data were obtained in 252 patients of the first series and 984 sets in the second series. Altogether over 100,000 measured and derived values were analyzed in the present study.
Definition of Therapeutic Goals and Strategies
Therapeutic goals in the control groups were normal values for those variables obtained from established normative standards and in current use in our institution. The relative priorities of the various physiologic variables measured in the CVP and PA-control groups were those of the current standard of care taught and practiced in the surgical department of our institution. In general, the maintenance of normal arterial and venous pressures as well as other hemodynamic variables were given priority. buy glucophage online
In the PA-protocol group, by contrast, the therapeutic goals were supranormal values for cardiac output (>4.5 L/minnn2), D02 (>600 ml/minnn2), and Vo2 (>170 ml/minnn2), previously defined empirically from the median values of patients surviving critical surgical illnesses (Table 2). Cardiac output and oxygen transport goals were given priority in the continuing management of these patients.
Therapy in both groups consisted of fluids including packed red blood cells, crystalloids and various colloids, inotropic agents— principally dobutamine, vasodilators including nitroprusside and nitroglycerine, and vasopressors such as dopamine and norepinephrine. The only difference in the therapy between the control and protocol groups was in the goals to which therapy was aimed. Patients who preoperatively had abnormally high Cl values (>5 L/minnn2) from associated severe sepsis and late stage cirrhosis were considered separately as they already were compensating in the preoperative state and had achieved spontaneously the therapeutic goals defined for the protocol patients.
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