ELEVATION OF SYSTEMIC OXYGEN DELIVERY IN THE TREATMENT OF CRITICALLY ILL PATIENTS

Background. Elevation of systemic oxygen delivery and consumption has been associated with an improved outcome in critically ill patients. W e conducted a randomized trial to determine whether boosting oxygen de livery by infusing the inotropic agent dobutamine would improve the ou tcome in a diverse group of such patients. Methods. On the basis of pr eviously published recommendations, we established the following goals : a cardiac index above 4.5 liters per minute per square meter of body -surface area, oxygen delivery above 600 ml per minute per square mete r, and oxygen consumption above 170 ml per minute per square meter. If these goals were not achieved with volume expansion alone, patients w ere randomly assigned to a treatment or control group. The treatment g roup received intravenous dobutamine (5 to 200 mu g per kilogram of bo dy weight per minute) until all three goals had been achieved. Dobutam ine was administered to the control group only if the cardiac index wa s below 2.8 liters per minute per square meter. Results. A total of 10 9 patients were studied. In nine patients the therapeutic goals were a chieved with volume expansion alone; all nine patients survived to lea ve the hospital. Fifty patients were randomly assigned to the treatmen t group, and 50 to the control group. During treatment, there were no differences between the two groups in mean arterial pressure or oxygen consumption, despite a significantly higher cardiac index and level o f oxygen delivery in the treatment group (P < 0.05). Although the pred icted risk of death during hospitalization was 34 percent for both gro ups, the in-hospital mortality was lower in the control group (34 perc ent) than in the treatment group (54 percent) (P = 0.04; 95 percent co nfidence interval, 0.9 to 39.1 percent). Conclusions. The use of dobut amine to boost the cardiac index and systemic oxygen delivery failed t o improve the outcome in this heterogeneous group of critically ill pa tients. Contrary to what might have been expected, our results suggest that in some cases aggressive efforts to increase oxygen consumption may have been detrimental.