EFFECTS OF DOBUTAMINE ON OXYGEN-TRANSPORT AND CONSUMPTION IN THE ADULT-RESPIRATORY-DISTRESS-SYNDROME

Objective: To determine if oxygen consumption (VO2) in patients with a dult respiratory distress syndrome (ARDS) is dependent on, and thus li mited by, oxygen transport (TO2) rather than O2 demand. Design: Prospe ctive study. Setting. Intensive care unit of a tertiary referral cente r. Patients: 12 patients with ARDS and sepsis syndrome. Interventions: Routine intensive care unit monitoring including pulmonary and radial artery catheters. Measurements: Dobutamine was used to increase cardi ac output, thereby directly varying TO2 under conditions of constant O 2 demand. After baseline measurements of TO2 and VO2, dobutamine was i nfused intravenously at progressively increasing doses of 5, 10, 15 an d 20 mug/kg/min and measurements Of TO2 and VO2 were repeated after 30 min at each dose. Results: Dobutamine increased TO2 in 8 of the 12 pa tients, by 29% at 5 mug/kg/min and by 45% (net) at 10 mug/kg/min, but not at higher doses. In these 8 patients dobutamine also increased VO2 by 15% at 5 mug/kg/min, but did not further increase VO2 at higher do ses. There was no correlation between baseline blood lactate concentra tion and the response of either TO2 or VO2 to dobutamine. Conclusions: In some but not all patients with ARDS and sepsis syndrome, short-ter m infusion of low-dose dobutamine can increase both TO2 and VO2. Achie vement of a TO2-independent level of VO2 could not be convincingly dem onstrated in any individual patient. The response of TO2 and VO2 to do butamine could not be predicted from baseline blood lactate concentrat ion. Determination of the impact on patient outcome of a more prolonge d infusion of dobutamine requires further study.