Myocardial oxygen consumption during dobutamine infusion in endotoxemic pigs

Purpose: Dobutamine infusion is used to increase whole-body oxygen delivery in septic patients to satisfy unmet oxygen demand of hypoxic tissues. Howe ver, dobutamine infusion also increases myocardial work and myocardial oxyg en consumption. Our goal was to determine the importance of this effect as a fraction of the increase in whole-body oxygen consumption, in a porcine m odel of septic shock. Materials and Methods: Four hours after a 50 mu g/kg infusion of Escherichi a coli endotoxin (0111: B4, Sigma) in eight anesthetized pigs, whole-body o xygen delivery and myocardial oxygen delivery and consumption were calculat ed from blood flow and arterial and venous oxygen content measurements. We directly measured whole-body oxygen consumption by analysis of inhaled and exhaled gases using a metabolic cart. Then dobutamine 10 and 20 mu g/kg/min was infused and measurements were repeated. Results: Dobutamine infusion increased whole-body oxygen delivery but did n ot increase metabolic cart measured whole-body oxygen consumption. Dobutami ne infusion of 10 and 20 mu g/kg/min increased myocardial oxygen consumptio n by 7.0 +/- 0.6 (80 +/- 10%) and 12.0 +/- 2.0 mL O-2/min (142 +/- 30%), re spectively (P < .01). Conclusions: In this porcine model of sepsis, dobutamine infusion significa ntly increases myocardial oxygen consumption. Because whole-body oxygen con sumption does not change, dobutamine infusion may fail to increase and may decrease oxygen consumption by other organs. Copyright (C) 1999 by W.B. Sau nders Company.