Myocardial oxygen consumption during dobutamine infusion in endotoxemic pigs.
OBJECTIVE
Dobutamine infusion is used to increase whole-body oxygen delivery in septic patients to satisfy unmet oxygen demand of hypoxic tissues. However, dobutamine infusion also increases myocardial work and myocardial oxygen 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 model of septic shock.


METHODS
Four hours after a 50 microg/kg infusion of Escherichia coli endotoxin (0111: B4, Sigma) in eight anesthetized pigs, whole-body oxygen delivery and myocardial oxygen delivery and consumption were calculated 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 microg/kg/min was infused and measurements were repeated.


RESULTS
Dobutamine infusion increased whole-body oxygen delivery but did not increase metabolic cart measured whole-body oxygen consumption. Dobutamine infusion of 10 and 20 microg/kg/min increased myocardial oxygen consumption by 7.0 +/- 0.6 (80 +/-10%) and 12.0 +/- 2.0 mL O2/min (142 +/- 30%), respectively (P < .01).


CONCLUSIONS
In this porcine model of sepsis, dobutamine infusion significantly increases myocardial oxygen consumption. Because whole-body oxygen consumption does not change, dobutamine infusion may fail to increase and may decrease oxygen consumption by other organs.
Herbertson
M J
MJ
Pulmonary Research Laboratory, Program of Critical Care Medicine, St. Paul's Hospital, University of British Columbia, Vancouver, Canada.
Russell
J A
JA
Walley
K R
KR
D000704:Analysis of Variance; D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology*; D003326:Coronary Circulation / Q000187:drug effects*; D004280:Dobutamine / Q000494:pharmacology*; D019446:Endotoxemia / Q000188:drug therapy; D006439:Hemodynamics / Q000187:drug effects; D007262:Infusions, Intravenous; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects*; D018805:Sepsis / Q000188:drug therapy*; D013552:Swine
D002316:Cardiotonic Agents; D004280:Dobutamine