Effects of norepinephrine, epinephrine, and dopamine infusions on oxygen consumption in volunteers

To determine the relationships between plasma concentrations of norepinephrine, epinephrine, and dopamine and oxygen consumption (Co2) during infusion of these catecholamines. DESIGN:Prospective, randomized variable dose, pharmacologic study in which a noncumu-lative infusion-rate design was used. SETTING:Laboratory of the Department of Anesthesiology at a University Hospital. PATIENTS:Twenty-one normal volunteers. INTERVENTIONS:After a control period of 20 mins, norepinephrine (three infusion rates; 0.06 to 0.2 ug/kg/min; n = 7), epinephrine (four infusion rates; 0.02 to 0.2 ug/kg/min; n = 7), or dopamine (three infusion rates; 3 to 12 ug/kg/min; n = 7) was administered to normal volunteers (n = 21) for the purpose of constructing plasma concentration/o2 response curves. MEASUREMENTS AND MAIN RESULTS:Systolic and diastolic blood pressure, heart rate, plasma concentrations of norepinephrine, epinephrine, and dopamine, and Vo2 were measured at the end of the control period and at the end of each cate-cholamine infusion. Vo2 was measured using a ventilated canopy system and a differential oxygen sensor. Typical hemodynamic responses to vasopressors were seen during adrenergic receptor agonist infusions. Vo2 increased from 132 ± 7 to 153 ± 10 mL/min/m during the highest infusion rate of norepinephrine, from 133 ± 7 to 182 ± 11 mL/min/m during the highest infusion rate of epinephrine, and from 132 ± 13 to 163 ± 8 mL/min/m during the highest infusion rate of dopamine (p < .05; paired t-test). Increases in Vo2 were correlated with the logarithms of the corresponding plasma catecholamine concentrations. Effects on Vo2 and hemodynamic responses occurred at similar plasma concentrations for each of the three catecholamines. CONCLUSIONS:Administration of norepinephrine, epinephrine, or dopamine results in marked increases in Vo2 in volunteers. In patients, the administration of catecholamines or sympathomimetics to attain optimal values of cardiac index, oxygen delivery (Vo2), and Vo2 may increase the oxygen demand and thus obscure the Vo2-Vo2 relationship.