EFFECTS OF NOREPINEPHRINE, EPINEPHRINE, AND DOPAMINE INFUSIONS ON OXYGEN-CONSUMPTION IN VOLUNTEERS

Objective: To determine the relationships between plasma concentration s of norepinephrine, epinephrine, and dopamine and oxygen consumption (Vo2) during infusion of these catecholamines. Design: Prospective, ra ndomized variable dose, pharmacologic study in which a noncumulative i nfusion-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, norepine phrine (three infusion rates; 0.06 to 0.2 mug/kg/min; n = 7), epinephr ine (four infusion rates; 0.02 to 0.2 mug/kg/min; n = 7), or dopamine (three infusion rates; 3 to 12 mug/kg/min; n = 7) was administered to normal volunteers (n = 21) for the purpose of constructing plasma conc entration/Vo2 response curves. Measurements and Main Results: Systolic and diastolic blood pressure, heart rate, plasma concentrations of no repinephrine, epinephrine, and dopamine, and Vo2 were measured at the end of the control period and at the end of each catecholamine infusio n. Vo2 was measured using a ventilated canopy system and a differentia l oxygen sensor. Typical hemodynamic responses to vasopressors were se en during adrenergic receptor agonist infusions. Vo2 increased from 13 2 +/- 7 to 153 +/- 10 mL/min/M2 during the highest infusion rate of no repinephrine, from 133 +/- 7 to 182 +/- 11 mL/min/M2 during the highes t infusion rate of epinephrine, and from 132 +/- 13 to 163 +/- 8 mL/mi n/M2 during the highest infusion rate of dopamine (p < .05; paired t-t est). Increases in Vo2 were correlated with the logarithms of the corr esponding plasma catecholamine concentrations. Effects on Vo2 and hemo dynamic responses occurred at similar plasma concentrations for each o f the three catecholamines. Conclusions: Administration of norepinephr ine, epinephrine, or dopamine results in marked increases in Vo2 in vo lunteers. In patients, the administration of catecholamines or sympath omimetics to attain optimal values of cardiac index, oxygen delivery ( Do2), and Vo2 may increase the oxygen demand and thus obscure the Do2- Vo2 relationship.