EFFECT OF EPINEPHRINE ON OXYGEN-CONSUMPTION AND DELIVERY DURING PROGRESSIVE HEMORRHAGE

Objective: To determine whether, during hemorrhagic shock, the effect of epinephrine on energy metabolism could be deleterious, by enhancing the oxygen requirement at a given level of oxygen delivery (Do(2)). D esign: Prospective, randomized, control trial, Setting: Experimental l aboratory, Subjects: Two groups of seven mongrel dogs were studied, Th e epinephrine group received a continuous infusion of epinephrine (1 m u g/min/kg) while the control group received saline, Intervention: Dog s were anesthetized with pentobarbital, and shock was produced by step wise hemorrhage, Measurements and Main Results: Oxygen consumption (Vo (2)) was continuously measured by the gas exchange technique, while Do (2) was independently calculated from cardiac output (measured by ther modilution) and blood oxygen content, A dual-lines regression fit was applied to the Do(2) vs. Vo(2) plot. The intersection of the two regre ssion lines defined the critical value of Do(2). Values above critical Do(2) belonged to phase 1, while phase 2 occurred below critical Do(2 ). In the control group, Vo(2) was independent of Do(2) during phase 1 ; Vo(2) was dependent on Do(2) during phase 2. In the epinephrine grou p, the expected increase in Vo(2) (+19%) and Do(2) (+50%) occurred und er normovolemic conditions. During hemorrhage, Vo(2) immediately decre ased, and the slope of phase 1 was significantly (p < .01) different f rom zero, and was significantly (p < .05) steeper than in the control group (0.025 +/- 0.005 vs, 0.005 +/- 0.010). However, the critical Do( 2) (8.7 +/- 1.7 vs, 9.7 +/- 2.4 mL/min/kg), the critical Vo(2) (5.6 +/ - 0.5 vs, 5.5 +/- 0.9 mL/min/kg), and the slope of phase 2 (0.487 +/- 0.080 vs, 0.441 +/- 0.130) were not different from control values. Con clusions: The administration of pharmacologic doses of epinephrine sig nificantly increased Vo(2) under normovolemic conditions due to the ep inephrine-induced thermogenic effect, This effect progressively decrea sed during hemorrhage. The critical Do(2) and the relationship between Do(2) and Vo(2) in the supply-dependent phase of shock were unaffecte d by epinephrine infusion, These results suggest that during hemorrhag ic shock, epinephrine administration did not exert a detrimental effec t on the relationship between Do(2) and Vo(2).