Epinephrine infusion in sheep: systemic and renal hemodynamic effects.
OBJECTIVE
To evaluate the dose-response effects of graded epinephrine infusions on systemic and renal hemodynamics.


METHODS
Prospective, dose-response study.


METHODS
Laboratory at a university hospital.


METHODS
Thirteen conscious, chronically catheterized, adult merino sheep.


METHODS
Ten sheep received five infusions of epinephrine (5, 10, 20, and 40 micrograms/min; the 40-micrograms/min dose was repeated) and a placebo (saline) on separate days (at least 1 day apart). Each drug infusion was administered for 4 hrs on separate days after a 90-min baseline was established. Plasma catecholamine values and renin activity were measured in an additional three sheep infused with 40 micrograms/min epinephrine.


RESULTS
Renal blood flow was measured, using an electromagnetic flow transducer; these data, along with aortic and pulmonary arterial pressure, were continuously recorded after analog-to-digital conversion. Cardiac output was intermittently measured by thermodilution. Epinephrine resulted in a dose-dependent increase in mean arterial pressure (p < .001), and in cardiac output at 30, 60, and 120 mins after the start of the infusion. Concurrently, systemic vascular resistance was initially depressed below baseline, but then gradually increased during the 4-hr infusion period. Although a dose-dependent increase in renal vascular resistance was found, 5- and 10-micrograms/min of epinephrine failed to alter renal vascular resistance. However, 20- and 40-micrograms/min of epinephrine increased renal vascular resistance by 77% and 94% respectively, at 10 mins, but these values decreased to 17% and 16% of baseline by 120 mins. Consequently, an early dose-dependent decrease in renal blood flow was also time dependent, with renal blood flow increasing back to or above baseline at all studied infusion rates of epinephrine.


CONCLUSIONS
Using a clinically relevant dose regimen, epinephrine increased mean arterial pressure and cardiac output. Renal blood flow decreased transiently, but returned to baseline within 30 to 60 mins.
Bersten
A D
AD
Department of Anesthesia, Flinders Medical Centre, Adelaide, South Australia.
Rutten
A J
AJ
Summersides
G
G
Ilsley
A H
AH
D000704:Analysis of Variance; D000818:Animals; D016001:Confidence Intervals; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000008:administration & dosage*; D006439:Hemodynamics / Q000187:drug effects*; D007262:Infusions, Intravenous / Q000706:statistics & numerical data; D007668:Kidney / Q000187:drug effects* / Q000502:physiology; D011446:Prospective Studies; D011897:Random Allocation; D012079:Renal Circulation / Q000187:drug effects; D012212:Rheology / Q000295:instrumentation / Q000706:statistics & numerical data; D012756:Sheep; D013997:Time Factors
D004837:Epinephrine