Efeitos da efedrina sobre as fun??es cardiovascular e renal de c?es sob anestesia com pentobarbital sódico

摘要

BACKGROUND AND OBJECTIVES: Some studies have shown differentiated dose-dependent effects of ephedrine on cardiovascular and renal functions. This study aimed at verifying whether different ephedrine doses determine differentiated hemodynamic and renal effects. METHODS: Cardiovascular and renal hemodynamics and renal function were evaluated in 32 dogs anesthetized with sodium pentobarbital (SP) for surgical preparation, catheterization, extracellular fluid volume expansion and mechanical ventilation. Dogs were randomly distributed in four groups: G control (n = 8), in which dogs remained only under the effect of SP; G ephedrine 2 μg (n = 8); G ephedrine 10 μg (n = 8); and G ephedrine 100 μg (n = 8), in which dogs received 2, 10, and 100 μg.kg-1.min-1 ephedrine, respectively. Cardiovascular and renal parameters were studied at control (M1 and M2), during ephedrine infusion (M3 and M4) and after ephedrine infusion withdrawal (M5). RESULTS: There were no significant differences among groups. There has been a significant increase in heart rate, aortic blood flow, urinary output and fractional sodium excretion in G ephedrine 2 μg. There has been a significant increase in heart rate and filtration fraction in G ephedrine 10 μg while in G ephedrine 100 μg there has been a significant increase in heart rate, mean blood pressure, aortic blood flow, central venous pressure, renal vascular resistance and hematocrit, and a significant decrease in renal plasma and blood flow. CONCLUSIONS: Our study has shown that ephedrine has differentiated dose-dependent hemodynamic and renal effects.