LAUSR

Objectives: To compare the effects of restoring mean arterial pressure with vasopressin or norepinephrine on systemic hemodynamics, renal blood flow, intrarenal perfusion and oxygenation, and renal function in ovine septic acute kidney injury. Design: Interventional Study. Setting: Research Institute. Subjects: Adult Merino ewes. Interventions: Flow probes were implanted on the pulmonary and renal arteries (and the mesenteric artery in sheep that received vasopressin). Fiber-optic probes were implanted in the renal cortex and medulla to measure tissue perfusion and oxygen tension (Po2). Conscious sheep were administered Escherichia coli to induce septic acute kidney injury. Vasopressin (0.03 IU/min [0.03–0.05 IU/min]; n = 7) or norepinephrine (0.60 μg/kg/min [0.30–0.70 μg/kg/min]; n = 7) was infused IV and titrated to restore baseline mean arterial pressure during 24–30 hours of sepsis. Measurements and Main Results: Ovine septic acute kidney injury was characterized by reduced mean arterial pressure (–16% ± 2%) and creatinine clearance (–65% ± 9%) and increased renal blood flow (+34% ± 7%) but reduced renal medullary perfusion (–44% ± 7%) and Po2 (–47% ± 10%). Vasopressin infusion did not significantly affect renal medullary perfusion or Po2 and induced a sustained (6 hr) ~2.5-fold increase in creatinine clearance. Vasopressin reduced sepsis-induced mesenteric hyperemia (+61 ± 13 to +9% ± 6%). Norepinephrine transiently (2 hr) improved creatinine clearance (by ~3.5-fold) but worsened renal medullary ischemia (to –64% ± 7%) and hypoxia (to –71% ± 6%). Conclusions: In ovine septic acute kidney injury, restoration of mean arterial pressure with vasopressin induced a more sustained improvement in renal function than norepinephrine, without exacerbating renal medullary ischemia and hypoxia or reducing mesenteric blood flow below baseline values.