Comparison of norepinephrine and dobutamine to epinephrine for hemodynamics, lactate metabolism, and gastric tonometric variables in septic shock: a prospective, randomized study
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Objectives: To compare the effects of norepinephrine and dobutamine to epinephrine on hemodynamics, lactate metabolism, and gastric tonometric variables in hyperdynamic dopamine-resistant septic shock. Design: A prospective, intervention, randomized clinical trial. Setting: Adult medical/surgical intensive care unit in a university hospital. Patients: 30 patients with a cardiac index (CI) > 3.5 l · min–1· m–2 and a mean arterial pressure (MAP) ≤ 60 mmHg after volume loading and dopamine 20 μg/kg per min and either oliguria or hyperlactatemia. Interventions: Patients were randomized to receive an infusion of either norepinephrine-dobutamine or epinephrine titrated to obtain an MAP greater than 80 mmHg with a stable or increased CI. Measurements and main results: Baseline measurements included: hemodynamic and tonometric parameters, arterial and mixed venous gases, and lactate and pyruvate blood levels. These measurements were repeated after 1, 6, 12, and 24 h. All the patients fulfilled the therapeutic goals. No statistical difference was found between epinephrine and norepinephrine-dobutamine for systemic hemodynamic measurements. Considering metabolic and tonometric measurements and compared to baseline values, after 6 h, epinephrine infusion was associated with an increase in lactate levels (from 3.1 ± 1.5 to 5.9 ± 1.0 mmol/l; p < 0.01), while lactate levels decreased in the norepinephrine-dobutamine group (from 3.1 ± 1.5 to 2.7 ± 1.0 mmol/l). The lactate/pyruvate ratio increased in the epinephrine group (from 15.5 ± 5.4 to 21 ± 5.8; p < 0.01) and did not change in the norepinephrine-dobutamine group (13.8 ± 5 to 14 ± 5.0). Gastric mucosal pH (pHi) decreased (from 7.29 ± 0.11 to 7.16 ± 0.07; p < 0.01) and the partial pressure of carbon dioxide (PCO2) gap (tonometer PCO2– arterial PCO2) increased (from 10 ± 2.7 to 14 ± 2.7 mmHg; p < 0.01) in the epinephrine group. In the norepinephrine-dobutamine group pHi (from 7.30 ± 0.11 to 7.35 ± 0.07) and the PCO2 gap (from 10 ± 3.0 to 4 ± 2.0 mmHg) were normalized within 6 h (p < 0.01). The decrease in pHi and the increase in the lactate/pyruvate ratio in the epinephrine group was transient, since it returned to normal within 24 h. Conclusions: Considering the global hemodynamic effects, epinephrine is as effective as norepinephrine-dobutamine. Nevertheless, gastric mucosal acidosis and global metabolic changes observed in epinephrine-treated patients are consistent with a markedly inadequate, although transient, splanchnic oxygen utilization. The metabolic and splanchnic effects of the combination of norepinephrine and dobutamine in hyperdynamic dopamine-resistant septic shock appeared to be more predictable and more appropriate to the current goals of septic shock therapy than those of epinephrine alone.
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