Dobutamine improves the adequacy of gastric mucosal perfusion in epinephrine-treated septic shock

Objective: To assess the effects of dobutamine at a rate of 5 mu g/kg/min on hemodynamics and gastric intramucosal acidosis in patients with hyperdynamic septic shock treated with epinephrine. Design: A prospective, interventional, clinical trial. Setting: An adult, 16-bed medical/surgical intensive care unit of a university hospital. Patients: Twenty septic shock patients with a mean arterial pressure of >75 mm Hg and a cardiac index of >3.5 L/min/m(2). Interventions: After baseline measurements (H0), each patient received dobutamine at a rate of 5 mu g/kg/min. Baseline measurements included: hemodynamic parameters, tonometric parameters, arterial and mixed venous gases, and arterial lactate concentrations. These measurements were repeated after 1 (H1), 2 (H2), and 3 (H3) hrs. After H2 measurements, dobutamine was stopped. The patients were separated into two groups according to their Pco(2) gap (tonometer Pco(2)-Paco(2)). The increased Pco(2) gap group was defined by a Pco(2) gap >8 torr (>1.1 kPa) (n=13), and the normal Pco(2) gap group by a Pco(2) gap less than or equal to 8 torr (less than or equal to 1.1 kPa) (n=7). Measurements and Main Results: Dobutamine at 5 mu g/kg/min had no significant effects on mean arterial pressure, heart rate, cardiac index, systemic vascular resistance, oxygen delivery, and oxygen consumption in epinephrine-treated septic shock. No patients developed arrhythmia or electrocardiographic signs of myocardial ischemia. During dobutamine infusion, arterial lactate concentration decreased from 5.1 +/- 0.4 in the increased Pco(2) gap group and 4.2 +/- 0.4 in the normal Pco(2) gap group to 3.9 +/- 0.3 and 3.5 +/- 0.3 mmol/L, respectively (p < .01). The Pco(2) gap decreased and gastric intramucosal pH increased in the increased Pco(2) gap group from 12 +/- 0.8 (1.6 +/- 0.1 kPa) to 3.5 +/- 0.8 torr (0.5 +/- 0.1 kPa)(p < .01) and from 7.11 +/- 0.03 to 7.18 +/- 0.02 (p < .01), respectively, and did not change in the normal Pco, gap group. After stopping dobutamine infusion, the Pco(2) gap and intramucosal pH returned to baseline values in the increased Pco(2) gap group. Conclusion: The addition of 5 mu g/kg/min of dobutamine added to epinephrine in hyperdynamic septic shock selectively improved the adequacy of gastric mucosal perfusion without modification in systemic hemodynamics.