Objective: To assess the effects of dobutamine at a rate of 5 micro 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/m2.
Interventions: After baseline measurements (H0), each patient received dobutamine at a rate of 5 micro 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 PCO2 gap (tonometer PCO2 - PaCO2). The increased PCO2 gap group was defined by a PCO2 gap >8 torr (>1.1 kPa) (n = 13), and the normal PCO2 gap group by a PCO2 gap <or=to8 torr (<or=to1.1 kPa) (n = 7).
Measurements and Main Results: Dobutamine at 5 micro 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 PCO2 gap group and 4.2 +/- 0.4 in the normal PCO2 gap group to 3.9 +/- 0.3 and 3.5 +/- 0.3 mmol/L, respectively (p < .01). The PCO sub 2 gap decreased and gastric intramucosal pH increased in the increased PCO2 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 PCO2 gap group. After stopping dobutamine infusion, the PCO2 gap and intramucosal pH returned to baseline values in the increased PCO2 gap group.
Conclusion: The addition of 5 micro 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. (Crit Care Med 1997; 25:1649-1654)