The effects of dobutamine on microcirculatory alterations in patients with septic shock are independent of its systemic effects*

OBJECTIVE: To evaluate the effects of dobutamine on microcirculatory blood flow alterations in patients with septic shock. DESIGN: Prospective, open-label study. SETTING: A 31-bed, medico-surgical intensive care unit of a university hospital. PATIENTS: Twenty-two patients with septic shock. INTERVENTIONS: Intravenous administration of dobutamine (5 mug/kg.min) for 2 hrs (n = 22) followed by the addition of 10 M acetylcholine (topically applied, n = 10). MEASUREMENTS AND MAIN RESULTS: Complete hemodynamic measurements were obtained before and after dobutamine administration. In addition, the sublingual microcirculation was investigated with an orthogonal polarization spectral imaging technique before and after dobutamine administration and after topical application of acetylcholine. Dobutamine significantly improved capillary perfusion (from 48 +/- 15 to 67 +/- 11%, p = .001), but with large individual variation, whereas capillary density remained stable. The addition of topical acetylcholine completely restored capillary perfusion (98 +/- 1%, p = .001) and capillary density. The changes in capillary perfusion during dobutamine administration were not related to changes in cardiac index (p = .45) or arterial pressure (p = .29). Interestingly, the decrease in lactate levels was proportional to the improvement in capillary perfusion (y = 0.07 - 0.02x, r = .46, p = .005) but not to changes in cardiac index (p = .55). CONCLUSIONS: The administration of 5 mug/kg.min dobutamine can improve but not restore capillary perfusion in patients with septic shock. These changes are independent of changes in systemic hemodynamic variables.