Dobutamine increases cerebral blood flow velocity and jugular bulb hemoglobin saturation in septic patients

Objective: To evaluate the effects of dobutamine on cerebral hemodynamics in septic patients with stable hemodynamic status. Design: Open-label, prospective study. Setting: Multidisciplinary department of intensive care in a university hospital. Patients: Fourteen mechanically ventilated septic patients with altered mental status and stable hemodynamic status. Interventions: Dobutamine infusion, in incremental doses of 2 mu g/kg/min every 10 mins, for less than or equal to 10 mu g/kg/min. Measurements and Main Results: Mean flow velocity in the right middle cerebral artery, as measured by transcranial Doppler, increased from 68 +/- 6 (SEM) cm/sec at baseline to 80 +/- 7 cm/sec (p < .001) with 10 mu g/kg/min of dobutamine, Cerebral arterial-venous oxygen content difference and cerebral oxygen extraction ratio concurrently decreased from 4.1 +/- 0.2 to 3.4 +/- 0.3 mL/dL (p <.05) and from 46 +/- 3% to 36 +/- 4% (p <.05), respectively, Dobutamine also increased cardiac index from 3.8 +/- 0.3 to 6.3 +/- 0.5 L/min/m(2) (p < .001) and systemic oxygen delivery (Do(2)) from 497 +/- 35 to 817 +/- 55 mL/min/m(2). Mean arterial pressure increased slightly from 77 +/- 3 mm Hg to a maximum value of 86 +/- 4 mm Hg (p <.05). Relative changes in mean flow velocity were better correlated with cardiac index (r(2) =.52, P <.001) than with arterial pressure (r(2) =.20; p < .001). Cerebral Do(2) (estimated by the product of mean flow velocity and arterial oxygen content) increased by 12% with dobutamine, whereas estimated cerebral oxygen consumption (Vo(2)) did not. Conclusion: These measurements of middle cerebral artery flow velocity and jugular bulb oximetry suggest that dobutamine increases cerebral blood flow but not cerebral Vo(2) in stable septic patients.