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

To evaluate the effects of dobutamine on cerebral hemodynamics in septic patients with stable hemodynamic status.

Open-label, prospective study.

Multidisciplinary department of intensive care in a university hospital.

Fourteen mechanically ventilated septic patients with altered mental status and stable hemodynamic status.

Dobutamine infusion, in incremental doses of 2 micrograms/kg/min every 10 mins, for < or = 10 micrograms/kg/min.

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 micrograms/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/m2 (p < .001) and systemic oxygen delivery (DO2) from 497 +/- 35 to 817 +/- 55 mL/min/m2. 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 (r2 = .52, p < .001) than with arterial pressure (r2 = .20; p < .001). Cerebral DO2 (estimated by the product of mean flow velocity and arterial oxygen content) increased by 12% with dobutamine, whereas estimated cerebral oxygen consumption (VO2) did not.

These measurements of middle cerebral artery flow velocity and jugular bulb oximetry suggest that dobutamine increases cerebral blood flow but not cerebral VO2 in stable septic patients.