DOBUTAMINE INCREASES CEREBRAL BLOOD-FLOW VELOCITY AND JUGULAR BULB HEMOGLOBIN SATURATION IN SEPTIC PATIENTS

Objective: To evaluate the effects of dobutamine on cerebral hemodynam ics in septic patients with stable hemodynamic status. Design: Open-la bel, prospective study. Setting: Multidisciplinary department of inten sive care in a university hospital. Patients: Fourteen mechanically ve ntilated septic patients with altered mental status and stable hemodyn amic 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/m in. Measurements and Main Results: Mean flow velocity in the right mid dle cerebral artery, as measured by transcranial Doppler, increased fr om 68 +/- 6 (SEM) cm/sec at baseline to 80 +/- 7 cm/sec (p < .001) wit h 10 mu g/kg/min of dobutamine, Cerebral arterial-venous oxygen conten t difference and cerebral oxygen extraction ratio concurrently decreas ed from 4.1 +/- 0.2 to 3.4 +/- 0.3 mL/dL (p <.05) and from 46 +/- 3% t o 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 system ic 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 max imum value of 86 +/- 4 mm Hg (p <.05). Relative changes in mean flow v elocity were better correlated with cardiac index (r(2) =.52, P <.001) than with arterial pressure (r(2) =.20; p < .001). Cerebral Do(2) (es timated by the product of mean flow velocity and arterial oxygen conte nt) increased by 12% with dobutamine, whereas estimated cerebral oxyge n consumption (Vo(2)) did not. Conclusion: These measurements of middl e cerebral artery flow velocity and jugular bulb oximetry suggest that dobutamine increases cerebral blood flow but not cerebral Vo(2) in st able septic patients.