Comparison of the cerebral effects of dopamine and norepinephrine in severely head-injured patients

Objective: To compare the cerebral effects of dopamine and norepinephrine a fter severe head injury. Design: Prospective, clinical study. Setting: Surgical intensive care unit in a university hospital. Patients: Nineteen patients with severe head-injuries already requiring vas opressor therapy. Group 1: patients receiving dopamine (n = 9); group 2: pa tients receiving norepinephrine (n = 10). Intervention: Vasopressor therapy was switched from dopamine to norepinephr ine in group 1 and from norepinephrine to dopamine in group 2, maintaining the same mean arterial pressure (MAP). Measurements and results: MAP, intracranial pressure (ICP), jugular venous oxygen saturation (SjvO(2)), transcranial Doppler mean velocity in the midd le cerebral artery (Vm), and transoesophagal Doppler aortic output (AO) wer e evaluated under dopamine and norepinephrine. Means for each group were co mpared with the paired Student's t-test. For the same MAP, ICP was signific antly higher with dopamine than norepinephrine in both groups (respectively , group 1: 26 +/- 11 vs 23 +/- 11 mmHg, P < 0.005; group 2: 39 +/- 13 vs 31 +/- 9 mmHg, P < 0.005). SjvO(2), Vm, and AO did not change significantly b etween treatments. The ICP variation between treatments was not correlated with the variation of any other measured parameter. The ICP variation betwe en treatments was significantly higher in group 2 than group 1, which could be explained by autoregulation mechanisms. Conclusions: For the same MAP, ICP was significantly higher with dopamine t han norepinephrine with no argument supporting an increase of cerebral bloo d flow.