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

Abstract

Objective: To compare the cerebral effects of dopamine and norepinephrine after 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 vasopressor therapy. Group 1: patients receiving dopamine (n=9); group 2: patients receiving norepinephrine (n=10). Intervention: Vasopressor therapy was switched from dopamine to norepinephrine 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 (SjvO₂), transcranial Doppler mean velocity in the middle cerebral artery (Vm), and transoesophagal Doppler aortic output (AO) were evaluated under dopamine and norepinephrine. Means for each group were compared with the paired Student's t-test. For the same MAP, ICP was significantly 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). SjvO₂, Vm, and AO did not change significantly between treatments. The ICP variation between treatments was not correlated with the variation of any other measured parameter. The ICP variation between 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 than norepinephrine with no argument supporting an increase of cerebral blood flow.