[How about blood pressure in brain injury?].

One of the goals of the medical management of head injured patients is to get a cerebral perfusion pressure between 60 and 70 mmHg. To reach such a goal, catecholamines are used after fluid challenge. Systemic effects of catecholamines depend on their affinity for the receptors alpha and beta. The topical application of norepinephrine (alpha predominant) induced a vasoconstriction on large cerebral arteries only. Cerebral blood flow increased in the pericontusionnal area, suggesting a loss of autoregulation. The topical application of dopamine at low concentration relaxed large cerebral arteries. Dopamine increased cerebral blood flow in the pericontusional area but data suggest a possible raise in the volume of contusion. Four human comparative studies have been published. The first study, which was not randomized, showed an intracranial pressure increase associated with dopamine. Two randomized clinical trials, published by the same group, demonstrated a better predictability with norepinephrine. The fourth study did not find any difference regarding cerebral haemodynamics. In conclusion, the quality of data on the effects of catecholamines on cerebral haemodynamics of head injured patients do not make it possible to conclude about their use.