الفهرس 
Principles of Cerebral MetabolismOnly 14 pages are availabe for public view
 |  | from | 150 |  |  |
| | | from | 150 | | |
Abstract
The Primary brain injury may be followed by secondary neuronal injury. These secondary insults may account for the poor predictive value of early clinical findings. The nature of secondary neuronal injury following severe head trauma has remained elusive. However, modern methods for monitoring various physical and biochemical parameters can detect potentially adverse episodes and also they are important in terms of prognosis. Aaslid introduced Transcranial Doppler ultrasonography (TCD) in 1982 as a non-invasive technique for monitoring blood flow velocity (FV) in the basal cerebral arteries. It is being used nowadays increasingly in anaesthesia and intensive care for clinical practice as well as in research. The aim of this study is to evaluate and compare changes in cerebral haemodynamic parameters under the effect of norepinephrine and dopamine using TCD in severely brain injured patients already requiring vasopressor support. There are few humans studies comparing the vasoactive agents on cerebral haemodynamics, catecholamines and vasoconstrictors have been used as first line for CPP augmentation for years. Norepinephrine increases the blood pressure without marked tachyarrythmia. This is due to the weak β-agonist chronotropic effect of norepinephrine is countered by vasoconstriction. In this study, we recruited fifty-two patients with severe brain injures with sustained episodes of arterial hypotension (twenty-five patients in group N and twenty-seven patients in group D) in the period between March 2014 to May 2016. There was no statistically significant difference in MAP between the group D and group N, this result was due to their α-adrenoreceptor agonist properties of the drugs. The present study approved statistically significant difference in HR between the two groups.HR was higher in group D than group N (p value < 0.001) due to potent β-chronotropic effect of dopamine and weak β-agonist chronotropic effect of norepinephrine. Finally, results of our study showed that patients who received norepinephrine were higher CPP than patients with dopamine without producing arrhythmias nor intracranial hypertension. So norepinephrine may be more efficient and safe in augmenting cerebral perfusion in patients with severe brain injuries.