Neurogenic Shock and Phenylephrine

Neurogenic shock occurs when loss of sympathetic tone from the brain or spinal cord causes the blood vessels to dilate. This in turn causes the vascular space to enlarge. If the patient doesn't loose a single drop of blood, this increase in the vascular space causes a hypovolemia that is relative to the newly enlarged vascular space. The initial treatment is the same as it is for all the other forms of shock. Fluids. Drug treatment for neurogenic shock is to increase the vascular tone of the blood vessels. This requires stimulation of the alpha adrenergic receptor. This is best done with the drug phenylephrine which is a pure alpha agonist. Other drugs that are sometimes used are dopamine or norepinephrine-- both of these drugs act on both alpha and beta-1 receptors.