The autonomic nervous system and adrenergic receptors in pediatric practice.

The autonomic nervous system, with its normal balance between sympathetic and parasympathetic effects, is responsible for control of the body's involuntary functions. The importance of this balance is shown by the severe physiologic derangements seen after cervical spine injury, when the absolute loss of sympathetic function leads to unopposed action of the parasympathetic system that causes bradycardia, vasodilation, and hypotension that can be life-threatening. The sympathetic nervous system controls a multiplicity of functions and can be manipulated pharmacologically to the pediatric patient's advantage in some disease states. A basic understanding of the actions of the available sympathetic receptor agonists and antagonists can simplify and clarify many of these therapeutic options and improve the care of these children.