Orthostatic Hypotension: : Causes, Classification, and Treatment (original) (raw)
Perhaps one of the most critical moments in the long process of human evolution was the adoption of upright posture. While greatly enhancing mobility, it placed a novel set of challenges on a blood pressure regulatory system that had developed to meet the needs of an animal in a dorsal position. Indeed, upright posture had the effect of placing the very organ that defines our humanity in a somewhat precarious position in regards to maintenance of cerebral perfusion and oxygenation. To maintain hemostasis, the body modified exising systems to accommodate both for the effects of gravity and activity mediated fluid shifts. While hormonal factors, such as the renin-angiotensinaldosterone system participate in the process, they do so over longer periods of time. Through the sympathetic efferent pathways, the autonomic nervous system plays the key part, being the primary source of both short-and medium-term responses to positional change. 1 Therefore, any disturbance in autonomic function that results in sympathetic failure can cause orthostatic (or positional) hypotension which, if sufficiently profound, can produce cerebral hypoperfusion, near syncope, and syncope. This review attempts to cover some of the causes of orthostatic hypotension, their clinical features, and management.
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