Orthostatic hypotension, also known as
postural hypotension, occurs when a person's blood pressure falls when suddenly
standing up from a lying or sitting position. It is defined as a fall in
systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of at
least 10 mm Hg when a person assumes a standing position. It occurs
predominantly by delayed constriction of the lower body blood vessels, which is
normally required to maintain an adequate blood pressure when changing position
to standing. As a result, blood pools in the blood vessels of the legs for a
longer period and less is returned to the heart, thereby leading to a reduced
cardiac output. Mild orthostatic hypotension is common and can occur briefly in
anyone, although it is prevalent in particular among the elderly and those with
known low blood pressure. Severe drops in blood pressure can lead to fainting,
with a possibility of injury.
There are numerous possible causes for
orthostatic hypotension, such as certain medications (e.g. alpha blockers),
autonomic neuropathy, decreased blood volume, and age-related blood vessel
stiffness.
Apart from
addressing the underlying cause, orthostatic hypotension may be treated with a
recommendation to increase salt and water intake (to increase the blood
volume), wearing compression stockings, and sometimes medication
(fludrocortisone, midodrine or others).
