Orthostatic Hypotension
Definition
A sustained fall in blood pressure that exceeds 20mmHg systolic or 10mmHg diastolic within 3 minutes of a stand test or upright tilt to >60 degrees.
True orthostatic hypotension is a sign of autonomic dysfunction and dysautonomia in adults and in children. It may also occur with reductions of blood or plasma volume, as an effect of medications
•Non-neurogenic
OH – are caused by Drugs, hypovolemia pheochromocytoma, Addison
Disease, and other ilnesses that critically reduce central blood volume
(e.g. severe gastroenteritis and dehydration)
•Neurogenic OH is identified with Autonomic
vasoconstrictor failure due to inadequate release of norepinephrine from
sympathetic vasomotor neurons.
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The figure (from Pharmacotherapy of autonomic failure. Shibao C.,
Okamoto L., Biaggioni I. Pharmacol Ther. 2011 Jun 8
Shows several well-known diseases causing neurogenic orthostatic hypotension.
Genetic (Dopamine beta-hydroxylase
deficiency) , autoimmune ganglionopathy occur and secondary
causes such as diabetes, and amyloidosis are the most common
causes of NOH.
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while blood pressure typically falls inexorably Hr does not usually increase in compensatory fashion. thus vagal-parasympathetic deficits are also usually present. |
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