Orthostatic

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In medicine, orthostatic refers to the state of standing. It is most frequently used to describe the condition orthostatic hypotension (ICD-9 458.0), which means an unusually low blood pressure when the patient is standing up.

Usually medical personnel have their patients "dangle" before rising from bed to decrease the likelihood of dizziness/falling due to orthostatic hypotension. The dangling is done by having the patient sit on the side of their bed for about a minute so they do not have the sudden dizziness.

Dangling is done with patients who are prone to orthostatic hypotension, the elderly, postpartum mothers, and those who have been on bedrest. It is a beneficial practice when waking in the morning as you have been laying flat for many hours. It is an intervention for fall prevention.

Another name for orthostatic hypotension is "orthostatic intolerance." This is an inability of the cardiopulmonary system to maintain sufficient blood pressure and adequate cerebral perfusion (blood supply) against gravity in the standing position.

For example, if a person changes from a lying position to standing, he or she will lose about 700 ml of blood from the thorax. This in turn produces a decreased stroke volume, systolic (contracting) blood pressure and increased diastolic (resting) blood pressure. To compensate for this we get an increase in heart rate and slight peripheral vasoconstriction.

With orthostatic intolerance, a person also gets venous pooling, decreased muscle and vascular tone and decreased circulatory blood volume in response to standing.

Orthostatic hypotension is present in many patients with Parkinson's Disease resulting from sympathetic denervation of the heart or as a side effect of dopaminomimetic therapy. This rarely leads to syncope unless the patient has developed true autonomic failure or has an unrelated cardiac problem.

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