Syncope and Postural Hypotension (Orthostatic Hypotension)
Edited by: Joe Hing Kwok Chu
Syncope is a brief loss of consciousness caused by a temporary deficiency of oxygen in the brain, also called swoon or blackout.
Causes of Syncope
II. Hemodynamic -- obstruction to blood flow
III .Neurally mediated
IV. Postural hypotension
usually caused by medication or dehydration.
Postural Hypotension 體位性低血壓
When a person changes his/her position from lying down to standing, and the systolic pressure drops 20 mm and diastolic pressure drops 10 mm, it is called postural (or orthostatic ) hypotension.
Postural hypotension can be classified into:
Per 1. idiopathic hypotension
Idiopathic hypotension is usually caused by disorders of the vegetative (or automatic) nervous system which cause the small arteries to be unable to constrict in time. Symptoms include low blood pressure, unstable standing, blurry eye sight, dizziness, lack of strength, incontinence, and in serious cases, syncope (sudden black-outs).
Per 2. secondary postural hypotension
Secondary postural hypotension usually occurs in diseases of the spine, acute or serious infections (like lobar pneumonia), endocrine disorder (like adreno-cortical hormone deficiency), heart failure, or chronic malnutrition. Secondary postural hypotension may also occur because of (or after cessation of) long-term use of medication to lower blood pressure or sedative medication. Dehydration also causes the blood pressure to drop.
There are 5 types of drugs that can cause postural hypotension:
Postural hypotension is an easily obtained measurement that may help to identify middle-aged persons at risk for stroke. 
If the symptoms are obvious, tight elastic stockings and waist bands can be used.
I. Traditional Chinese herb formulae commonly used in chronic postural hypotension according to TCM diagnostics.﹕
II. Western medicine: steroids like prednisone, fludrocortisone are commonly used, but they have undesirable long term side effects which include osteoporosis, ulcers, memory loss, seizures, yeast infection, weakened auto-immune system, atrophy of thymus and adrenal glands, sodium retention, and potassium deficiency. Steroids should only be used if patients show signs of adreno-cortical deficiency.
If the problem is caused by adrenocortical hormone deficiency, the body rejects sodium and retains potassium. This condition shows in patient with shenyangxu (kidney yang deficient) syndromes. Then, the patients should eat less of those foods that are high in potassium and may have to increase salt intake.
Blood pressure drops when the body is dehydrated. Because the feeling of thirst becomes dull as a person ages, it is important to monitor the intake of water.
Also see Vertigo.
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Last update: Sept 15, 2013; 11:18 a.m. LAH