Complementary and Alternative Healing University  現代中藥辭典

Postural Hypotension 體位性低血壓

Edited by: Joe Hing Kwok Chu

When a person changes his/her lying position 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:

1. idiopathic hypotension

2. secondary postural hypotension

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),  or chronic malnutrition. Secondary postural hypotension may also occur because of (or after cessation of) long-term use of  sedatives or medication for lowering blood pressure.. Dehydration also causes the blood pressure to drop.

There are 5 types of drugs that can cause postural hypotension:

1. Hypertension drugs such as guanethidine sulfate (Ismelin) and ganglionic blocking agents are the most common. Other include: hydralazine, dihydralazine, pargyline hydrochloridum (Eutonyl), nifedipine,  (Adalat; Procardia)  (calcium channel blocking agents) and methyldopa (Aldomet, Dopamet). These types of drugs lower the tension of blood vessels and lower blood pressure. Long-term usage may cause postural hypotension.

2. Sedatives like Chlorpromazine injected into the muscle or veins may cause postural hypotension because of their anti-adrenogenic and anti-epinephrine effects which cause the lowering of the tension of blood vessels thus lowering blood pressure. These types of sedatives also dilate the small veins and hamper the return flow of circulation to the heart.

3. Anti-epinephrine drugs like: Tolazoline, Benzazoline, Phentolamine are intended to affect  the α-adrenoceptors of norepinephrine that constrict the blood vessels.

4. Vaso-dilating drugs like: nitroglycerin (nitroglycerine, trinitroglycerin, or glyceryl trinitrate) are intended to relax the smooth muscles of the blood vessels.

5. Diuretics: loop diuretics such as furosemide, bumetanide, and ethacrynic acid

Treatment

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.﹕

1. bu zhong yi qi tang,

2. shi quan da bu tang, 　

3. sheng mai yin

4. jin gui shen qi wan (if feet are cold, with shenyangxu (kidney yang deficient) syndromes.

5. liu wei di huang wan (if feet not cold with shenyinxu (kidney yin deficient) )

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, potassium deficiency. They should not be used if patients do not 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 their salt intake.

Note:

Blood pressure drops when the body is dehydrated. Since the feeling of thirst becomes dull as a person ages, it is important to monitor the intake of water.