ORTHOSTATIC HYPOTENSION

Timothy C. Hain, MD. Please read our disclaimer. Return to Index. Content last updated: 12/2002

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Orthostasis means upright posture, and hypotension means low blood pressure. Thus, orthostatic hypotension consists of symptoms of dizziness, faintness or lightheadedness which appear only on standing, and which are caused by low blood pressure. Only rarely is spinning vertigo caused by orthostasis.

Symptoms that often accompany orthostatic hypotension include chest pain, trouble holding the urine, impotence, and dry skin from loss of sweating.

What Causes Orthostatic Hypotension ?Blood pressure cuf

Blood pressure is maintained by a combination of several things. The heart is the central pump, and a weak or irregular heart can cause orthostasis. Conditions such as arrhythmia, heart failure, deconditioning, and pregnancy are examples where the heart may not be up to the task of providing an adequate blood pressure.

The heart pumps blood, and if there is too little blood volume (anemia, dehydration, dialysis), the pressure drops. The blood vessels in the body also can squeeze (constrict) to raise blood pressure, and if this action is paralyzed, blood pressure may fall. Numerous medications affect blood vessels including most of the medications used for blood pressure, and many of the medications used in psychiatry and for anginal heart pain. Heat, such as a hot shower or from a fever can also dilate blood vessels and cause orthostasis. The nervous system senses and responds to regulate blood pressure. If something is wrong in this control system, blood pressure may fluctuate.

Blood pressure is usually lowered (in persons with orthostasis) by upright posture, food, infection, hyperventilation, hot weather, and lifting of heavy objects. General anesthesia may be unusually dangerous due to blood pressure fluctuations (Bevan et al, 1979).

Vestibular disorders may interact with blood pressure and heart rate control. The vestibular system is one source of information about uprightness (the otoliths), there are some effects of vestibular stimulation on the heart (Radtke, 1992), and there are some patients who have a combination of autonomic and vestibular symptoms.

Neurological disorders can also be caused by orthostasis. This usually takes the form of a TIA precipitated by a blood pressure drop (Brozman et al, 2002).

Diagnosis of Orthostatic Hypotension

Syndromes with orthostatic dizziness or lightheadedness, not associated with low blood pressure include:

  1. Positional orthostatic tachycardia (POT) syndrome. Here, the pulse races on standing.
  2. Low CSF pressure syndrome
  3. Primary orthostatic tremor
  4. Positional vertigo (i.e. BPPV)

 

Syndromes with orthostatic hypotension that may be diagnosed include:

  1. Cardiogenic (heart related) orthostatic hypotension. In this instance the heart doesn't respond to demands for greater pumping and blood pressure drops.
  2. Low blood volume (e.g. anemia, dehydration, dialysis)
  3. Medication related (usually too high doses of blood pressure medications or medications for depression)
  4. Neurogenic orthostatic hypotension
    1. Sensory neuropathies (diabetes, alcohol, syphilis, Holmes-Adie syndrome, Carotid sinus obliteration by endarterectomy, Riley-Day syndrome)
    2. Central types:
      1. MSA - multiple system atrophy or Shy-Drager, Parkinsons
      2. Medullary strokes or injuries (rare)
      3. Wernickes (rare)
    3. Output types:
      1. Peripheral neuropathy, especially diabetes and amyloidosis
      2. Spinal cord lesions
      3. PAF - pure autonomic failure or idiopathic orthostatic hypotension
      4. Parkinson's disease (sympathetic denervation)
      5. Dopamine beta-hydroxylase deficiency (hereditary, very rare)
  5. Unknown type
    1. Orthostatic intolerance in chronic fatigue syndrome (this mainly seems to be a syndrome of adolescents)

The diagnosis of orthostatis is made by finding that the systolic/diastolic blood pressure drops at least 25/10 mm mercury on going from lying to standing. The pulse should be checked also. The lack of a pulse response increase when the blood pressure drops implies a neurological cause. An excessive pulse response is termed "POTS" or positional orthostatic tachycardia syndrome. Once an orthostatic syndrome is determined, additional tests are used to determine why the blood pressure isn't properly regulated.

TESTS for orthostatic hyptension

TEST RATIONALE
CBC (blood count) Check for anemia
EKG, other heart tests Check for weakness or irregularity of the heart
CT or MRI scan of head Exclude nervous system disorders such as multiple system atrophy (MSA)
Autonomic testing Localize lesion in nervous system
Plasma norepinephrine (supine and standing) Low levels indicate post-ganglionic level lesion(vasoconstrictors like midodrine will not work in this case)
Glucose tolerance test Diabetes
RPR or FTA Syphilis
Urine porphyrins Porphyria
Serum electrolytes Dehydration
Serum Creatinine and BUN Kidney failure
Rectal biopsy If amyloid is suspected

Not every test is needed in every situation. More tests may be recommended based on the results of the previous tests. Tilt table tests are not needed in orthostatic hypotension, but may be indicated in persons with fainting (syncope).

CASE EXAMPLE:

A 57 year old man presented complaining of lightheadness on standing and a pressure sensation in the back of his neck (on standing). Other medical problems included a low thyroid. Blood pressure was 90/65 standing vs 130/80 supine (on medication). This documents a significant orthostatic hypotension. A sweat test showed about 50% anhidrosis. Norepinephrine level was about 30 units lower supine than upright. He was diagnosed as having neurogenic orthostatic hypotension. Present treatment includes Proamatine (mitodrine) 10 mg TID, salt supplements, and erythropoetin.

TREATMENT

Note that neither drug nor non-drug treatment can do as good a job as a  well working body. All of the strategies outlined in the next section are intended to alleviate symptoms, but they are unlikely to cure orthostatic hypotension.

Non-Drug Treatment for Orthostatic Hypotension

    Generally it is best to start with non-pharmacological treatment, and proceed to drug treatment only when this fails.

  1. Use an automatic blood pressure cuff (about $30 at Walgreens or Radio Shack). Check blood pressure daily, preferably standing and lying flat, and record it. Also check blood pressure when you have symptoms.
  2. If possible, eliminate medications that lower blood pressure (usually blood-pressure or heart medications). Check with your doctor first, however, to be sure that this is safe.
  3. Take in extra amounts of salt - about 10 gm/day total. If you start to have trouble breathing or get excessive swelling at the ankles, you may have to use less than 10 gm.
  4. Wear Jobst stockings (tight custom made leotard like garment -- worn by both men and women).
  5. Sleep with head of bed elevated about 15-20 degrees (4-6 inches). This maneuver increases blood volume and, after a few days, is helpful.  It is also helpful in that it may reduce supine hypertension( sometimes blood pressure is too high lying flat, and too low standing up). Try to be up during the day, not lying in bed. Reconditioning may be helpful for persons who have been on bed rest for long periods of time.
  6. Eat frequent small meals (because eating lowers blood pressure). Avoid sudden standing after eating.
  7. Avoid straining at stool (because this may lower the blood pressure)
  8. Avoid hot showers or excessive heat. Use air conditioners.
  9. Get up gradually in the morning. Take 5 minutes to get up and use support. Perform isometric exercises before moving about.

DRUG TREATMENT for Orthostatic Hypotension

Certain medications may be helpful, usually as a combination. Most useful drugs are Florinef (fludrocortisone), erythropoetin and Midodrine.

OTHER TREATMENTS:

Atrial pacing can be considered when the heart rate is very low

3,4 Dl-threo-dihydroxyphenylserine (DOPS), an artificial amino-acid, may be helpful in certain situations (Freeman, 1996) including dopamine beta-hydroxylase deficiency and post-prandial hypotension from various etiologies.

REFERENCES:

Relevent Books (with links to Amazon.com)