Orthostatic hypotension

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Sogand Goudarzi, MD [2]

Synonyms and keywords: Postural hypotension; orthostatic intolerance; head rush; dizzy spell

Overview

Orthostatic hypotension is a physical finding demarcated by the American Academy of Neurology and the American Autonomic Society as a reduction in systolic blood pressure of 20 mm Hg or a drop of 10 mm Hg in diastolic blood pressure within three minutes of standing compared with blood pressure from the sitting or supine position. Orthostatic hypotension is frequently found in frail patients and those who are older.2 It is noticed in up to 20 percent of patients older than 65 years .

Classification

Initial orthostatic hypotension (iOH)

It is most common in healthy adolescents and is demarcated as a brief BP decrease of >40 mmHg systolic or >20 mmHg diastolic with symptomatic cerebral hypoperfusion within five to fifteen seconds after standing, typically resolves by twenty seconds.

Neurogenic orthostatic hypotension (nOH)

In Neurogenic orthostatic hypotension, the sympathetic noradrenergic nerves continually fail to facilitate the reflexive cardiovascular responses essential to sustain blood pressure in response to orthostatic stress. It is described as a constant BP decrease of >20 mmHg systolic or >10 mmHg diastolic, without or with symptoms, within three minutes of head-up tilt or standing.

Delayed orthostatic hypotension (dOH)

Delayed orthostatic hypotension (dOH) is demarcated as a fall in blood pressure that accomplishes neurogenic orthostatic hypotension criteria but ensues after three minutes.

Neurally mediated syncope (vOH)

It is also recognized as vasodepressor or vasovagal syncope, It involves a paroxysmal extraction of sympathetic vasopressor tone, frequently during prolonged standing, in patients with an effective autonomic nervous system.

Cardiovascular orthostatic hypotension (cOH)

Cardiovascular orthostatic hypotension occurs from intravascular hypovolemia or reduced cardiac output along with compensatory tachycardia.

Orthostatic pseudohypotension (pOH)

It is stated as apparent orthostatic hypotension when baseline supine blood pressure is raised, which may be due to a short time at rest to create a valid baseline, related recumbent hypertension, or fluctuation of baseline blood pressure with labile hypertension.

Pathophysiology

• In standing position, 300 to 800 mL of blood pools in the lower extremities. Preservation of blood pressure while changing the position requires many organs like cardiac, neurologic, vascular, muscular, and neurohumoral to respond rapidly.9 If any of these responses are irregular, organ perfusion and blood pressure can be reduced. Therefore, symptoms of central nervous system hypoperfusion may arise, including nausea, weakness, dizziness, headache, lightheadedness, fatigue, blurred vision, palpitations, tremulousness, vertigo, and impaired cognition.
• The autonomic nervous system plays a significant role in sustaining blood pressure when a person changes position. The sympathetic nervous system regulates the tone in the heart, arteries, and veins.
• Baroreceptors located mainly in the aorta and carotid arteries are very sensitive to fluctuations in blood pressure. As soon as the baroreceptors sense the minor decrease in blood pressure, a synchronized increase in sympathetic stimulation occurs. Arteries contract to increase blood pressure and peripheral resistance, and subsequently increases heart rate and contractility.
• All of these responses are designed to sustain perfusion and blood pressure. Additional physiologic mechanisms can also be involved including the renin-angiotensin-aldosterone system, low-pressure receptors in the heart and lungs, the systemic release of norepinephrine, and vasopressin.
• Over-all, all parts of the nervous systems and cardiovascular must work together. If there is insufficient intravascular volume, a decrease of venous return, impairment of the autonomic nervous system, or the heart's incapability to pump with the higher power, orthostatic hypotension may result.

Causes

Common Causes

Common causes of orthostatic hypotension may include:

• Medical conditions:
  • Pregnancy
  • Heart problems: Bradycardia, heart valve problems, heart attack and heart failure.
  • Dehydration: Fever, vomiting, severe diarrhea, overuse of diuretics and strenuous exercise can lead to dehydration.
  • Endocrine problems
  • Blood loss
  • Septicemia
  • Aanaphylaxis: reaction include foods, certain medications, insect venoms and latex.
  • Anemia: Lack of nutrients (vitamins B-12, folate)
• Medication:
  • Apomorphine hydrochloride
  • Bromocriptine
  • Cidofovir
  • Entacapone
  • Ethacrynic Acid
  • Fluphenazine
  • Hydrochlorothiazide
  • Iloperidone
  • Loxapine
  • Niacin
  • Pergolide
  • Perphenazine
  • Rasagiline
  • Risperidone
  • Ritonavir
  • Rotigotine
  • Thioridazine hydrochloride
  • Thiothixene,
  • Tiagabine
  • Vincristine sulfate liposome
  • Diuretics especially furosemide, Lisinopril and Hydrochlorothiazide
  • Beta Blockers,
  • Calcium channel blockers
  • ACE Inhibitors
  • Prazosin
  • Tamsulosin
  • Nitrates
  • Anti-psychotics Clozapine, zotepine, Olanzapine,
  • Neuroleptics
  • Sedative hypnotics
  • Anti-depressants,duloxetine,tricyclics
  • MAOIs
  • Pramipexole
  • Ropinirole.

Harnesses

The use of a safety harness can also contribute to orthostatic hypotension in the event of a fall. While a harness may safely rescue its user from a fall, the leg loops of a standard safety or climbing harness further restrict return blood flow from the legs to the heart, contributing to the decrease in blood pressure.

Risk Factors

Common risk factors in the development of orthostatic hypotension include:

• Age (y>65)
• Medications (alpha blockers)
• Disease: Parkinson's disease, diabetes
• Postpartum mothers
• Patients who have been on bedrest.

Natural History

• The symptoms of orthostatic hypotension usually develop in the first/ second/ third decade of life, and start with symptoms such as ___.
• The symptoms of (disease name) typically develop ___ years after exposure to ___.
• If left untreated, [#]% of patients with [disease name] may progress to develop [manifestation 1], [manifestation 2], and [manifestation 3].

Complications

Common complications of orthostatic hypotension include:

• Moderate low blood pressure:
  • Dizziness
  • Weakness
  • Fainting (increase risk of injury by falling down)
    
• Severely low blood pressure:
  • Heart damage (Heart failur)
  • Brian damage (Stroke)

Prognosis

• Prognosis is generally excellent/good/poor, and the 1/5/10-year mortality/survival rate of patients with [disease name] is approximately [--]%.
• Depending on the extent of the [tumor/disease progression] at the time of diagnosis, the prognosis may vary. However, the prognosis is generally regarded as poor/good/excellent.
• The presence of [characteristic of disease] is associated with a particularly [good/poor] prognosis among patients with [disease/malignancy].
• [Subtype of disease/malignancy] is associated with the most favorable prognosis.
• The prognosis varies with the [characteristic] of tumor; [subtype of disease/malignancy] have the most favorable prognosis.

Diagnosis

History and Symptoms

Symptoms, which generally occur after sudden standing, include dizziness, lightheadedness, headache, blurred or dimmed vision (possibly to the point of momentary blindness), and fainting. They are consequences of insufficient blood pressure and cerebral perfusion(blood supply).

---

Symptoms

• Symptoms of orthostatic hypotension may include the following:

• Generalized weakness,
• Fatigue
• Cognitive slowing
• Leg buckling
• Neck pain
• Localized headache (in the suboccipital, posterior cervical, and shoulder region)

Physical Examination

• Patients with orthostatic hypotension usually appear well, pallor and tiredness.
• Physical examination may be remarkable for:

• Fall in blood pressure, typically greater than 20/10 mm

Treatment

Medical Therapy

There are medications to treat hypotension. In addition, there are many lifestyle advices. Many of them, however, are specific for a certain cause of orthostatic hypotension.

Some drugs that are used in the treatment of orthostatic hypotension include fludrocortisone (Florinef), erythropoietin and midodrine. Pyridostigmine bromide (Mestinon) is now also used to treat orthostatic hypotension.

• Treatment of neurogenic orthostatic hypotension:
• Avoid triggers: large meals, hot bath, prolong standig

Lifestyle Advice

Some suggestions for minimizing the effects include:

• Checking blood pressure regularly with a home monitoring kit. Check when lying flat and when standing as well as when symptoms occur.
• Standing slowly rather than quickly, as the delay can give the blood vessels more time to constrict properly. This can help avoid incidents of syncope (fainting).
• Take a deep breath and flex your abdominal muscles while rising to maintain blood and oxygen in the brain. This, however, may be contraindicated in individuals with Stage 3 hypertension. 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.
• Maintaining an elevated salt intake, through sodium supplements or electrolyte-enriched drinks. A suggested value is 10 g per day; overuse can lead to hypertension and should be avoided.
• Maintaining a proper fluid intake to prevent the effects of dehydration.
• As eating lowers blood pressure, eat multiple smaller meals rather than fewer larger meals. Take extra care when standing after eating.
• When orthostatic hypotension is caused by hypovolemia due to medications, the disorder may be reversed by adjusting the dosage or by discontinuing the medication.
• When the condition is caused by prolonged bed rest, improvement may occur by sitting up with increasing frequency each day. In some cases, physical counterpressure such as elastic hose or whole-body inflatable suits may be required.

External Links

• John G. Bradley, M.D., and Kathy A. Davis, R.N. Orthostatic Hypotension American Family Physician
• DYNA Dysautonomia Youth Network of America, Inc.

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