Orthostatic hypotension

Orthostatic hypotension, also known as postural hypotension,[2] is a medical condition wherein a person's blood pressure drops when standing up or sitting down. The drop in blood pressure may be sudden (vasovagal orthostatic hypotension), within 3 minutes (classic orthostatic hypotension) or gradual (delayed orthostatic hypotension).[3] It is defined as a fall in systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of at least 10 mm Hg when a person assumes a standing position. It occurs predominantly by delayed (or absent) constriction of the lower body blood vessels, which is normally required to maintain an adequate blood pressure when changing position to standing. As a result, blood pools in the blood vessels of the legs for a longer period and less is returned to the heart, thereby leading to a reduced cardiac output and inadequate blood flow to the brain.

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Orthostatic hypotension
Other namesOrthostasis, postural, positional hypotension
SpecialtyCardiology, Neurology
Symptomssymptoms that are worse when sitting or standing and improve when lying down, including lightheadedness, vertigo, tinnitus, slurred speech, confusion, coathanger pain in neck and shoulders, grayed or blurred vision, severe fatigue, fainting or near fainting
Complicationscumulative brain damage, sudden death from falls
Diagnostic methodin-office (lay down for at least 20 minutes, take BP; stand for 3 minutes, take BP), or tilt-table testing by an autonomic specialist
Treatmentidentify and treat causes (medications, dehydration), midodrine, compression garments, bed tilting
Prognosisdepends on frequency, severity, and underlying cause; neurogenic orthostatic hypotension is a chronic, debilitating, and often progressively fatal condition[1]

Very mild occasional orthostatic hypotension is common and can occur briefly in anyone, although it is prevalent in particular among the elderly and those with known low blood pressure. Severe drops in blood pressure can lead to fainting, with a possibility of injury. Moderate drops in blood pressure can cause confusion/inattention, delirium, and episodes of ataxia. Chronic orthostatic hypotension is associated with cerebral hypoperfusion that may accelerate the pathophysiology of dementia.[4] Whether it is a causative factor in dementia is unclear. [5]

There are numerous possible causes for orthostatic hypotension, such as certain medications (e.g. alpha blockers), autonomic neuropathy, decreased blood volume, multiple system atrophy, and age-related blood vessel stiffness.

Apart from addressing the underlying cause, orthostatic hypotension may be treated with a recommendation to increase salt and water intake (to increase the blood volume), wearing compression stockings, and sometimes medication (fludrocortisone, midodrine or others). Salt loading (dramatic increases in salt intake) must be supervised by a doctor, as this can cause severe neurological problems if done too aggressively.

Signs and symptoms

Orthostatic hypotension is characterized by symptoms that occur after standing (from lying or sitting), particularly when this is done rapidly. Many report lightheadedness (a feeling that one might be about to faint), sometimes severe. With chronic orthostatic hypotension, the condition and its effects may worsen even as fainting and many other symptoms become less frequent. Generalized weakness or tiredness may also occur. Some also report difficulty concentrating, blurred vision, tremulousness, vertigo, anxiety, palpitations (awareness of the heartbeat), unsteadiness, feeling sweaty or clammy, and sometimes nausea. A person may look pale.[6] Some people may experience severe orthostatic hypotension with the only symptoms being confusion or extreme fatigue. Chronic severe orthostatic hypotension may present as fluctuating cognition/delirium.

Associated diseases

The disorder may be associated with Addison's disease, atherosclerosis (build-up of fatty deposits in the arteries), diabetes, pheochromocytoma, porphyria,[7] and certain neurological disorders, including autoimmune autonomic ganglionopathy, multiple system atrophy and other forms of dysautonomia. It is also associated with Ehlers–Danlos syndrome and anorexia nervosa. It is also present in many patients with Parkinson's disease or Lewy body dementia resulting from sympathetic denervation of the heart or as a side-effect of dopaminomimetic therapy. This rarely leads to fainting unless the person has developed true autonomic failure or has an unrelated heart problem.

Another disease, dopamine beta hydroxylase deficiency, also thought to be underdiagnosed, causes loss of sympathetic noradrenergic function and is characterized by a low or extremely low levels of norepinephrine, but an excess of dopamine.[8]

Quadriplegics and paraplegics also might experience these symptoms due to multiple systems' inability to maintain a normal blood pressure and blood flow to the upper part of the body.

Causes

Some causes of orthostatic hypotension include: neurodegenerative disorders, low blood volume (e.g. caused by dehydration, bleeding, or the use of diuretics), drugs that cause vasodilation, other types of drugs (notably, narcotics and marijuana, discontinuation of vasoconstrictors, prolonged bed rest (immobility), significant recent weight loss, anemia,[9] or recent bariatric surgery.[10]

Medication
Tetrahydrocannabinol

Orthostatic hypotension can be a side-effect of certain antidepressants, such as tricyclics[11] or monoamine oxidase inhibitors (MAOIs).[12] Marijuana and tetrahydrocannabinol can on occasion produce marked orthostatic hypotension.[13] Alcohol can potentiate orthostatic hypotension to the point of syncope.[14] Orthostatic hypotension can also be a side effect of alpha-1 blockers (alpha1 adrenergic blocking agents). Alpha1 blockers inhibit vasoconstriction normally initiated by the baroreceptor reflex upon postural change and the subsequent drop in pressure.[15]

Other factors

Patients prone to orthostatic hypotension are the elderly, post partum mothers, and those having been on bedrest. People suffering from anorexia nervosa and bulimia nervosa often suffer from orthostatic hypotension as a common side-effect. Consuming alcohol may also lead to orthostatic hypotension due to its dehydrating effects.

Mechanism

Orthostatic hypotension happens when gravity causes blood to pool in the lower extremities, which in turn compromises venous return, resulting in decreased cardiac output and subsequent lowering of arterial pressure. For example, changing from a lying position to standing loses about 700 ml of blood from the thorax, with a decrease in systolic and diastolic blood pressures.[16] The overall effect is an insufficient blood perfusion in the upper part of the body.

Normally, a series of cardiac, vascular, neurologic, muscular, and neurohumoral responses occur quickly so the blood pressure does not fall very much. One response is a vasoconstriction (baroreceptor reflex), pressing the blood up into the body again. (Often, this mechanism is exaggerated and is why diastolic blood pressure is a bit higher when a person is standing up, compared to a person in the horizontal position.) Therefore, some factor that inhibits one of these responses and causes a greater than normal fall in blood pressure is required. Such factors include low blood volume, diseases, and medications.

Diagnosis

Orthostatic hypotension can be confirmed by measuring a person's blood pressure after lying flat for 5 minutes, then 1 minute after standing, and 3 minutes after standing.[17] Orthostatic hypotension is defined as a fall in systolic blood pressure of at least 20 mmHg or in the diastolic blood pressure of at least 10 mmHg between the supine reading and the upright reading. In addition, the heart rate should also be measured for both positions. A significant increase in heart rate from supine to standing may indicate a compensatory effort by the heart to maintain cardiac output. A related syndrome, postural orthostatic tachycardia syndrome (POTS), is diagnosed when there is at least a 30 bpm increase in heart rate with little or no change on blood pressure. A tilt table test may also be performed.[18]

Definition

Orthostatic hypotension (or postural hypotension) is a drop in blood pressure upon standing. One definition (AAFP) calls for a systolic blood pressure decrease of at least 20 mm Hg or a diastolic blood pressure decrease of at least 10 mm Hg within three minutes of standing.[19] A common first symptom is lightheadedness upon standing, possibly followed by more severe symptoms: narrowing or loss of vision, dizziness, weakness, and even syncope (fainting).

Subcategories

Orthostatic hypotension can be subcategorized into three groups: initial, 'classic', and delayed.[20][21][22]

Initial orthostatic hypotension is frequently characterized by a systolic blood pressure decrease of ≥40 mmHg or diastolic blood pressure decrease of ≥20 mmHg within 15 seconds of standing.[20] Blood pressure then spontaneously and rapidly returns to normal, so the period of hypotension and symptoms is short (<30 s).[20] Only continuous beat-to-beat BP measurement during an active standing-up maneuver can document this condition.[20]

'Classic' orthostatic hypotension is frequently characterized by a systolic blood pressure decrease of ≥20 mmHg or diastolic blood pressure decrease of ≥10 mmHg between 30 seconds and 3 min of standing.[21]

Delayed orthostatic hypotension is frequently characterized a sustained systolic blood pressure decrease of ≥20 mm Hg or a sustained diastolic blood pressure decrease ≥10 mm Hg beyond 3 minutes of standing or upright tilt table testing.[22]

Management

Lifestyle changes

Apart from treating underlying reversible causes (e.g., stopping or reducing certain medications, treating autoimmune causes), there are a number of measures that can improve the symptoms of orthostatic hypotension and prevent episodes of syncope. Even small increases in the blood pressure may be sufficient to maintain blood flow to the brain on standing.[21]

In people who do not have a diagnosis of high blood pressure, drinking 2–3 liters of fluid a day and taking 10 grams of salt can improve symptoms, by maximizing the amount of fluid in the bloodstream.[21] Another strategy is keeping the head of the bed slightly elevated. This reduces the return of fluid from the limbs to the kidneys at night, thereby reducing nighttime urine production and maintaining fluid in the circulation.[21] Various measures can be used to improve the return of blood to the heart: the wearing of compression stockings and exercises ("physical counterpressure manoeuvres" or PCMs) that can be undertaken just before standing up (e.g., leg crossing and squatting).[21]

Medications

The medication midodrine can benefit people with orthostatic hypotension,[21][23] The main side-effect is piloerection ("goose bumps").[23] Fludrocortisone is also used, although based on more limited evidence.[21]

A number of other measures have slight evidence to support their use indomethacin, fluoxetine, dopamine antagonists, metoclopramide, domperidone, monoamine oxidase inhibitors with tyramine (can produce severe hypertension), oxilofrine, potassium chloride, and yohimbine.[24]

Prognosis

Orthostatic hypotension may cause accidental falls.[25] It is also linked to an increased risk of cardiovascular disease, heart failure, and stroke.[26] There is also observational data suggesting that orthostatic hypotension in middle age increases the risk of eventual dementia and reduced cognitive function.[27]

See also

References
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  2. "Orthostatic hypotension" at Dorland's Medical Dictionary
  3. "Orthostatic Hypotension Information Page | National Institute of Neurological Disorders and Stroke". www.ninds.nih.gov. Retrieved 2017-03-26.
  4. Hase Y, Polvikoski TM, Firbank MJ, Craggs LJ, Hawthorne E, Platten C, Stevenson W, Deramecourt V, Ballard C, Kenny RA, Perry RH, Ince P, Carare RO, Allan LM, Horsburgh K, Kalaria RN (January 2020). "Small vessel disease pathological changes in neurodegenerative and vascular dementias concomitant with autonomic dysfunction". Brain Pathology. 30 (1): 191–202. doi:10.1007/s10072-014-1686-8. PMID 31357238.
  5. Sambati L, Calandra-Buonaura G, Poda R, Guaraldi P, Cortelli P (June 2014). "Orthostatic hypotension and cognitive impairment: a dangerous association?". Neurol. Sci. 35 (6): 951–7. doi:10.1007/s10072-014-1686-8. PMID 24590841.
  6. Kasper DL, Fauci AS, Hauser SL, Longo DL, James JL, Loscalzo J (2015). Harrison's principles of internal medicine. 2 (19th ed.). New York: McGraw-Hill Medical Publishing Division. p. 2639. ISBN 978-0-07-180215-4.
  7. Sim M, Hudon R (October 1979). "Acute intermittent porphyria associated with postural hypotension". Canadian Medical Association Journal. 121 (7): 845–6. PMC 1704473. PMID 497968.
  8. Robertson D, Garland EM (September 2003). "Dopamine Beta-Hydroxylase Deficiency". In Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJ, Stephens K, Amemiya A (eds.). GeneReviews. University of Washington, Seattle. PMID 20301647 – via NCBI Bookshelf.
  9. "What Causes Hypotension? -". National Heart, Lung, and Blood Institute (NHLBI). U.S. National Institutes of Health. Retrieved 27 March 2017.
  10. Christou GA, Kiortsis DN (March 2017). "The effects of body weight status on orthostatic intolerance and predisposition to noncardiac syncope". Obesity Reviews. 18 (3): 370–379. doi:10.1111/obr.12501. PMID 28112481.
  11. Jiang W, Davidson JR (November 2005). "Antidepressant therapy in patients with ischemic heart disease". American Heart Journal. 150 (5): 871–81. doi:10.1016/j.ahj.2005.01.041. PMID 16290952.
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  17. "Measurement of lying and standing blood pressure: A brief guide for clinical staff". RCP London. 2017-01-13. Retrieved 2019-09-23.
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  19. Bradley JG, Davis KA (December 2003). "Orthostatic hypotension". American Family Physician. 68 (12): 2393–8. PMID 14705758.
  20. Wieling W, Krediet CT, van Dijk N, Linzer M, Tschakovsky ME (February 2007). "Initial orthostatic hypotension: review of a forgotten condition". Clinical Science. 112 (3): 157–65. doi:10.1042/CS20060091. PMID 17199559.
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  27. Rawlings A, Juraschek S, Heiss G, Hughes T, Meyer M, Selvin E, Sharrett AR, Windham BG, Gottesman R (March 2017). Orthostatic Hypotension is Associated With 20-year Cognitive Decline and Incident Dementia: the Atherosclerosis Risk in Communities (ARIC) Study (PDF). Epidemiology and Prevention / Lifestyle and Cardiometabolic Health 2017 Scientific Sessions. Portland, Oregon. Archived from the original (PDF) on 2017-03-15. Retrieved 2017-03-14.
Classification
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