Orthostatic hypotension

Orthostatic hypotension
Synonyms orthostasis, postural, positional hypotension
Pronunciation
  • /ˌɔːrθəˈstætɪkˌhaɪpəˈtɛnʃən/
Specialty Cardiology

Orthostatic hypotension, also known as postural hypotension,[1] occurs when a person's blood pressure falls when suddenly standing up from a lying or sitting position.[2] 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 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. Mild 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.

There are numerous possible causes for orthostatic hypotension, such as certain medications (e.g. alpha blockers), autonomic neuropathy, decreased blood volume, 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).

Signs and symptoms

Orthostatic hypotension is characterised 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. Generalized weakness or tiredness may also occur. Some also report difficulty concentrating, blurred vision, tremulousness, vertigo, anxiety, palpitations (awareness of the heartbeat), feeling sweaty or clammy, and sometimes nausea. A person may look pale.[3]

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.[4] It is not a disease, but a physical finding. It may or may not be associated with symptoms (or disease), but 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).

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.[5] 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.

Causes

Orthostatic hypotension may be caused by low blood volume, bleeding, the excessive use of diuretics, vasodilators, or other types of drugs, dehydration, or prolonged bed rest (immobility); as well as occurring in people with anemia.[6]

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 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 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.

Medication

Tetrahydrocannabinol

Orthostatic hypotension can be a side-effect of certain antidepressants, such as tricyclics[9] or monoamine oxidase inhibitors (MAOIs).[10] Marijuana and tetrahydrocannabinol can on occasion produce marked orthostatic hypotension.[11] Alcohol can also potentiate orthostatic hypotension to the point of syncope.[12] 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.[13]

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.

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.[14] Orthostatic hypotension is defined as a fall in systolic blood pressure of at least 20 mmHg and/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 or postural orthostatic tachycardia syndrome (POTS). A tilt table test may also be performed.

Management

Non-pharmacological management

Apart from treating underlying reversible causes (e.g., stopping or reducing certain medications), 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.[15]

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.[15] 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.[15] 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).[15]

Pharmacological management

The medication midodrine can benefit people with orthostatic hypotension,[15][16] The main side-effect is piloerection ("goose bumps").[16] Fludrocortisone is also used, although based on more limited evidence.[15]

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.[17]

Prognosis

Orthostatic hypotension may cause accidental falls.[18] It is also linked to an increased risk of cardiovascular disease, heart failure, and stroke.[19] There is also observational data suggesting that orthostatic hypotension in middle age increases the risk of eventual dementia and reduced cognitive function.[20]

See also

References

  1. ↑ "Orthostatic hypotension" at Dorland's Medical Dictionary
  2. ↑ "Orthostatic Hypotension Information Page | National Institute of Neurological Disorders and Stroke". www.ninds.nih.gov. Retrieved 2017-03-26.
  3. ↑ 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.
  4. ↑ https://www.aafp.org/afp/2003/1215/p2393.html
  5. ↑ Idiopathic Orthostatic Hypotension and other Autonomic Failure Syndromes at eMedicine
  6. ↑ "What Causes Hypotension? - NHLBI, NIH". www.nhlbi.nih.gov. Retrieved 27 March 2017.
  7. ↑ Sim, M; Hudon, R (1979). "Acute intermittent porphyria associated with postural hypotension". Canadian Medical Association Journal. 121 (7): 845–6. PMC 1704473. PMID 497968.
  8. ↑ "Dopamine Beta-Hydroxylase Deficiency". GeneReviews — NCBI Bookshelf.
  9. ↑ Jiang, Wei; Davidson, Jonathan R.T (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.
  10. ↑ Delini-Stula, A; Baier, D; Kohnen, R; Laux, G; Philipp, M; Scholz, H.-J (2007). "Undesirable Blood Pressure Changes Under Naturalistic Treatment with Moclobemide, a Reversible MAO-A Inhibitor - Results of the Drug Utilization Observation Studies". Pharmacopsychiatry. 32 (2): 61–7. doi:10.1055/s-2007-979193. PMID 10333164.
  11. ↑ Jones, Reese T (2002). "Cardiovascular System Effects of Marijuana". The Journal of Clinical Pharmacology. 42 (11 Suppl): 58S–63S. doi:10.1002/j.1552-4604.2002.tb06004.x. PMID 12412837.
  12. ↑ Narkiewicz, K; Cooley, R. L; Somers, V. K (2000). "Alcohol potentiates orthostatic hypotension : Implications for alcohol-related syncope". Circulation. 101 (4): 398–402. PMID 10653831.
  13. ↑ Orthostatic Hypotension at Merck Manual of Diagnosis and Therapy Home Edition
  14. ↑ "STEADI - Measuring Orthostatic Blood Pressure" (PDF). Centers for Disease Control and Prevention. Retrieved 20 December 2014.
  15. 1 2 3 4 5 6 Moya, A; Sutton, R; Ammirati, F; Blanc, J.-J; Brignole, M; Dahm, J. B; Deharo, J.-C; Gajek, J; Gjesdal, K; Krahn, A; Massin, M; Pepi, M; Pezawas, T; Granell, R. R; Sarasin, F; Ungar, A; Van Dijk, J. G; Walma, E. P; Wieling, W; Abe, H; Benditt, D. G; Decker, W. W; Grubb, B. P; Kaufmann, H; Morillo, C; Olshansky, B; Parry, S. W; Sheldon, R; Shen, W. K; et al. (2009). "Guidelines for the diagnosis and management of syncope (version 2009): The Task Force for the Diagnosis and Management of Syncope of the European Society of Cardiology (ESC)". European Heart Journal. 30 (21): 2631–71. doi:10.1093/eurheartj/ehp298. PMC 3295536. PMID 19713422.
  16. 1 2 Izcovich, A; Gonzalez Malla, C; Manzotti, M; Catalano, H. N; Guyatt, G (2014). "Midodrine for orthostatic hypotension and recurrent reflex syncope: A systematic review". Neurology. 83 (13): 1170–7. doi:10.1212/WNL.0000000000000815. PMID 25150287.
  17. ↑ Logan, Ian C; Witham, Miles D (2012). "Efficacy of treatments for orthostatic hypotension: A systematic review". Age and Ageing. 41 (5): 587–94. doi:10.1093/ageing/afs061. PMID 22591985.
  18. ↑ Romero-Ortuno, Roman; Cogan, Lisa; Foran, Tim; Kenny, Rose Anne; Fan, Chie Wei (2011). "Continuous Noninvasive Orthostatic Blood Pressure Measurements and Their Relationship with Orthostatic Intolerance, Falls, and Frailty in Older People" (PDF). Journal of the American Geriatrics Society. 59 (4): 655–65. doi:10.1111/j.1532-5415.2011.03352.x. PMID 21438868.
  19. ↑ Ricci, Fabrizio; Fedorowski, Artur; Radico, Francesco; Romanello, Mattia; Tatasciore, Alfonso; Di Nicola, Marta; Zimarino, Marco; De Caterina, Raffaele (2015). "Cardiovascular morbidity and mortality related to orthostatic hypotension: A meta-analysis of prospective observational studies". European Heart Journal. 36 (25): 1609–17. doi:10.1093/eurheartj/ehv093. PMID 25852216.
  20. ↑ Rawlings, Andreea; et al. (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.
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