Orthostatic hypotension

Last updated
Orthostatic hypotension
Other namesOrthostasis (elliptical jargon), postural hypotension, positional hypotension, neurogenic orthostatic hypotension
Specialty Cardiology, neurology
Symptoms Symptoms 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
Complications Cumulative brain damage, sudden death from falls
Diagnostic method In-office (lie 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
Prognosis Depends on frequency, severity, and underlying cause; neurogenic orthostatic hypotension is a chronic, debilitating, and often progressively fatal condition [1]

Orthostatic hypotension, also known as postural hypotension, [2] is a medical condition wherein a person's blood pressure drops when they are standing up (orthostasis) or sitting down. Primary orthostatic hypotension is also often referred to as neurogenic orthostatic hypotension. [3] The drop in blood pressure may be sudden (vasovagal orthostatic hypotension), within 3 minutes (classic orthostatic hypotension) or gradual (delayed orthostatic hypotension). [4] It is defined as a fall in systolic blood pressure of at least 20 mmHg or diastolic blood pressure of at least 10 mmHg after 3 minutes of standing. It occurs predominantly by delayed (or absent) constriction of the lower body blood vessels, which is normally required to maintain adequate blood pressure when changing the 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.

Contents

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. [5] Whether it is a causative factor in dementia is unclear. [6]

The numerous possible causes for orthostatic hypotension include 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.

Anatomy and physiology

To maintain sufficient blood pressure, the body has several compensatory mechanisms. Baroreceptors, a kind of mechanoreceptors, play a crucial role in conveying data about blood pressure in the autonomic nervous system. The data is conveyed to regulate the peripheral resistance and heart output, keeping blood pressure within an established normal limit. [7] There are two kinds of baroreceptors: high-pressure arterial baroreceptors and low-pressure volume receptors, both activated by the stretching of vessel walls. [7] Arterial baroreceptors are situated in the carotid sinuses and the aortic arch, while the low-pressure volume receptors, known as cardiopulmonary receptors, are in the atria, ventricles, and pulmonary vasculature. [7] Arterial baroreceptors detect changes in blood pressure and transmit this information to the brainstem, the nucleus of the solitary tract, which modulates the activity of the autonomic nervous system (ANS). [8] This results in decreased blood pressure, which leads to an increase in heart rate. [8] What's more, the venoarteriolar axon reflex, which results in the constriction of arterial flow to muscles, skin, and adipose tissue also helps stabilize blood pressure. [8]

Signs and symptoms

Orthostatic hypotension is characterized by symptoms that occur after standing (from lying or sitting), particularly when done rapidly. Many report lightheadedness (a feeling that one might be about to faint), sometimes severe, or even actual fainting with associated fall risk. [9] [10] [11] 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. [12] 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. [ citation needed ] Women who are pregnant are also susceptible to orthostatic hypotension. [13] [14] [15] [16]

Associated diseases

The disorder may be associated with Addison's disease, atherosclerosis (build-up of fatty deposits in the arteries), diabetes, pheochromocytoma, porphyria, [17] long COVID, [18] [19] 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 dementias 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.[ citation needed ]

Another disease, dopamine beta hydroxylase deficiency, also thought to be underdiagnosed, causes loss of sympathetic noradrenergic function and is characterized by low or extremely low levels of norepinephrine, but an excess of dopamine. [20]

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

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, [21] vitamin B12 deficiency, or recent bariatric surgery. [22]

Medication

Tetrahydrocannabinol Tetrahydrocannabinol.svg
Tetrahydrocannabinol

Orthostatic hypotension can be a side effect of certain antidepressants, such as tricyclics [23] or monoamine oxidase inhibitors (MAOIs). [24] Marijuana and tetrahydrocannabinol can on occasion produce marked orthostatic hypotension. [25] Alcohol can potentiate orthostatic hypotension to the point of syncope. [26] 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. [27] Other antihypertensive medications may also cause orthostatic hypotension, in addition to anticholinergics, dopaminergic drugs, opiates and psychoactive medications. [28]

Other factors

Patients prone to orthostatic hypotension are the elderly, post partum mothers, and those having been on bed rest. People with anorexia nervosa and bulimia nervosa often develop orthostatic hypotension as a common side effect. Consuming alcohol may also lead to orthostatic hypotension due to its dehydrating effects.[ citation needed ]

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. [29] The overall effect is insufficient blood perfusion in the upper part of the body.[ citation needed ]

Normally, a series of cardiac, vascular, neurologic, muscular, and neurohumoral responses occurs 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. [ citation needed ]

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. [30] Orthostatic hypotension is defined as a fall in systolic blood pressure of at least 20 mmHg or the diastolic blood pressure of at least 10 mmHg between the supine reading and the upright reading. Also, the heart rate should 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 at least a 30 bpm increase in heart rate occurs with little or no change in blood pressure. A tilt table test may also be performed. [31]

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 3 minutes of standing. [32] 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).[ citation needed ]

Subcategories

Orthostatic hypotension can be subcategorized into three groups – initial, classic, and delayed. [33] [34] [35]

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. [33] Blood pressure then spontaneously and rapidly returns to normal, so the period of hypotension and symptoms is short (<30 s). [33] Only continuous beat-to-beat BP measurement during an active standing-up maneuver can document this condition. [33]

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. [34]

Delayed orthostatic hypotension is frequently characterized by a sustained systolic blood pressure decrease of ≥20 mm Hg or a sustained diastolic blood pressure decrease ≥of 10 mm Hg beyond 3 minutes of standing or upright tilt table testing. [35]

Management

Lifestyle changes

Apart from treating underlying reversible causes (e.g., stopping or reducing certain medications, treating autoimmune causes), several measures can improve the symptoms of orthostatic hypotension and prevent episodes of syncope (fainting). Even small increases in the blood pressure may be sufficient to maintain blood flow to the brain on standing. [34]

In dysautonomic patients who do not have a diagnosis of high blood pressure, drinking 2–3 liters of fluid a day and taking 10 g of salt can improve symptoms, by maximizing the amount of fluid in the bloodstream. [34] 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. [34] Various measures can be used to improve the return of blood to the heart; the wearing of compression stockings and exercises ("physical counterpressure maneuvers" or PCMs) can be undertaken just before standing up (e.g., leg crossing and squatting), as muscular contraction helps return blood from the legs to the upper body. [34]

Medications

The medication midodrine, an α1-adrenergic receptor agonsit, can benefit people with orthostatic hypotension, [34] [36] The main side effect is piloerection ("goose bumps"). [36] Fludrocortisone is also used, although based on more limited evidence. [34]

Droxidopa, a norepinephrine prodrug and hence non-selective adrenergic receptor agonist, has been shown to be effective as well, [37] with few, mostly mild side effects reported. [38]

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. [39]

Ampreloxetine (TD-9855), a norepinephrine reuptake inhibitor, is in late-stage development for treatment of the condition. [40] [41]

Other

Robotic devices, such as the Erigo medical device, have been proven to help orthostatic hypotension in some patients. These machines adjust a patient's position from 0 degrees to 90 degrees in progressive increments, allowing the blood pressure to adjust more slowly. [42]

Prognosis

Orthostatic hypotension may cause accidental falls. [11] It is also linked to an increased risk of cardiovascular disease, heart failure, and stroke. [43] [28] Also, observational data suggest that orthostatic hypotension in middle age increases the risk of eventual dementia and reduced cognitive function. [44]

See also

Related Research Articles

<span class="mw-page-title-main">Blood pressure</span> Pressure exerted by circulating blood upon the walls of arteries

Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" refers to the pressure in a brachial artery, where it is most commonly measured. Blood pressure is usually expressed in terms of the systolic pressure over diastolic pressure in the cardiac cycle. It is measured in millimeters of mercury (mmHg) above the surrounding atmospheric pressure, or in kilopascals (kPa). The difference between the systolic and diastolic pressures is known as pulse pressure, while the average pressure during a cardiac cycle is known as mean arterial pressure.

Baroreceptors are sensors located in the carotid sinus and in the aortic arch. They sense the blood pressure and relay the information to the brain, so that a proper blood pressure can be maintained.

<span class="mw-page-title-main">Dysautonomia</span> Any disease or malfunction of the autonomic nervous system

Dysautonomia, autonomic failure, or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels. Dysautonomia has many causes, not all of which may be classified as neuropathic. A number of conditions can feature dysautonomia, such as Parkinson's disease, multiple system atrophy, dementia with Lewy bodies, Ehlers–Danlos syndromes, autoimmune autonomic ganglionopathy and autonomic neuropathy, HIV/AIDS, mitochondrial cytopathy, pure autonomic failure, autism, and postural orthostatic tachycardia syndrome.

<span class="mw-page-title-main">Hypotension</span> Abnormally low blood pressure

Hypotension, also known as low blood pressure, is a cardiovascular condition characterized by abnormally reduced blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood and is indicated by two numbers, the systolic blood pressure and the diastolic blood pressure, which are the maximum and minimum blood pressures within the cardiac cycle, respectively. A systolic blood pressure of less than 90 millimeters of mercury (mmHg) or diastolic of less than 60 mmHg is generally considered to be hypotension. Different numbers apply to children. However, in practice, blood pressure is considered too low only if noticeable symptoms are present.

<span class="mw-page-title-main">Pulse pressure</span> Difference between systolic and diastolic blood pressure

Pulse pressure is the difference between systolic and diastolic blood pressure. It is measured in millimeters of mercury (mmHg). It represents the force that the heart generates each time it contracts. Healthy pulse pressure is around 40 mmHg. A pulse pressure that is consistently 60 mmHg or greater is likely to be associated with disease, and a pulse pressure of 50 mmHg or more increases the risk of cardiovascular disease. Pulse pressure is considered low if it is less than 25% of the systolic. A very low pulse pressure can be a symptom of disorders such as congestive heart failure.

<span class="mw-page-title-main">Reflex syncope</span> Brief loss of consciousness due to a neurologically induced drop in blood pressure

Reflex syncope is a brief loss of consciousness due to a neurologically induced drop in blood pressure and/or a decrease in heart rate. Before an affected person passes out, there may be sweating, a decreased ability to see, or ringing in the ears. Occasionally, the person may twitch while unconscious. Complications of reflex syncope include injury due to a fall.

<span class="mw-page-title-main">Carotid sinus</span> Dilated area near internal carotid artery above bifurcation

In human anatomy, the carotid sinus is a dilated area at the base of the internal carotid artery just superior to the bifurcation of the internal carotid and external carotid at the level of the superior border of thyroid cartilage. The carotid sinus extends from the bifurcation to the "true" internal carotid artery. The carotid sinus is sensitive to pressure changes in the arterial blood at this level. It is the major baroreception site in humans and most mammals.

Orthostatic intolerance (OI) is the development of symptoms when standing upright that are relieved when reclining. There are many types of orthostatic intolerance. OI can be a subcategory of dysautonomia, a disorder of the autonomic nervous system occurring when an individual stands up. Some animal species with orthostatic hypotension have evolved to cope with orthostatic disturbances.

<span class="mw-page-title-main">Postural orthostatic tachycardia syndrome</span> Abnormally high heart rate after a postural change

Postural orthostatic tachycardia syndrome (POTS) is a condition characterized by an abnormally large increase in heart rate upon sitting up or standing. POTS is a disorder of the autonomic nervous system that can lead to a variety of symptoms, including lightheadedness, brain fog, blurred vision, weakness, fatigue, headaches, heart palpitations, exercise intolerance, nausea, diminished concentration, tremulousness (shaking), syncope (fainting), coldness or pain in the extremities, numbness or tingling in the extremities, chest pain, and shortness of breath. Other conditions associated with POTS include myalgic encephalomyelitis/chronic fatigue syndrome, migraine headaches, Ehlers–Danlos syndrome, asthma, autoimmune disease, vasovagal syncope, and mast cell activation syndrome. POTS symptoms may be treated with lifestyle changes such as increasing fluid, electrolyte, and salt intake, wearing compression stockings, gentle and slow postural changes, avoiding prolonged bedrest, medication, and physical therapy.

<span class="mw-page-title-main">Tilt table test</span> Medical procedure often used to diagnose dysautonomia or syncope

A tilt table test (TTT), occasionally called upright tilt testing (UTT), is a medical procedure often used to diagnose dysautonomia or syncope. Patients with symptoms of dizziness or lightheadedness, with or without a loss of consciousness (fainting), suspected to be associated with a drop in blood pressure or positional tachycardia are good candidates for this test.

<span class="mw-page-title-main">Hypertensive emergency</span> Very high blood pressure and signs of organ damage

A hypertensive emergency is very high blood pressure with potentially life-threatening symptoms and signs of acute damage to one or more organ systems. It is different from a hypertensive urgency by this additional evidence for impending irreversible hypertension-mediated organ damage (HMOD). Blood pressure is often above 200/120 mmHg, however there are no universally accepted cutoff values.

<span class="mw-page-title-main">Pure autonomic failure</span> Medical condition

Pure autonomic failure (PAF) is an uncommon, sporadic neurodegenerative condition marked by a steadily declining autonomic regulation. Bradbury and Eggleston originally described pure autonomic failure in 1925.

Autonomic dysreflexia (AD) is a potentially fatal medical emergency classically characterized by uncontrolled hypertension and cardiac arrhythmia. AD occurs most often in individuals with spinal cord injuries with lesions at or above the T6 spinal cord level, although it has been reported in patients with lesions as low as T10. Guillain–Barré syndrome may also cause autonomic dysreflexia.

<span class="mw-page-title-main">Droxidopa</span> Synthetic amino acid/norepinephrine prodrug

Droxidopa, also known as L-threo-dihydroxyphenylserine (L-DOPS) and sold under the brand names Northera and Dops among others, is sympathomimetic medication which is used in the treatment of hypotension and for other indications. It is taken by mouth.

The Bezold–Jarisch reflex involves a variety of cardiovascular and neurological processes which cause hypopnea, hypotension and bradycardia in response to noxious stimuli detected in the cardiac ventricles. The reflex is named after Albert von Bezold and Adolf Jarisch Junior. The significance of the discovery is that it was the first recognition of a chemical (non-mechanical) reflex.

<span class="mw-page-title-main">Syncope (medicine)</span> Transient loss of consciousness and postural tone

Syncope, commonly known as fainting or passing out, is a loss of consciousness and muscle strength characterized by a fast onset, short duration, and spontaneous recovery. It is caused by a decrease in blood flow to the brain, typically from low blood pressure. There are sometimes symptoms before the loss of consciousness such as lightheadedness, sweating, pale skin, blurred vision, nausea, vomiting, or feeling warm. Syncope may also be associated with a short episode of muscle twitching. Psychiatric causes can also be determined when a patient experiences fear, anxiety, or panic; particularly before a stressful event, usually medical in nature. When consciousness and muscle strength are not completely lost, it is called presyncope. It is recommended that presyncope be treated the same as syncope.

<span class="mw-page-title-main">Orthostatic headache</span> Medical condition

Orthostatic headache is a medical condition in which a person develops a headache while vertical and the headache is relieved when horizontal. Previously it was often misdiagnosed as different primary headache disorders such as migraine or tension headaches. Increasing awareness of the symptom and its causes has prevented delayed or missed diagnosis.

<span class="mw-page-title-main">Dopamine beta hydroxylase deficiency</span> Medical condition

Dopamine beta (β)-hydroxylase deficiency is a human medical condition involving inadequate dopamine beta-hydroxylase. It is characterized by increased amounts of serum dopamine and the absence of norepinephrine (NE) and epinephrine.

Orthostatic syncope refers to syncope resulting from a postural decrease in blood pressure, termed orthostatic hypotension.

<span class="mw-page-title-main">Orthostatic hypertension</span> Medical condition

Orthostatic hypertension is a medical condition consisting of a sudden and abrupt increase in blood pressure (BP) when a person stands up. Orthostatic hypertension is diagnosed by a rise in systolic BP of 20 mmHg or more when standing. Orthostatic diastolic hypertension is a condition in which the diastolic BP raises to 98 mmHg or over in response to standing, but this definition currently lacks clear medical consensus, so is subject to change. Orthostatic hypertension involving the systolic BP is known as systolic orthostatic hypertension.

References

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