Orthostatic hypotension , also known as postural hypotension , occurs when a person's blood pressure falls when suddenly standing from a lying or sitting position. This is defined as a drop in systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of at least 10 mmHg when a person takes a standing position. This occurs mainly by the delayed constriction of the lower body blood vessels, which are usually required to maintain adequate blood pressure when changing positions to standing. As a result, pools of blood in leg veins for longer and fewer times are restored to the heart, resulting in reduced cardiac output. Mild orthostatic hypotension is common and may occur briefly to anyone, although it is particularly prevalent among the elderly and those with known low blood pressure. A severe decrease in blood pressure can lead to fainting, with the possibility of injury.
There are many possible causes of orthostatic hypotension, such as certain drugs (eg alpha blockers), autonomic neuropathy, decreased blood volume, and age-related vascular stiffness.
In addition to addressing the underlying cause, orthostatic hypotension can be treated with recommendations to increase salt and water intake (to increase blood volume), wear compression stockings, and sometimes medications (fludrocortisone, midodrine or others).
Video Orthostatic hypotension
Signs and symptoms
Orthostatic hypotension is characterized by symptoms that occur after standing (from lying down or sitting), especially when this is done quickly. Many reported mild headaches (a feeling that someone might faint), sometimes heavy. Common weakness or fatigue can also occur. Some also report difficulty concentrating, blurred vision, trembling, vertigo, anxiety, palpitations (awareness of heartbeat), feeling sweaty or sweating, and sometimes nausea. Someone may look pale.
Maps Orthostatic hypotension
Cause
Orthostatic hypotension is primarily caused by blood clots induced by gravity in the lower extremities, which in turn harm the venous return, resulting in a decrease in cardiac output and lowered subsequent arterial pressure. For example, changing from a lying down position to standing loses about 700 ml of blood from the thorax, with a decrease in systolic and diastolic blood pressure. The overall effect is inadequate blood perfusion at the top of the body.
Even so, blood pressure usually does not drop very much, because it immediately triggers vasoconstriction (baroreceptor reflex), pressing the blood into the body again. (Often, this mechanism is exaggerated and why diastolic blood pressure is slightly higher when a person stands up, compared to someone in a horizontal position.) Therefore, a secondary factor that causes a greater than normal blood pressure drop is often required. These factors include low blood volume, illness, and medication.
Hypovolaemia
Orthostatic hypotension can be caused by low blood volume, hemorrhage, excessive use of diuretics, vasodilators, or other types of drugs, dehydration, or prolonged bed rest (immobility); and occurs in people with anemia.
Disease
This disorder may be associated with Addison's disease, atherosclerosis (accumulation of fat deposits in the arteries), diabetes, pheochromocytoma, porphyria, and certain neurological disorders, including multi-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. It rarely causes fainting unless the person has developed a genuine autonomic failure or has an unrelated heart problem.
Other diseases, dopamine beta hydroxylase deficiency, also considered undiagnosed, lead to loss of sympathetic noradrenergic function and characterized by low or very low levels of norepinephrine, but excess dopamine.
Quadriplegic and paraplegic may also experience these symptoms due to the inability of some systems to maintain normal blood pressure and blood flow to the upper body.
Medication
Orthostatic hypotension can be a side effect of certain antidepressants, such as tricyclics or monoamine oxidase inhibitors (MAOIs). Marijuana and tetrahydrocannabinol can sometimes produce marked orthostatic hypotension. Alcohol can also potentiate orthostatic hypotension to the syncope point. Orthostatic hypotension can also be a side effect of alpha-1 blockers (alpha 1 adrenergic blocking agents). Alpha 1 blockers inhibit vasoconstriction usually initiated by baroreceptor reflexes on postural changes and subsequent pressure drops.
Other factors
Patients susceptible to orthostatic hypotension are the elderly, postpartum mothers, and those who have slept in bed. People suffering from anorexia nervosa and bulimia nervosa often suffer from orthostatic hypotension as a common side effect. Consuming alcohol can also cause orthostatic hypotension because of the dehydration effect.
Diagnosis
Orthostatic hypotension can be confirmed by measuring one's blood pressure after lying flat for 5 minutes, then 1 minute after standing, and 3 minutes after standing. Orthostatic hypotension is defined as a decrease in systolic blood pressure of at least 20 mmHg and/or diastolic blood pressure of at least 10 mmHg between supine reading and vertical 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 compensatory efforts by the heart to maintain cardiac output or postural orthostatic tachycardia syndrome (POTS). A tilt table test can also be performed.
Management
Non-pharmacological management
In addition to treating the underlying reversible causes (eg, stopping or reducing certain drugs), there are a number of measures that can improve the symptoms of orthostatic hypotension and prevent syncope episodes. Even a small increase in blood pressure may be enough to maintain blood flow to the brain while standing.
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. Another strategy is to keep the head of the bed slightly higher. It reduces the return of fluid from the limb to the kidneys at night, thus reducing the production of urine at night and maintaining fluid in the circulation. Steps can be used to improve the return of blood to the heart: use of stockings and compression exercises ("physical counter-physical maneuvers" or PCM) that can be done just before standing (for example, foot crossings and squats).
Pharmacological management
Midodrine drugs can be beneficial for people with orthostatic hypotension, The main side effect is piloerection ("goose bumps"). Fludrocortisone is also used, although based on more limited evidence.
A number of other measures have little evidence to support the use of indomethacin, fluoxetine, dopamine antagonists, metoclopramide, domperidone, monoamine oxidase inhibitors with tyramine (can produce severe hypertension), oxylofrine, potassium chloride, and yohimbine.
Prognosis
Orthostatic hypotension can lead to accidental fall. It is also associated with an increased risk of cardiovascular disease, heart failure, and stroke. There is also observational data suggesting that orthostatic hypotension in middle age increases the risk of dementia and reduces cognitive function.
See also
- Orthostatic intolerance
- orthostatic hypertension
- Postural orthostatic tachycardia syndrome
- Vasovagal Response
References
External links
- Orthostatic Hypotension in Curlie (based on DMOZ)
Source of the article : Wikipedia
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