Standing Up and Passing Out or, 'Orthostatic Hypotension'

Orthostatic hypotension is a form of chronic and debilitating illness that is associated with common neurologic conditions such as Parkinson’s disease or diabetic neuropathy. The illness is commonly experienced by seniors, particularly seniors who are living in facilities or other institutions and are on multiple medications. Treatment of orthostatic hypotension can present challenges, most notably if the illness is neurogenic. While the condition has no cure, the symptoms vary among people who experience it, and the treatment for it is not specific – aggressive treatment may lead to a level of resolution.

Events Upon Standing Up

When a person stands up, their blood goes down from their chest to their, ‘distensible venous capacitance system,’ which is below their diaphragm. The shift in their blood produces a decrease in the amount of blood returning and ventricular filling, as well as their cardiac output and blood pressure. The drop in a person’s blood pressure upon standing up is gravity-induced and is detected by, ‘arterial baroreceptors,’ in their aortic arch and carotid sinus; something that triggers a compensatory reflex tachycardia and vasoconstriction which restores normotension in an upright position. The mechanism is a compensatory one and is referred to as a, ‘baroreflex;’ one that is mediated by both afferent and efferent autonomic peripheral nerves and is integrated into a person’s autonomic centers in their brainstem.

Orthostatic hypotension is the result of, ‘baroreflex,’ or autonomic failure, end-organ dysfunction, or volume depletion. If a person experiences an injury to any limb of their baroreflex it causes neurogenic orthostatic hypotension, yet with afferent lesions alone the hypotension is often modest, accompanied by a variety of fluctuations in the person’s blood pressure, to include severe hypertension. Medications may produce orthostatic hypotension through interference with a person’s autonomic pathways, or their target end-organs, or by affecting intravascular volume. Brain hypoperfusion as a result of orthostatic hypotension due to any cause may lead to a person experiencing symptoms of orthostatic intolerance, such as lightheadedness and falls, or if the hypotension is severe – to syncope.

Changes in Blood Pressure

The generally accepted definition of orthostatic hypotension involves a reduction of a person’s systolic blood pressure of at least 20 mm Hg, or a reduction of their diastolic blood pressure of at least 10 mm Hg within 3 minutes of standing. A, ‘transient,’ drop that happens when a person stands abruptly and resolves quickly suggests a benign condition such as dehydration instead of autonomic failure.

To test for orthostatic hypotension, a person might be placed on a tilt table in a heads-up position at an angle of at least 60 degrees in order to detect orthostatic changes in their blood pressure. In a doctor’s office, 1 minute of standing will most likely detect almost everyone who experiences orthostatic hypotension, although standing more than 2 minutes would assist with establishing the severity of the condition such as a further drop in a person’s blood pressure. Orthostatic hypotension that develops after 3 minutes of standing is not common and might represent a, ‘reflex presyncope,’ or a mild or early form of sympathetic adrenergic dysfunction.

Neurogenic and Non-Neurogenic Causes of Orthostatic Hypotension

Orthostatic hypotension may also be the result of either neurogenic or non-neurogenic causes, such as diabetic or autoimmune neuropathies, or central lesions like those associated with multiple system atrophy or Parkinson’s disease. Non-neurogenic causes include conditions such as cardiac impairments like aortic stenosis or myocardial infarction, as well as dehydration, adrenal insufficiency, vasodilation due to fever, or systemic mastocytosis.

There is a list of common medications that cause orthostatic hypotension. These medications include the following:

• Diuretics
• Antihypertensive drugs
• Calcium channel blockers
• Alpha-adrenoceptor blockers for prostatic hypertrophy

Levodopa, insulin, as well as tricyclic antidepressants may also cause vasodilation and orthostatic hypotension in some people. In a study performed by Poon and Braun involving senior veterans the medications lisinopril, hydroclorothiazide, furosemide, trazedone, and terazosin were found to cause orthostatic hypotension.

Prevalence and Symptoms of Orthostatic Hypotension

Orthostatic hypotension is highly prevalent in the senior population depending on the characteristics of the population being studied. For example; the age group, their use of certain medications, as well as any co-existing conditions are all known to be associated with orthostatic hypotension. The condition is more common among seniors in facilities and other institutionalized settings, approaching 68% of the population of seniors, compared to those who live in their own communities. The vast prevalence of this condition among seniors in institutions most likely reflects the disease process, to include cardiac and neurologic conditions, as well as medications that are associated with orthostatic hypotension.

The symptoms of orthostatic hypotension are related to cerebral hypoperfusion, as well as the resulting lack of cerebral oxygenation. The lack of cerebral oxygenation causes a number of symptoms which may include:

• Nausea
• Dizziness
• Headache
• Weakness
• Chest pain
• Palpitations
• Feeling faint
• Tremulousness
• Lightheadedness
• Difficulty thinking
• Coldness of extremities

Feeling lightheaded is a common symptom of orthostatic hypotension, although more subtle issues to include weakness, difficulty with thinking, as well as neck pain are also common symptoms among seniors who experience the condition. Unexplained or recurrent falls in seniors might be a manifestation of feeling faint due to orthostatic hypotension.

Pages in this Book:

• Orthostatic Hypotension, Part II

  "Orthostatic hypotension is a syndrome – its prognosis is dependent on its particular cause, its severity, as well as the distribution of its autonomic and non-autonomic involvement. In people who experience, ‘extrapyramidal,’ and cerebellar disorders such as multiple system atrophy or Parkinson’s disease, the earlier and more severe the involvement of the person’s autonomic nervous system, the more poor their prognosis is likely to be unfortunately."