| Orthostatic hypotension | |
|---|---|
| Classification and external resources | |
| ICD-10 | I95.1 |
| ICD-9 | 458.0 |
| DiseasesDB | 10470 |
| eMedicine | ped/2860 |
| MeSH | D007024 |
Orthostatic hypotension, also known as postural hypotension,[1] orthostasis, and colloquially as head rush or dizzy spell, is a form of hypotension in which a person's blood pressure suddenly falls when the person stands up or stretches. The decrease is typically greater than 20/10 mm Hg,[2] and may be most pronounced after resting. The incidence increases with age.[3]
Contents |
Symptoms, which generally occur after sudden standing or stretching (after standing), include :
euphoria or dysphoria,
bodily dissociation,
distortions in hearing,
lightheadedness,
nausea,
blurred or dimmed vision (possibly to the point of momentary blindness),
generalized (or extremity) numbness/tingling and fainting,
coat hanger pain (pain centered in the neck and shoulders),
and in rare, extreme cases, vasovagal syncope (a specific type of fainting).
They are consequences of insufficient blood pressure and cerebral perfusion (blood supply). Occasionally, there may be a feeling of warmth in the head and shoulders for a few seconds after the dizziness subsides.
Orthostatic hypotension is primarily caused by gravity-induced blood pooling 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. It can also be noted that there is a decreased systolic blood pressure and a decreased diastolic blood pressure.[4] The overall effect is an insufficient blood perfusion in the upper part of the body.
Still, the blood pressure does not normally fall very much, because it immediately triggers a vasoconstriction (baroreceptor reflex), pressing the blood up into the body again. (Often this mechanism is exaggerated and that is why diastolic blood pressure is a bit higher when a person is standing up, compared to a person in horizontal position.) Therefore, a secondary factor that causes a greater than normal fall in blood pressure is often required. Such factors include hypovolemia, diseases, medications, or, very rarely, safety harnesses.[5]
Heat exhaustion can also be a cause of postural hypotension.
Orthostatic hypotension may be caused by hypovolemia (a decreased amount of blood in the body), resulting from bleeding, the excessive use of diuretics, vasodilators, or other types of drugs, dehydration, or prolonged bed rest. It also occurs in people with anemia.
The disorder may be associated with Addison's disease, atherosclerosis (build-up of fatty deposits in the arteries), diabetes, pheochromocytoma, and certain neurological disorders including multiple system atrophy and other forms of dysautonomia. It is also associated with Ehlers-Danlos Syndrome. 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 syncope unless the patient has developed true autonomic failure or has an unrelated cardiac problem.
Another disease is called dopamine beta hydroxylase deficiency, that is thought to be underdiagnosed also, that causes loss of sympathetic noradrenergic function and is characterized by a low or extremely low levels of norepinephrine but an excess of dopamine.[6]
It is a symptom that quadriplegics and paraplegics might experience due to multiple systems' inability to maintain a normal blood pressure and blood flow to the upper part of the body.
Recently, a common but underdiagnosed condition that is suspected to be closely related to orthostatic hypotension is spontaneous intracranial hypotension, which results from cerebrospinal fluid leakage. It affects women more than men and peaks at ages between 40 to 50.
A study by a Harvard Medical School team found that two sacs in the inner ear, the utricle and the saccule, affect brain blood flow; thus inner ear problems, which increase with old age, may be involved in orthostatic hypotension.[7]
Orthostatic hypotension can be a side effect of certain anti-depressants, such as tricyclics[8] or MAOIs.[9] Marijuana and delta9-tetrahydrocannabinol (THC) can on occasion produce marked orthostatic hypotension.[10] Orthostatic hypotension can also be a side effect of alpha1 adrenergic blocking agents. Alpha1 blockers inhibit vasoconstriction normally initiated by the baroreceptor reflex upon postural change and the subsequent drop in pressure.[11]
The use of a safety harness can also contribute to orthostatic hypotension in the event of a fall. While a harness may safely rescue its user from a fall, the leg loops of a standard safety or climbing harness further restrict return blood flow from the legs to the heart, contributing to the decrease in blood pressure.
Patients who are prone to orthostatic hypotension are the elderly, postpartum mothers, those who have been on bedrest and teenagers because of their large amounts of growth in a short period of time. People suffering from anorexia nervosa and bulimia nervosa often suffer from orthostatic hypotension and it is a common side effect of these mental illnesses. Consuming alcohol may also lead to orthostatic hypotension due to its dehydrating effects on the body.
There is a simple test for OH which measures the person's blood pressure while seated or reclining at rest, and again upon standing up. A sudden, significant fall in blood pressure (>20 mmHg) between 2 and 5 minutes after standing from the supine position indicates orthostatic hypotension. In addition, the heart rate should also be measured for both positions. A significant increase from supine to standing may indicate a compensatory effort by the heart to maintain cardiac output.
A tilt table test may also be performed.
There are medications to treat hypotension. In addition there are several lifestyle issues, which however are most often specific to a certain cause of orthostatic hypotension.
Some drugs that are used in the treatment of orthostatic hypotension include fludrocortisone (Florinef) and erythropoietin to aid in fluid retention, and vasoconstrictors like midodrine. Pyridostigmine bromide (Mestinon) is also now used to treat the condition.[12]
Orthostatic hypotension may cause accidental falls.[13]
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