Orthostatic hypotension


Orthostatic hypotension
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 a 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

Signs and symptoms

Symptoms, which generally occur after sudden standing or stretching (after standing), include dizziness, euphoria or dysphoria, bodily dissociation, distortions in hearing, lightheadedness, nausea, headache, 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.

Causes

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.[citation needed]

Hypovolemia

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.

Diseases

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,[citation needed] 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]

Medication

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]

Harnesses

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.

Other risk factors

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 increasing evidence from a number of studies at Liverpool John Moores University that orthostatic tolerance is worse in the morning even when the effects of prior rest and sleep are controlled

Diagnosis

A simple test for OH 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.

Management

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.

Medical

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]

Lifestyle factors

  • Standing up more slowly can give the blood vessels more time to constrict properly. This can help avoid incidents of syncope (fainting).
  • Breathing deeply and flexing the abdominal muscles while rising helps maintain blood and oxygen flow to the brain. This may be contraindicated in individuals with Stage 2 hypertension. Usually medical personnel have their patients "dangle" before rising from bed to decrease the likelihood of dizziness/falling due to orthostatic hypotension. The dangling is done by having the patient sit on the side of their bed for about a minute so they do not have the sudden dizziness.
  • Maintaining an elevated salt intake, through sodium supplements or electrolyte-enriched drinks, can reduce incidence of orthostatic hypotension. A suggested value is 10g per day; overuse can lead to hypertension and should be avoided.
  • Maintaining proper fluid intake helps prevent the effects of dehydration, a potential causative factor.
  • Eating more, smaller meals can help, as digestion lowers blood pressure more when eating larger meals.
  • Taking extra care when standing after eating.
  • When orthostatic hypotension is caused by hypovolemia due to medications, the disorder may be reversed by adjusting the dosage or by discontinuing the medication.
  • When the condition is caused by prolonged bed rest, improvement may occur by sitting up with increasing frequency each day. In some cases, physical counter-pressure such as elastic hose (stockings) or whole-body inflatable suits may be required.
  • Many people who experience orthostatic hypotension are able to recognize the symptoms and quickly adopt a "squat position" to avoid falling during an episode. This is because they are usually unable to co-ordinate a return to sitting in a chair, once the episode has commenced.
  • Many also find it helpful to slightly clench muscles in the upper body (abdominals and diaphragm) in order to slow the flow of blood out of upper extremities. (A procedure similar to this is the Anti-G-Maneuver (AGM), used by some personnel in racing or performance aviation to avoid unconsciousness as blood leaves the head, due to similar forces of gravity)
  • Avoiding bodily positions that impede blood flow, such as sitting with knees up to chest or crossing legs, can help prevent incidents.

Prognosis

Orthostatic hypotension may cause accidental falls.[13]

See also

References

  1. ^ "Orthostatic hypotension" at Dorland's Medical Dictionary
  2. ^ Medow MS, Stewart JM, Sanyal S, Mumtaz A, Sica D, Frishman WH (2008). "Pathophysiology, diagnosis, and treatment of orthostatic hypotension and vasovagal syncope". Cardiol Rev 16 (1): 4–20. doi:10.1097/CRD.0b013e31815c8032. PMID 18091397. http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?an=00045415-200801000-00002. 
  3. ^ Shibao C, Grijalva CG, Raj SR, Biaggioni I, Griffin MR (2007). "Orthostatic hypotension-related hospitalizations in the United States". Am. J. Med. 120 (11): 975–80. doi:10.1016/j.amjmed.2007.05.009. PMID 17976425. http://linkinghub.elsevier.com/retrieve/pii/S0002-9343(07)00655-9. 
  4. ^ http://emedicine.medscape.com/article/1154266-overview
  5. ^ Lee C, Porter KM (Apr 2007). "Suspension trauma". Emerg Med J. 24 (4): 237–8. doi:10.1136/emj.2007.046391. PMC 2658225. PMID 17384373. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2658225. 
  6. ^ "Dopamine Beta-Hydroxylase Deficiency". GeneReviews — NCBI Bookshelf. http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=dbh#dbh. 
  7. ^ "Minute organs in the ear can alter brain blood flow". BBC News. 2009-12-27. http://news.bbc.co.uk/2/hi/health/8268336.stm. Retrieved 2009-12-27. 
  8. ^ Jiang W, Davidson JR. (2005). "Antidepressant therapy in patients with ischemic heart disease". Am Heart J 150 (5): 871–81. doi:10.1016/j.ahj.2005.01.041. PMID 16290952. 
  9. ^ Delini-Stula A, Baier D, Kohnen R, Laux G, Philipp M, Scholz HJ. (1999). "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. 
  10. ^ Jones RT. (2002). "Cardiovascular system effects of marijuana". J Clin Pharmacol 42 (11 Suppl): 58S–63S. PMID 12412837. 
  11. ^ Orthostatic Hypotension at Merck Manual of Diagnosis and Therapy Home Edition
  12. ^ Singer W, Opfer-Gehrking TL, McPhee BR, Hilz MJ, Bharucha AE, Low PA. (2003). "Acetylcholinesterase inhibition: a novel approach in the treatment of neurogenic orthostatic hypotension". J Neurol Nosurg Psychiatry 74 (9): 1294–8. doi:10.1136/jnnp.74.9.1294. PMC 1738643. PMID 12933939. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1738643. .
  13. ^ Romero-Ortuno R, Cogan L, Foran T, Kenny RA, Fan CW (2011). "Continuous noninvasive orthostatic blood pressure measurements and their relationship with orthostatic intolerance, falls, and frailty in older people". J Am Geriatr Soc 59 (4): 655–65. doi:10.1111/j.1532-5415.2011.03352.x. PMID 21438868. 

External links


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Look at other dictionaries:

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