Orthostatic Hypotension

The orthostatic hypotension is defined by a fall of the blood Pressure from 10 to 20 mm of mercury at the time of the passage in position upright and results in a feeling of Malaise after a rising brutal or a prolonged confinement.

This fall of the blood pressure results from a postural defect of adaptation of the blood pressure at the time of the passage in position upright, defect of adaptation which involves a cerebral Ischémie.

That can go from the simple faintness to the loss of conscience, of a few seconds to a few minutes. It should not be confused with hypoglycemic faintness due to a lack of sugar, with a Lipothymie (feeling of abrupt faintness and derobation of the legs), or a syncope (loss of conscience prolonged with cardiovascular disorders).

Physiopathology

The passage in position upright involves a redistribution from 500 to 1000 ml of blood of the upper part of the body towards the lower extremities.

Under normal conditions, a system of regulation (neuro-hormonal mechanisms and cardiovascular reflexes) makes it possible to prevent the sharp decline of blood Pressure which could result from the passage to the station upright. This system in particular will act on vascular resistances and the heart rate.

The subjects presenting a defect of this system of regulation will not be able to modulate vascular resistances at the time of the passage in station upright and thus will have an important venous blood pool.

A disproportionate reaction vagale will cause a Malaise, even a loss of consciousness per deceleration of the heart rate (Bradycardie) and a fall of the blood Pressure by Vasodilatation.

Symptoms

The subject can feel, after the rising, a feeling of weakness, Céphalée S (headaches), a visual blur, Vertige S, a disorder or a loss of balance of short duration, sometimes a Lipothymie, even more rarely, a Syncope.

It should be noted that the Symptôme S can occur sometimes a long time after the rising (because of a progressive venous filling, at the time of the peak of activity of a drug)

To confirm orthostatic hypotension

The search for an orthostatic hypotension is done in measuring the blood pressure and the Pouls under the following conditions:

  • at rest,
  • then, after a fast rising (immediately, to 1 then to 3 then at 5 minutes).

The diagnosis is positive if:

  • the systolic blood pressure falls of more than 20 mmHg in the 5 minutes following the rising (that there are or not clinical signs),
  • the diastolic blood pressure falls of more than 10 mmHg in the 5 minutes following the rising (that there are or not clinical signs).

NB: The search for an orthostatic hypotension according to this method can be negative but does not allow however to eliminate the diagnosis formally.

Other examinations

A electrocardiogram will be systematically carried out in the search of a disorder of the cardiac rhythm or conduction, repolarization.

It is possible to carry out a Tilt-Test or test of passive slope.

Causes

Hypotension associated with a reduction with the heart rate

  • Syncope vagale by hypertonicity vagale,

  • drugs.

Hypotension associated with an increased or normal heart rate

Deterioration of the autonomous Nervous system (asympathicotonic origin)

One then speaks about Dystonie neurovégétative or dysautonomy.

The causes are multiple:

Sympathicotonic origin

Assumption of responsibility

It always includes the treatment of the cause when that is possible.
Il exists symptomatic treatments, but which present little effectiveness.

There exist medicamentous treatments, reserved for the serious cases:

  • Fludrocortisone, a Corticoid,
  • the midodrine (mainly in the dysautonomies),
  • the Dihydroergotamine, a Derived from the rye pin,
  • anti-inflammatory drugs not stéroïdiens,
  • Beat-blocking S nonselective (Propranolol for example),
  • the bromide of pyridostigmine was also proposed.

Prevention

  • according to the cases, stop of a désodé mode,

  • progressive passage to the night station upright
  • surrelevation of the head of the bed,
  • regular physical-activity,
  • elastic application of the lower extremities (to be put before the rising) (low of application),
  • monitoring of the state of hydration,
  • regular revisions of the ordinance S (especially in the old adult).

References

  • (in) This article is partially resulting from a translation of the English article: " Orthostatic hypotension ".
  • Chobanian A.V. Volicer L. Tifft C.P. and Al Mineralocorticoid-induced hypertension in patients with orthostatic hypotension. NR Engl J Med 1979 ; 301: 68-73.
  • Low P.A. Opfer-Gehrking T.L. Prospective McPhee B.R. evaluation off clinical characteristics off orthostatic hypotension. Mayo Covering joint Proc 1995 ; 70: 617-22.
  • Ward C. Kenny R.A. Reproducibility off orthostatic hypotension in symptomatic elderly. Am J Med 1996 ; 100: 418.
  • Low P.A. Gilden J.L. Freeman R. and Al Efficacy off midodrine vs placebo in neurogenic orthostatic hypotension. With randomized, double-blind multicenter study. Midodrine Group Study. JAMA 1997 ; 277: 1046-51.
  • Smit A.A., Halliwill J.R. Low P.A. Wieling W. Pathophysiological basis off orthostatic hypotension in autonomic failure. J Physiol 1999 ; 519 (1): 1-10.
  • Singer W. Opfer-Gehrking T.L. McPhee B.R. Hilz M.J. Bharucha A.E. Low P.A. Acetylcholinesterase inhibition: Novell approach in the treatment off neurogenic orthostatic hypotension has. Newspaper off Neurology Neurosurgery and Psychiatry 2003 ; 74: 1294-1298.

See

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