Orthostatic hypotension, also known as postural hypotension, 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. The decrease is typically greater than 20/10 mm Hg, and may be most pronounced after resting. The incidence increases with age.
Signs and symptoms
Symptoms, which generally occur after sudden standing or stretching (after standing), include dizziness, euphoria, 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.
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, if a person changes from a lying position to standing, he or she will lose 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. The overall effect is an insufficient blood perfusion in the upper part of the body.
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